Effect of Hydrogel and Irrigation Regimes on Chlorophyll Content, Nitrogen and Some Growth Indices and Yield of Forage Millet (Pennisetum glaucum L.)

Drought stress has an important role in yield reduction of crops. To investigate the effects of applying zeolite hydrogel (as a superabsorbent) in reduction of adverse effects of drought stress on chlorophyll content, nitrogen, growth indices and their relationships with quantitative and qualitative yield of pearl millet (cv. Nitrifeed), a split plot experiment (in space and time), based on randomized complete blocks design with three replications, was carried out at Research Farm of Shahid Bahonar University, Kerman, Iran, in 2011. Treatments included drought stress at four levels (irrigation at 40, 60, 80 and 100% of field capacity) as the main factor and superabsorbent hydrogel at three levels (0, 150 and 300 kg/ha) as the sub-factor. Results revealed that there was a positive and significant correlation (r = 0.97**) between chlorophyll content and leaf nitrogen percentage. Also, significant correlation was observed between these traits and forage fresh and dry weight of forage, protein yield and raw fiber percentage of the forage. As drought stress increased, the measured traits showed a descending trend. The superabsorbent polymer increased the fresh and dry weight of forage, growth indices and qualitative traits of pearl millet. Mean fresh weight of forage, chlorophyll content, protein content and percentage of fiber showed no significant difference between 100% and 80% irrigation levels. Superabsorbent application led to 20% water saving. Therefore, it can be said that superabsorbent hydrogel application under drought stress will improve yield, qualitative traits and growth indices of pearl millet through increasing soil water holding capacity, reducing nutrient leaching, fast and optimal growth of roots and better soil aeration.