Studies on Impact of Bee Pollination on Yam Bean (Pachyrhizus erosus L.)
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Date
2023
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Dr.RPCAU, Pusa
Abstract
The current investigation titled “Studies on Impact of Bee Pollination on Yam bean (Pachyrhizus erosus L).” was executed at the experimental farm of TCA, Dholi (Muzaffarpur), RPCAU, Pusa during two consecutive Kharif seasons of 2020-21 and 2021-22 with Rajendra Mishrikand -1 variety of Yam bean. Findings related to bees and important insect visitors, their relative abundance and foraging behavior and impact of bee pollination on Yam bean seed yield and the results have been outlined below:
A total of 6 important insect species visiting Yam bean flowers were recorded during the year 2020-21 and 2021-22 from Yam bean flowers. Collected insect species were killed and dried preserved properly labelled. Based on the number of insect visitors recorded, the most frequent and important insect visitors were in hymenoptera order and hence were counted for observations viz. Giant Honeybee (Apis dorsata Fabricius 1793), Eastern honeybee (Apis cerana Fabricius 1798), Dwarf honeybee (Apis florea Fabricius 1787), European honeybee (Apis mellifera Linnaeus 1758), Megachile sp. Fabricius 1781 and Carpenter bee (Xylocopa fenestrata Linnaeus 1758). Pooled mean population of Giant honeybee (Apis dorsata) was highest on 43rd SMW (15.50 insects/m2/10min) and during 13:00hrs (17.27 insects/m2/10min) of the day having Pooled mean population of 12.47 insects/m2/10min. Eastern honeybee (Apis cerana) population also attains peak on 43rd SMW (12.92 insects/m2/10min) and during 13:00hrs (13.94 insects/m2/10min) of the day with Pooled mean population of 10.79 insects/m2/10min. Dwarf honeybee (Apis florea) population attained peak on 44th SMW (10.52 insects/m2/10min) and at 13:00hrs (12.17 insects/m2/10min) of the day with mean population of 8.57 insects/m2/10min. European Honeybee (Apis mellifera) reaches peak on 43rd SMW (13.50 insects/m2/10min) and during 13:00hrs (14.30 insects/m2/10min) of the day and mean population of 11.31 insects/m2/10min. Population of Megachile sp. observed highest on 43rd SMW with mean population of 11.77 insects/m2/10min during 13:00hrs (12.67 insects/m2/10min) of the day with Pooled mean population of 9.28 insects/m2/10min. Carpenter bee (Xylocopa fenestrata) population was highest on 43rd SMW with mean population of 13.73 insects/m2/10min and during 13:00hrs (15.18 insects/m2/10min) of the with Pooled mean population 10.87 insects/m2/10min.
Correlation and Regression studies of the Pooled data for all the observed bees and important insect visitors showed positive relation with average temperature and negatively related with average relative humidity. Apis dorsata showed positive and significantly correlation with average temperature and negatively non-significant with relative humidity in Pooled data (0.816* and -0.495), Apis cerana (0.894** and -0.608), Apis florea (0.817* and -0.367), Apis mellifera (0.792* and -0.434), Megachile sp. (0.837* and -0.483) and Xylocopa fenestrata (0.803* and -0.523) respectively. Regression coefficient (R2) recorded for Apis dorsata, Apis cerana, Apis florea, Apis mellifera, Megachile sp. and Xylocopa fenestrata for Pooled data (0.855, 0.918, 0.849, 0.895, 0.949, 0.772), respectively.
Initiation time and Cessation time (Pooled mean) of Apis dorsata for both the season was 07:49hrs and 17:01hrs, respectively with duration of foraging (09:11hrs). Apis cerana (07:55hrs and 16:49hrs) with foraging duration (08:54hrs), Apis florea (07:58hrs and 16:45hrs) with duration of foraging (08:46hrs), Apis mellifera (07:51hrs and 16:49hrs), with duration of foraging (08:58hrs), Megachile sp. (08:06hrs and 16:33hrs), with foraging duration (08:26hrs). Xylocopa fenestrata (08:14hrs and 16:58hrs), with foraging duration (08:44hrs). The pollen load carried out by Apis mellifera (Pooled) was heaviest (11.68mg) at 07:00hrs and lightest (6.28mg) at 13:00hrs of the day. Also the mean pollen load by Apis mellifera during both the season was 9.20mg. Data on foraging rate (Pooled mean) reveals Apis dorsata on different dates was highest of 12.86 flowers/min with maximum during 11:00hrs (13.57flowers/min) and mean foraging rate (10.37flowers/min). Apis cerana attained peak of 10.50flowers/min with maximum during 13:00hrs (11.64 flowers/min) and mean foraging rate (8.22 flowers/min). Apis florea was attained highest of 10.23 flowers/min with maximum during 13:00hrs (11.86 flowers/min) and mean foraging rate (8.58flowers/min). Mean foraging rate of Apis mellifera attained highest of 10.14flowers/min with maximum during 11:00hrs (12.07flowers/min) and mean foraging rate (8.17flowers/min). Mean foraging rate of Megachile sp. attained peak of 9.66flowers/min with maximum during 13:00hrs (11.57flowers/min) and mean foraging rate (7.83 flowers/min). Mean foraging rate of Xylocopa fenestrata was highest of 13.18flowers/min with maximum during 13:00hrs (15.71flowers/min) and mean foraging rate (10.27 flowers/min).
The Pooled mean Foraging speed of Apis dorsata during different dates was highest of 7.82 sec/flower with minimum at 13:00hrs (5.37sec/flower) and mean Foraging speed was 6.61 sec/flower. Apis cerana Foraging speed reached highest of 7.07 sec/flower with minimum at 11:00hrs (6.44sec/flower) with mean Foraging speed of Apis cerana (5.57 sec/flower). Apis florea Foraging speed was found minimum at 13:00hrs with mean Foraging speed of 4.39 sec/flower. Apis mellifera foraging speed reached highest of 7.22 sec/flower with minimum at 13:00hrs (5.40sec/flower) and mean Foraging speed of 5.65sec/flower. Megachile sp. reached highest of 7.45 sec/flower with minimum at 13:00hrs (6.49sec/flower) and mean Foraging speed of Megachile sp. (5.57 sec/flower). Xylocopa fenestrata Foraging speed reached highest of 5.35 sec/flower with minimum at 13:00hrs (4.22sec/flower) and mean Foraging speed of Xylocopa fenestrata was 3.41 sec/flower.
Bees play a crucial role in seed production over the pollinator exclusion condition. Yield parameters of open pollination conditions are found to be superior over other pollination conditions. Pooled values showed that there is no relation between number of inflorescence/plant and number of flower/inflorescence and different pollination methods.
Number of pod/inflorescence showed significant differences among the treatments i.e. open to all pollinators (8.45), pollinator exclusion (6.98) and bee pollination (7.45). Number of seeds/pod showed significant differences among the treatments i.e. open to all pollinators (8.02), pollinator exclusion (6.26) and bee pollination (6.94). Seed yield/plant observed maximum in open to all treatment (79.05kg/ha), followed by bee pollination treatment with 66.37kg/ha and pollinator exclusion treatment with 50.31kg/ha. All the treatments were significantly different and seed yield of Yam bean is highly influenced by different pollination methods. 100- Seed weight was observed maximum in open to all treatment (27.27g) and followed by bee pollination treatment with 26.71g and pollination exclusion treatment with 24.13g. Percent increase in seed yield was highest recorded in open to all treatment with 56.93%, and increase of 31.89% was observed in seed yield of bee pollination treatment over the pollinator exclusion treatment.