EFFECT OF MANGANESE DEFICIENCY ON GAS EXCHANGE PARAMETERS, LEAF GREENNESS (SPAD) AND YIELD OF PERENNIAL RYEGRASS (LOLIUM PERENNE L.) AND ORCHARD GRASS (DACTYLIS GLOMERATA L.)

The objective of this study was to determine the effect of manganese deficiency in soil on the rate of photosynthesis and transpiration, water use efficiency, leaf greenness and the yield of selected cultivars of perennial ryegrass (Lolium perenne L.) and orchard grass (Dactylis glomerata L.). During the growing season, the rate of photosynthesis and transpiration was measured using a LI-COR 6400 gas analyzer (Portable Photosynthesis System), and leaf greenness was estimated with a Minolta SPAD-502 chlorophyll meter. Water use efficiency (WUE) was calculated based on instantaneous values of photosynthesis and transpiration. Dry matter yield was determined by green matter drying to constant weight at 105 degrees C. The results of the study indicate that the response of grasses to manganese deficiency in soil was dependent on plant species and cultivar. In the present experiment perennial ryegrass cultivars showed a stronger response to manganese deficit than orchard grass cultivars. Their response involved a decrease in the rate of photosynthesis and transpiration, and in the chlorophyll content of leaves. Among the tested cultivars, perennial ryegrass cv. Maja was found to be most sensitive to manganese deficiency in soil, as confirmed by the highest decrease in the values of all examined parameters.