Emergence and seedling establishment in maize under low temperature stress and its amelioration with salicylic acid

Emergence experiments were carried out under laboratory conditions at optimum (25°C) and suboptimum (15°C) temperatures at PPFD 450–500 μmol m⁻² s⁻¹ and photoperiod (h) of 16:8 (L:D) in two maize cultivars, viz. Sheetal and Paras (recommended for rabi and main season respectively). Suboptimum temperature had no adverse effect on emergence percentage, while days to emergence were deleteriously affected. Biochemical parameters, viz. root metabolic activity, chlorophyll content, Hill reaction activity and catalase activity (estimated from 3^rd leaf of seedling) decreased while total sugars, sucrose, proline content and peroxidase activity increased at 15°C in both the cultivars. Salicylic acid (SA) (10, 20 and 50 μg ml⁻¹) used as seed soaking pre-treatment improved per cent emergence, root metabolic activity, total sugars and sucrose at both 25°C and 15°C in the two cultivars. In the cultivar Sheetal, chlorophyll content and Hill reaction activity decreased at 25°C but increased at 15°C. While in Paras, there was non-significant difference in chlorophyll content and Hill reaction activity at 25°C but increased at 15°C. Proline content increased at 15°C in both the cultivars. SA increased peroxidase but decreased catalase activity in the two cultivars at both the temperatures. SA (20 g ml⁻¹) was most effective in ameliorating chilling tolerance.