Iranian Journal of Crop Sciences
Year:2006 | Volume:8 | Issue:3 (31)|Papers Count:7

In order to evaluate grain yield and associated characteristics in soybean (cv. Clark) under the conditions of drought stress and Bradyrhizobium japonicum strains, an experiment was carridout in 2003 & 2004 cropping seasons, using split plot arrangements based on randomized complete block design with three replications in Agriculture Research Statioin of Borujerd, Iran. Irrigation levels were assigned to the main plots (four levels); full irrigation, mild stress (85% plant water requirement), moderate stress (70% plant water requirement), severe stress (55% plant water requirement). Sub-plots were Bradyrhizobium japonicum strains (four levels); control, Helinitro, Rizoking, Nitragin. The amount of irrigation water was calculated using plant water requirement and the atmometer. At planting seeds were inoculated with bacterium strains. Biological yield, grain yield, harvest index and hundred grain weight was measured and determined. Results indicated that grain yield was different under stress and full irrigation conditions. In full irrigation condition maximum grain yield (458 g.m-2) and biological yield (870 g.m-2) were produced by Nitragin strain. Under stress conditions, the efficiency of strains was not different under mild and moderate stresses. Higher grain and biological yield obtained by Rizoking strain. Therefore, this strain had better adaptation to modrate drought stress condition, however in severe drought stress no difference among bacterium strains was observed.

Rice (Oryza sativa L.), a salt-sensitive species, has considerable genetic variation for salt tolerance within the cultivated gene pool. To evaluate salinity effect on ABA and IAA concentrations and distributions in different parts of two rice genotypes (IR29 and IR651, sensitive and tolerant, respectively) a green house experiment were grown in normal condition till 6th leaf was fully expanded. Seedlings were exposed to salinity, EC=12 dS m-1 and normal conditions (EC=1.65 dS m-1, Ushida solution base EC) for one week. Samples were taken 0, 4, 12, 24, 48, 96, 168 hours after application of treatments. Amount of ABA and IAA in different leaves, leafsheaths and roots were measured by HPLC. Results showed that ABA concentration in sensitive genotype was much higher than tolerant genotype. However, salinity stress had no significant effects on ABA concentration while rate of ABA transport from root to shoot significantly changed in IR651. IAA concentration was higher in tolerant genotype and its distribution change by duration of exposure. At the beginning in salinity treatment, IAA concentration of root and leaf sheaths of both genotypes had no significant difference, however as salinity stress increased, distribution of IAA in tolerant cultivar gradually changed and concentrated from roots and leaf sheaths to leaves, especially in older leaves.

In order to determine optimum seed density and sowing time of lentil (Lens culinaris Medik) in Northern Khorasan, this study was conducted in Shirvan field experiment station in Northern Khorasan in 2002-2004 growing seasons. There were four seed density levels: 50, 100, 200 and 400 seed/m2, and two sowing seasons: Winter (Entezary) and spring, arranged in a factorial experiment in randomized complete block design with three replications. During growing season, agronomic traits such as flowering date, plant height and physiological maturity date were recorded. After harvesting, 100 grain-weight and grain yield were measured and recorded. Results of combined analysis of variance indicated that there was significant differences between the grain yield of the crop in spring and winter (entezary) seasons. The highest grain yield belonged to 200 seed per m2 in Entezary sowing time (812 Kg/ha), that was a significantly different in comparison to the other treatments. These results recommend that in dryland conditions of Northern Khorasan lentil are to be grown as Entezary crop with 200 seed per m2.

Black cumin (Nigella sativa) belongs to Ranunculaceae family, is one of the most useful medicinal plants which grows wildly in some region of Iran inclucling; Kermanshah. Considering the importance of this medicinal plant, a study with main objective of determination of phonological development cycle of the plant, and to find the best row spacings, was carried out in 2000 in the Faculty of Agriculture of the University of Razi, Kermanshah, Iran. Effect of four row spacings (40, 50, 60 and 70 cm) were studied using randomized complete block design with four replications. The measured traits were as follows; plant height, the number of follicle per plant, the number of seeds per follicle, 1000 kernel weight, biological yield, grain yield, harvest index, oil, and essence percentage. Mean comparison for grain yield, using Duncan Multiple Range Test, revealed that when the seeds were planted in 40 centimeters row spacing, the grain yield was highest (660 Kg/ha), and was significantly different when compared with means of the other treatments. The average oil and essence percentages of seeds in this study were 28% and 0.148%, respectively.

