CROP PHYSIOLOGY
Year:2010 | Volume:1 | Issue:4|Papers Count:12

The effect of irrigation time and Electric Conductivity (EC) of irrigation water have been investigated on wheat yield (Chamran cultivar) and its components in Shavour area, north of Ahwaz city in 2009. Objectives of this research studied are 1) The determination of the most suitable irrigation time in saline conditions 2) Study the effect of different water salinities 3) The study of interaction effect of irrigation time and water salinity on wheat yield and its components. The experiment was conducted as a factorial form, in a Randomized Completely Block Design (RCBD) with two factors and three replications. Three different levels of irrigation time were (I1) 30%, (I2) 50% and (I3) 70% soil moisture reduction from Field Capacity limit. Three levels of irrigation salinity were (S1) less than 2, (S2) 3-5, and (S3) 6-8 ds/m as well. The first and second factors were irrigation regimes and salinity in field conditions respectively. Results indicated that wheat yield under effect of different regimes of irrigation was significant (5%), whereas the effect of different levels of salinity on yield was not significant. Taking account of yield components, different regimes of irrigation were not significant on plant height, number of spikes per square meter and the length of spike; however it was significant for number of grains per spike and Thousand Grains Weight (TGW). Water salinity had no significant effect on yield and its components. The interaction effects of salinity and irrigation time were not significant on yield, TGW and number of grains per spike; however there was no significant effect on other factors. As a result, although two factors of irrigation time and water salinity had significant effect on soil salinity changes, however, the maximum soil salinity obtained from irrigation with different levels of salinity (6-8 ds/m) is related to I2S3 treatment that is the threshold of wheat salinity tolerance. Therefore yield reduction is not expected. Thus yield has been the only effective factor in making decision for the better treatment. According to studies, irrigation time due to 30% allowable depletion of moisture from Field Capacity limit has been optimum with only salinity level up to 8 ds/m (treatments I1S1, I1S2, I1S3).

In order to study the effect of N fertilizer and drought stress on biological yield, grain yield and yield components of different wheat cultivars, a factorial experiment in a randomized compeletely block design was conducted in 2003-2004 with four replications, at Islamic Azad University, Shushtar branch. The treatments included wheat cultivars (Chamran, Showa and Falat), N fertilizer in two levels (50 and 150 kgN. ha-1) and two levels of drought stress (without stress, and stress in grain filling stage). Chamran and Falat were bread wheats and Showa was durum wheat. Results indicated that in drought stress, Chamran had higher grain yield (5584 kg/ha) compared to Showa (5332 kg/ha) and Falat (4821 kg/ha). The increasing nitrogen caused an increase in grain yield by 45% compared to the treatment of lower consumption of nitrogen. Responseto N fertilizer in Chamran and Showa was more than that of Falat cultivar.Spike number in square meter, grain number per spike and thousand grain weight were effective in increasing grain yield.

In order to evaluate the effect of foliar application of iron (Fe) as a micro nutrient on quantitative yield of soybean genotypes, a split plot experiment was conducted in a randomized completely block design (RCBD) with four replications in a research farm of Azad university in Kamalvand region in Khoramabad city during 2009.Testing factors included foliar treatments, in three levels including control without foliar application= F1, foliar application (2/ 1000)= F2, and foliar application (4/1000)= F3 in 50% flowering, and podding. Utilized cultivars, included (V1=M9, V2=M9, V3=M7) In this experiment, the traits such as grain yield, biomass yield, thousand grain yield, pod number per plant, plant height, protein and oil percentage, were measured.Foliar application of iron fertilizer, caused an increase in grain yield, biomass yield, protein and oil percentage. There was no significant increase for traits such as thousand grain yield, pod number per plant, and plant height. It was specified that foliar application of iron fertilizer has improved the average increase of dry matter and grain yield of soybean genotypes significantly. Among three soybean genotypes, Genotype M7 had more biomass yield and pod number per plant, as it was considered that it would be possible to obtain more grain yield by use of appropriate genotypes and foliar application of 4/1000 iron fertilizer.

