جستجوی مقالات مرتبط با کلیدواژه « سرعت رشد نسبی » در نشریات گروه « زراعت »

The production of oilseeds, edible leaves, and secondary metabolites of dragon's head makes it an important food, forage, and medicinal plant. Choosing a proper planting date and plant nutrition can make a significant effecton crop plantsgrowth, quality and yield.The effects of planting date (16 March, 14 April, and 13 May 2019) and foliar application of zinc sulfate (zero as control, 2 and 4 g.L-1) on growth indices and seed yield of dragon's head was evaluated under a field experiment.Delayed planting date reduced the days to flowering, days to seed ripening, plant height, leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR) and grain yield, and yield components.In contrast, the use of zinc sulfate increased plant height, LAI, CGR and RGR. There was a correlation between plant height and number of branches and consequently there were more capsules per plant.The highest effect of zinc sulfate application on seed yield and yield components was observed in the first planting date and with delay in planting, the efficiency of zinc sulfate fertilizer application decreased. On the third planting date, zinc sulfate application had no significant effect on grain yield. As a result of late planting, fewer branches, fewer capsules per plant, and smaller seeds contributed to the yield reduction.It was found that early cultivation and application of zinc sulfate increased plant height, number of branches, number of capsules per plant, 1000-seed weight, and thus seed yield, by increasing the days to flowering, days to ripening, LAI, CGR, and RGR.

The availability of organic matter in deficit irrigation conditions can be a practical solution to compensate the negative effects of drought stress. In order to investigate the effect of deficit irrigation and chemical fertilizers on yield and some physiological traits of quinoa an experiment was conducted in 2019 as split plot based on a randomized complete block design in two locations (Mashhad and Neishabour). Irrigation levels included, I0: full irrigation, I1: irrigation at emergence stage, I2: irrigation at stem elongation stage, I3: irrigation at flowering stage, I4: irrigation at seed setting stage. Fertilizer treatments included control (no fertilizer application); chemical fertilizer application according to local practices; manure application of 10 tons; and manure application of 20 tons per hectare. Seed yield and yield components, leaf area index, crop growth rate and relative growth rate were measured. The highest 1000-seed weight was obtained in 20 tons of manure and I2 treatment in Neishabour. The lowest 1000-seed weight was obtained in 10 and 20 tons of manure and I1 in Neishabour. The lowest grain yield in I1 treatment was observed in Neishabour and the highest grain yield in I0 treatment with 20 t.ha-1 manure was observed in Mashhad. Fertilizer treatments increased crop growth rate in both experimental sites, but the effect of manure on increasing crop growth rate was greater than the effect of chemical fertilizer. However, due to the high fat content of quinoa, the use of 20 tons of manure per hectare is recommended if it is purely economic. In general, I2 treatment along with the application of manure in both places had high grain yield and dry matter production.

Deficit irrigation offers a solution for optimizing crop production under water stress conditions, albeit with an initial reduction in yield per unit area. Employing deficit irrigation aids in farm management in scenarios where land availability isn’t constrained, enabling the determination of optimal cultivation patterns while conserving water consumption. However, deficit irrigation may influence plant growth and development by inducing drought stress. Due to several capabilities, quinoa shows resistance to solar radiation, temperature, water availability, and atmospheric CO2 concentration, which makes it possible to cultivate it in different agricultural areas. Quinoa also has a great capacity for cultivation in dry and low-water soils. Although growth analysis sometimes provides valuable clues, it does not provide any physicochemical information related to the environmental reactions of plants; in other words, the main benefit of many quantities involved in growth analysis is to provide an accurate estimate of the ability and efficiency of the plant in the community at certain time intervals. In general, growth analysis evaluates the system based on the results of physiological manifestations. The purpose of this research was to evaluate the physiological growth analyses of three quinoa cultivars under different moisture levels in summer and spring planting dates in the South Khorasan region.

To evaluate the physiological traits of three quinoa cultivars under deficit irrigation conditions, four separate experiments were conducted using a factorial layout based on a randomized complete block design. These experiments included three replications and were carried out in two regions (Birjand and Sarbisheh) during two planting dates (March and July) in 2018-2019. The experimental factors consisted of five moisture levels (ranging from 25% to 125% of crop water requirement) and three quinoa cultivars (Titicaca, Giza1, and Redcarina). To compare the cultivars and assess the impact of humidity levels, several physiological indices—such as leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), and net assimilation rate (NAR)—were studied. Regression curves were fitted to the data from all four experiments separately, and separate analyses of variance were also performed for each sampling time.

