جستجوی مقالات مرتبط با کلیدواژه « SPAD » در نشریات گروه « زراعت »

In order to investigate the effect of chemical and biological nitrogen fertilizer on canola, a field experiment was conducted as a split plot based on a randomized complete block design with three replications at the research station of the Faculty of Agriculture, Yasouj University, located in Deshtrum region, in 2019. The main factor consisted of nitrogen fertilizer (zero, 25, 50, 75, 100 and 125 kg/ha of pure nitrogen from urea source) and the secondary factor consisted of nitroxin biofertilizer contained Azotobacter and Azospirillium bacteria (use and non-use). The results showed that nitrogen fertilizer and nitroxin had a significant effect on all investigated traits. Nitrogen fertilizer significantly increased plant height, number of lateral branches, chlorophyll index and oil yield. The highest grain (8790.60 kg/ha) and biological (23910.93 kg/ha) yield were obtained in 125 kg/ha of nitrogen and the use of nitroxin. With the consumption of 125 kg/ha of nitrogen and nitroxin, the lowest percentage of seed oil, and contrastingly the highest percentage of seed protein (36.65%) was obtained. In general, combined application of biofertilizer with chemical nitrogen increased grain, biological and oil yield. Nitroxin bio-fertilizer could reduce the consumption of chemical nitrogen fertilizer. The results showed that there was no significant difference between the application of 50 kg/ha of nitrogen + bacteria and the application of higher levels of nitrogen (75, 100 and 125 kg/ha) alone in most of the investigated traits.

Water resources limitation and plant stress due to water shortage is one of the important and common environmental stresses in agricultural production, including forage production in hot and dry areas. Therefore, the selection and development of drought-tolerant cultivars are very important. In irrigated lands of Iran, the average of irrigation efficiency is 37% and water productivity is 0.8 kg per cubic meters, which is lower than the world average. For increasing water efficiency, maintaining the production capacity and creating sustainable agriculture, it is necessary to identify the effective factors on the reduction of irrigation water productivity and provide an appropriate solution. In arid regions such as Khuzestan province, by using both a proper irrigation program and irrigation levels below the water requirement, obtaining the acceptable yield of alfalfa could be expected. In order to achieve these objectives, determination of the irrigation water productivity of tropical alfalfa cultivars and their drought tolerance under different irrigation regimes were the main aims of this study.

For evaluating tropical alfalfa genotypes under different drought stresses, an experiment was carried out based on split plots design with three replications in Safiabad Agricultural Research Center, Dezful, Iran, in 2019-2020. The main factor was four levels of irrigation (25, 50, 75 and 100% of water requirement) and the second factor was five alfalfa cultivars (Baghdadi, Nikshahri, Yazdi, Mesasirsa, and Omid). In this experiments, plant characteristics including dry and wet forage yield, percentage of dry forage, leaf to stem weight ratio, chlorophyll index (SPAD), electrolyte leakage from the leaf cell membrane (EL), relative leaf water content (RWC), and Maximum quantum yield in the dark-adapted conditions (ΦPSɪɪ) were determined.

The results showed that by applying drought stress, wet and dry forage yields, RWC, and ΦPSɪɪ were decreased but the percentage of dry forage, leaf to stem weight ratio, EL, and SPAD were increased. Among the studied genotypes, the Baghdadi genotype had the highest dry forage yield in all situations; non-stress conditions (16.9 t/ha), mild drought stress (15.094 t/ha), moderate drought stress (9.58 t/ha) and severe drought stress (4.664 t/ha). The Yazdi genotype had the lowest dry forage yield; 9.9, 9.7, 5.7 and 3.6 t/ha for non-stress, mild, moderate, and severe drought stresses conditions, respectively.

In our experiment, the Baghdadi genotype showed a high-stress tolerance index (STI) and we highly recommend planting it in the north of Khuzestan province, but the Yazdi alfalfa genotype despite low dry forage yield under both non-stress and drought stress conditions is not recommended due to low production. We suggest using Yazdi genotype in eugenic plans due to high yield stability index (YSI) under drought stress conditions and having some favorable physiological and photosynthetic parameters associated with drought stress tolerance.

Medicinal plants in the world are very important and currently the demand for medicinal herbs is on the rise due to higher requirement of products need in the pharmaceutical, health and food industry. Therefore, the assessment of various systems of plant nutrition is one of the important needs of agricultural planning in order to achieve high yield with high quality, especially in medicinal plants. Manure increase soil fertility and improves the growth and yield. This experiment was conducted to investigate the effect of planting density and single or combined application of cow manure (CM) and chemical fertilizers (CF) on growth, yield and pigment content of Isabgol (Plantago ovata Forsk).