In order to evaluate the effects of density and the ratio of maternal to paternal lines of parent lines of maize single cross 704 on yield of seed production of maize hybrids and some agronomic traits, an experiment was conducted in the farm of seed production of Shahid Beheshti Agro-Industry company in Khuzestan province in a split plot form and in a randomized completely block design (RCBD) with four replications in 2009. Density (60000, 70000, 80000 and 90000 plants per hectare) was considered as a main factor and planting pattern of maternal and paternal lines in 6:2 and 4:2 was placed in subplots. Analysis of variance indicated that plant density had significant effects on ear number square meter, ear number per plant, and ear length, but it didn't have any effects on other traits. Mean evaluation of these three traits, indicated that ear number per square, ear number per plant, and ear length didn't have significant difference from 70000 to 90000 plants per hectare. The minimum ear number square meter was obtained 3.36 plants from 60000 plant density. Analysis of variance indicated that the proportion of maternal to paternal lines had only a significant effect on ear diameter, but it had no effects on other traits. Ear diameter decreased significantly with the increase of maternal line numbers. But their interaction was effective on ear number per plant and ear diameter. The highest direct significant correlation with yield was attributed to ear number square metre. Therefore the increase of grain yield is due to an increase of ear number per square which has compensated the yield decrease of each plant. The highest grain yield (2.8 ton/h) was obtained through the interaction of the highest density (90000 plants) with the most maternal line numbers (6 lines).

Considering the importance of medicinal plants, especially in drug industry and their shortage in nature, the study of different aspects of agronomy of these plants is of great value. Thyme is one of the most important medicinal plants that due to containing timol and karakerol, has benefits including antibloated antityphoid, antidiphtheria and antipulmonary poisoning. The salt and drought stresses are known to be important factors in yield decrease of this plant. In order to study the effect of salt and drought stresses, two experiments were conducted separably in a completely randomized design on Shirazian Thyme with four replications. The drought stress was applied in four levels with different osmotic pressures (0, 0.19, 0.41 and 0.99 Mega Pascal) using Polyethylene Glycol (Molecular weight 6000). Salt stress was also applied in four levels including 0, 30, 60 and 90 Mmol/Lit NaCl. After the exertion of treatments, counting of germinated seeds was continued daily for ten days, and characteristics such as germination percentage, germination speed, radicle and primary shoot dry weight, and radicle and primary shoot length were measured. The most germination percentage and speed belonged to control treatment (1.288) and the minimum belonged to 0.99 mega Pascal (1.058). There was a significant difference among different salt stress treatments for germination speed, radicle length and primary shoot length. The most reduction in germination percentage, germination speed, radicle and primary shoot length was observed in 90 Mmol/Lit NaCl. Obtained results indicated that drought and salt stress caused a significant decrease in germination percentage and germination speed, radicle and primary shoot length, as well as primary shoot and radicle dry weight.

This research was conducted in order to study of different levels of zinc sulfate and manganese sulfate micronutrient fertilizers, as a combined form, on three wheat cultivars in irrigated conditions in Abestan, (a part of Zagheh region located in Khoramabad city) during 2008-2009. The experiment was accomplished in a factorial form in a randomized completely block design (RCBD) with three replications. Treatments with three fertilizer levels included control treatment of no fertilizer (F1), zinc sulfate with 25 kg /ha plus manganese sulfate with 45 kg/ha (F2), and zinc sulfate with 50 kg/ha, plus manganese sulfate with 90 kg/ha (F3) in the soil- applied form on three wheat cultivars in irrigated conditions from cold regions namely Bahar (V1), Shiraz (V2) and Pishtaz (V3). The treatments were applied at the time of planting.Measured traits, included zinc and manganese contents of grain, protein percentage, protein yield and grain yield.Results indicated that maximum and minimum contents belonged to treatment F2 in Shiraz cultivar and control treatment in Bahar cultivar with 29.32 and 23.67 mg/kg respectively. On the other side, manganese contents in seeds indicated its most effect on treatment F3 in Bahar cultivar, with 67. 77 mg/ kg. The lowest amount was in control treatment in Bahar cultivar with 52. 33 mg/ kg. Besides, the most protein percentage of grain was attributed to treatment F3 in Pishtaz cultivar with 18.66 percent and the lowest, belonged to control treatment in Bahar cultivar with 12.41 percent. The highest protein yield in grain was attributed to the fertilizer treatment F2 in Shiraz cultivar with 1247 kg/h, and the lowest was attributed to fertilizer treatment (control) in Bahar cultivar with 840 Kg/h. It should be cited, that the highest grain yield belonged to fertilizer treatment F2 in Shiraz cultivar, with 7.383 ton/h, and the lowest belonged to control fertilizer treatment in Bahar cultivar with 5.794 ton/h.Therefore, the results indicated that with applying fertilizer treatments in a combined form in different amounts, an increasing trend could be observed in zinc and manganese contents in seeds of all cultivars used in the experiment, and in the case of protein yield and grain yield, they had direct relation, because the decrease or increase of each one will have a positive or negative effect on another.

