THE EFFECT OF HARVEST DATE ON THE HARVEST OF MALTING BARLEY

The harvest date of spring barley had a significant influence on achie ving the grain quality. In premature or delayed harvest worsened value s of qualitative factors were manifested. In the field experiment cond ucted with spring barley varieties Rubin and Malvaz the influence of d ifferent dates of harvest on selected characteristics of malting barle y, as affected the grain moisture, grain fraction above sieve of 2.5 m m in diameter, minus mesh of 2.2 mm, grain content in brown tips, gree n grain fraction, germination capacity, crude protein content in grain , and 1000-kernel weight (TKW) was studied. First of all, marked main blades, the dynamic increasing weight of grain dry matter was investig ated. In three to four days' intervals, ten days after flowering, a we ight of grain dry matter was observed. The following years were charac terized by drought conditions during the grain formation. In 1991 spor adic rainfalls were in a half of this period. Increasing weight of gri n dry matter, recorded ten days after flowering, was due to the fast i ncrease in weight (Figs 1, 2). Daily increase in weight per grain betw een the 17th and 31st days was 1.35 to 2.13 mg and to the end of this period its weight was 35.19 to 38.26 mg. During next twenty days daily increase fell. In plants established in 1990 the TKW was 46.57 to 47. 78 g (Tab. I), while in non-established plants with higher proportion of weaker tillers in 1991, the TKW decreased to 40.01 to 41.60 g (Tab. II). With such a continuous higher proportion of grain fraction above sieve of 2.5 mm in diameter compared with 1991. With decreasing grain moisture, the proportion of grain fraction above sieve of 2.5 mm in d iameter increased, and the proportion of fraction minus mesh of 2.2 mm decreased. In the premature harvest the lower yield of grain fraction above sieve of 2.5 in diameter was recorded. The content of grains ha ving the brown tips was later stabilized. The year with a lack of rain fall in July of 1990 was characterized by a low incidence of coloured grains to 1 %. With a few of rainfalls during the grain formation, hig her inclination to browning of grain was observed in the Rubin variety (3.9 %) compared with the Malvaz variety (0.8 %). In the optimal time of harvest (August 3-8, 1990; August 16, 1991) no occurrence of green grains was recorded. A high germination capacity over 90 % was observ ed as soon as in the second half of the grain formation and increased to an optimal date of harvest. Crude protein content in grains increas ed three to ten days before achievement of grain moisture of about 14 %.