In order to evaluate the effects of different levels of fertilizer on isabgol (Plantago ovata Forsk) an experiment was arranged as factorial based on a randomized complete block design with three replications at Sarayan Faculty of Agriculture, University of Birjand, during 2017. Experimental factors were included: Fertilization treatments consisted of single (40 ton.ha-1 CM and 40 kg.ha-1 CF from the source of NPK) and combined (40 ton.ha-1 CM + 20 kg.ha-1 CF and 20 ton. CM + 40 kg.ha-1 CF) application of organic and chemical fertilizers along with a control treatment (no-fertilizer) which were evaluated at three levels of density (20, 40 and 60 plants.m2). Measurements of chlorophyll a, b, carotenoid and SPAD: Firstly, 0.1g samples were taken from the collected leaves. Subsequently each sample was extracted by 80% acetone and put in the centrifuges with rotation speed of 6000 per minute for 10 minute. Absorbance using a spectrophotometer at wavelengths of 470, 647, 663 nm was measured. Also, chlorophyll index was measured by manual chlorophyll meter. Measurements of Yield and yield components: In the sampling stage (full flowering stage), 3 plants of cultivation lines were harvested with respect to the elimination of marginal effects. After measuring plant height, the plants were cut from above the soil, immediately weighed (fresh weight) and then the samples were placed in separate bags and after drying in an oven at 72°C for 48 hours, the leaf weight, total dry weight and grain yield of each sample were measured. Finally, Statistical analyses were carried out by ANOVA, with  least significant difference test (LSD) at 5% probability level for subsequent pairwise comparisons.

 The results indicated the significant effect of treatments on plant dry weight, biological yield, seed yield and chlorophyll b content. The highest biological and seed yields (2080 and 806.6 kg.ha-1, respectively), were obtained from planting density of 60 plants m2, while the highest leaf chlorophyll content was gained from 20 plants m2 treatment. The effect of fertilizer resources on all traits (except plant dry weight) and interaction effect of experimental factors on all studied indices were no-significant. The plant showed an appropriate adaptation to low nutritional and its maximum yield was obtained when at least 60 plants.m2 was used.

Based on the obtained results, it could be concluded that isabgol is a low-input medicinal plants in terms of nutrient requirements. Therefore, it seems that the application of fertilizer resources in crops which are located prior to isabgol in a rotation and availability of remaining nutrients can provide the nutritional requirements of this plant. Moreover, consider to open canopy of the plant even when the plant density was 60 plant.m-2, it seems that more densities must be considered in future studies.

Rice is one of the most important crops in Iran and all over the world, and Salinity stress is a significant limiting factor in producing this crop. In this experimen 11 rice genotypes as split-plot based on randomized complete block design with three replications in summer 2012, at the college of Agriculture, at Yasouj University. The main plot of salinity at 4 levels (0, 44, 88 and 132 mM) and subplot were 11 rice genotypes, include: Gharib, Local Yasouj, Champa and Shahri Loudab, 304, Lenjan- Askari, Kamfirooze, Domsiah Mamasani, Mossa-Tarom, Hassan-Seraei, and Dollar. Triats evaluated consist of flouresance cholorophyll indices (F0, Fm, Fv and Fv/Fm, respectively), cholorophyll soluble sugars, proline and protein leaf and grain yield. The results analysis of variance showed that the traits of chlorophyll fluorescence indices (F0, Fm, Fv and Fv/Fm, respectively), chlorophyll, soluble sugars, and proline and leaf protein were affected by interaction of salinity and genotype. With increasing tension stress, proline accumulation, protein and leaf soluble sugars increased in plants under salinity levels, but genotypes differed in this regard. Increasing salt stress levels reduced the relative chlorophyll content and grain yield. Mean of comparison rice genotypes showed that the highest grain yield belonged to Lanjan askari genotype and the lowest was genotype Dollar. Cluster analysis with minimum variance Ward's method in salinity stress conditions classified all genotypes in four groups and the highest genetic distance was observed between cluster 1 and cluster 4, that can from genotypes this two cluster for breeding program like hetrosis and transgrissive segregation used.

water limitation is often the most important preventive factor in spring rapeseed in semi-arid Mediterranean regions. The use of nutrient nanoparticles and exogenous plant growth regulators by influencing plant physiological processes can play an important role in tolerance to water limitation. The aim of this study was to investigate the changes of some physiological traits and seed yield of spring rapeseed in response to foliar spray of nano silicone and salicylic acid under water limitation conditions.

This experiment was conducted as a factorial split plot based on a randomized complete block design with four replications at the Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardebili, in 2017. Water limitation treatments (control or full irrigation, irrigation withholding at stem elongation, flowering and seed formation stages), and foliar spray of silicon in form of Nano- silicon dioxide (nSiO2) at three levels (0, 60 and 300 mg.L-1) and salicylic acid (SA) at three levels (0, 0.5 and 2.5 mM).

The results showed that the main effects of experiment factors on physiological traits and seed yield are significant. The lowest value of leaf greenness index (SPAD) was observed on Full Irrigation, whereas the highest values were obtained from foliar spray 60 mg.L-1 nSiO2 and 2.5 mM SA under irrigation withholding at flowering stage. At full irrigation and irrigation withholding at seed formation stage treatments, the spraying of 300 mg / l nSiO2 resulted in a significant reduction in the quantum efficiency of photosystem II (Fv/Fm) in compared to the lower level of nSiO2. Foliar Spray 300 mg.L-1 of nSiO2 with SA consumption resulted in the reduction of electrolyte leakage from membrane (EC) compared to control treatment. In full irrigation, the highest value of relative water content (RWC) was obtained, especially with foliar spray 300 mg.L-1 nSiO2. Also in between different levels of SA, The foliar spray 2.5 mM SA caused the highest RWC trait. The highest seed yield was obtained from full irrigation In combination with 300 mg. L-1 nSiO2 and 0.5 mM SA (2847.3 kg.ha-1), and the lowest value was belonged to irrigation withholding at flowering and stem elongation stages without foliar spray of nSiO2 and or SA .