The trend of changes in the leaf area index (LAI) showed that the time needed to reach the maximum LAI was observed between 106 to 107 days after emergence in March and between 73 to 76 days after emergence in July in Birjand, respectively. In Sarbisheh, the maximum LAI was observed on day 104 after emergence in March and between 65 to 72 days after emergence in July. In March, in both studied areas, Redcarina had the highest LAI values (4.5 in Birjand and 6.7 in Sarbisheh), along with the maximum crop growth rate (CGR) of 17.93 g m-2 day-1 in Birjand and 20.63 g m-2 day-1 in Sarbisheh. Conversely, in July, Giza1 exhibited the highest LAI (6.4 in Birjand and 6 in Sarbisheh), along with the maximum CGR of 19.32 g m-2 day-1 in Birjand and 18.11 g m-2 day-1 in Sarbisheh. Additionally, the highest relative growth rate (RGR) and net assimilation rate (NAR) at the beginning of the growing season in March were observed for Redcarina, while in July, Giza1 demonstrated the highest RGR and NAR in both studied areas. Considering the effect of humidity levels, the highest levels of LAI, CGR, RGR, and NAR indices were observed at the 125% water requirement level. Specifically, the maximum LAI values in March (in Sarbisheh and Birjand) and August (in Sarbisheh and Birjand) were 8.2, 5.3, 6.5, and 7.2, respectively. The maximum CGR values were 28.78, 23.56, 22.96, and 26.18 g m-2 day-1, respectively. Furthermore, the highest RGR at the beginning of the growing season ranged from 0.189 to 0.214 g g-1 day-1, and the highest NAR at the beginning of the growing season ranged from 6.16 to 10.22 g m-2 day-1. Conversely, the lowest values of these indices were observed at the 25% water requirement level.

Overall, Redcarina, cultivated in March, and Giza1, cultivated in July, exhibited the most favorable growth analysis indices and grain yield compared to other cultivars. Additionally, deficit irrigation resulted in a decrease in all of these indices and grain yield.

Potato plays an important role in global food security and it growth and tuber yield are influenced by many biotic and abiotic stresses, such as drought and low or high temperatures. Potato in Khuzestan province is facing unfavorable weather conditions, especially high temperature. Humic acid and amino acid, as well-known biostimulants, can directly or indirectly influence on plant growth and yield and significantly mitigates the injuries caused by abiotic stresses. In some studies, the use of humic acid has been reported increase root length, improve nutrient uptake, and increase chlorophyll synthesis. Amino acids in potato plant increase natural resistance to stresses. It seems that biostimulants and some nutrition elements can be applied as a strategy to reduce the negative effects of high temperatures. Therefore, this study was conducted to evaluate the effect of plant growth biostimulants on growth indices, yield and yield components of potato cultivars in Khuzestan region.

This research was conducted in two studies. First study was carried out as a factorial experiment in a randomized complete block design (RCBD) with two factors including 16 treatments in three replications at Behbahan Agricultural Research Station in 2019-2020. The first factor was application of plant growth biostimulants at eight levels: control (application of chemical fertilizers according to soil test), humic acid, free amino acid (L), amino acid-Zn, amino acid-K, amino acid-Ca, amino acid-K-Ca and application of all studied biostimulants (except free amino acid). The second factor consisted of two potato cultivars: 'Ottawa and Sante'. In the second study, growth analysis was done in a split plot factorial based on RCBD with three replications. Main plot consisted of five sampling periods with 15 days intervals. Sub plot consisted of combination of eight plants growth biostimulants and two cultivars of potato as factorial. Tubers were planted at mid January. One week before harvesting haulms were defoliated and tubers were harvested at mid May. Humic acid was used as fertigation at 10 kg.ha-1 in the early stages of growth. Foliar application of amino acid, amino acid-Zn was done at two stages, tuber initiation and the beginning of tuber bulking. Foliar application of amino acid-K, amino acid-Ca was done at two stages, the beginning and middle of tuber bulking. Amino acid and amino acid-nutritional element were done at a concentration of 0.5 %. Varince analysis were done by MSTATC statistical software and meanes were compared using Duncan’s multiple test range at the 5% level.

The results showed that in two cultivars, application of all studied biostimulants (except free amino acid) significantly increased tuber yield compared with control. In Sante cultivar, the highest yield was dedicated in the treatment of combined, and the yield of this treatment was significantly higher than the yield of  alone application of these substances. In Ottawa cultivar, the highest yield was achieved by application of combined biostimulants, but the differences of tuber yield among this treatment and treatments of amino acid-K, amino acid-Ca and amino acid-K-Ca and humic acid were not significant. The results of growth analysis showed, in the most sampling periods, the highest tuber and crop growth rate were recorded in the combined treatment. Therefore the highest tuber yield was observed in this treatment. In the first and second sampling periods, application of humic acid or amino acid-Zn were more effective than other treatments. But, in the third and fourth sampling periods, treatments of amino acid-K, amino acid-Ca were more effective in comparision to alone of these substances. In different sampling periods, tuber and crop growth rate in Ottawa cultivar was significantly higher than Sante cultivar.

According to results, in Sante cultivar, the combined treatment of plant growth biostimulants produced the highest yield in comparision to any individuals of these substances. Therefore, use of humic acid as fertigation in the early stages of growth and foliar application of amino acid- Zn at two stages tuber initiation and the beginning of tuber growth and amino acid-K-Ca at two stages the beginning and middle of tuber growth, are recommended. In Ottawa cultivar, the differences of tuber yield among treatment of combined application of growth biostimulants, amino acid-K, amino acid-Ca and amino acid-K-Ca and humic acid were not significant. Therefore, based on the finding of the present study, it could be concluded that treatments of amino acid-K, amino acid-Ca or humic acid may be an effective growth biostimulants for improving yield of Ottawa cultivar.

