CROP PRODUCTION IN ENVIRONMENTAL STRESS
Year:2010 | Volume:2 | Issue:1-2 (SERIAL 4)|Papers Count:8

This experiment was conducted to study the effect of different Irrigation levels on yield and water use efficiency (WUE) of four varieties of rapeseed in Karaj during 2003-2004. The experiment was a randomized split-plots as complete block design with three replications. Irrigation levels including, 50, 75, 100 and 125 percentage of water requirement were considered as a main plots and four varieties: Licord, SLM046, Okapi and Reg Cobra as sub plots. The water requirement calculated on the basis of meteorolgicale data using Penman-Monteith method. ANOVA and averages comparison indicated as blow: Irrigation levels, varieties and interaction effects were not significant at 5% on plant height. Irrigation levels effect was significant at 5% level on branches numbers per plant. The interaction effects were significant in 5% level on seeds number per pod. The irrigation levels and varieties effects were not significant at 5% level on 1000 seed weight. The effect of irrigation levels and varieties on gratin yield were significant at 1% level. The irrigation with 75% water reopurement 2727 kg/ha yield was maximum and the level of 50% with 1912 kg/ha was minimum respectively. Although, Reg Cobra variety with 2783 kg/ha and Licord variety with 2132 kg/ha were maximum and minimum respectively. The interaction effects were significant at 5% on seed yield. The 75% Irrigation level in variety Reg Cobra with 3229 kg/ha and the 50% level in variety Licord was minimum of yield. The irrigation Levels and variety effects on WUE was significant at 1% level. The 75% level with 1.114 and the 50% level with 0.684 kg/m3 were maximum and minimum respectively.Water use efficiency of level 75% was 62.86% more than level 125% with 99% probability. Reg Cobra variety with 1.064 kg/m3 and Licord variety with 0.826 kg/m3 were maximum and minimum respectively. Water use efficiency of Reg Cobra variety was 28.8% more than of Licord variety.

In order to investigate the effect of sowing date and different nitrogen levels on quality and quantity characteristics of Linseed, an experiment performed in split plot in form of Randomized Complete Block Design, with 4 replication and during 2005-2006 and 2006-2007 in Yasouj Agriculture Research Station.5 sowing date included 10 March, 1, 10 and 20 April and 1 May in main plots and 4 fertilizer levels in subplots included 0, 50, 100 and 150 kg/ha pure N from urea fertiliser that 50% was applied at sowing and 50% as top-dressing. The results of 2-year analysis of data indicated that with delayed sowing, plant height, number of branch, number of fruits, grain yield, 1000 seed weight, leaf area index, dry mater, crop growth rate and oil percentage were reduced significantly. The use of 100kg/ha N significantly increased plant height, number of branches, pod of fruits, grain yield, leaf area index, dry mater, crop growth.First sowing date with 1801.12 kg/ha had the most yield and fifth sowing date with 760.48 had the least yield. The most and the least yield rate of grain in 100kg/ha N and control were 1895.22 and 1351.87. The most oil was 34.6% that obtained in the first date of sowing. The first sowing date with 52.38% produced the most and the fifth sowing date with 50.58% produced the least acid linolenic. The sowing date had no significant effect on acid oleic and acid linoleic. The most acid linolenic 52.64% and acid linoleic 15.36% were obtained by the use of 150 kg/ha N and the most acid oleic 20.59% were obtained without N.

In order to study allelopathic effect of canola residues on growth of corn two greenhouse and laboratory experiments were conducted. The design of experiment was randomized complete block design in factorial with 12 treatments and four replications. The treatments were residues in four levels (0, 0.07, 0.09, and 0.11) and time of residues maintenance in three levels (planting at the same time mixing residues with soil, 15, and 30 days afterwarth. The laboratory experiment based on randomized completely design with four replications. The treatments were four concentrations extract (0, 5%, 10%, and 15%) of canola residues. The reasults showed in first week that planting at the same time mixing residues with soil deacreased stem length (2.05-3, 43 cm), root length (6.35-8.03 cm), root dry weight (0, 15, 0, 23 gr), stem dry weight (0.03 gr), root/stem dry weight ratio (0.63, 1.11units), In the second week decreased stem length (4.3 cm), root dry weight (0.15-0.19 gr), stem dry weight (0.079-0.102gr), in the third week decreased stem length (5.32-7.89 cm), stem dry weight (3.07, 4.93gr), root volume (0.3 cm3), root/stem dry weight ratio (0.23unit), in forth week decreased root length (11.56-13.38 cm), root volume (4.36-6.01cm3), stem dry weight (0.75gr), root/stem dry weight ratio (0.29-0.37 units). The effect of residues was notsignificant.So the interaction between planting date and residues in all four week was not-significant. Results of laboratory experiment showed that effect of canola extracts on germination and the time to 50% germination was significant.

