EFFECT OF FOLIAR APPLICATIONS OF GLYCINEBETAINE ON STRESS TOLERANCE, GROWTH, AND YIELD OF SPRING CEREALS AND SUMMER TURNIP RAPE IN FINLAND

Crop losses caused by environmental stresses might be reduced by apply ing osmoprotectans to crop canopies. Glycinebetaine is endogenously ac cumulated by some halophytes under stress conditions and represents su ch a compound. Glycinebetaine was applied exogenously to barley (Horde um vulgare L.), oat (Avena sativa L.), spring wheat (Triticum aestivum L.), and summer turnip rape (Brassica rapa ssp. oleifera DC.) canopie s and its optimal concentration was monitored in the greenhouse. In fi eld experiments the response of crop plants to betaine applications wa s assessed by measuring accumulation of above ground biomass, leaf are a index (LAI), leaf chlorophyll, and yield. The optimum betaine concen tration producing advantageous effects on growth and crop physiology i n turnip rape was close to 0.1 M and for wheat 0.3 M. Such concentrati ons promoted accumulation of betaine similar to that of halophytes und er stress conditions [ca. 200 mu mol (g DM)(-1)]. In the 1993 field ex periment peak LAIs were recorded in irrigated wheat and barley treated with 17.5 kg ha(-1) betaine applied at 300 l ha(-1). Green leaf area was slightly more persistent in wheat treated twice with 1 kg ha(-1) b etaine applied at 200 l ha(-1) in 1994, although it was not associated with increased grain yield. Our results indicated that betaine has no actual potential in Finland for the principal grain crops but further studies are needed in stress prone environments to assess the potenti al of betaine treatments for preventing crop failures.