CROP PRODUCTION IN ENVIRONMENTAL STRESS
Year:2011 | Volume:3 | Issue:1-2 (SERIAL 6)|Papers Count:8

In order to evaluate the effects of water deficit on yield and some physiological traits of five corn varieties (SC108, SC500, SC647, SC700 and SC704) at both vegetative and reproductive stages, two separate field experiments were conducted based on Randomized Complete Blocks design with five replications in Kahriz agricultural research station at years of 2004-5 under normal and water deficit conditions with 75 and 150mm evaporation class A pan, respectively. Also, a second green house experiment based on Randomized Completely design with five replications was conducted to evaluate the effect of PEG8000 on seedlings of corn varieties. Results showed that grain yield was significantly decreased under drought stress. Maximum variation percentage for Brix Coefficient, Electrical Conductivity and Potassium Accumulation was 49.48, 51.31 and 106.51, respectively. Maximum and minimum grain yield under water deficit conditions were devoted to SC704 (305.54g/m2) and SC108 (143.01g/m2), respectively. Results of green house experiment, also, showed that PEG8000 significantly decreased radical and plumule lengths and dry weights of them. In this study, hybrid SC500 due to more radical and plumule dry weights was characterized the most suitable variety under water deficit during seedling stage.

In order to evaluate stability analysis and also to study the relative contribution of the yield components under rainfed condition, an experiment was conducted using 17 genotypes of chickpea in a randomized completely block design (RCBD) with four replications in Kermanshah, Lorestan, Ilam, Gachsaran and Gorgan Research Stations for two years (2003-2004). Significant genotype × environment interaction, suggesting different responses of genotypes to different environments. The results of yield stability analysis of genotypes (Eberhart and Russell) showed that genotype FLIP 97-114 had a better performance in different environment. Using within location variance and within location coefficient of variation genotypes FLIP 97-78 and FLIP 97-41 were identified as stable genotypes with high grain yield. Superiority index found genotype FLIP 97-78 as a stable genotype. Finally based on different stability analysis methods, genotype FLIP 97-78 was considered as the most stable with genotype with high grain. The relative contribution of the number of seeds per pod was higher than that of number of pods per plant and 100 seed weight. It was also observed that the sensitivity of number of seeds per pod to the environmental fluctuations was less than that of the other two components, namely number of pods per plant and 100 seed weight, hence plays more important role in the yield stability of chickpea under different conditions of rainfed cultivation.

In Khuzestan province, the conditions of alternative cropping in some case have a negative effect on yield after summer cropping, because of canola delay planting. But according to agronomic necessary, we are able to make a suitable managing by considering growth curve. Thus, experiment on the basis of split plot arrangement in randomized complete block performance in khuzestan agriculture research center in 2005-2006 agronomic years. Design was used, with 4 planting date (Nov, 6 and 21, Dec, 6, 21) as the main plot and 4 genotypes (Hyola 401, Pp401/15E, RGS 003, Option 500) as the subplots. Because of being synchronous of main stage of development with final heart season in Late planting, cause that first planting date made a better yield and growth parameters compare with other planting date. Hyola 401 Hybrid is made the highest yield and yield component to other genotypes, because of leaf Area Index (LAI), Total Dry Matter (TDM), Crop Growth Rate (CGR), Net assimilation Rate (NAR) and Relative Growth Rate (RGR) is better than all genotypes. Finally according the result of this research recommended to planting Hyola 401 Hybrid in 6 Nov as suitable planting date.

In Order to evaluate the freezing tolerance of lentil genotypes under controlled conditions, a study was conducted as a completely randomized factorial design with three replications at Collage of Agriculture, Ferdowsi University of Mashhad. Experimental factors were seven genotypes (MLC-7, MLC-60, MLC-185, MLC-225, MLC-357, Robat and Qazvin) and nine freezing temperatures (0, -6, -9, -12, -15, -18, -21 & -21oC). Results showed that MLC-60 and Robatwith%51 and %39 had the highest and the lowest survival percentage, respectively. The effect of freezing temperature on plant survival was significant (P£0.01) and all genotypes were killed at less than -12oC freezing temperature. MLC-7and MLC-60 genotypes had the highest stem, branch and plant dry matter and stem and branch height, after three weeks recovery period. Plant dry matter (r=0.91**), stem height (r=0.89**), branch dry weight after recovery period (r=0.88**) and LT50 (r=-0.87**) had high significant correlation with survival percentage. In general, results showed that MLC-60 genotype had the highest freezing tolerant and good re- growth traits after freezing treatment.

