BENEFIT OF USING PLANT-GROWTH REGULATORS IN FODDER BARLEY

The study was conducted to investigate the effect and benefit of apply ing plant growth regulators (PGR) to two easily lodging barley cultiva rs, Arra and Kilta, which were commonly used for fodder production all over Finland. Field trials were conducted at six experimental sites i n different parts of the country. Of the PGRs tested, ethephon and mep iquat/ethephon were the most effective in shortening the culm and prev enting lodging. However, neither could prevent the lodge adequately in all growing circumstances. When applied at flag-leaf stage (FS 10) th ey increased yield under conditions favourable for lodging. They also raised the volume weight of barley, which was important for the final price of the yield. The most important factors determining future lodg ing of barley were an effective temperature sum of over +5 degrees C a nd precipitation during the period from sowing to the beginning of til lering (FS 2). About 64-68% of the lodging risk of the cultivars studi ed could be predicted from weather conditions during early development of the crop. Local growing conditions and the presence of lodge had a marked impact on the results obtained with PGRs. In the case of moder ate lodging the compound used determined whether a profit or loss was made on the crop. In the case of heavy lodging, compounds containing e thephon contributed to an economic return. Their application at flag-l eaf stage gave a profit of FIM 70 - 390 ha(-1). Since the profitabilit y of PGR treatments de pended on lodging, treatments are recommended f or fodder barley only when lodging is expected. The lodging risk can b e predicted within certain limits at the tillering stage of barley.