It was concluded that foliar spray nSiO2 and SA alone or combined in both conditions of irrigation and or water limitation showed a positive effect on physiological traits and seed yield, however a higher amount of nSiO2 could have a deterrent effect on the positive effects of SA.

Knowledge of freezing stress tolerance in wild barley and feral rye as the most important weeds in wheat fields can be used to predict their geographical distribution and management plannings. To this end, an experiment was conducted in Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran, in autumn 2017. Two wheat genotypes (cultivar Pishgam and Iranian landrace Ghezel Khoushe) and two weeds (wild barley and feral rye) were grown up to two to four true leaves stage under natural conditions and then exposed to a temperature range of +4 to -20 °C (+4 oC as control and 0, -4, -8, -12, -16 and -20 oC as freezing temperatures). The results showed that reducing temperature from -8 to -12 °C led to a 36% decrease in survival of wild barley, while the survival of wheat (Pishgam and Ghezel Khoushe) and feral rye was 100%. Wild barley had the highest lethal temperature reducing 50% of survival (LT50su = -12.8 °C) and temperature rducing 50% of leaf area (RLAT50 = -11.2 °C). Among the studied plant species, wheat (landrace Ghezel Khoushe) and feral rye with -11.8 °C and -11.6 °C, respectively, had the lowest temperature rducing 50% of shoot dry weight (RSDWT50), while the wild barley with -8.1 °C had the highest RSDWT50. The highest and lowest chlorophyll content (SPAD) among the living plants were observed at +4 and -12 °C, respectively, and  feral rye with 19.5 and wild barley with 10.3 SPAD unit showed the highest and lowest chlorophyll content, respectively. The results of this study showed that high tolerance of feral rye to freezing stress is probably one of the main reasons for its widespread distribution in winter wheat fields. Therefore, it is necessary to predict dispersion and possible invasion and consequently appropriate strategies to manage this weed in areas with cold climates.

The nutrient management is one of the most important factors in relation to quantitative and qualitative characteristics of saffron (Crocus sativus L.). In order to investigate the effects of different of cow manure and fulvic acid levels on yield and vegetative characteristics of saffron, an experiment was conducted as factorial based on a randomized complete block design with three replications at the Agricultural Research Station, University of Birjand during growing season of 2015. Treatments were four levels of cow manure (0, 10, 20 and 30 t.ha-1) and three fulvic acid (0, 5 and 10 kg.ha-1). . Results showed that cow manure improved the saffron flower characteristics (flower number and fresh total yield and stigma yield). The highest flower fresh total (6.289 g.m-2) and stigma fresh (0.299 g.m-2) yield were obtained in plants treated with 10 t.ha-1 cow manure, while the lowest values were recorded in control (5.18 and 0.235 g.m-2). Leaf photosynthetic pigments (chl a and total) were influenced by cow manure. Results also showed that fulvic acid has a positive effect flower number and fresh total yield, stigma yield and average weight and SPAD. The highest of flower number (17.29 per.m-2) and SPAD (14.39) were observed in 10 kg.ha-1 fulvic acid. Application of different levels of cow manure and fulvic acid had a positive effect on the flower fresh total yield, stigma, total chl and SPAD. The highest of stigma dry yield (0.085 g.m-2) were obtained in plants treated with 10 t.ha-1 cow manure and 5 kg.ha-1 fulvic acid. Thus, results showed that cow manure and fulvic acid have significant impact on flower yield and photosynthetic pigments of saffron.

To study the effect of chemical fertilizer and chicken manure on yield and yield components of rice cv. Hashemi, a field experiment was conducted in randomized complete block design with three replications at Rice Research Institute of Iran (RRII), Rasht, Iran, in 2017. The studied fertilizer treatments were chicken manure (33 t.ha-1), chemical fertilizer (recommended by RRII) and control (no-fertilizer). The studied traits included grain yield, 1000-grain weight, filled grain percentage, number of total tiller per plant, number of fertile tiller, SPAD value, stomatal conductivity and some growth indices. The results indicated that the highest grain yield (3664 kg.ha-1), 1000-grain weight (23.31g), filled grain (96.6 %) and total dry matter (900 g.m-2) were obtained from chemical fertilizer. In contrast, the use of chicken manure produced the highest flag leaf length (40.6 cm) and the highest net assimilation rate (4.6 g.m-2.day-1). Application of chicken manure caused the leaf area index (LAI) to decrease than other treatments. The highest specific leaf area (SLA) was observed in chemical fertilizer. SLA was less in chicken manure at the beginning of the growth period, but over time and reaching next growth stages, it approached to chemical fertilizer. The highest LAI and leaf greenness (SPAD value) obtained from chicken manure application, but the highest stomatal conductivity was observed in chemical fertilizers. According to results of this research, although the application of chemical fertilizers more increased the yield and improved the yield components than chicken manure, but application of chicken manure could be improved the net assimilation rate (NAR), flag leaf length, LAI and SPAD than chemical fertilizer. Probably due to the more greater value of nutrients in chemical fertilizer than chicken manure, the yield produced by chemical fertilizer was higher than chicken manure. In total, according to the harmful environmental effects of chemical fertilizer and the not-significant reduction of grain yield of rice cv. Hashemi in chicken manure treatment, chicken manure instead of chemical fertilizer is recommended.