To study the effect of nitrogen fertilizer and irrigation regimes on some crop growth indices of forage maize under conventional and conservation tillage system, an experiment has been conducted in split plots with a randomized complete block design and three replications at University of Tehran’s farm during 2018. Tillage systems, as the main plot in two factors, include conversation and conventional tillage, whereas water stress, being the subplot, is in three levels which are 30%, 60%, and 90% of moisture requirement. Also, nitrogen fertilizer, as the sub-sub plot, is at three levels, 0, 50%, and 100% of the recommended rate. Results in the flowering stage show that the highest leaf area index (6.28) and crop growth rate (34.01 gr m-2 day-1) have been obtained from the interaction between slight water stress (90% of crop water demand) and nitrogen (100% of crop demand) as well as the interaction between slightly water stress and 100% nitrogen in conventional tillage, respectively. The highest relative growth rate (0.08 gr gr-1 day-1) and total dry matter (1006.86 gr m-2) belong to simple impact of 100% nitrogen along with the interaction of slightly water stress and 100% nitrogen in conventional tillage, respectively. Results show that under severe water stress and higher application of nitrogen, the fertilizer will cause less crop dry matter under conventional tillage.

Quinoa is an annual plant belonging to the Amaranthus family with high adaptability in different environments and the only plant food that contains all the essential amino acids, micronutrients and vitamins and has the ability to adapt to different environments. Planting date affects the growth potential and yield of the plant by creating temperature and light restrictions and will reduce or increase plant growth. Proper planting date will produce higher economic yields without increasing additional costs and will allow the plant to show its full growth potential. Plant growth analysis is performed by a series of parameters, the most important of which are leaf area index (LAI), total dry matter (TDM), relative growth rate (RGR), crop growth rate (CGR) and net assimilation rate . A rapid increase in leaf area and maximum LAI at the beginning of plant life can lead to increase radiation intake, photosynthesis rate, and ultimately increased yield. Crop growth rate is one of the main factors affecting crop production and yield. Various studies on quinoa showed that leaf area index, crop growth rate, relative growth rate and net photosynthesis rate were affected by different planting dates.

This study was conducted in the greenhouse complex of Jihad Keshavarzi in Khalil Abad, Khorasan Razavi province, Iran, in the form of a complete randomized block design with three replications and 12 different planting dates during the two crop years of 2018 and 2019. Cultivation treatments were performed once every 15 days from March 6th. During the experiment, the trend of changes in growth parameters including: LAI, TDM, RGR, CGR and NAR was Measured and estimated.

The results showed that the trend of changes in leaf area index in different dates had a slow trend at the beginning of leaf growth period, which continued until shortly before the emergence of flowers, but then the slope of leaf area index increased until the maximum leaf area index continued. With the aging of the leaves, yellowing and shedding of the lower leaves of the plant, due to the shading and re-transfer of material from the leaves to the seeds during the grain filling period, this process decreased and a relatively low decline was observed in the leaf area index. In total, the highest amount of total dry matter in two years was related to the planting date of March 6, but in general, the amount of total dry matter in the second year was less than the first year. Crop growth rate was higher than the planting date on the March 6th in both research years. Crop growth rate in the second year was generally lower than in the first year. This was due to the temperature difference in the two years of study. The relative growth rate during the Quinoa growth season was declining. The net assimilation rate among planting dates did not follow the same pattern, but overall this parameter showed a declining trend from the beginning of the season to the end of the growing season.

The results showed that the highest values of quinoa growth indices were related to the date of first plantings. This indicated the existence of suitable environmental conditions including suitable temperature and light to better achieve growth indices in the first dates For example, the highest index of leaf area was related to the planting date of March 20 and April 20 during two years of experiment, or other growth indicators had the highest values on March 6th. There was a difference between different planting dates in terms of the amount of growth characteristics studied.

The Identification of the factors affecting the yield and edible quality of spinach (Spinach oleracea L.) and their interaction with the environmental conditions are the most important issues in crop production management. In this experiment, the effect of three levels of plant density (71, 45 and 33 plant m-2), six levels of nitrogen fertilizer (100, 200, 250, 300, 350 and 400 kg urea ha-1) and control on yield, growth indices and quality of spinach was evaluated in the field condition. These experiments were carried in 2014-15 and 2015-16, in a randomized complete block design with three replicates. The results showed that interaction effects of nitrogen fertilizer and plant density and year only had Significant effcet on nitrate content (p < 0.001). Nitrogen fertilizer increased biomass, yield, growth parameters like leaf area index, crop growth rate, and qualitative parameters like nitrate content, potassium percentage, chlorophyll a,b and total traits while had not significant effect on net assimilation rate and relative growth rate. Interaction effects of plant density and year had a significant effect on all traits except potassium percentage (p < 0.001). The increase in plant density led to increase in the biomass, leaf area index and nitrate content but chlorophyll content was significantly decreased. It is suggested that in autumn cropping in Karaj region, and under high light and temperature conditions, 71 plants m-2 and 250kg urea ha-1 could be better to estimate the aims of economic profitability for highest yield and maintaining a healthy level of nitrate in the plant tissue.

