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Subject: Agronomy × Author: KAU × Author: Rekha Bhaskar × End date: 1991 × Start date: 1991 ×
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    ThesisItemOpen Access
    Nitrate Reductase Activity in Cocoa (Theobroma cacap L.)
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1991) Rekha Bhaskar; KAU; Balachandran, P V
    An investigation on the nitrate reductase activity in cocoa (Theobroma cacao L.) was conducted at the College of Horticulture, Vellanikkara during the period 1990-1991. Forty plants belonging to the shade trial, thirty accessions of the H VI series and twenty hybrids and their parents were used for the study. All the plants used in the study belonged to the Cadbury-KAU Co-operative Cocoa Research Project. Genotypic and seasonal variations in NRA and NRA in different parts of cocoa plant were studied. The effect of N03-N and shade on NRA were also investigated. Heritability of NR, heterosis and relationship between NRA and yield were also worked out. Based on genotypic differences in NRA, the thirty accessions were grouped into three categories of low, medium and high activity. The highest NRA was observed in October with two lesser peaks in June and August respectively. The season x genotype interaction was found to be significant. Among the plant parts studied, viz., leaf, petiole .and pod, 'nitrate reductase activity was exhibited only by the leaf. There was significant increase ,in mean NRA with increase in NO3-N levels. Under irrigated condition, NRA increased with decrease in shade intensity. NRA at 0% shade intensity was superior to that at 50% and 75% shade levels, while the least activity was observed at 25% shade level. Under rainfed condition, high NRA was observed at 75% shade level followed by those at 25%, 0% and 50% shade levels. Heritability in the broad sense was found to be high in cocoa. In general, all the hybrids studied showed negative relative heterosis and heterobeltiosis. No significant correlation between NRA and yield could be obtained in this study.