IMPACT OF WEATHER ON PHENOLOGY OF MUSTARD (Brassica juncea L.) AND ITS EFFECT ON INSECT POLLINATORS DIVERSITY AND POLLINATION
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Date
2017-12
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UHF,NAUNI
Abstract
ABSTRACT
The present study was conducted to determine the impact of weather on phenology of mustard
(Brassica juncea L.) and its effect on insect pollinators diversity and pollination. The studies were conducted in
mustard crop by inducing the plant to flower early or late through different sowing dates. The crop was sown
during two major seasons first from October- November (season 1) and second from February to March (season
2) in three different dates in each season at an interval of fifteen days. Season 1 and season 2 had significant
effect on flower phenology, insect pollinators diversity and relative abundance of insects and seed set of mustard
crop. Flower bud development was significantly more in mustard crop grown in season 1 (11.12 days) as
compared to season 2 (8.55 days). Season 1 had longest flowering duration (39 days). Flower phenology
characters like duration of flowering, days to flowering, longevity of flower, pollen viability and nectar sugar
concentration have been found sensitive to change in weather conditions like temperature, relative humidity and
rainfall. Flower bud development, longevity of flower was positively correlated with temperature. Nectar sugar
concentration decreased with decreasing relative humidity and had a direct correlation with air temperature.
Cool temperature at the time of flowering favoured nectar flow. Open mode of pollination was superior to hand
pollination and pollinators exclusion. Higher seed set percentage was observed in open pollination (66.87 %) as
compared to hand pollination (51.55 %) and pollinator’s exclusion (42.68 %) during both the seasons. Seed set
in mustard was higher in season 1 (62.15 %). Delayed sowing of mustard resulted into reduction in the seed set
due to short flowering duration, low nectar sugar concentration, which were affected by weather conditions. The
population of insect visitors was higher in season 1 as compared to season 2. A total of 88 insects belonging to
63 genera under 31 families and 9 orders were found to visit the mustard bloom in season 1. Forty one insects
belonging to 23 families and 9 orders were observed in season 2. Order Hymenoptera contributed higher
percentage of the insect visitors. Hive bees (Apis cerana F. and A. mellifera L.) were the most efficient
pollinators of mustard. High temperature, heavy rainfall and low temperature had negative influence on
abundance of insect visitors on mustard flower. Shannon Weiner pollinator diversity indices indicated that for
sampling pollinator diversity, all the methods have to be collectively employed as no single method is fully
reliable.
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