The production of crops especially cereals in Iran is a challenge due to the presence of arid and semi-arid climates. Zeolite application is one of approach to ameliorate the effect of water deficit on crops. High water absorption zeolite is able to absorb water in the soil to a maximum level and maintain it for a long time within its network. Regarding the problem of water deficit and the necessity of managing agricultural production in conditions of water deficit and the possibility of using millet as a premature and compatible plant with most regions of Iran, this experiment was conducted out to evaluation of the effect of deficit irrigation and zeolite application on Proso millet. In order to study the influence of deficit irrigation and zeolite application on Proso millet, an experiment was conducted as strip block in randomized complete block design base, at Shahrekord University, in 2015. Irrigation regime gad four levels (supply of 100, 75, 50 and 25 percent of field capacity) and zeolite had three levels (0, 0.5 and 1 kg m-2). Plant water requirement was calculated by FAO Penman-Monteith equation. Irrigation regimes were applied at V4 stage (4th three foliate leaf has unfolded) and continued until the end of the growing season. Plant water requirement was calculated by FAO Penman-Monteith equation. Results showed that leaf area index (LAI) had sigmoidal pattern. The highest LAI (3.3) was recorded in 100%FC and one kg m-2 zeolite interaction. Also lowest LAI (1.1) was observed in 25% FC and 0 kg m-2 zeolite interaction. Results also showed that water deficit reduced dry matter accumulation but in each irrigation treatment increase of zeolite amount resulted in ameliorated the effect of deficit irrigation. Maximum and minimum of dry matter were recorded in 100% FC*1 kg m-2 zeolite and 25 % FC* 0 kg m-2 zeolite interactions respectively. The crop growth rate in all of the treatments increased until mid-growing season and then reduced. The deficit irrigation reduced membrane stability but zeolite application increased it. Membrane stability in 75, 50 and 25 percent of FC reduced by 23%, 66% and 57% respectively. Water deficit also reduced relative water content. RWC were reduced by 13%, 26% and 41% in 75, 50 and 25 percent of FC respectively. Stomatal conductance reduced by deficit irrigation but in each level of irrigation treatment the highest stomatal conductance was observed in 1 kg m-2 zeolite application condition. The grain yield of Proso millet was higher under 1 kg.m-2 zeolite application condition in all deficit irrigation treatments. The highest grain yield reduction compared to control treatment (100% FC and no zeolite application) was observed in 25% FC and no zeolite application condition. Finally results showed that however zeolite application under 100% FC condition had little effect but under deficit irrigation condition, zeolite reduced the harmful effects of deficit irrigation on studied traits and in this context uses of 1 kg.m-2 zeolite is recommended.

In order to evaluate radiation absorption and use efficiency for wheat cultivars under effect of nitrogen fertilizer levels, a split-plot experiment based on the randomized complete block design with three replications was conducted during 2015-2016. The treatments were four nitrogen fertilizer levels (90, 180, 300, 360 kg.ha-1 of urea) as main-plot and four wheat cultivars (Parsi, Zare, Pishgam and Orum) as sub-plot. The evaluated traits were included leaf area index, radiation absorption, crop growth rate, relative growth ratio, leaf dry weight, stem dry weight, total dry weight, radiation use efficiency and grain yield. The results showed that Pishgam cultivar compared to other cultivars had the most satisfying in terms of evaluated characteristics under nitrogen fertilizer rate treatments. By increasing the rate of urea fertilizer from 90 to 360 kg.ha-1, maximum leaf area index, radiation absorption, crop growth rate, relative growth ratio, leaf dry weight, stem dry weight, total dry weight and grain yield were improved. The most (8950 kg.ha-1) and the lowest (1264 kg.ha-1) grain yield weight were observed for Pishgam cultivar in 360 kgurea. ha-1 treatment and for cultivar variety in 90 kgurea. ha-1 treatment, respectively. The results also showed that the highest and the lowest radiation use efficiency were related to Pishgam cultivar (1.59 g.MJ-1) in 360 kgurea.ha-1 treatment and Orum cultivar (0.67 g.MJ-1) in 90 kgurea.ha-1 treatment, respectively. It seems that rising of nitrogen fertilizer by improvement of photosynthesis and crop growth rate caused to pick up dry matter accumulation and finally increased wheat radiation use efficiency.