In ording to investigate the effects of irrigation intervalson different varieties of canola in Jiroft, an experiment was conducted in split plot design in the scheme of completely Blocks Randomized Design with three replicates. This study was conducted in Agronomic season of 1385 – 86. Irrigation levels (I1: 40, I2: 60, I3: 80, I4: 100 and I5: 120 milimeter evaporation from class A pan unit) as main plot and Varienties (V1: Hyola 401, V2: Hyola 308 and V3: Sarygol) as sub plot. The results revealed highly significant effect of different irrigation regimes on the canola yield and the highest grain yield (2/424 ton per hectar) obtained at 40 millimeter evaporation from class A pan, also the varieties showed different response and the highest yield (2/287 ton per hectar) was obtained from Hyola 308. There was a non-significant different between interaction effects of two factors. Pod per plant showd highly significant defference basd on irrigation intervals and the plant cultivars.

In order to compare the efficiency of multivariate statistical methods (cluster analysis and Principal Component Analysis: PCA) with a new method known as "2- step screening method" for selection of wheat genotypes with high yield potential and good drought tolerance, this study was performed. For this, 180 hexaploid wheat genotypes were studied during 2005/2006 cropping season under two conditions of well irrigation and shortage of water (from anthesis on wards) in Karaj. Drought resistance indices including stress susceptibility index (SSI), tolerance index (TOL), mean productivity (MP), stress tolerance index (STI) and geometric mean productivity (GMP) were calculated for all investigated genotypes. Study of correlation coefficients among these indices and grain yield in two conditions for all genotypes showed that STI is better than other indices for screening genotypes with favorable yield in both conditions. But, because the STI value was still significantly affected by higher grain yield in normal conditions, identifying favorable genotypes followed using 3 methods. Study of grain yield under normal and stress conditions and tolerance indices showed that "2-step screening method" is more efficient than the other two methods. This method is based on completing cluster analysis with application of a defined cut off line for SSI index (through establishing a relationship between SI and SSI) to screen out stress susceptible genotypes among first step selected genotypes, hence suggested to be applied in breeding programs.

To study the interaction of Rovral-TS fungicide and Rhizobium bacteria on Fusariumroot rot of bean, study was conducted in a randomized complete design with four replications for two years (2007-2008) in greenhouse conditions. Treatments included 5 strains of Rhizobium, Rovral-TS fungicide, combinations of Rhizobium strains and fungicide, healthy and infected controls. Results indicated that all treatments of Rhizobium +Rovral-TS decreased disease severity and increased root dry weight, foliar plant dry weight and nitrogen content, as a result of improved plant growth. However these treatments had lower effect than Rhizobium treatments alone.Treatments of Rb-115+Rovral-TS and Rb-115 reduced disease severity by 33.5% and 42% respectively compared with control. Also the other treatments of combination of Rhizobiumand fungicide had lower effect on reducing disease severity and increasing plant growth compared with treatment of Rhizobium alone. Results of this study showed that fungicide may have adverse effect on activity of Rhizobium.

Ascochyta blight caused byAscochyta rabiei (Pass.) Lab. is the most damaging disease of chickpea worldwide. A sever epidemic of disease can totally destroy the crop. Finding resistant or tolerant cultivars is the best way of controlling this disease.In the present study, pathogenic diversity in A. rabiei was determined using 30 isolates collected from chickpea fields in East-Azarbayjan, Ilam, Kermanshah, Lorestan and Kohgiluyeh-Boyerahmad Provinces of Iran. The interactions between isolates of the fungus with seven differential chickpea lines (ILC-202, ILC-1929, ILC-194, ILC-5928, ILC-72, ICC-3996 and PCH-15) were studied to evaluate their virulence. A 9 point disease rating scale was used for greenhouse observations. In this study, virulence of 30 isolates of A. rabiei was determined and the isolates fell into 16 distinct groups when they were subjected to virulence assessment. The results indicated that a high level of virulence variability exists among A. rabiei isolates in Iran that should be taken into account for future breeding programs. In this regard, the line (ILC-72) was moderately resistant. This genotype is additional sources of resistance to be used in hybridization program to develop chickpea resistant cultivars. It would be desirable to use cultivars carrying non-race specific resistance gene to A. rabiei.

Sunflower requires favorable environmental conditions during plant vegetative growth and reproductive development stages to produce optimum yield. To study how oil sunflower seeds were changed by planting date and density, an experiment was conducted in a split plot as base of randomized complete block design in Seed and Plant Improvement Institute for two years. Planting dates interval were 21 days including of 19 May, 9 June, 0 3 June and 20 July and plant densities as 6, 8, 10 and 12 plants.m-2, set in main and sub plots, respectively. The results indicated that the year was not significant in measured traits except of total dry matter. Planting date had significant difference on all traits except of harvest index. Seed oil yield and TDM were affected by plant density at 1% probability level, but it had not significant effect on seed oil percentage and harvest index. Interaction of planting date and density was significant only on TDM. Therefore, planting date between May 19 to 9 june and 12 plants.m-2 was appropriate to get the optimal oil yield for sunflower new hybrid, CMS-26 ÍR-103.