IntroductionCanola (Brassica napus L.) is one of the most important plants to produce edible oil in Iran and in the world and also one of the negative factors for crop plants is the relative salinity of irrigation water in some areas of Iran. According to the researchers, salinity incorporates high concentration of minerals that prevents plant growth. Effects of Salinity significantly in arid and semi-arid areas, areas with limited rainfall, high temperatures combined with high evaporation with high chemical fertilizers, and poor water and soil management, is observed and is an important crop production problem in these areas. Zeolites are a group of natural porous minerals that acts as a molecular sieve with its crystal structure practices and allow some passage of some ions and block the passage of some others, due to open channels in their ionic lattice. Due to zeolites high porosity and stems from its crystal structure, they can absorb up to 70% of bulk with water. Recent research on various applications of zeolites in crop plants as well as its effect on the process of how to prevent the entry of toxic ions such as sodium and absorption of essential nutrients has been concentrated crop and the interaction effect of the two substances necessary to appear on canola This experiment intends to determine the ways of control damage caused by 5 and 10 10 ds m-1 salinity on yield and yield components on four canola cultivars with application of 8 ton hec-1 zeolite.
Materials and methodsThe experiment was conducted as split plot factorial in randomized complete block design with three replication at the greenhouse research station of Agricultural Faculty of Tarbiat Modares University started in autumn 2013 and at the end of spring 2014 greenhouse operation was ended. Treatments were salt stress from beginning of flowering at three levels included control, 5 and 10 ds m-1, zeolite application with two levels included control and 8 ton hec-1 and varieties with foul levels Zarfam, Sarigol, Hayola and RGS. From 29 October 2013 (sowing) to 20 May 2014 (harvesting), Greenhouse environment was with normal light and temperature conditions. The soil of pots was sand mixed with field soil in ratio of 1:1. Applied zeolite was clinoptilolite. To creation of appropriate drainage and prevent the accumulation of salt, three holes with one centimeter diameter was generated at the bottom of each pot. Salinity was started by adding salt mixture to irrigation water, before flowering. The final salt was mixed with salt water of Tehran, Gom and Kashan wells with ration of 2:2:4:3:4 and after standardization calculated with electrical conductivity meter and finally the salt water was transferred to each pot with graduated containers. On this experiment grain yield, yield components, yield and oil percentage and SPAD were measured. Mean comparisons were performed by LSD test using in SAS 9.2.
Results and discussionThe results showed that the effect on all traits except harvest index was significant, and none of the treatments had no significant effect on oil percent Number of grain per pod, and salt stress did not affect harvest index and zeolite on grain yield, number of pods, number of grain per pod, harvest index and greenness significant effect. Results showed that application of zeolite increases grain yield 9 and 26 percentage in control and average stress levels of RGS. But in severe stress condition because of severe prevent water absorption by increasing the osmotic potential into the roots environment, had not significant effect on experimental varieties. Application of zeolite in control condition and non-application of zeolite in severe stress on Zarfam number of pod were the highest and lowest with the difference of 36 %, respectively. Sarigol in control condition and Zarfam in severe showed the highest and lowest of 1000 grain yield with the difference of 22 %, respectively and RGS in control condition and Hayola in severe showed the highest and lowest of number of grain in pod with the difference of 54 %, respectively. It was also observed that application of zeolite in control stress condition on RGS and non-application of zeolite on Hayola in severe stress condition showed the highest and lowest of dry weight with the difference of 50 %, respectively. Results showed that, Sarigol in control condition of salt stress and zeolite was the highest of oil yield compared to Zarfam in condition of severe stress and non-application of zeolite with 66 percentage. Results of the experiment was shown, Zarfam in average stress and non-application of zeolite showed the highest amount of SPAD compaire to the same variety in severe stress and non-application of zeolite with more than double.
ConclusionsApplication of Zeolite increases grain yield of Zarfam and all three levels of salinity reduces this trait in canola varieties, significantly. Due to the low price (500 rials per kg) of zeolite and abundance of this mineral in our country, it can be used to prevent performance degradation of the material used in high salinity lands. Sarigol showed higher values of SPAD index than other cultivars, in terms of salinity and application of zeolite prevent the reduction of SPAD index values in terms of stress.