In the region of Khorassan, chickpea often is sown traditionally at the end of the rainy season (March or April) based on the moisture stored in the soil. On the other hand, the amount and distribution of rainfall during the growing season is also very unsuitable. Therefore, the plants usually encounter intermittent drought stress during the vegetative growth and in the reproductive growth stage and may meet terminal drought stress and heat, simultaneously; resulting in a disturbance on pollination and assimilate the seed that leads to severe yield reduction. In these areas, the synchronization critical stages of plant phenology with adequate moisture in the soil is important. So, the selection of genotypes that their life cycle is completed before the heat and drought occurrence at the end of the season, is considered as a first step to improve the chickpea production under rainfed conditions. In order to evaluate the morphophenological characteristics, yield and yield components of promising drought tolerant chickpea (Cicer arietinum L.) genotypes under supplementary irrigation, this study was carried out in Educational-Researching Farm of Shahid Rajaei, College of Agriculture in Neyshabour during 2010-2011. This study was performed based on Randomized Compelete Blocks Design with five promising chickpea drought tolerant genotypes (MCC80, MCC352, MCC392, MCC537 and MCC696) and two genotypes as control (ILC482 and Karaj 12-60-31) with four replications. Seeds were prepared from seed bank of Research Center for Plant Sciences, Ferdowsi University of Mashhad (Mashhad Chickpea Collection; MCC). Planting operations was performed in April 2011. Planting density was 30 plants.m-2 and row spacing was 50 cm. Two times irrigation as supplementary irrigation were applied at planting and flowering stages. Some characteristics such as days from planting to 50% of emergence, flowering and podding; plant height; primary and secondary branches number per plant; leaf area index (LAI); crop growth rate (CGR); relative growth rate (RGR); seed yield and yield components (pods number per plant and 100Seed weight) were measured. Based on the results, there were significantly differences among genotypes for all traits. Genotypes MCC80, MCC696, MCC392 and MCC537 had the lowest and genotypes MCC358 and MCC252 had the highest number of days from planting to flowering, in which the difference between them was significant (P≤0.05). MCC80 had the lowest plant height and MCC537 and MCC392 showed the highest. MCC80 and MCC358 had the highest and lowest number of pods per plant, respectively. It seems that MCC80 growth would avoid collisions with high temperatures and consequently the flowering has taken place in lower temperatures and higher soil moisture. The above factors led to a reduction of the failure of flowers, so the number of pods per plant increased in MCC80 (23 pods) significantly, compared other genotypes. Based on the results, on both grain yield per plant and seed yield, genotypes MCC252 and MCC358 showed the lowest and MCC80 had the highest rate. Although Karaj12-60-31 (MCC358) as a commercial genotype, showed the highest plant height and growth indices, but for traits such as number of pods per plant, 100 seed weight and seed yield, was poor. The results showed that MCC80 with 970 Kg.ha-1 had the highest seed yield and ILC482 (MCC252) and Karaj12-60-31 (MCC358) had the lowest. The average yield for the MCC80 with supplementary irrigation in this region, was twice more than the yield in rainfed and 75% of yield in irrigated conditions in the region. However, the seed yield of commercial genotypes of Karaj12-60-31 (MCC358) and ILC482 (MCC252), were 324 and 320 Kg.ha-1 respectively. Totally, we recommend the repetition of such tests in this ares; in addition we can consider the genotypes such as MCC392, MCC352 and especially MCC80 as promising chickpea drought tolerant genotypes with supplementary irrigation during flowering in this area.

Dry matter produced by crops is a function of absorbed radiation and radiation use efficiency. Radiation use efficiency is an effective approach to quantify total dry matter accumulation. It is defined as biomass produced by plant for solar radiation absorbed during growing season. Radiation use efficiency is often calculated from the linear regression slope between total dry matter accumulation and cumulative solar radiation absorbed. It is affected by species, weather conditions, crop management, plant development stages, and the production of photosynthesis compounds. Among the factors of agronomic management, nitrogen fertilizer and crop species are the most important aspects that affect the radiation use efficiency. Therefore, by considering the fact that Kermanshah province has favorable condition in terms of more natural resources such as solar radiation, the aims of the present study were evaluation of nitrogen effect on radiation use efficiency, growth indices and yield of some current maize hybrids.
A split plot experiment was done based on randomized complete block design with 4 replications at 2014. Treatments were 4 levels of nitrogen fertilizer application (40%, 70%, 100% and 140% of the maize demand to nitrogen which based on the amount recommended by soil experiment equivalent to 138, 238, 350 and 483 kg.ha-1 of urea) as main plots and 3 maize hybrids KSC-704, BC-678 and Simon as sub plots. Leaf area index and total dry matter yield measured during growing season. Crop growth rate and relative growth ratio calculated by differentiation from fitted equation on total dry matter yield data. In order to calculate radiation use efficiency, sunny hours for Kermanshah latitude obtained from the nearest weather station. Daily solar radiation simulated by the method cited by Goudriaan and Van Laar (1993) for growing season. The absorbed radiation in each stage obtained through the multiplication simulated daily solar radiation in percent of absorbed radiation. The amount of cumulative absorbed radiation calculated through the multiplication simulated daily radiation in integral of absorbed photosynthetically active radiation fraction. Finally, radiation use efficiency calculated through the slope of linear regression between dry matter accumulation and cumulative absorbed photosynthetically active radiation. Also, grain yield measured for each treatment separately in the physiological maturity time.
The results showed that maximum and minimum of leaf area index, leaf area duration, crop growth rate and total dry matter yield were observed in KSC-704 and BC-678 hybrids, respectively. Also in all 3 hybrids, maximum leaf area index, leaf area duration, radiation absorption, crop growth rate, relative growth ratio and total dry matter yield improved by increasing of nitrogen fertilizer application from 138 to 483 kg.ha-1 of urea. The highest total dry matter yield (20450 kg ha-1) was related to 704 hybrid and consumption of 483 kg ha-1 of urea. Simon hybrid had higher grain yield than other hybrids at 483 kgha-1 of urea condition (10467 kg ha-1). Radiation use efficiency was not significantly different among maize hybrids. Regardless maize hybrids, by increasing of nitrogen fertilizer application from 138 to 238, 350 and 483 kg ha-1 of urea, radiation use efficiency improved from 2.33 to 2.63, 2.81 and 2.84 g MJ-1 (about 13%, 21% and 22%), respectively. Our results also indicated that there was a positive and significant correlation between radiation use efficiency and maximum leaf area index, maximum radiation absorption, maximum crop growth rate, maximum relative growth ratio, and maximum total dry matter. The positive correlation between radiation absorption with crop growth rate (0.98) and total dry matter (0.97) demonstrated more radiation absorbed lead to more crop growth rate subsequently higher total dry matter production by maize hybrids. Nitrogen fertilizer also improved total dry matter yield (58%) and grain yield (63%).
The results indicated that despite effects of nitrogen fertilizer application on maize grain yield, but unfavorable application of nitrogen would be led to intensify environmental pollution. Therefore, consumption of nitrogen fertilizer based on plant demand leads to increase resources use efficiency and reduce environmental risks.

