Flood Tolerance of Hybrid Napier (Pennisetum purpureum x Pennisetum glaucum) Cultivars

A pot culture study was conducted from February to May 2020 at the Agronomy Farm, Department of Agronomy, College of Agriculture, Vellanikkara, Kerala to study the effects of short-term flooding on the growth, physiology, and yield of four high-yielding cultivars of hybrid napier (Pennisetum purpureum x Pennisetum glaucum) cultivated in Kerala. The experiment followed a 4 x 2 factorial Completely Randomized Design with three replications. The treatments comprised two factors: varieties and flooding treatments. The four hybrid napier varieties used in the study were CO-3 (V1), CO-5 (V2), IGFRI -3 (V3), and Suguna (V4). The flooding treatments included no flooding (F0) as a control and short-term flooding stress treatment (F1) at three different growth stages: 30 days after planting (DAP), 60 DAP and just after the first harvest (75 DAP). Flooding stress was imposed for seven days by inundating water in the pots up to 3-4 cm above the soil level. Flooding at all three stages resulted in a significant reduction in plant height, tiller number, leaf number and above-ground biomass for all varieties. A severe reduction in growth and yield parameters was observed when flooding stress was imposed immediately after the first harvest. Among the varieties, CO-5 had the tallest plants, followed by Suguna, CO-3, and IGFRI-3. When exposed to flooding stress, variety CO-5 was also found to be significantly superior in terms of above-ground biomass production, followed by CO-3. Superoxide dismutase (SOD) activity increased in all varieties due to flooding stress, with a pronounced increase observed in Suguna. Variety CO-5, which exhibited greater plant height and above-ground biomass production, was found to be more tolerant to flooding stress, while variety IGFRI-3, with a dwarf plant stature and the lowest biomass yield, was identified as sensitive to short-term flooding stress.