Effect of drought stress on osmolyte accumulation, photosynthetic pigment and growth of three Foxtail Millet (Setaria italica L.) species

Drought stress is one of the most important factors limiting crop productivity, and reduce crop production more than 50% in the world (Lata et al., 2011). Development of drought-resistant plants can be a useful strategy for avoiding drought induced damages to the crops. Using C4 plants such as foxtail millet is a suitable alternative (Vitkauskaite and Venskaityte, 2011). These plants are known to be resistance to water shortage. Drought stress effect on physiological traits such as Osmotic adjustment, chlorophyll pigmant and morphological trait such as plant height and ear length (Mohammadkhani and Heidari, 2008). Understanding the physiological and morphological basis of drought tolerance and its relation with yield in this plant would possibly contribute greatly to the understanding and planting development of drought resistant plants species. In this regard howeverlittle information is available on millet. So the aim of this study was to evaluate the physiological and morphological traits under drought stress in millet.
Material and This study was carried out in Research field of Birjand University in 2014. A split-plot arrangement of treatments in a randomized complete block design with four replications was used. The main factor was drought stress with three levels including 100, 75 and 50 percent of plant water requirement (non-stress control, moderate stress and severe stress respectively) and the sub-factor was millet cultivar with three levels (including Bastan, KFM5 and KFM20).. Osmolyte regulated and photosynthesis pigments was measured 30and 45 days after drought stress (Schlegel, 1956; Bates et al., 1973; Sairam and Saxena, 2000). Seed yield and its component and morphological traits were measured after plant maturity. Software SAS software (ver 9.1 windows edition) was used for statistical analysis and means were compared using tukey test.
Results showed that drought stress at different growth stages increased proline content and soluble Carbohydrates and reduced photosynthesis pigment and carotenoid content compared to control treatment. Drought stress also reduced plant height, internode length, ear length, number of ears per square meter, number of grains per ear, seed weight and seed yield compared to control treatment but had no effect on the number of nodes per plant. Highest and lowest seed yield was observed in control treatment(461.88 g.m-2) and severe stress (171.08 g.m-2) respectively. Reduced height possibly resulted in reduced yield by affecting radiation use efficiency. According these results plant height, ear length, seed number in ear a,d 1000 seed weight have direct effects on seed yield in Foxtail Millet so that their enhancement would result in seed weight improvement.
According to results a reduction in height, osmolyte compatible and carotenoids are Compatibility and drought resistance mechanisms.