Studies on resource partitioning by honey bees and nectar secretion rhythms in different Brassica spp
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Date
2021-02
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CCSHAU, Hisar
Abstract
The present study was carried out on eleven genotypes/varieties belonging to eight Brassica spp. at Research Area of Oilseeds Section, Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar during 2019-20. The flowering phenology of various rapeseed-mustard genotypes/varieties showed that flowering initiation and cessation was earliest on TH 68 (32.67 and 81.67 DAS) while total flowering period was highest on RH 725 (53.00 DAS). The flower morphological parameters i.e. flower length, flower breadth, corolla and calyx length of different genotypes varied from 1.41 to 1.74 cm, 1.42 to 2.23 cm, 0.76 to 1.14 cm, 0.49 to 1.06 cm respectively and flower color was bright yellow in all genotypes/varieties. Eighteen bee species belonging to twelve families of five orders (Hymenoptera, Diptera, Lepidoptera, Hemiptera and Coleoptera) were recorded. The Apis spp. were most abundant on variety TH 68 (16.77 bees/m2/10 min). The mean densities of A. mellifera was maximum (15.50 bees/m2/10 min) followed by A. cerana (12.90 bees/m2/10 min), A. dorsata (12.25 bees/m2/10 min) and A. florea (9.37 bees/m2/10 min). The foraging rate of Apis spp. was highest on HNS 0901 (15.16 flowers/min). The mean foraging rate of A. cerana was maximum (18.06 flowers/min) followed by A. dorsata (16.65 flowers/min), A. mellifera (16.66 flowers/min) and A. florea (6.57 flowers/min). The comparative mean time spent per flower was highest on variety T-27 (3.52flowers/sec). The mean foraging speed of A. florea was maximum (6.38 flowers/sec) followed by A. dorsata (2.39 flowers/sec), A. mellifera (1.94 flowers/sec) and A. cerana (1.83 flowers/sec). Highest mean percentage of nectar, pollen and both nectar plus pollen gatherers were observed at 2nd fortnight of December i.e. 37.67, 24.84 and 43.08 per cent respectively. Top workers were highest in case of A. dorsata (97.33%) followed by A. mellifera (90.33%) A.cerana (90.00%) and A. florea (66.33%) and the highest percentage of side workers was observed in A. florea (43.33%) followed by A. mellifera (21.00%), A. cerana (21.33%) and A. dorsata (4.33%). The maximum DNS was produced by the flowers of HC-212 and T-27 (1.50 and 1.49 mg/flower) and also amount of energy produced by nectar was highest in HC-212 and T-27 (25.11 and 24.92 joules energy). Abundance of all four honey bee species showed positive non-significant correlation with maximum and minimum temperature. Relative humidity was significantly positive correlated with the abundance of. A. mellifera, A. cerana, A. dorsata but showed non-significant positive correlation in case of A. florea at morning and analysis of relative humidity resulted significant positive correlation with the all bees at the evening. Wind speed showed significant positive correlation with all Apis spp. and sunshine hours were non-significantly correlated.