WEED DIVERSITY AND SEED BANK STUDIES IN DIFFERENT AGRICULTURE FIELDS IN SOME AREAS OF BHAKTAPUR DISTRICT
Date
2023-08-14
Authors
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Publisher
Amrit Campus
Abstract
Weeds in agricultural fields reduces crop yields by competating in nutrients, sunlight, and
moisture, among other things.Weeds have the ability to produce a huge number of seeds, and
propagate rapidly in agricultural fields due to presence of congenial environment and
ultimately reduces crop yield. The weeds present in different fields may be different due to
agricultural practices and crops grown there. The aim of present study was to compare the weed
diversity in different agricultural fields having cultivation of wheat, cabage and potato. Besides
this the aim of this study was also to find out differences in seed bank at different agriculture
fields of Bhaktapur. To understand this five different sites (Sudal, Wonti, Chitapole, Gundu,
and Jhaukhel) of Bhaktapur district were selected as theses places were having similar crops
and agricultural practices. From each sites potato, cabbage and wheat fields were selected for
weed diversity and seed bank study in January to Februrary of the year 2020 and 2021. The
study of weed diversity was conducted using quadrats of 2×2m2
in both years whereas the study
of seed bank was conducted only in 2021. For seed bank study, soil samples from each field
was collected using composite sampling, then the seed germination was observed in the
collected soil samples by spreading it on plastic plate along with regular watering after 2nd
weeks from February 16
th to March 27th 2021. Altogether 49 weed species belonging to 16
families were found in three different agriculture fields. Among them 47 were found in first
year and 49 were found in second year. Asteraceae (16) was the dominant family followed by
poaceae (8). Poa annua, Soliva anthemifolia, Stellaria media, Chenopodium album, Persicaria
hydropiper were the most dominant species as their IVI and weed density/m2 were high in most
of the sites except Jhaukhel. Spergula arvensis scored highest IVI and highest weed density/m2
in wheat field of Jhaukhel. The weed density in agriculture fields were increased in second year
in compare to first year. From the seed bank study, altogether 1023 seeds of 37 weed species
belonging to 15 families were recorded in soil. The dominant families in soil seed bank were
Poaceae, Asteracea and Caryophyllaceae. The most abundant species recorded in soil seed
bank were Poa annua, Stellaria media, Soliva anthemifolia. Emergence of Cynodon dactylon,
Poa annua, Stellaria uliginosa and Persicaria hydropiper were not significantly different at
P=0.05 in all selected sites in potato field. Emergence of common weeds Poa annua, Soliva
anthemifolia, Stellaria media, Chenopodium album, Persicaria hydropiper were significantly
different at P=0.05 in all selected sites in cabbage field and wheat field. Weed seed density of
three different agriculture fields in selected sites were insignificantly different. Weed species diversity was high in Gundu whereas it was low in wheat and potato fields of Jhaukhel. But
high weed diversity was recorded at cabbage fields of Jhaukhel and low diversity was found in
cabbage fields of Wonti. Weed seed bank diversity was high in Gundu and low in Wonti. The
similariy index of weeds in agriculture fields and soil seed bank is high in cabbage field of
Chitapole and low in wheat field of Jhaukhel. Species richness of soil seed bank followed the
same pattern as in fields, with the highest richness in Gundu and lowest richness in Wonti.
From both field studies and seed bank study by germination method, weed species richness
was found to be high at wheat field and low at cabbage fields. The Shannon diversity index
was found to be higher in seed banks than in agricultural field weeds, indicating the importance
of seeds in the soil as a reservoir of biodiversity. The similarity index of weeds in cabbage
fields and soil seed bank were foud to be highest (86.96%). Some of the weeds like Rorripa
palustris, and Amaranthus spinosus, of which A. spinosus is an invasive species, were recorded
in the soil seed bank study only but were not found in field study. This finding indicated the
possibilities of invasive weed infestation in the agriculture field in future. From this it is evident
that the study of a weed seed bank is important as it provided more information about the weed
seed infestations at present and also warns us for the future as well.
Description
Keywords
Weed, IVI, Seedling emergence, Wheat, Potato, Cabbage