PHOSPHORUS ALLOCATION IN P-EFFICIENT AND INEFFICIENT BARLEY CULTIVARSAS AFFECTED BY MYCORRHIZAL INFECTION

A glasshouse experiment was undertaken to investigate the effect of my corrhizal infection on the allocation of phosphorus (P) in agronomical ly P-efficient (i.e. high yields at low P supply) and inefficient barl ey (Hordeum vulgare L.) cultivars. Four barley cultivars differing in agronomic P-efficiency were inoculated or not inoculated with Glomus e tunicatum. Cultivars did not differ in percentage of root length infec ted. The concentration of P in roots of the inefficient cultivars was higher than that of the efficient cultivars. However, because of chang es in root to shoot dry weight ratio and below-ground productivity, my corrhizal infection significantly reduced the percentage of total plan t P in roots of the inefficient cultivars. The distribution of P betwe en root and shoot of P-efficient cultivars was not affected by mycorrh izal infection. Root to shoot dry weight ratio of the P-efficient cult ivars was lower than that of the inefficient cultivars, and the decrea se in the ratio following infection was significant in inefficient but not in P-efficient cultivars. This study indicates that mycorrhizal i nfection alters the allocation of P in inefficient cultivars and effec tively improves the efficiency of P utilization with respect to shoot growth.