The effects of applications of nitroxin and vermicompost on indicators of growth, flowering and chlorophyll of saffron were evaluated under field conditions. Treatments were there levels of nitroxin (0, 5, 10 liters.ha-1) and four levels of vermicompost (0, 5, 10 and 15 tons.ha-1). This experiment was carried out as factorial based on randomized completely block design with three replications in research farm of Birjand University, Iran, n two growing seasons of 2015 and 2016.The traits such as number of flowers and yield of fresh flowers and the dry stigmas. Leaves components (number, length and fresh and dry weight) and its pigments (chlorophyll a, b, total and SPAD) were studied. Number, flower yield and dry stigmawas influenced by nitroxin treatments.So that in the first year and the second Respectively The highest number flower (8.75 , 45.33 per Per.m-2), flower yield (2.76, 13.04 g.m-2),and dry Stigma yield (0.006, 0.03 g.m-2) was obtained in plants treated with 5 liter.ha-1 nitroxin,while the lowest values was recorded in the control. Results showed that nitroxin improved the leaf growth indices (number, dry Stigma yield, length, and fresh weight of leaf) and photosynthetic pigments (chl a, b, total chl and spad). Application of different levels of vermicompost had a positive effect on the leaf number, leaf length, fresh and dry weight of leaf and chlorophyll a, b, total and spad. The highest chlorophyll b, total and SPAD was obtained in plants treated with 10 tons.ha-1 vermicompost while the lowest values was recorded in the control. Interactive effects of nitroxin and vermicompost have a positive effect on the dry Stigma yield, number and length leaf of leaves, chlorophyll a, b, total and spad. Thus, results showed that nitroxin and vermicompost have strong impact on quantitative and qualitative characteristics of saffron under field conditions.

Chlorophyll, RWC, electrolyte leakage and seed performance of three maize hybrid varieties under draught and chilling stress conditions were examined. The experiment was carried out in split-split plots using random completely blocks design with three replications in 2013-2014 in research farm and greenhouse Mashhad University of Ferdowsi, Agronomy Faculty. The main plot was chilling stress at two levels (present and absence of chilling stress); the subplot were drought stress at three levels (100% irritation, 75% irritation, and 50% irritation); sub-subplot was maize hybrid variety (single cross 704, single cross 400, and single cross 260). Results showed that stress conditions affected SPAD so that draught stress declined RWC and stability of cytoplasm membrane. The highest RWC and stability of cytoplasmic membrane were seen in single cross 260 and 400. Mutual effects of the treatments showed that the chilling and 100% irritation single cross 704 treatments had the highest SPAD. In addition, SPAD, RWC, and electrolyte leakage at the end of season decreased relative to the emergence time of male inflorescence. In presence of chilling and draught stresses, single cross 400 had higher performance comparing with the two other hybrids. This, in turn, indicates better performance of such treatment comparing with the other hybrids.

There are different methods for crop fertilizing nowadays. This study was conducted to assess effects of soil nitrogen on sugar beet traits such as chlorophyll content (SPAD) and also possibility of use of SPADfor sugar beet varieties differentiation as well as a distinguishing lack of nitrogen. A factorial experiment based on completely randomized blocks design with four replications was conducted. The first factor was domestic (Zarghan) and foreign (Flores) sugar beet cultivars and second factor was four nitrogen levels (control, 70, 100 and 130 kg N ha from urea). Sugar content, root and white sugar yields, SPADand application of nitrogen fertilizer of Flores were more and its petiole total nitrogen was less than Zarghan. The most percentage of root yield increase in both varieties was observed in application of 100 kg/ha.in comparison with control treatment. There were positive and significant correlation between sugar beet root yield with blade and petiole total nitrogenand radiation absorption during harvest time and also between root and white sugar yield with SPAD at 8-12 leaf growth stage (June) and also SPAD with blade total nitrogen at the same time. So SPADcould be used in sugar beet establishment growth stage for evaluation of nitrogen status and also for sooner line and hybrid selection. If the value of chlorophyll meter in the bottom of fifth leaf was lower than 45 at establishment, root yield would be increased by nitrogen fertilizer application. Also sugar beet selection would be faster by calibration of this method.

