جستجوی مقالات مرتبط با کلیدواژه "dry matter accumulation" در نشریات گروه "زراعت"

Growth analysis has a significant perspective on the function of agricultural plants. In the early stages of plant growth, the growth indicators, including the leaf area index, the growth rate of the product decreases, and then due to suitable vegetation, the absorption of light radiation is better, and the accumulation of plant dry matter also increases, and after that Due to aging and yellowing, the leaves are reduced. The amount of light radiation absorbed by the plant varies during the growth period, which depends on the leaf surface index and the arrangement of the leaves of the plant.

The experiment was conducted in the research farm of Khuzestan University of Agricultural Sciences and Natural Resources in 2021-2022. In this research, the effect of three factors of irrigation interruption, cultivars and density was investigated in the form of factorial split with the base design of randomized complete blocks in three replications. The factor (no interruption of irrigation (control), interruption of irrigation at the beginning of flowering until the formation of 50% of the pod and interruption irrigation at the stage of pod formation until harvest the main factor, rapeseed cultivars Hayola 4815 and Aram and plant density per meter square (80, 110 and 140 plants per square meter) were considered as secondary factors.

Irrigation interruption caused a decrease in growth indicators, including the amount of plant dry matter accumulation, leaf surface index, and leaf surface durability. The changes in harvest index and durability of leaf surface and accumulation of dry matter at the beginning of the development of leaves had a slow trend until a little before the appearance of inflorescences, but after that the slope of the mentioned parameters increased. During the experiment, changes in growth parameters including LAI, LAD, RGR, CGR and TDW were evaluated. At the beginning of the plant growth season, the growth rate of the product was low due to the lack of complete vegetation cover and proper light consumption efficiency. In all treatments, with the passage of time, the growth rate of the crop was gradually increasing and it reached the maximum value in the reproductive stages and then went through a decreasing process. The effects of stopping irrigation on dry weight were evident and the accumulation of dry matter was observed during the increasing time. which can be due to the increase in dry weight of stems, leaves and reproductive organs over time. Also The relative growth rate also showed an increasing trend with the increase of the leaf area index at first and then a decreasing trend.

It seems that the second-stage irrigation interruption treatment at a density of 80 plants per square meter and Haiola 4815 variety, by maintaining more green area through more leaf surface durability and lower light consumption in the condition of irrigation interruption at the end of the growing season, was able to achieve a higher RUE100 compared to other treatments. to dedicate The highest seed yield (1572.61 kg per hectare) was obtained from the density of 110 plants per square meter and Hayola variety 4815.

In order to investigate the effect(s) of biologic and organic fertilizers on light consumption efficiency in growing maize-bean mixture, an experiment has been conducted in the form of split plots in a randomized complete block design with 12 treatments. Main plots, containing different fertilizer systems in four levels, include 30 kg/ha urea, Azotobacter, vermicompost, and Azotobacter + vermicompost, and the subplots contain cultivation compound of pure maize and pure bean being 50% maize + 50% bean, 60% maize + 60% pinto bean, and 80% maize + 80% pinto bean. Results show that leaf area index, dry matter accumulation, and light consumption efficiency of maize have been significantly higher than pure culture. The highest light use efficiency is related to the combined use of Azotobacter and vermicompost in mixed culture of 80% maize + 80% pinto beans with an average of 2.29 g / MJ, which increase light use efficiency by 63%, compared to 30 kg/ha of pure culture. Also, the highest dry matter, related to the mixed culture of 60% maize + 60% pinto beans, belongs to the amount of 1728 g/m2, which increase the dry matter accumulation by 16%, compared to pure culture. In general, the combined composition of organic and biologic fertilizers in intercropping has the ability to compete with urea chemical fertilizer in terms of mechanistic indicators of plant growth analysis.

