[Thresholds of weed plant harmfulness in soybean crops]
2006
Korpanov, R.V. | Soroka, S.V.,The National Academy of Sciences, Minsk (Belarus). Institute of Plant Protection
It is determined that the threshold of harmfulness in soybean crops makes 2-6 pcs/square m depending on weather conditions (under dry conditions and unstable positive temperatures during the period planting-seedlings -2, under humid and close to average perennial -6). The appropriateness is proved: the more weeds grow in the crop the larger vegetative weight they form and in accordance with it the negative influence on soybean yield is increased. So, by years of research at weed number 10 pcs/square m the yield is decreased for 46,8-77,7%; 25 pcs/square m - 53,2-86,0%; 50 pcs/square m - 64,9-89,3%. The coefficient of weed communities harmfulness reflecting yield losses by soybean weed infestation increase for one weed/square 2, has made 0,02-0,12 by number and 0,002-0,006 cwt/ha by weight. The determination coefficient (R square) shows that soybean yield decrease for 36-59% depends on weed number and 73-94% on their weight. At increase in a contamination parameters of structure of a crop decrease. Decrease in productivity of a soybeans occurs due to deterioration of all parameters of elements of structure of a crop: more low-grown plants are formed, the weight of 1000 seeds decreases. Density of standing of a soybeans by the moment of cleaning, quantity of beans on plants and seeds quantity in bean decreases as well
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