IntroductionSalinity is an important abiotic stress that reduces the crop production potential and the efficiency of plants in arid and semi-arid regions. Soil salinity can be increased by irrigation, inappropriate drainage, sea advancement to coastal regions and the accumulation of salts in desert and semi-desert regions. Salinity is a limiting factor for plant growth because it limits the feeding of the plants through reducing the uptake of P, K, nitrate and Ca and increasing inter-cellular ion concentration and osmotic stress. In addition to its adverse impacts on the yield and yield components of crops, salinity affects most processes involved in the growth and development of the plants too.
Materials and MethodsThe present study was conducted in research greenhouse of Department of Agriculture, Birjand University in 2013 on the basis of a Randomized Complete Block Design with four replications. The soil salinity treatments included five levels of 1, 3, 5, 7 and 9 dSm-1. Soil texture was loam-sandy with the pH of 8.09 and EC of 1 dS m-1. The irrigation water was filtered with EC Results and DiscussionIt was found that salinity level significantly influenced all measured traits. Salinity slightly increased SPAD index and adversely affected leaf relative water content (RWC), electrolytes leakage and grain yield, so that the highest level of salinity resulted in 17.7% lower RWC, 27.7% higher electrolytes leakage, and 59.8% lower grain yield per plant. Under salinity stress, plants reduce their leaf area to counteract the stress resulting in greater thickness of the leaves, the accumulation of more chloroplast per unit leaf area and the increase in leaf chlorophyll content. As a result, the leaves turn darker and SPAD index increases. Leaf relative water content is one of the photosynthesis-related indices in crops with is closely related to the yield. Membrane stability is a physiological trait that is influenced by environmental stresses. Higher accumulation of hydrogen peroxide and lipid peroxides due to salinity reduces membrane stability. Salinity stress causes the production of active oxygen species which is followed with the leakage of cellular membrane. One effect of salinity is on grain yield through changing 1000-grain weight. Lower 1000-grain weight can be associated with shorter grain filling period in salinity treatments and also with lower synthesis of assimilates. On the other hand, the changes in the pathway of assimilate partitioning to roots for counteracting the salinity can be another reason for lower dry weight of the grains. As well, salinity enhanced the activities of antioxidant enzymes in peas. It was revealed that the increase in salinity level from 1 to 7 dS m-1 increased the activity of enzyme catalase (CAT) by 63.79% and further increase to 9 dS m-1 resulted in the loss of its activity. The activity of enzyme superoxide dismutase (SOD) increased up to the salinity of 5 dS m-1 (by 57.22%), did not change up to 7 dS m-1 and decreased at 9 dS m-1. The highest salinity levels as compared to control increased the activity of enzyme ascorbate peroxidase (APX). The highest effects of salinity on the measured traits of peas were observed at the level of 7 dS m-1. As the first defense line, superoxide dismutase converts superoxide to hydrogen peroxide. This enzyme is capable of converting superoxide ions into oxygen and hydrogen peroxide and is active in Glyoxylate cycle. The detoxification of hydrogen superoxide is complemented with ascorbate peroxidase, thioredoxin peroxidase, glutathione peroxidase and catalase. Ascrobate peroxidase is an important enzymetic antioxidant in plants whose function is to detoxify H2O2 with ascorbic acid.
ConclusionsIn total, the examination of the effect of different levels of salinity on the measured traits showed that salinity did not significantly affect SPAD index of peas. It had negative impacts on physiological traits and reduced grain yield. In addition, it increased the activity of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) as salinity was intensified. A look at the status of the activities of antioxidants revealed that they were increased with salinity. It seems that this increase played a role in counteracting the adverse effects of salinity so that their decrease deteriorates the effects of salinity stress of plants. In total, the application of these levels of salinity indicated that peas are moderately sensitive plants to salinity, particularly salinity stress level of >7 dS m-1.

In terms of production and area under cultivation, wheat is the most important crop in Iran. Weeds problem is possibly the mostserious agricultural problems in the wheat growing regions of the world (Kafi et al., 2005). Rye as an annual plant with long stems is frequently seen as weed in wheat fields around our country (Krimi, 2004). Low environmental demands and allelopathic ability of rye accompanied with similar morphology and life cycle to wheat has increased its stability and occupied area in winter wheat fields (Pester et al., 2000). Competition is one of key issues in ecophysiological debates of plant communities. In competition as a type of Interference, weeds compete for light, water and nutrient resources with neighbor crops and thereby affect growth, development and yield of them (Evans et al., 2003). Considering the severe restriction of water resources in most regions of our country, drought stress is the most important stress, affecting crops (Kafi et al., 2009). Both resource availability and environmental conditions affect the result of a competition. Weed competition for water decreases soil water content which could finally causes water stress and reduces weed growth and crop yield. There are few studies about mechanisms of competition for water. Most of these studies have been implemented under controlled conditions. Nevertheless, these studies have led to an insight intothese possible mechanisms of competition for water (Zand et al., 2004).
In order to study the effect of inter and intra-species competition on morphological and growth characteristics of wheat (Triticum aesativum L.)and rye (Secale cereale L.)under drought stress conditions, a pot experiment was conducted in the greenhouse of college of Agriculture at University of Birjand in 2012. The experiment had factorial arrangement based on completely randomized design with three replications. The factors were wheat density (0, 8, 16, 24 plants/pot), rye density (0, 2, 4, 6 plants/pot) and drought stress (irrigation at 20 and 60% moisture depletion of field capacity). Number of leaves and their SPAD index in wheat and rye were measured at the time of spikes emergence of wheat, while plant height, peduncle and cluster length and stem diameter of wheat were measured at 95 days after planting (the end of the growing period).
Results showed when density of wheat and rye increased, height (maximum of 23.51% and 13.39% in wheat and 24.45% and 6.56% in rye respectively), leaf numbers (35.80% and 30.73% in wheat and 71.37% and 31.71% in rye respectively) and SPAD (12% and 11.38% in wheat and 13.75% and 0.38% in rye respectively) were significantly decreased. Drought stress also significantly decreased the height and leaf number of wheat (17.58% and 8.48% respectively) and rye (7.64% and 26.75% respectively) and significantly increased the SPAD index of wheat and rye (20% and 7.78%, respectively). Increasing of drought stress however had not effect on cluster length, significantly decreased the peduncle length (26.03%) and stem diameter (3.49%). When the rye and wheat density increased, length of wheat cluster (maximum of 13.70% and 24.21% respectively), length of wheat peduncle (maximum of 17.39% and 22.72% respectively) and wheat stem diameter (maximum of 11.11% and 18% respectively).
Result totally showed that in drought stress conditions, intra specific competition had just significantly affected on SPAD index, but inter specific completion had significantly affected on both SPAD index and leaf number of wheat and height and leaf number of rye. Simultaneous presence of drought stress and plant competition resulted in severe reduction of these traits with a further reduction in wheat compared to rye. Accordingly, in the wheat fields where rye is considered as an important weed, the damage of this weed is even higher when drought stress occurs and therefore, controlling this weed in water limited conditions is of major importance.