Low quality of seeds resulting from seed deterioration is of major concerns underlying reduction in both quality and quantity of production in agricultural sector. Therefore, applying compounds like CA to alleviate seed aging deleterious effects and eventually to ensure final crop yield is important. Effects of five different CA on germination percentage and seed vigor were assessed as a factorial based on completely randomized design in seed lab of plant physiology group in Wageningen University.  Effects of three different concentrations of CA on physiological traits, yield and yield components of cowpea plants from seeds with different primary qualities were assessed in a two-year field experiment as factorial based on completely randomized blocks in three replications. Results indicated that CA had no significant effect on germination of unaged seeds, but concentrations of 15 and 30 µM improved seed vigor. In aged seeds CA pretreatment induced a 13-percent (45 and 60 µM) and 38-peercent (45 µM) in germination and seed vigor, respectively. Assessed characteristics differently responded to CA application based on their primary seed quality. So that when the CA application improved a trait, the trait was reduced in plants of different seed primary quality. In total, CA foliar application in plants from aged seeds was more effective to enhance yield and yield components while the reverse result was obtained for plants from unaged seeds.In case of dry matter accumulation, aged seed pretreatment was more effective than foliar application while a reverse result was obtained for plants from unaged seeds.

Extended Abstract: Effect of different densities of wild mustard (Sinapis arvensis) on the growth indices of wheat (Triticum aestivumL.)cultivars in Gorgan Introduction There are many species of weeds that damage wheat farms in Golestan province, however, Sinapis arvensis is one of the most common weed species in the wheat farms, which results in lower yields and increased production costs (Pawar, 2009). Growing cultivars with high competitive potential is one of the strategies for combating weeds in the integrated weed management system. Agronomic competition is one of the least expensive and the most commonly used methodsby farmers to control weeds, which is consistent with the goals and new criteria of sustainable agriculture practices(Kristense et al., 2008). Among the factors contributing to weed competition with crops, cultivars and planting intensity are of great importance. In this regard, plant growth analysis canbe indicative of the competitive ability of crops against weeds. The aim of this study was to investigate the effect of different densities of Sinapis arvensis on some growth indices and yield loss in four wheat cultivarsunder climatic condition of Gorgan. In order to investigate the effect of wild mustard (Sinapis arvensis) competition on the growth indices of wheat cultivars, an experiment was conducted at agricultural research station of Gorgan in two cropping years (2009-2011). The experiment was conducted as factorial in a randomized complete block design with four replications. The experimental factors consisted of four wheat cultivars: Arta, Tajan, Moghan and Morvarid and five wild mustarddensities of 0, 4, 8, 16 and 32 plants/m2. Wheat density was maintained at a constant 350 plants/m2 during the two years of the experiment. The evaluated traits included leaf area index(LAR), crop growth rate(CGR), relative growth rate(RGR), dry matter accumulation (DMA)and wheat grain yield. The leaf area index was measured using the Delta-T model leaflet. These data were used to determine growth indices. Statistical analysis of data was performed using SAS software. Charts were drawn using Excel 2007 and Sigma plot software. The combined analysis results showed that the effect of year on the all traits was not significant at 1% probability level. But the effects of cultivar, density and interaction of cultivar and wild mustard (Sinapis arvensis) density were significant. The results of the mean comparison showed that by increasing the density of Sinapis arvensis from 4 to 32plants/m2, the trend of changes for the growth indices of the wheat cultivars was decreasing. However, the trend of yield reduction among the wheat cultivars due to competition with Sinapis arvensiswas not similar. The significant interaction between cultivars and density levels onwheat grain yield indicates that the economic performance of different wheat cultivars did not decline in the same rateunder thedifferent densities ofwild mustard. In this study, Morvarid cultivar was found to be highly resistant to Sinapis arvensis because it was able to produce higher DM yields, LAI, CGR and RGR in competition with wild mustard than the other cultivars. One of the important factors for dry matter production and crop yield formation is the increase in leaf area index. The higher LAI and greater light consumption efficiency can facilitate the optimized light absorption, leading to increased yield production. In other words, if a plant can efficiently convert the absorbed light to higher biomass yied, it will be more successful in biomass production and yield formation (Blackshaw et al., 2008).In general, the resultsshowed that the grain yield performance of wheat cultivars while competing with wild mustard weed was influenced by the growth indices and Morvarid cultivar was more successful than the three other cultivars. The results of this study showed that the competition ability of the wheat plants was strongly influenced by wild mustard (Sinapis arvensis) density. Wild mustard has a high potential competitivenessagainst wheat due to its unlimited growth pattern and greater height, LAI and DMA, facilitating the capture of resources needed for growth. Therefore, in the wheat producing areas wherewild mustardis problematic, in addition to implementing other management practices, it is necessary to grow suitable cultivars such as Morvarid.

