ISHS Acta Horticulturae 631: XXVI International Horticultural Congress: Issues and Advances in Transplant Production and Stand Establishment Research
ONION SEED CROP POLLINATION: A MISSING DIMENSION IN MOUNTAIN HORTICULTURE |
| Authors: | R.S. Chandel, R.K. Thakur, N.R. Bhardwaj, N. Pathania |
| Keywords: | honeybees, Allium cepa L., pollination efficiency, seed production, Apis cerana, A. dorsata, A. florea, syrphids |
| Abstract:
Onion (Allium cepa L.) does not produce quality seed if insects do not visit the flowers. In mountainous regions of India, availability of natural pollinators has been a major drawback in seed production. Studies were conducted on the abundance of different natural pollinators and on the effect of bee pollination on quantity and quality of onion seed (var. Nasik Red) under sub-temperate conditions of Himachal Pradesh situated at an altitude of 1200 m above mean sea level. Two colonies each of Apis mellifera and A. cerana were introduced into the crop ecosystem. Besides, a natural nest of A. dorsata, A. florea and syrphids (Episyrphus balteatus, Metasyrphus conferator and M. corollae) were also visiting the crop. A control experiment was maintained at 2000 m distance where no pollinator was introduced. A. dorsata proved to be the dominant visitor (7.4 bees/m2/2 minutes) and most efficient pollinator covering on an average 7.5 flowers/umbel/visit during peak hours of their foraging activity (1200-1400 hrs) compared with A. cerana (5.4 flower/umbel/visit). Apis florea and A. mellifera visited onion flowers least and ranked fourth and fifth overall in visiting frequency. Syrphids covered a minimum of 1.6 flowers/umbel/visit, yet spent maximum time (8.8 seconds) on the flowers during 800-1200 hours. Apis dorsata had the maximum foraging period (0630-1855 hrs) followed by A. cerana (0645-1830 hrs) and A. mellifera had the least foraging period (0725-1820 hrs) on onion seed crop. Induced bee pollination increased seed yield by 2.5 times and produced on an average 971 seeds per umbel compared to 406 in the control. The seeds from induced pollination field resulted in 90 percent germination compared to 69.5 percent germination from the control. | |
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