CAVITATION AND ITS INFLUENCE ON BEAN SEED DAMAGE DURING THE THRESING PROCESS

One of the legumes’ peculiarities is cavitation - formation of an air (cavitation) cavity between the cotyledons. The effect of cavitation on bean seed damage was observed; it is the most conspicuous, upon threshing. Thus, we set an objective to determine the dependence of bean seed damage on cavitation and other seed parameters, as well as the dependence of the cavitation magnitude on the effects of intrinsic and extrinsic factors. The results of 1995-2017 studies showed that among the extrinsic factors the ambient air temperature was the most important one during the bean seed filling and maturing phases: the higher air temperature is, the larger cavitation chamber is. Among the seed parameters (intrinsic factors), 1000-seed weight (correlation coefficient 0,66) and the seed length (correlation coefficient 0,63) have the most significant effects: the larger seeds are, the higher magnitude and degree of cavitation are. The seed shape and the other seed parameters have no significant effects on the cavitation magnitude (correlation coefficients 0,34, 0,43 and 0,19 for shape, width and thickness, respectively. The cavitation degree, which is determined by the ratio of cavitation magnitude to seed thickness, is of great importance (correlation coefficient 0,86). This parameter is the main one for predicting the seed damage during mechanized harvesting of beans: with a low degree of cavitation (≤ 39 × 103), the seed damage will be negligible (10% of damaged seeds). We distinguished ten accessions with weak cavitation. They are Ukrainian varieties Perlyna, Nadiia, Yasochka, Nespodivanka, Odesytka; Bulgarian varieties Prelom, Bistrenski, Sakharnaya; Hungarian variety Balvanyasi feher and Hungarian local form UD0300104. To calculate the cavitation degree on bean seeds, we proposed a direct method for determining the cavitation magnitude. This method consists in measuring the cavitation magnitude with a microscope equipped with an eyepiece micrometer on cross sections of 25 seeds taken from a standard amount weighted from a seed batch