Growth analysis is a valuable method to quantify crop growth, development and production. Because, parameters of nonlinear regression models have significant physiological meanings, it was decided to study the effect of topping and variety on crop growth indices by using a logistic nonlinear regression model in a factorial experiment, based on randomized complete block design with 3 replications, at the Research Farm of Gonbad University during 2014-2015. The first factor consisted of five faba bean verities (Zohreh, Shami, Sheshband, Sarazeri and Barkat) and the second factor of two levels, topping and control. Results showed that using this molel described well the variation pattern of dry matter accumulation and LAI by time. It was also revealel that the difference between verities for the time to reach maximum leaf area index and the time required to reach 50 percent of maximum dry matter were not significant. The effect of variety on leaf area index was significant at the 5% level. The maximum and minimum leaf area index, total dry matter and crop growth rate of Barkat, Zohre and the Saraziri were higher than Shami and Sheshband varieties, and thus this was resulted in higher yield. Leaf area index in all varieties was the critical leaf area index. The average critical leaf area index in varieties was 1.37. The maximum and minimum relative growth rate at the beginning of the growing season belonged to the Saraziri and Barkat with 0.066 and 0.055 g/g.day, respectively.

The maize as the oldest cultivated plant, is ranked second and first in terms of cultivated area and amount of production, in the world respectively. Although, researchers have improved the yield of corn by introducing new lines and hybrids, new genotypes alone cannot increase agricultural production, and it is necessary that appropriate and advanced agricultural techniques also be used to maximize corn yield. Maize is one of the most important crops in Golestan province, which is planted in more than 5000 hectares of agricultural land. In Golestan Province, different tillage systems are used for planting maize. Conservation tillage is a new and widespread method in this province, which many farmers use this method every year for cultivating their crops. The main objective of this study was to investigate the effects of different tillage systems on growth indices and yield of maize.
To study the effects of different tillage systems on qrowth indices and forage yield of corn, an experiment was conducted using a Nested design at Azadshahr city. Treatments included no-tillage, minimum-tillage and conventional tillage. Each treatment was carried out in a separate 30 × 50 m plot. Cultivar 770 was planted in all plots with row spacing of 75 cmand the distance between plants on the ridges was 14 cm. Sampling was done by a 1*1 m2 quadrate in six phenological stages of maize including two leaf-stage (9 days after planting), six-leaf stage (26 days after planting), flowering (55 days after planting), (71 days after planting), (85 days after planting) and 86 days after planting. At each stage, 15 quadrates were randomly sampled in each plot. Leaf area and dry weight, height of each plant and total fresh and dry weight of maize was measured at laboratory.
Net assimilation rate decreased following a quadratic equation in all treatments. Although the amount of NAR was estimated 13.5, 13.16 and 13.11 g.m-2.day-1 for conventional, minimum and no tillage, respectively but there was not significance different between the tillage systems in this regard. The maximum amount of NAR occurred at 17.3, 17.4 and 17.5 days after planting for conventional, minimum and no tillage, respectively. The value of this index at the end of the growing season (86 days after planting) was estimated as 0.41, 0.45 and 0.47 g.m-2.day-1 for conventional, minimum and no tillage, respectively.
Relative growth rate decreased following a quadratic trend for all tillage systems. In conventional tillage, RGR declined from 0.24 g.g-1.day-1 at the beginning of the growing season to 0.01 g.g-1.day-1 at the end of the growing season. There was no difference between estimated RGR of the tillage systems both at beginning and at the end of growing season.
Maximum crop growth rate occurred at 54 days after planting in all three tillage systems. The maximum value of CGR was estimated 41, 41 and 40 g.m-2.day-1 for maize in conventional, minimum and no tillage systems, respectively. CGR was estimated as 3 g.m-2.day-1 at the beginning of the growing season for all treatments; this index was estimated 15, 15 and 14 g.m-2.day-1 at the end of the growing season, for conventional, minimum and no tillage systems, respectively.
Result showed that although tillage systems did not effect on dry weight of maize, forage yield of maize in conventional system (71 ton.ha-1) was significantly more than minimum (67 ton.ha-1) and no tillage (64 ton.ha-1) systems.