To determine the best sowing time and cultivar of forage sorghum in summer cropping as a substitute for maize under water deficit conditions in the temperate region of Koohdasht, Lorestan, Iran, a split plot
experiment in randomized complete block design layout was conducted with four replications and four planting times (June 25 and 2th, 9th and 16th July) (after wheat harvest) and two forage sorghum cultivars (Pegah and Speedfeed) in main and sub plots, respectively, in the summer of 2013 and 2014 at Lorestan Agricultural and Natural Resources Research and Education Center, Khorramabad, Iran. Results showed that delayed planting reduced dry matter accumulation and crop growth rate (CGR) and Pegah cultivar performed better than Speedfeed cultivar. Maximum plant height was achieved in Speedfeed cultivar in second planting time in first and second years (173.3 and 211.6 cm, respectively). Pegah cultivar had better performance than Speedfeed in leaf area index and stem diameter in most planting times. Pegah cultivar in first planting time had highest fresh forage yield (94.0 and 110.2 ton.ha-1 in first and second years, respectively) and delay planting reduced dry and fresh forage yield. It concluded that the maximum dry and fresh forage yield of sorghum
(cv. Pegah) could be produced in June seed sowing and seems to be more suitable for temperate regions like Koohdasht, Lorestan, Iran.

To investigate the effect of Piriformospora indica fungus on absorption and radiation use efficiency of millet under water stress, an experiment was carried out as a split plot in randomized complete block design with three replications in research field of Faculty of Agriculture, University of Bu-Ali Sina, Hamedan, Iran, during 2014 and 2015. The main factor was irrigation in three levels (irrigation after 60, 90 and 120 mm evaporation from pan class A) and sub factor was in two levels of fungus P. indica (inoculated and non-inoculated). In the both years, water stress decreased leaf area and dry matter accumulation of millet. Inoculation with fungus, increased leaf area and dry matter of millet plants in different irrigation levels. The highest radiation use efficiency (2.31 and 2.53 g.MJ-1 in 1st and 2nd years, respectively) was obtained in inoculated millet plants under well-watered, and the lowest (1.96 and 2.08 g.MJ-1 in 1st and 2nd years, respectively) was observed in non-inoculated plants under severe water stress. Severe water stress significantly decreased grain yield of millet in both 1st and 2nd years about 57.53 and 46.91 percent, respectively. Under severe water stress, inoculating increased grain yield by 35.34 and 32.50 percent in 1st and 2nd years, respectively, compared to control (non-inoculated). The results showed P. indica fungus, had a positive effect on absorption and radiation use efficiency of millet in different irrigation levels, so that the application of fungus mitigated the effects of water stress and improved the yield of millet under water stress.