In order to study of effect of different amounts of nitrogen and forage harvest time on grain and forage yield and remobilization of barely cultivar Jonoob, an experiment was conducted in a factorial form in a randomized completely block design (RCBD) in Ghalechenen, located in Kootabdollah in Ahvaz city during 2008-2009.The experiment treatments included four levels of nitrogen per hectare (60, 90, 120, and 150) in the form of urea fertilizer, and three forage harvest time including none- forage harvest, forage harvest at the time of stem elongation without reproductive meristem cut, and forage harvest at the time of stem elongation with reproductive meristem cut of main stem. The results indicated that forage harvest treatments had a significant reduction in grain yield compared to control treatment (none- forage harvest). Among the nitrogen fertilizer treatments, the most grain yield belonged to 120 kg pure nitrogen in hectare. Protein yield of dry forage had a significant increase with the increase of nitrogen application, but with a delay in forage harvest time, protein percentage decreased and its yield increased significantly. Obtained results of this experiment indicated that high amounts of nitrogen couldn’ t compensate the damage of delay in forage harvest time for seed production. The remobilization and current photosynthesis in both treatments of forage harvest decreased, as it was significant in forage harvest treatment in the middle of stem elongation. The increase of nitrogen fertilizer from 60 to 120 kg caused an increase of remobilization and current photosynthesis. According to measured compartments, it is said that nitrogen consumption with applying 120 kg pure nitrogen in hectare and forage harvest in the stage of stem initiation, had an appropriate preference for dual purpose planting (forage and seed) compared to other treatments.

In order to study the effect of tillage systems and weed control on wheat grain yield and yield components, cultivar Virinak, an experiment was conducted as a split plot form in a randomized completely block design with three replications in farms located in the south of Dezful, during 2003-2004. The main treatment was in two levels including weed control and without weed control. The secondary treatment was in three levels including conventional tillage, minimum tillage and no-tillage. Conventional tillage included a moldboard plow, disk, levelers and then planting by grain drill. Minimum tillage included one disk and then planting by grain drill. No-tillage included no tillage practices and planting by grain drill. and. disk was applied for the minimum tillage treatment. Post emergence topic herbicide (750 ml/ha), mixed with three beneron meteel herbicide (20 gr/ha) was applied. Results indicated that herbicides treatments, tillage systems and their interaction were significantly (1%) different on grain per spike and grain per spikelets. Besides, the difference between herbicide treatment in plant height and tillage systems treatment and the interaction between tillage and herbicide on Spikelet numbers per spike was significant. The interaction between tillage systems and herbicide on thousand seed weight were evaluated significantly (5%). The maximum and minimum grain yield belonged to conventional and minimum tillage respectively, but not significantly. Soil bulk density in tillage systems and the interaction of tillage systems and herbicide, were significant (5%), at the depth of 0-5 cm and 5-10 cm. The emergence percentages were significant in 7th, 10th, 11th, and 12th days. Conventional and minimum tillage systems indicated a significant difference for emergence speed, as the highest belonged to minimum tillage.