The study of growth parameters such as net assimilation rate (NAR), leaf area ratio (LAR), relative growth rate (RGR) and leaf area duration (LAD) are important for analyzing yield constraints. The growth parameters can be used to understand the crop response to environmental variables during the growing season. The aims of the present study were to 1) consider the growth indices using regression method and 2) identify relationships between growth parameters and grain yield in different safflower cultivars and sowing dates.
A factorial experiment based on randomized complete block design with four replicates was conducted in 2012 in Research Farm of Vali-e-Asr University of Rafsanjan. The factors were included sowing dates (4 April, 25 April and 16 May) and safflower cultivars (411, Sina, Local Esfahan and Sofeh). Leaf area, leaf dry weight and stem dry weight were measured in 7–14 days intervals during the growth season. Grain yield was determined at the end of the growing season. The trend of variation for NAR, LAR, RGR and LAD during the season growth was determined by the nonlinear regression method using SAS software. Finally, the correlation between grain yield and growth parameters was identified by the PROC CORR procedure.
In all sowing dates, NAR increased to 43-53 days after sowing and then it showed a declining trend. Results showed that there was no significant difference among cultivars in terms of the time to maximum NAR among all sowing dates and among cultivars. As the growing season progressed, gradual increases in leaf area improved which resulted in increasing solar radiation interception and NAR. The NAR declining trend related to increasing leaves shading. In the first and third sowing dates, there was no significant difference in time to achieve maximum LAI among cultivars.
The maximum LAR was obtained in early growth season and its value decreased with slope of 0.033 to 0.051 cm2 g-1 d-1 among the cultivars and sowing dates. The rate of decreasing in LAR during growing season was the same among all sowing dates and cultivars. In the early growing season, the value of LAR in the first and second sowing dates was higher than third sowing date. It was probably due to high temperature effect on crop growth duration. As the growing season progressed, LAR started to decrease due to decrease in partitioning of dry matter to leaves. In the early growing season, the allocated dry matter to leaves were great which is resulted the higher ratio of leaf dry matter to total dry matter (LAR). The high LAR in early growing season is due to more interception of solar radiation by crop.
The trend of RGR during growing season was the same among all sowing dates and cultivars. The estimated maximum RGR varied between 0.149 to 0.169 g g-1 d-1 for the first sowing date, 0.087 to 0.211 g g-1 d-1 for the second sowing date and 0.192 to 0.251 g g-1 d-1 for the third sowing date. For each sowing date, the estimated maximum RGR had no significant difference among cultivars except for the second dates. However, the value of RGR was decreasing with progress towards the end of the growing season. The high RGR in the early growing season was due to the rapid crop growth, the more young tissues in plant and the low initial weight.
The value of LAD had the increasing trend in the early growth season and its value started to decrease between 50 and 62 days after sowing. In the second and third sowing dates, the maximum value of LAD obtained earlier than the third sowing date however, the value of LAD was lower than the first sowing date. It is probably due to decreasing the leaf area index and increasing the senesce rate in higher temperature in the last sowing date.
It is resulted that the highest grain yield obtained for the 411 and Local Esfahan cultivars in the first sowing date and the significant and positive correlation between grain yield and LAD (r = 0.88, Pr ≤ 0.01) observed whereas the value of grain yield increased 12.2 g m-2 per unit increase of LAD. Increasing the LAD increase solar radiation interception by crops and consequently the grain yield would increase.
Generally, it is concluded that the first sowing date with the highest LAD resulted the highest yield.

In order to evaluate eight bean genotypes for drought tolerance, an experiment in randomized complete block design with three replications was conducted at the Agricultural Research Station of Islamic Azad University of Tabriz, Iran in 2014. Drought stress was applied by cutting irrigation for two week at pod filling stage. Results of analysis of variance showed significant differences among genotypes in terms of stomata resistance, number of pods per plant,weight of dry pods per plant, number of seeds per pod, plant dry weight, 100 seed weight, seed yield per plant, biological yield per plant and leaf area index at 1% and harvest index at 5% probability levels. Weight of dry pods per plant had the highest correlation with seed yield (r = 0.89). In regression analysis for seed yield, number of seeds per pod, 100 seed weight, leaf area index and weight of dry pods per plant as effective traits were entered into the model. Path analysis for seed yield showed that number of seeds per pod, weight of dry pods per plant,100 seed weight and leaf area index had the maximum influence on the seed yield, respectively. The maximum Crop Growth Rate (CGR) and maximum Relative Growth Rate (RGR) in drought stress and non-stress conditions were recorded in Goli cultivar. According to GMP, MP, STI, and HARM indices, Goli cultivar was evaluated as the most tolerant genotype.