Lentil (Lens Culinarris Medik.) is an important pulse crop in Iran and is usually grown in rainfed areas. The average lentil yield in Iran is 1195 and 476 Kg.ha-1 in irrigated and rainfed farms, respectively. Low productivity occurs due to different factors. One of these factors is poor agronomic management practices that applied by the farmers, e.g. Limitation or inappropriate fertilizer distribution. Plant development occurs in a number of consecutive phases. These phases can be affected by temperature, moisture, photoperiod, cultivar and other factors. The amount of available nitrogen affects the distribution of assimilates between vegetative and reproductive organs and phenological stages of growth. Therefore, analysis of growth indices and its effective factors can be used as a suitable tool in evaluating the yield. The aim of this study was to evaluate the effect of different nitrogen levels on phenology and growth indices of two lentil cultivars in rainfed conditions of Mashhad.
The experiment was conducted as split plot layout based on randomized complete blocks design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, during growth season 2016. Nitrogen fertilizer as urea (in three levels i.e. 0, 40 and 80 kg.ha-1) and cultivar (in two levels i.e. Birjand and Robat) were in main plots and sub plots, respectively. To determine the leaf area and dry matter, sampling was done every two weeks during the growing season. Phenological stages timing for each plot were determined based on 50% of emergence, 50% of flowering, 50% of maturity. Final yield was estimated from three square meter from each plot. Data were analyzed with the SAS software; the means were compared with Duncan's multiple range tests at the 5% level of probability. The graphs were prepared by SigmaPlot software.
The results showed that the effect of urea fertilizer was significant on vegetative, reproductive and overall plant growth based on days and growth degree-days. Also, 40 kg urea fertilizer per hectare showed that maximum of these traits. The effect of cultivar was significant on days and growth degree-days of planting to emergence, vegetative growth, reproductive growth and overall plant growth. Maximum of these traits were obtained in the Birjand cultivar. The difference in two lentil cultivars is related to genetic differences and their different adaptations to region. Urea fertilizer and cultivar interaction effects was not significant on phenological stages.
Urea fertilizer had a significant effect on leaf area index, dry matter accumulation and yield. The highest leaf area index was obtained in treatment of 40 kg urea fertilizer per hectare. More production of leaf area affected on other growth indices and led to increasing of crop production. The highest grain and biological yield were achieved in this treatment. Cultivar effect was significant on maximum leaf area index, dry matter accumulation and yield. Birjand cultivar had maximum leaf area index, dry matter accumulation, crop growth rate, grain and biological yield. Since the most of growth indices are dependent on leaf area index, changes in this indicator through change in the nitrogen fertilizer levels, is one of the most important practices to improve yield. Correlation analysis showed that, grain yield had positive and significant correlations with vegetative growth, reproductive growth, overall plant growth, maximum leaf area index and dry matter accumulation.
In this study, using of 40 kg urea fertilizer per hectare had a greater effect on leaf area index in comparison to other nitrogen fertilizer levels. That leads to an increase in the dry mater accumulation, crop growth rate and eventually increased the seed yield. So, application of 40 kg urea fertilizer per hectare is advised to achieve maximum crop production. Birjand cultivar had a good situation in terms of all growth indices and produced the highest yield, but it is a late cultivar and requires the optimum planting date for cultivation in this region. According to the observed correlations, leaf area index and dry matter accumulation can be introduced as traits affecting the yield of the two lentil cultivars.

