Pollination studies in Egyptian clover (Trifolium alexandrinum L.)
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Date
2013
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CCSHAU
Abstract
Field experiment entitled “Pollination studies in Egyptian clover (Trifolium alexandrinum L.)” as conducted at Forage Section, Department of Genetic and Plant Breeding, CCS Haryana Agricultural University, Hisar during 2012 and 2013. The flower of T. Alexandrinum completed their life cycle on an average 173.3±13.3 hours during 2012 and 200.4±2.4 hours during 2013. A total of forty five insect species belonging to 25 families of 6 orders were recorded on the T. alexandrinum flowers. Apis dorsata F. was most abundant floral visitor (4.90/m2/5 min.) followed by A. mellifera (2.69/m2/5 min.) and A. florea 0.30/m2/5 min. during 2012. A. dorsata (3.08/m2/5 min.) was the most abundant species followed by A. mellifera (2.61/m2/5 min.) and Eristalinus spp. During 2013. The maximum amount of dry nectar sugars was produced by fully opened flower at 10.00 h (2.468 mg/flower), 13.00 (2.446) and 16.00 (2.444). The fully opened flowers produced maximum amount of energy 41.05 joules/flower followed by half open flowers (31.80 joules). The overall mean foraging rate was maximum in A. florea and A. mellifera (7.2 and 7.1 flowers/min., respectively) and minimum (5.1) in nectar forager A. dorsata. A. dorsata visited maximum number of flowers/minute while collecting N+P (7.2) followed by P (6.3) and least for nectar (5.1). The mean foraging speed of A. dorsata was maximum (17.9 seconds/flower) followed by A. florea (16.1) and A. mellifera (5.6).The A. mellifera foragers spent least time on T. alexandrinum flowers while foraging for N+P (4.6 second) followed by P (4.9) and N (7.4). Highest number of loose pollen grains were carried on the body of A. dorsata foragers (79,625) followed by A. mellifera (73,250) and A. florea (36,375). The overall mean relative pollination efficiency (RPE) ranking for the forager groups of three honey bee species in descending order were: (N+P) A. dorsata > (P) A. dorsata > (P) A. mellifera > (N+P) A. mellifera > (N) A. dorsata > (N) A. mellifera > (P) A. florea > (N+P) A. florea = (N) A. florea. It was concluded that N+P foragers (16.4 RPE) of A. dorsata were the most efficient pollinators of T. alexandrinum flowers followed closely by pollen forager (13.3 RPE). The seeds setting (%), seed yield, 1000 grains seed weight and per cent germination of T. alexandrinum significantly increased under bee pollination treatments than compared to other treatments. Saturated bee pollination by employing an 8- frame A. mellifera colony resulted in significantly higher yield over lower intensity bee pollination (4 and 2 frame colonies) and open pollination. The utility of T. alexandrinum crop as highly valuable nectar and pollen sources was confirmed for A. mellifera colony development.
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Keywords
Biological phenomena, Developmental stages, Honey, Sowing, Crops, Sets, Yields, Grain, Manpower, Fruits