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 applying osmoprotectans to crop canopies. Glycinebetaine is endogenously accumulated by some halophytes under stress conditions and represents such a compound. Glycinebetaine was applied exogenously to barley (Hordeum vulgare L.), oat (Avena sativa L.), spring wheat (Triticum aestwum L.), and summer turnip rape (Brassica rapa ssp. oleifera DC.) canopies and its optimal concentration was monitored in the greenhouse. In field experiments the response of crop plants to betaine applications was assessed by measuring accumulation of above ground biomass, leaf area index (LAI), leaf chlorophyll, and yield. The optimum betaine concentration producing advantageous effects on growth and crop physiology in turnip rape was close to 0.1 M and for wheat 0.3 M. Such concentrations promoted accumulation of betaine similar to that of halophytes under stress conditions [ca. 200 μmol (g DM)−1]. In the 1993 field experiment peak LAIs were recorded in irrigated wheat and barley treated with 17.5 kg ha−1 betaine applied at 300 1 ha−1. Green leaf area was slightly more persistent in wheat treated twice with 1 kg ha−1 betaine applied at 200 1 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 potential of betaine treatments for preventing crop failures.