IntroductionAbscisic acid (ABA) is a phytohormone which has a main role in plant life cycle and regulates many physiological processes including plant development and adoptability to environmental stresses. ABA controls water status of plants under stress and noticeably decreases undesirable heat stress damages. Since high temperature stress is a limiting factor for many crops growth and according to literature review there are evidences that ABA can induce thermo tolerance in plants, the present study was designed to evaluate the response of corn to heat stress when seeds are pretreated by ABA.
Materials and methodsThe experiment was factorial in a completely randomized block design with three replications and was done in agricultural college of Vali-e-Asr University of Rafsanjan in 2013. First factor was seed pretreatment by ABA solutions (zero, 50, 100 and 200 µM L-1) and second factor was different durations (zero, 8, 16 and 24 h) of heat stress in 40º C exerted on hybrid S.C.704 corn seedlings. In darkness seeds were soaked in ABA solutions for 24 h at the temperature of 25 ± 1º C. Following pretreatments seeds were sterilized by distilled water and finally were planted in pots in the depth of 1.5 cm. Seedlings were transported to growth chamber with the temperature of 40º C in four foliate stage to be treated by different heat durations. After thermo treatments seedling were transported to green house and plant responses were measured two weeks later.
Results and discussionResults indicated that the highest dry weight of shoots was obtained in ABA concentration of 50 µM L-1 but there were no significant differences at probability level of one percent among other concentrations. In addition corn seedlings were able to tolerate 8 h heat duration but negative effects of heat stress was significantly increased in 16 and 24 durations which led to the reduction of shoot dry matter production. Increase in heat duration and ABA concentration caused a significant raise in shoot to root weight ratio so that the highest ratio (31.66 percent) was observed in control treatment and the lowest (3.83 percent) in heat duration of 24 h accompanied with 200 µM L-1 ABA. Leaf relative water content in ABA concentrations of 50 and 100 µM L-1 showed a significant increase at probability level of five percent in respect to control and ABA concentration of 200 µM L-1 which can probably be due to stomata resistance in these treatments and may be used as suitable approach to increase plant thermo tolerance. Negative effect of ABA concentration of 200 µM L-1 on leaf relative water content indicated that ABA concentration must be chosen precisely. Increase in heat duration caused a significant raise in leaf temperature. In heat durations of 16 and 24 h the highest leaf chlorophyll index (27.2 and 24.5 respectively) was obtained in 50 µM L-1 ABA and the lowest ones (21.9 and 18.7 respectively) in 200 µM L-1. Increase in ABA concentration and heat stress led to a significant reduction of chlorophyll a content in corn leaf so that in heat duration of 24 h and ABA concentration of 200 µM L-1 a reduction of 36.9 percent was observed compared to control. In addition a reduction of 17 percent in carotenoids was associated with 24 h heat stress in respect to control. In all three durations of heat stress, rise in ABA concentration up to 100 µM L-1 made a decline in ion leakage while in the highest concentration (200 µM L-1) an increment in ion leakage was observed.
ConclusionsIn conclusion the results of the present study showed that high levels of heat stress in combination with undesirable concentrations of ABA can create negative effect on plant ability to preserve leaf relative water content and can lead to the destruction of chlorophyll and carotenoids structure and increase the ion leakage. On the other side ABA concentration of 50 and 100 µM L-1 decreased ion leakage while increased the leaf relative water content and chlorophyll index. By these simultaneous effects the corn shoot dry weight was improved under heat stress condition. It seems that external use of ABA can have positive and negative effects on plant growth depending on its concentration. Concentrations higher than threshold tolerance to ABA can cause disturbance in plant physiological processes and restrict plant growth and development.

In order to investigate the effect of methanol foliar application and drought tension on growth indices of soybean, an experiment was conducted as split plots in a randomized complete blocks design with three replications in the research field of Faculty of Agriculture, Islamic Azad University of Karaj Branch in 2015. Drought tension included irrigation after 40, 60 and 70 percent available moisture evacuation as the main factor and methanol foliar application included no spraying (control), spraying with 7, 14 and 21 percent by methanol volume as the sub factor were considered. Spraying was carried out three times during the plant growth season and at intervals of 15 days on the aerial parts. The measured traits included: dry matter accumulation, grain yield, crop growth rate, relative growth rate, net assimilation rate, Proline, soluble sugars, Peroxide hydrogen and relative moisture content. The results showed that the effect of methanol foliar application in drought tension conditions, was significant on the relative increase of all growth indices and yield. The comparison of the average of the examined traits showed that methanol foliar application had a positive and significant effect on soybean growth indices which led to increasing dry matter and grain yield of soybean; as the highest grain yield was obtained during methanol foliar application with 21 percent volume. Moreover, under mild and severe tension conditions with application of the highest amount of methanol, the amount of peroxide hydrogen reached to the lowest level. According to the obtained results, with application of 14 percent methanol, more increase was observed in the efficiency of proline under severe tension conditions. Increasing the volume of methanol from 7 to 14 percent, the relative water content was preserved under tension conditions.

