Identification of yard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) genotypes suitable for polyhouse cultivation

Abstract

The present investigation entitled “Identification of yard long bean (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) genotypes suitable for polyhouse cultivation” was taken up at the Department of Olericulture, College of Agriculture, Vellayani, during 2014- 2015 with the objective of identifying yard long bean genotypes with high yield and quality suitable for cultivation in naturally ventilated polyhouse. The experiment was conducted in the saw tooth type naturally ventilated polyhouse of size 1000 m2 (50 m x20 m) located at Instructional Farm, Vellayani. The experimental materials consisted of 30 yard long bean accessions, including 18 landraces, three KAU varieties and nine hybrids/varieties collected from private seed firms. The experiment was laid out in RBD with three replications. During the cropping period the maximum and minimum temperature in the polyhouse ranged from 30.4 0C to 41.3 0C and 21.5 to 24.5 0C respectively. The relative humidity ranged from 81 to 94 per cent and light intensity from 60.3 klux to 70.1 klux. CO 2 concentration varied between 269.38 to 293.32 ppm at 7am and 261.23 to 288.75 ppm at 4 pm. Analysis of variance showed significant difference between the accessions for all the characters studied. The longest vines were observed in NS-634 (T 23) followed by Anad Local (T 5). Primary branches per plant varied from 3.95 (T 23) to 6.57 (T16) and petiole length ranged from 14.27 (T4) cm to 21.27 (T10) cm. The variety Rani (T19) was the earliest for flowering (30.41 days) and harvest (40.65 days) under poly house. Among the accessions, Anad Local (T 5) had the highest yield (1627.12 g) which is on par with NS-634 (T 23), Githika (T 1) and Hari Rani (T 64), while Super Green (T 17) recorded the highest pod length (85.07 cm) and pod weight (64.77 g). Highest pod girth was noticed in NS -634 (T 23) and Neyyattinkara Local (T 13) recorded highest number of pods per plant. The crop was free from collar rot, pythium rot, viral diseases and pod borers. However mild incidence of web blight and fusarium wilt was noticed in few accessions while low incidence of mites was observed in most of the accessions at high temperature and low relative humidity. High values of PCV and GCV were observed for pod weight, pods per plant and 100 seed weight. High heritability coupled with high genetic advance were recorded for peduncle length, pod length, pod girth, pod weight, pods per plant, yield per plant, 100 seed weight, protein content and stomatal density indicating that selection based on these characters would be effective. Positive phenotypic and genotypic correlation with yield was observed for pod length, pod weight, pod girth, pods per plant and days to first flowering. The path analysis revealed that pod weight had the highest positive direct effect on pod yield (0.8724) followed by pods per plant. The selection indices were worked out based on seven characters namely vine length, number of primary branches, days to first flowering, pod length, pod weight, pod girth and number of pods per plant. Githika (T 1) was ranked first followed by Neyyattinkara Local (T 13), Hari Rani (T 18) and Anad Local (T 5). On the basis of per se performance and selection index values, the top yielders Anad Local (T 5), NS 643 (T 23) and Githika (T1) were identified as the most suitable for cultivation in naturally ventilated polyhouse.