An experiment was conducted to evaluate the effect of different levels of nitrogen and plant density on quantitative and qualitative characteristics of silage maize (cv. SC704) in Varamin experimental field station in three consecutive growing seasons (2000-2002). The experiment was arranged in split plot, using randomizd compble block design (RCBD) with three replications. Four levels of nitrogen induding; No nitrogen fertilizer (N0), nitrogen fertilizer equal to the recommended rate based on soil test (N180), nitrogen fertilizer 30% more than recommended rate and nitrogen fertilizer 30% less than recommended rate (N230 and N130, respectively) assigned to main plots and plant density at four levels; 70 thousand plant/ha (D70), 90 thousand plants/ha (D90), 110 thousand plants/ha (D110) and 130 thousand plants/ha (D130) randomized in sub-plots. Combined analysis of variance showed that different nitrogen levels did not significantly affect total dry matter yield, stem, leaf, cobb, protein yield, diameter and plant height. Plant density significantly affected ear and leaf dry matter yield at 5% probability level, and interaction of nitrogen and plant density was significant on ear dry matter yield at 1% probability level. The highest dry matter 10.2 T/ha was produced in D130, treatment. Total dry matter 11.4, 11.3 and 10.2 T/ha, leaf dry matter yield of 2.2, 1.2 and 1.3 T/ha, cobb dry matter yield 3.3, 3.4 and 3.4 T/ha and protein yield 0.9, 0.8 and 0.7 Kg/ha were recorded in N230D110, N230D130, N180D130, respectively. Hence, it can be concluded that by increasing plant density to more than 50% of recommended and using of nitrogen fertilizer equal to the recommended rates based on soil test, can increase yield of silage maize and its quality.

This experiment was conducted to study effects of inter and intra row spacing on yield and yield components of sering safflower line (Isfahan-24) in summer sowing in Isfahan at the Agriculture Research Station of Khorasgan Islamic Azad University, during 2002 cropping season. Three inter-spacing row (30, 40 and 50 cm) were assigned to the main plots and three intra-spacing row (5, 10 and 15 cm) were arranged in the sub-plots using a randomized complete block design with four replications. In this research traits as: number of heads per plant, number of grains in main and axiuary-heads, 1000 kernel weight, grain yield were measured and recorded. Results showed that the effect of inter-spacing row on traits such as number of heads in plant and 1000 kernel weight were significant. The effect of the inter-row spacing on the grain yield was not significant. The effect of intra-row spacing on the most of the measured traits were significant. Interaction of inter and intra row spacing on the most of meausured traits was not significant. It can be concluded that 30 cm inter row spacing with 5 cm intra row spacing between plants on the row is the best planting pattern for safflower under the conditions of this study.

Plant growth regulators are the most important internal regulatory agents that adjust plant growth and development in relationship to genetic and environmental conditions. Among the plant growth regulators, cytokinins (CK) and abscisic acid (ABA) not only regulating the process of senescence and remobilization, but also have major roles on formation of sink and source strength and capacity. This study carried out to determine effect of exogenous application of CK and ABA (50mM) on some physiological aspects of source and sink strength of two wheat cultivars (Marvdasht, Zagros), using a split plot arrangement based on Randomized Complete Block Design (RCBD) with three replications, in experimental field of the university of Tehran, in 2005-2006 growing season. Results showed that when these plant growth regulators applied at different stages of grain growth including cell division (CD) and grain filling (GF), grain yield, biomass, harvest index (HI), 1000 grain weight and grain no. spike-1, significantly changed. Application of CK at CD stage, led to higher grain yield, biomass and grain no. spike-1. However, ABA at GF stage and CK at CD stage increased HI and significantly affected soluble proteins, chlorophyll content, photosynthesis rate, stomatal conductance and ABA and CK concentrations in flag leaves. In contrary, exogenous application of ABA increased ABA concentration of developing grains, while had inverse effect on IAA of the same grains. It can be concluded that exogenous application of CK at cell division stage in grain growth phase may significantly improve biomass and grain yield.