Stem reserves of barely can be an important contributor to grain filling particularly under condition is limited such as salinity stress. The aim of this research was to study dry matter accumulation and remobilization ability in different internodes of some Iranian Barley varieties and promising lines under salinity and normal conditions. The research was set up as two Randomized Complete Block design with three replications at the agriculture research station of Neishabur, Khorasan Razavi, during 2013-2014. The amount of dry matter accumulation and remobilization were determined using method. The relationship between length and specific weight of internodes with dry matter accumulation and Remobilization was investigated. The results showed that lower internodes had maximum dry weight and specific weight in both of experimental conditions. Maximum remobilization was obtained from penultimate and lower internodes in normal and salinity conditions, respectively. A positively significant correlation was observed between seed weight per spike and the amount of Remobilization from all of internodes in saline condition. Results indicated that dry matter accumulation and remobilization ability are two different mechanisms that inherent from parents to progeny. Also in this study it was found that new tolerant promising lines compared to old tolerant varieties, had internodes specific weight, dry matter accumulation and remobilization ability.

Priming is one of the most common methods of improving seed quality, which significantly affects their storability. Seed priming is a seed treatment that allows imbibition and activation of the initial metabolic events associated with seed germination, but prevents radicle emergence and growth. In other words, phase one and two of seed water imbibition curve are passed, but seeds do not enter the third phase of water uptake. Then seeds are dried back to their original water content. Seed priming is a pre-sowing strategy for influencing seed germination and seedling development by modulating pre-germination metabolic activity prior to emergence of the radicle and generally enhances germination rate and plant performance. Naturally, when speed and percentage emergence of germinating seeds are being high, growing sources like light, water and nutrient will be more used. Another factor that can affect the seed germination and seedling establishment is the seed size. As generally known, among producing factors, seed as the first consumer store, plays an important role in the transfer of genetic characters and improvement of qualitative and quantitative traits of production. One of the most important factors in maximizing crop yield is planting high quality seed. Seed size is an important physical indicator of seed quality that affects vegetative growth and is frequently related to yield, market grade factors and harvest efficiency. In the present paper, effects of different pre-sowing treatments and seed size on physiological growth indices and bulb dry yield of onion cultivars were investigated. In order to determine the response of physiological growth indices and bulb dry yield of onion to priming and seed size, a field experiment was conducted in 2012-2013 cropping season at Agriculture and Natural Resources Research Center of East, Azarbayjan, Iran. This experiment was a factorial experiment based on a randomized complete block design with three replications. Experiment treatments included priminig at four levels: hydropriming, osmopriming (in %2KNO3), priminig with falomin amino acid (in 2%) and control (without priming). Seed samples of the two cultivars were sieved by slotted screens and placed into three groups of seed diameter size: small, medium and large and cultivars at two levels: Red Azarshahr and Zarghun. The physiological growth indices such as total dry matter, leaf area index, crop growth rate, net assimilation rate, bulb growth rate and bulb fresh and dry yield were studied. Results of field experiment showed that seed priming improved growth indices such as dry matter accumulation (DMA), crop growth rate (CGR), net assimilation rate (NAR), relative growth rate (RGR), bulb growth rate (BGR) and leaf aria index (LAI) in both cultivars. The highest bulb fresh, dry yield and dry matter percentage (54400, 6800 kg/ha and11/80 %) belonged to priminig with folammine amino acid, respectively. The results of growth analysis indicated that the maximum and minimum growth indices values were obtained from large and small seeds, respectively. Mean comparison showed that the highest bulb fresh yield (53.26 ton/ha), bulb dry yield (9.95 ton/ha) and bulb dry matter (11.47 %) were achieved from large seeds. Mean comparison indicated that the highest bulb fresh yield (43.40 ton/ha), bulb dry yield (5.43 ton/ha) and bulb dry matter (11.47 %) were observed in Red Azarshahr. Seed priming treatments improved bulb fresh and dry yield, total dry matter, leaf area index, crop growth rate, bulb growth rate, relative growth rate and net assimilation rate as compared to the unprimed. Among the treatments, seed priming with Falomin Amino Acid 2% was more effective than the potassium nitrite 2% and hydropriming. Large seed size significantly increased the bulb fresh and dry yield and physiological growth indices. The highest bulb fresh and dry yield, total dry matter, leaf area index, crop growth rate, bulb growth rate, relative growth rate and net assimilation rate were achieved in larger seeds compared to other sizes. Accordingly, the importance of seed priming and grading seeds were obvious in this study, so seed priming with Falomin Amino Acid 2% and large seed size should be used for onion planting in order to insure high bulb fresh and dry yield and physiological growth indices of onion. Nevertheless, seed priming and seed size improved bulb fresh, and dry yield and physiological growth indices of onion cultivars were attributed to rapid seedling emergence and establishment, and consequently the optimum use of light, soil moisture and nutrients by the plants developed from the primed seeds and seed size. Therefore priming with falomin Amino Acid 2% and large seeds are recommended in onion planting for the places with the same environmental conditions of this experiment.