Pumpkin is one the most important cultivated medicinal plants. Because of high quality oil it uses as edible and herbal medicine. To find out the effects of different rates of pelleted animal manure and urea levels and some micronutrients on morphophysiological characteristics and oil yield of medicinal pumpkin, a split plot experiment based on RCBD with three replicates was conducted at the Research Farm of Abouraihan Campus, University of Tehran. The pelleted animal manure and urea with four levels (150 kg urea, 50 kg urea.5 tone animal manure, 100 kg urea.5 tone animal manure and 150 kg urea.5 tone animal manure) were considered as the main plot and micronutrients with three levels (1000, 2000 and 3000 (mg. kg-1); including iron, zinc, manganese from a chelate source and boron from boric acid source) were considered as sub plots. results showed main factor had significant effect on plant height, sub branches, female flower, oil percentage and oil yield (p0.01). 150 Kg Urea.5 tone animal manure as pellet had most oil yield (481.8 kg.h-1). 2000 mg. kg-1 of micronutrients had most female flower (5.14), oil percentage (46.5%) and oil yield (431.6 kg.h-1).Overall results showed applying 150Kg Urea.5 tone plleted animal manure with 2000 (mg.kg-1) of micronutrients could be suggested as the best option for achievement of the best morphophysiologial characteristics and oil yield of pumpkin medicinal plant.

Water is the most important factor for production of agricultural crops. Adequate water supply is necessary to obtaining maximum productivity of horticultural crops (Jones and Tardieu, 1998). According to Global Circulation Models precipitation scarcity might become worse in the near future over the world. Severe drought periods might decline yield and quality of crops (Delfine et al., 2005). Unfortunately, water deficiency is increasingly becoming a serious problem in agriculture in Iran whereas the national average annual precipitation is less than 249 mm (Baghalian et al., 2011). Therefore in our country, production of agricultural crops always accost many problems because of water scarcity (Hassani et al., 2009). Thus it is important to understand to what extent water stress impairs plant growth and yield in alternative crops (Delfine et al., 2005).
Plants respond quickly to water stress in order to prevent the photosynthesis. Stomata closure in response to water deficit stress primarily results in decline in the rate of photosynthesis.
Photosynthesis limitation causes growth and yield decreasing (Alaei et al, 2013).
Shortage of water in arid and semiarid regions of the world can reduce growth and production of medicinal and aromatic plants, especially Mentha species. Frequent irrigation is necessary during mint plant growth, as mentha species need moist soil conditions in the 100 centimeters of soil where rhizomes are located. This layer of soil has the greatest root density and always must be kept moist (Mitchell and Yang, 1998). But excessive irrigation may decrease mints yield because of limitation of oxygen for plant roots, promoting root diseases, leaching of plant nutrients especially nitrogen and losing more leaves than normal (Mitchell, 1997). According to the results of statistical analysis of Alaei et al (2013), irrigation treatments had significant effects on growth and yield of Dracocephalum moldavica. In this experiment as the amount of irrigation water declined, the plant height, leaf area, leaf number, fresh and dry weight of root and shoot, root length, branch number, and yield per pot decreased. This was while root to shoot ratio, and days to first bloom, first flower and first fruit increased. Study on effects of water deficit stress on Balm (Mellisa officinalis L.) showed that the effect of this stress on shoot yield, leaf and stem yield, stem height was significant at 1% probability level. This was while the number of lateral stem was not significant (Ardakani, 2007). Petropoulos et al., (2007) showed that parsley growth (foliage weight, root weight and leaf number) was significantly reduced by water stress, even at 30-45% water deficit levels. Water deficit has been revealed as effective on growth parameters, yield and biomass. Water stress has decreased plant height, number of secondary branches, dry and fresh weight of shoot, root mass, dry and fresh weight of root and length root (Babaee, 2010). The study on the effect of different levels of water stress on moldavian balm demonstrated that there was not a significant effect of water stress on leaf area and number of leaves, but it was significant on fresh and dry herb (Gholizadeh, 2007).
Material and In order to evaluate response of three Mentha species to water deficit stress, an experiment was carried out in a factorial-randomized design with five replications in controlled conditions and Mentha longifolia (wildmint), Mentha spicata (spearmint) and Mentha piperita (peppermint) species were subjected to four soil moisture regimes (100 (control), 80, 60, 40 of field capacity (FC)) and studied characteristics were included percent of survival, number of branches and stolon, number of leaves, length of branches and relative chlorophyll content were measured every ten days Besides all characteristics that were mentioned before, total dry weights were determined after both harvest.
The results showed that soil moisture treatments had significant effect on survival of three mint species. Trends of branch’s number and length and number of leaves indicate that adequate soil water could achieved better growth in wildmint than two other species in control and 80% of FC, but number and length of stolon in peppermint were significantly excel as compare as two other species in all treatments. However reduction of soil moisture to the 60% of FC severely decreased number and length of branches, number of leaves and number and length of stolon in all species, but spearmint had better growth in this treatment. There were low differences among SPAD of these species in control treatment, though spearmint’s SPAD was higher than two other species in 60 percent of FC in whole growing season. Total dry weight of spearmint in 80% of FC was 31 percent lower than control treatment, while in peppermint and wildmint 40 and 61 percent reduction were observed, respectively. In 60% of FC leaf dry weight of peppermint and wildmint were 92 and 96 percent lower than control, but in spearmint the mentioned parameter in this treatment was 66 percent lower than control treatment.
Water deficit stress reduced growth characteristics of all three species, but growth of spearmint in 20 and 40% deficiency of soil water (as compare with control) was better than two other species. Although spearmint was more tolerant than two other species to water deficit stress, but more study must be achieved for better understanding of mint responses to water deficit stress.
Our results regarding the effect of water stress on dry weight were in coincidence with those reported by Simon et al., (1992) in basil; Ardakani (2007) in balm; Johnson (1995) in Spanish thyme and Safikhani (2007) in moldavian balm who confirmed that water deficit could affect yield by decreasing growth.

