Abstract
The soybean is a crop of global importance, which cultivate in worldwide. However, the soybean is more susceptible to water shortages during germination and reproductive growth stages. Stress is an in ordinary physical process of environmental factors effects and it has traumatic ability, which causes unusual metabolism in plants, and it is possible; reduce plant product or causes plant death. Drought indices provide a measure of drought based on loss of yield under drought conditions in comparison to normal and have been used for screening drought tolerant genotypes. We cultivated Ten genotypes of soybean in the research field of seed and plant improvement institute in Karaj- Iran in 2015 June. The experimental design was a randomized block with three replicate in two separate field experiments for normal and stress conditions. We irrigated the normal experiment in 85% field capacity and got 50% filed capacity for stress conditions. Seventeen drought tolerance indices were calculated. Four methods were used to identify more resistant and more susceptible genotypes. After genotypes selection, we carried out experiment in green house with two selected genotypes. Results showed using the indices such as MP, GMP and STI, alone, cannot select a stable genotype and we have to use a combine of all indices or use indices that showed reduction and average yield, together. In second year, results showed that we had a true selection.Int. J. Agril. Res. Innov. & Tech. 7 (2): 7-17, December, 2017
Highlights
The Soybean is a globally important crop, which cultivated as frequently crop in the worldwide
If we consider the angle between the Yp and yield between the stress (Ys) (Chart1), GMp, Harm, mean productivity (MP) and Stress tolerance index (STI) located between these two and it seems, they are as the best indices to separate genotypes which have high yield in stress and non stress conditions
Indices such as Abiotic tolerance index (ATI), SSpi that align with Yp and have high correlation with the second component are able to separated genotypes in normal condition while indices such as Drought resistance index (DRI), Yield stability index (YSI), Yield index (YI), susceptibility index (SSI) and SDI are aligned with Ys and the first component
Summary
The Soybean is a globally important crop, which cultivated as frequently crop in the worldwide. About 1.2 million/ha of lands under dry cultivation, more than 400 mm rainfall will receive (Mohammadi et al, 2006).The increase in drought events in the last decade has caused production losses in recent harvests This fact compels us to understand the drought tolerance mechanisms in soybean, considering its variability among commercial and developing cultivars (Vidal et al, 2012).Water stress is one of the most important factors limiting plant performance and yield worldwide (Boyer, 1982). Purcell and King (1996) has reported bush high affected from drought stress, but have no correlation with yield It has been proved, environmental factors, decrease the yield usually by reducing the seed number to the grain
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