Recent research studies show that the foliar application of methanol increases the growth of C₃ crops in arid regions. An experiment was carried out in a split plot based on randomized complete block design with three replications at the Research Station of Faculty of Agriculture, Ferdowsi University of Mashhad in spring 2010. Three irrigation levels (100, 75 and 50 percent of water requirement) and four foliar application levels of methanol (0, 20, 40 and 60 volumetric percent) formed the main and sub plots, respectively. Methanol was sprayed on chickpea shoots after pod stage in 3 times with a 10- day interval. The result showed that the effects of foliar application of methanol on physiological traits were significant. So that spraying of 60 volumetric percent of methanol affected physiological traits greater than other treatments and caused increasing in dry matter, leaf area index and crop growth rate while had no effect on relative growth rate. In drought stress treatment, leaf area index, cumulative dry weight and crop growth rate, relative growth rate were in their maximum amounts under adequate moisture treatment (control) compared with the drought stress conditions due to continued vegetative growth in control plants. In this experiment, the differences observed in the amount of dry matter accumulation and crop growth rate are mainly due to decreased leaf area index under drought stress conditions.

In order to investigate the effect of different weed-free and weed-infested periods on the growth indices of black seed، a field experiment was conducted at the Agricultural Research Station of Ferdowsi University of Mashhad، during 2009-2010 growing season. The experiment was laid out in randomized complete block design with 12 treatments and 3 replications. Twelve experimental treatments consist of six initial weed-free periods in which plots were kept free of weeds for 0 (WF 0)، 14 (WF 14)، 28 (WF 28)، 42 (WF 42)، 56 (WF56)، 70 (WF 70) days after crop emergence (DAE)، and then weeds were allow to grow until harvesting، and six initial weed-infested periods in which weed allowed to grow for 0 (WI 0)، 14 (WI 14)، 28 (WI 28)، 42 (WI 42)، 56 (WI56)، 70 (WI 70) DAE، then plots kept free of weeds to harvesting. The results indicated that black seed height was strongly affected by different weed free and weed-infested periods. Interestingly، weed interference for entire growing season caused increase in black seed height by 39% compared with the treatment that was weed free throughout the growing season. Also، these periods had significant effects on leaf area index، green area index، dry matter accumulation، crop growth rate and relative growth rate. Mentioned traits increased with increasing duration of weed- free periods and were reduced by increasing length of weed- infested periods. However، these periods had no significant effects on net assimilation rate، specific leaf area and specific leaf weight.