To study the effect of humic acid and drought stress on some physiological characteristics of roselle (Hibiscus sabdariffa) an experiment was conducted in the research field of Agricultural Education Centre of Jiroft in 2013. Field experiment was carried out as split plot design with three replications. Water deficit stress as main factor with three levels (A1 = Irrigation after 50، A2 = 100 and A3 = 150 mm evaporation from pan class A) and humic acid was sub plots in four methods of application (B1 = non humic acid، B2 = with irrigation، B3 = with irrigation + once spraying، B4 = with irrigation + twice spraying). Humic acid was used with irrigation at 10kg/ha and for spraying at 250ml/100l. Drought stress had significant effect on chlorophyll a، chlorophyll b، carotenoids، relative humidity content and proline of roselle leaves. Interaction effect of humic acid and drought stress was only significant for total chlorophyll and soluble carbohydrate. Drought stress decreased chlorophyll a (48. 22 percent)، chlorophyll b (32. 77 percent)، carotenoid content (79. 64 percent) and relative humidity (12. 59 percent)، while increased proline content (12. 59 percent). Humic acid increased chlorophyll a، chlorophyll b and carotenoids but reduced proline content (15. 04 percent).

To study the effect of IAA and Kinetin phytohormones on the improvement of drought tolerance in rice seedlings (Oryza sativa L.), an experiment was carried out as factorial experiment with three factors based in completely randomized design with three replications in Agricultural Science Faculty, University of Guilan, Rasht, Iran, in 2013. The experimental factors included: 1: four rice genotypes; Gharib, Khazar, Sepidrood and Upland (IR 83750-131-1), 2: drought stress condition; control (non-stress) and drought stress from 1 to 4 of Vergara coding system and 3: hormone in three levels; control (without hormone application), IAA (5×10-5 M) and Kinetin (5×10-5 M) as foliar application. Tiller No., day to leaf rolling, leaf temperature, relative water content, electrolyte leakage, SPAD value and chlorophyll fluorescence parameters were measured. Analysis of variance indicated that all studied traits were significantly affected by all experimental factors and their interactions. Sepidrood cultivar had the highest relative water content RWC in drought condition (46.3%). The lowest relative water content (34.5%) belonged to cv. Gharib in drought stress condition. Application of IAA in both control and drought stress conditions increased RWC to 92.4% and 43.7%, respectively. In non-stress condition, Upland cultivar had the highest relative chlorophyll content (47.1%). The lowest SPAD value (30.6) belonged to Gharib in drought stress condition. IAA and Kinetin hormones increased the leaf relative chlorophyll content in Gharib cultivar to 18% and 13.7%, respectively. Drought stress without hormone application increased electrolyte leakage (32.1%). The lowest electrolyte leakage 16.3%) was observed in Sepidrood cultivar in non-stress condition. The highest photosystem II quantum efficiency (Fv/Fm) was 0.81 which belonged to Khazar cultivar in non-stress condition and IAA application. Results of this experiment indicated that the application of IAA and Kinetin hormones improved the drought tolerance related traits in rice seedlings under drought stress conditions. IAA had more effective role than Kinetin in improving drought stress tolerance in rice seedlings. Also results indicated that the Upland and Sepidrood rice cultivars were more tolerant than Gharib and Khazar. Generally, upland cultivar was more responsive to IAA application under drought stress condition.