Nitrate reductase activity in black pepper (Piper nigrum L.)

Abstract

An investigation on the nitrate reductase activity in black pepper (Piper nigrum L.) was conducted at the College of Horticulture, Vellanikkara during the. period 1989-1990. Six varieties of pepper vines from the Pepper Research Scheme, Vellanikkara were used for the study viz., Panniyur-1, Karimunda, Kottanadan, Kuthiravali, Uthirankotta and Cheryakaniakadan. Seasonal and genotypic variations in NRA and NRA in different parts of pepper vine were studied. The effect of NO3-N and light on NRA were also investigated. Heritability of NR, heterosis and relationship between NRA and yield were also worked out. In Panniyur-1 fairly high NRA was noted in June which declined till September and increased and peaked in February. Significant positive correlation between NRA and NO3 content was obtained in all months except in February. The six varieties of pepper were brought under two groups based on the pattern of NRA. One group comprising of Karimunda, Kottanadan, Kuthiravali and Uthirankotta. The second group comprised of Panniyur-1 and Cheryakaniakadan. The mean leaf NRA in the different parts of pepper followed the order, runner shoot y plageotrope orthotrope y flag leaf > berry. There was significant increase1 in NRA with increase in NO3-N levels in both Panniyur-1 and Karimunda. In general NRA increased with increase in light intensity. NRA at 60 and 100 per cent light were superior to that at 10 and 30 per cent light in Panniyur-1. In Karimunda NRA at 30 and 100 per cent light were found to be superior to that at 10 and 60 per cent light intensity Heritability in the broad sense of NR was found to be low in blacK pepper. Relative heterosis in Panniyur-1 was 26 per cent while heterobeltiosis was 23 per cent. Significant positive correlation was observed between mean NRA and yield-in Panniyur-1.