To study the effects of intercropping system of barley and broad leaf vetch (Vicia narbonensis) on forage yield and some morphological characters، an experiment was conducted during 2007-2008 cropping season in Experimental Farm of Agricultural College of Shahid Chamran University، Ahvaz. The experiment was split plots based on Randomized Complete Block Design (RCBD) with three replications. Planting method had three levels (row intercropping، mixed intercropping and intercropping on row) as the main factors. Planting proportions had four levels (sole-cropping of barley and vetch، 2 to 1 proportion of barley to vetch and 1 to 2 barley to vetch) as the sub factors. In order to make the mixtures، the replacement series technique was used. Dry matter yield، vetch and barley height، number of tiller and number of fertile tillers in barley and number of stems in vetch plants was measured. In this study، intercropping had the highest dry forage yield، vetch and barley plant height، number of tillers and number of fertile tillers in barley compared to sole cropping of barley and vetch plants. The trend of dry forage accumulation was very slow during first 60 days for all treatments، and then increased rapidly until 138 days after planting، except for barley sole cropping which increased up to 120 days after planting. Barley plant height had a slow positive trend at first 75 days، during next 45 days it increased faster. Then plant height had slower increasing trend in row intercropping and intercropping on row، while in mixed intercropping increasing trend did not change. Vetch plant height positive sigmoid trend in all treatments، i. e. slow increase during first 90 days، faster increase in the next 30 days، then a mild increase to the end of growing period.

Growth indices are useful for interpreting plant reaction to environmental factor. Using Growing Degree Days (GDD) for estimating the phonological growth stages is more valid instead of calendar time. In order to study effect of salinity on growth analysis in three different plantago species, a greenhouse experiment was conducted in Vali-e-Asr University of Rafsanjan in 2009. The study was carried out factorial experiment based on RCBD design with 4 replications to determine the influence of salinity (9, 15, 21 dS/m and control with distilled water) and three plantago species (Isabgul, French psyllium, Great plantain). Polynomial equations with the 88 to 98 distinction coefficient (R2) were known as the best indicator for interpreting of growth indices fluctuation to GDD. In all three species, the highest dry matter accumulation, leaf area, Crop growth rates (CGR) were observed in 900-1000 GDD at all salinity levels and in higher GDD, the decreeing trend of dry matter accumulation, leaf area and CGR were observed in all salinity levels. The lowest relative growth rate, crop growth rate, Leaf area ratio, dry matter accumulation were observed in 21 dS/m NaCl salinity. Results also indicated that maximum dry matter accumulation was observed in 800, 900 and 1100 degree day in Isabgul, French psyllium, Great plantain, respectively. No seed harvested from Isabgul and French psyllium in 21 dS/m. Among three species, great plantain could remain the highest leaf area; consequently this species produced higher dry matter (0.4 gr per plant) and relative growth rate (0.06 g.g-1.10GDD-1) compared to other species. In general, among three species, great plantain was better species from a growth and seed yield point of view in salinity stress.

Pattern of leaf area and plant dry matter distribution, can play key role in weed-crop competition for achieving the light. A field study was undertaken to aim of investigation of leaf area and dry matter profile of soybean cultivars and weeds. The experimental design was a randomized complete block using a split-plot arrangement with three replications. Main plots were weed infested (natural infestation) and weed free, and subplots were four soybean cultivars (Sahar, Hil, Sari, Telar) and two lines (033, 032). At soybean canopy closure stage, sampling of leaf area and dry matter profile of cultivars and weeds was carried out. Interference with weeds caused different cultivars of soybean shift the maximum layer of leaf area and dry matter to the upper layer of canopy. Distribution of leaf area and dry matter in weeds canopy was related to its species and the growth form. Abutilon theophrasti increased its height and height of branching, and spread its leaves on the soybean canopy. The hill cultivar in weedy plots produced maximum grain yield and had more weed suppressive ability than other ones.