CROP PHYSIOLOGY
Year:2012 | Volume:4 | Issue:14|Papers Count:14

This research was designed and carried out with the aim of determining the role of heat stress on rice cultivars grain milling quality and physical traits in Khuzestan province. An experiment with two sowing date and cultivar elements was carried out in a split-plot arrangement using randomized complete block design with three replications at Shavoor Agricultural Research Station field dependent in Khuzestan Agricultural and Natural Resources Research Center in two years (2006 and 2007). Main plots were assigned to three sowing dates (5/2, 25/2 and 15/3) and five rice cultivars including Hoveizeh and Hamar cultivars (heat tolerance) Ghermez Anbori and Champa (heat sensitive) and Danial full product cultivar (relatively heat tolerance) were placed in sub-plots. The results of combined analysis showed that there was a significant interaction between planting date and cultivar in all of the traits. In other words, the cultivars had different reaction related to temperature conditions. So that because of lower temperature and cooler weather in the third planting date milling efficiency, total rice percentage, milling degrade, brown rice percentage and grain length and width, had the highest amount but the lowest percent of the hull and brane and broken rice.

In order to study the impact of water deficiency stress on the physiological characteristics and grain yield of oil sunflower during the years of 2004-2005 in Agricultural Research staition of Khoy, an experiment was done in split plot on the basis of randomized complete block design in four replications. The irrigation levels, as the main factor in 6 levels (including 70-70 -70, 90 -90 -90, 110-110-110, 90-70-90, 110-70-110, and 110 -90 -90 mm of evaporation from class A evaporation tray were put into action, respectively, from shrub settlement stage to the appearance of head, the appearance of head till the start of turning into yellow and the start of turning to yellow till to physiological ripening and the cultivars including: Hisun33 Records and Armaverski were chosen as sub factor. The results of the research showed that with increasing in the alterations of irrigations, there was reduction in length ripening period, leaf area index and relative water content of leaves, grain and oil yield, and there was increased in proline amount of leaves. The irrigation levels of 70- 70-70 and 90-70-90 mm evaporation with LAI= 4.7 at pollination stage produced the most grain and oil yield respectively: 5125 and 2382 kg per hectare. Record and Hisun33 cultivars with desired ripening stage, LAI and RWC, had the highest grain and oil yield in comparison with Armaverski cultivar. With regards to significant interactions between experimental factors concerning with LAI, grain and oil yield with using deficiency stress and irrigation after 110 mm evaporation decreased leaves development and the same affair led to the reduction of grain and oil yield, because the lowest amounts of three mentioned traits (LAI, grain and oil yield) was observed in irrigation treatment after 110 mm.

Study the biochemical and physiological changes in drought stress conditions and application of Potassium and Zinc elements can help to identify the effective factors and potassium and Zinc elements role in plants tolerance to drought stress. For this purpose a field experiment was conducted on corn (cvsc 704) in Bavanat county in 2010 year in the form of split factorial in randomiszed complete blocks design with 3 replications. Drought stress was considered as main plots (control and stress in the vegetative stage (70 days after planting)) and subplots included various levels of Potassium Sulfate (0, 150 and 300) kg/ha and different levels of Zinc Sulfate (0, 15 and 30) kg/ha were considered. In this experiment chlorophyll concentration, proline, protein, Potassium and Zinc in corn leaf, in favorable conditions of moisture and drought stress conditions was investigated. The results showed a significant increase in chlorophyll content (5% alpha level) and protein (5% alpha level) in leaf in drought stress conditions. Application of Potassium sulfate and Zinc sulfate causes increasing in the proline content, protein and chlorophyll in the leaf under drought stress conditions.Application of Potassium sulfate and Zinc sulfate through increasing uptake of Potassium and Zinc elements, increasing the protein content, the leaf chlorophyll conservation and thus more effective photosynthesis, and also increasing concentration of proline in the leaf plant, reduced the osmotic stress due to drought stress and improved the drought stress tolerance in corn.

In order to study G*E interaction on location and the response of wheat lines and cultivars to different environmental conditions by using 20 lines and cultivars, this research was done in the form of randomized completely block design with 3 replications and in 3 places (Isfahan, Kermanshah, Varamin). The results of combined analysis of variance for grain yield showed significant difference for genotype, location effects and G*E interaction in location. With regards to significant G*E interaction on location, AMMI method was used for grain stability analysis. The results of AMMI method showed that based on the results of G*E interaction main parameter IPCI, genotypes 5, 11 and 15 showed general stability response and so lines 4 and 10 had specific adaptability to Varamin environment. Genotype 13 had specific adaptability to Isfahan environment and Marvdasht and Crossalboraz cultivars had specific adaptability to Kermanshah environment. Yield components stability analysis by using Kathenberg and Fransiss environmental changes index showed 1000 grain weight trait with the lowest (C.V) enviromenal changes index, was the most stable trait, so it can be considered in well- breeding plans.

