Effects of Soil Moisture Stress on the Nitrate Reductase Activity of Selected Chilli (Capsicum annuum L.) Cultivars during the Flowering Stage and its Impact on Yield

Abstract

Enzyme nitrate reductase (NR) plays a key role in the nitrogen metabolism in the plant kingdom. NR activity is sensitive to the changes in the water status of the plant and is inhibited when the water potential of the plants decreases. An experiment was conducted to determine the effects of soil moisture stress on the NR activity of three chilli cultivars viz. MI 2, KA 2 and "Arunalu”. Moisture stress was imposed for a period of 15 days during the flowering stage. The plants, which served as the control, were watered to Field Capacity at 5 day intervals. Moisture stress significantlyreduced the NR activity of all the chilli cultivars. The highest reduction was observed in the Ml 2 followed by KA 2 and "Arunalu". Cultivar "Arunalu" showed the highest NR activity among the tested cultivars, despite the severe stress situation. A high NR activity would have contributed for stress tolerance in this cultivar. Moisture stress significantly reduced the yield of all the chilli cultivars. The highest reduction was found in the MI 2 followed by KA 2 and "Arunalu". No significant difference was observed in the yield of KA 2 and "Arunalu". These two cultivars were able to produce substantially high yields under water deficit situation. Increased NR activity of “Arunalu" under drought situation would have enhanced the growth and development, which would have resulted in a substantially high yield in this cultivar compared to the others.