To evaluate the effect of seedling age and consumption cycocel (CCC) on yield cultivars Tarom Hashemi, the experiment in split plot randomized complete block design with four replications in 1388 at the Islamic Azad University research farm was run Chalus. Three main levels of seedling age Hashemi Tarom variety (20, 30 and 40 days) and the sub plot with three levels cycocel (0, 1 / 2, 2 / 4 liters per hectare) were considered. Results showed that with increasing age of seedling yield ratio decreased approximately 33 percent. Highest grain yield, seedling age 20 and 30 days (respectively 299 / 2 and 341 / 8 grams per square meter) and lowest for the 40-day old seedlings (215 / 9 grams per square meter) was obtained. Highest panicle length, maximum number of spikes per square meter, the total number of tillers per plant and number of effective tillers per plant for transplanting 20 days of age were obtained. Cycocel taking on traits such as number of spikes per square meter, what percentage of filled cluster of clusters, the total number of tillers per plant and number of effective tillers per plant was significantly different. Interaction in traits cycocel old seedlings was not significantly tested. The lowest harvest index for 20-day old seedlings (23/28 percent) and the highest harvest index for ages 30 and 40-day seedlings (35/68 and 38/40 percent, respectively) were obtained. Greatest resistance to fracture under the influence cycocel 4 / 2 liters per hectare (25 / 52 g shoot) and the least affected cycocel control (18/35 g stems) was observed. So that the highest grain yield under the effect of age transplanting 20 and 30 days (respectively 299 / 2 and 341 / 8 grams per square meter) at a Department of Statistics and the lowest grain yield at the age of transplanting 40-day rate (215 / 9 grams per square meter) was obtained.

In order to evaluation the effect of zeolite application and selenium spraying on physiologic and agronomic traits of medicinal pumpkin (Cucurbita pepo L.) at different irrigation regimes, a experiment was conducted in factorial factorial based on randomized complete block design with three replications during 2010 in Takestan, Iran. In the where, the three levels of irrigation factor as the normal irrigation (control), withheld irrigation at the flowering stage and withheld irrigation at fruit formation stage, zeolite factor was at two levels of non application and use of 10 tons per hectare and selenium was sprayed at two concentration zero and 30 grams per liter per hectare. For this purpose traits such as chlorophyll index, RWC, fruit weight, seed number, seed length and width, 100 seed weight, seed yield and oil percent were evaluated. The results showed that water deficit stress reduced all traits were evaluated. Zeolite application of 10 tons per hectare in water deficit stress conditions, improved traits such as chlorophyll index, RWC, seed number, 100 seed weight, seed yield and oil percentage but its application in normal irrigation conditions had not significant effect on mentioned traits and only increased the number of seeds per fruit. Selenium spraying under total irrigation levels, had a positive effect on evaluated traits. In normal irrigation, Selenium spraying increased RWC, fruit weight, number of seeds per fruit and fruit yield and in stress conditions also had positive effect on RWC and seed yield.

To study planting dates on agronomical characteristics of corn in double cropping after rice harvesting rice, an experiment was done during of 2009, growing season in the research field of Islamic Azad university, Chalus, Iran. Treatments were arranged in split plot experiment bossed on randomized complete block design, with four replication. Planting date was in four levels (20 August, 28 August, 2 September and 10 September) as main factor and two levels of semi -early genotype (Ksc304) and late one (Ksc 304) were considered as sub-factor. The results showed that planting date has significant effect on all traits (p<1%). The amount of grain yield in planting date of 10th September, with comparison to 20 August and 28 August, 2 September reduced about 90/3%, 90/6% and 81/9%, respectively. Only, the length of ear, the grains number in ear and plant dry weigh were not influenced by variety. Statistically. Grain yield in Ksc 704 was more than Ksc 304.The most grain yield for Ksc 704 in planting dates of 28 August and 20 August was (730/63 and 718/59 m-2 respectively) and for Ksc 304, in planting date of 20 August obtained 674/90 m-2.The Ksc 304 had only a vegetative growth in planting date of 10 September. The most ratio of grain weight to stem that obtained in Ksc 704 with 28 August planting date was 70%.

This study was conducted to evaluate grain yield in 10 hull-less barley lines under salinity stress (ECsoil=12.1-18.2) and normal conditions at gorgan Agricultural Research Station during 2005-2007 cropping season. Experimental design was randomized complete block with 4 replications. Results of analysis of variance for grain yield showed genetic variation among lines under normal condition and salinity stress. Quantitative criteria for stress resistance as; Stress Tolerance index (STI), Stress Susceptibility index (SSI), Mean Productivity (MP), Tolerance index (TOL), Harmonic Mean (Harm) and Geometric Mean Productivity (GMP) were used for evaluation lines response to stress. Results of combined analysis of variance showed significant difference among lines for grain yield trait. Under stress condition effects of year and line were significant (P£0.05) on grain yield. In non-stressed condition the main effects of year and lines were significant (P£0.05) on grain yield. Among the criteria were calculated and lines of 5 and 6 showed the highest tolerance in salinity stress. Also, correlation coefficient for tolerance were estimated and showed that tolerance indicies of SSI and Harm in salinity stress and tolerance indicies of MP, GMP, TOL, SSI and STI had the highest correlation with grain yield under non-stress conditions. Thus indicies recommended for screening and selection of susceptible and resistant hull-less barley lines.