In order to investigate the effect of planting date on yield and yield components of six promising hybrids of corn, an experiment was conducted as a split plot based on randomized complete block design with 4 replications at Research center of Safiabad in 2008 year. Treatments included 6 planting dates (30th of June, 7th, 14th, 21th, 28th of July and 4th of August) as main factor and sub factor consisted of six promising hybrids of corn and the hybrid SC704 as control. The results showed the highest grain yield with about 9000 kg per hectar was related to the planting date 4th of August and the lowest was related to the planting date 30 th of June. The most seed number per ear was in the planting date 28 th of July and equels to 581.18 seeds. Hybrid H4 with average 469.71 seeds per ear had the most and hybrid H1 with average 347.33 seeds per ear the lowest seed number per ear.1000 grain weight when going to the last plantings date had an increasing trend. The most biological yield with the amount of 22000 kg per hectar was obtained in planting date 4th of August. Biological yield in hybrid H4 was more than other hybrids and equals to 16500 kg per hectar. Based on the results of this study in north region of Khuzestan because of high temperature and heat stress in pollination time and lack of harvesting in suitable time and considering (corn- wheat) region alternation, the fifth planting date (28th of July) and hybrid H4 as the superior treatment was recognized.

In order to study the effect of water deficit stress on quantitative and qualitative traits in different oil sunflower cultivars a design was carried out as split-split plot based on randomized complete block design with four replications. In this experiment irrigation treatments including interrupt of irrigation at the beginning of flowering and normal irrigation in the main plot, the following cultivars: Record, Armavierski, Chernianka, Zaria and Progress in sub-plot and Selenium treatment (without using Selenium and using Selenium) with source of Sodium Selenite was placed in sub-sub plot. During the growth period the traits such as grain yield and the rate of antioxidant enzymes were assayed. The study of results showed that there was a significant difference in irrigation and cultivars treatments and also using Selenium at 1% level, as grain yield was increased 47% with affected by Selenium on water deficit stress. Also the activity level of antioxidant enzymes was affected severely by Selenium and water deficit stress and showed increasing. In general, in this experiment Progress cultivar was recognized as the most stable and Zaria cultivar the most sensitive cultivar to water deficit stress.

In order to study of plant density effect on forage yield and some agronomic traits four cultivars of sorghum bicolour, an experiment was conducted as split-plot in a randomized complete block design with four replications in Lorestan Agricultural and Natural Rresources Research Center in 2003-2004 cropping year. Two densities 166000 and 133000 plants per hectar (60 and 75 cm distance between planting rows and 10 cm distance between plants on the row, respectively) were assigned as main factor and four cultivars karaj 1, karaj 2, karaj 3 and karaj 4 as sub factor. Results showed that cultivar and also density had significant effect on total fresh and dry matter yield, stem and leaf dry weight, leaf area index, plant height and stem diameter. In 166000 plants density per hectar all traits except of stem diameter had significant superiority than 133000 plants per hectar density. Karaj 2 cultivar regards to dry and fresh matter yield, stem and leaf dry weight and leaf area index had significant superiority than other cultivars. Karaj 1 had the highest stem height (193.3 cm) and karaj 3 had the highest diameter stem (2.26 cm).

In order to identify drought tolerance lines and screening indices of drought resistance, 10 advanced lines of durum wheat with control cultivar Dehdasht were studied in a randomized complete blocks design under two drought mild and sever stress conditions in Gachsaran region. Based on the yield trait on mild stress (YP) and severe stress (YS) conditions, quantities indices of drought resistance including: Mean productivity (MP), Tolerance index (TOL), Geometric mean productivity (GMP), Stress Susceptibility index (SSI) and Stress tolerance index (STI) were calculated. Genotypes no 1 and 6 with relatively high first principal component amount and low component amount in both enviroment, were selected as the best genotyps. Correlation yeild between two environment and drought tolerance indices revealed that STI and GMP indices are the best indices for screening of Durum wheat genotypes. Biplot multivariate graph showed that genotypes 1 and 6 are located in the vicinity of the vectors associated with drought resistance indices such as MP, GMP, STI and therfore were selected as the most resistant genotypes. In this research the plant canopy temperature difference with environment (CTD) in three growth stages was measuered that genotypes no 9, 10 and 6 had the coldest growing environment. Positive and significant correlation between SSI and CTD showed that canopy temperature index can have an important role in identification of drought tolerance genotypes.