Intercropping systems are one of the best approaches in development of sustainable agriculture. Based on this purpose, the present study was conducted to evaluate effect of strip intercropping on maize and bean growth analysis and their yield during 2009. The experiment was set up in a completely randomized block with 3 replications and 6 treatments based on replacement design. The treatments were strip width, which included 2 rows bean plus 2 rows maize, 3 rows bean plus 3 rows maize, 4 rows bean plus 4 rows maize, 5 rows bean plus 5 rows maize, maize monoculture, and bean monoculture. Crop growth ratio, relative growth ratio, biological yield, economic yield, harvest index and land equivalent ratio were measured. Our results indicated that all of the measured traits were increased in the strip intercropping treatments compare to the monoculture treatments. Increasing of strip width in the central row of intercropping treatments in comparison with the two rows bean plus two rows maize treatment led to decrease crop growth rate (15.3% and 28.7%), relative growth rate (17.5% and 19.2%), biological yield (30.9% and 14%), economic yield (52.9% and 20.2%), harvest index (31.9% and 7.3%) in maize and bean, respectively. With increasing of strip width, all of the measured traits decreased more in the central rows than the side rows. The highest (1.45) and the lowest (1.22) land equivalent ratio were found in the two rows bean plus two rows maize treatment and five rows bean plus five rows maize treatment, respectively. Partial of maize had more role compare to bean in terms of enhance land equivalent ratio.

In order to investigate the effects of plant growth promoting rhizobacteria inoculation on growth criteria and yield of spring barley in different levels of nitrogen and phosphorus fertilizers, an experimental was conducted in two years at the Research Farm of Islamic Azad University, Ardabil branch during two growing seasons of 2009-2010 and 2010-2011 years. Experiment was conducted as Factorial split-plot design with three replications. The combination of nitrogen fertilizer in three levels (0, 40 and 80 kg N ha-1 as urea) and phosphorus fertilizer (0, 30 and 60 kg P2O5 ha-1) were factorialy assigned to the main plots and seed inoculation with plant growth promoting rhizobacteria in four levels (no inoculation, seed inoculation with Azotobacter chorchorum strain 5, Azosprilium lipoferum strain OF and combination of Azotobacter + Azosprilium) were assigned to the subplots. The results showed that with increasing of nitrogen and phosphor rates and seed inoculionat with plant growth promoting rhizobacteria, all of growth indices such as total dry matter, crop growth rate, relative growth rate and leaf area index were increased. Also, seed inoculation with both of Azospirillum and Azetobacter in all of sampling stages in growth indices was more than control (no seed inoculation). Maximum grain yield and leaf dry weight were obtained in highest rates of nitrogen and phosphor fertilizers with seed inoculation with both of Azosprilium and Azotobacter and minimum of they were obtained in no application of them.

The major problems in transplanting the landscape trees are high level of mortality and low establishment rate of transplanted trees, especially in the first year. In order to achieve the best condition for successful transplanting of pine and plane trees in Isfahan landscape, the present study was carried out based on a completely randomized block design with four replicates and three treatments including transplanting method (balled and burlapped and bare root), tree age (immature and mature) and IBA application (0 and 150 mg/L). Trees were transplanted during 2009 and 2010 in three times (dormant season, early and late growing season). Survival rate and Relative Growth Rate index based on tree height (RGRH) and trunk diameter (RGRD) were measured during the first and second years. Trees transplanted early in the growing season showed the most survival percentage during the two years, as compared to other transplanting dates. Survival of Balled and burlapped and immature transplanted trees was significantly greater than bare root or mature trees. The significant effect of age treatment was continued in the second year. IBA treatment had no effect on survival rate of the studied species. Balled and burlapped and immature transplanted pine trees also had higher RGRH and RGRD compared to bare root or mature trees. According to the results of this study, early growing season is the best time for transplanting pine and plane trees. Also, transplanting of immature trees using balled and burlapped method is recommended to increase the survival and establishment rate.

In order to study phenology, some growth indices and qualitative and quantitative characteristics of potato cultivars (Savalan, Sante and Cozima) an experiment was conducted for one year (2010-2011) at Behbahan Agriculture Research Station. The experimental design was randomized complete block design with three treatments and three replications. Tubers were planted at mid January 2010 and were harvested at mid May 2011. The results indicated that the yield of potato in Khouzestan province is lower than that in temperate regions due to the long sprout development stage and high temperature during the tuber bulking stage. The duration of the vegetative stage was short and the maturation stage was not observed. The haulm and tuber growth rate increased during the early season while reached a maximum value, following decline in the late season. The tuber and crop growth rate of Savalan cultivar (19.4 and 21.72 g m-2 day-1 respectively) was higher than other cultivars. Therefore, this cultivar produced the highest yield of tuber dry weight (4.20 t ha-1). The maximum of relative growth rate (0.598 g g-1 day-1) and maximum of tuber growth rate (0.320 g g-1 day-1) belong to Savalan and Cozima cultivars respectively. Cozima cultivar produced the highest total and marketable yield (19.91 and 18.38 t ha-1 respectively). In regard to, total and marketable yield the difference between Cozima and Savalan cultivars was not significant. Savalan cultivar produced the highest tuber dry weight percentage (22.38).