Seed ageing and field performance of maize under water stress
A sub-sample of maize (cv.Ksc 301) seeds was kept as control or high vigor seed lot (V1) and two other sub-samples with about 15% moisture content were artificially aged at 40°C for 9 and 12 days (V2 and V3, respectively). Hence, three seed lots with acceptable normal germinations of 98% (V1), 92% (V2) and 88% (V3), but with different levels of vigor were provided. Laboratory tests were carried out as completely randomized design with four replicates. However, the field experiment was conducted as factorial based on RCB design in three replicates. Factors were seed ageing (three levels) and irrigation treatments (irrigation after 70, 90, 110 and 130 mm evaporation). Seeds were then sown with a density of 10 seeds m-2 on the 9th May, 2010. Mean germination and emergence times significantly increased, but normal germination percentage, seedling dry weight and emergence percentage decreased with increasing seed ageing and decreasing seed vigor. As a result, plant biomass and grain yield per unit area for plants from aged seeds were considerably lower than those from non-aged seeds. No significant interaction of irrigation × seed ageing was observed for grain yield, suggesting that aged seeds had low yield under both well and limited irrigation conditions. Therefore, production of high vigor seeds and proper storage are necessary to ensure optimum stand establishment and satisfactory yield of maize under favorable and unfavorable field conditions.
Key words: Biomass, harvest index, maize, seed ageing, seedling emergence.