Molybdenum Requirement of Leguminous Plants Supplied with Fixed Nitrogen

Abstract

Peas (Pisum sativum) and beans (Phaseolus vulgaris) grown with nitrate as the N source require Mo for the completion of their life cycle. Because of the large amts. of Mo in commercially available seed (0.5 to 5 [mu]g. per seed), demonstration of the need of these spp. for Mo required the use of first generation seeds from plants grown on purified culture solns. Seeds of plants grown on purified culture solns. contained from 0.05 to 0.1 [mu]g Mo and gave rise to Mo deficient plants when grown on purified culture solns. Mo deficiency of beans was characterized by interveinal mottling with eventual collapse of tissue in interveinal areas. Mo deficiency in peas shows very different foliage symptoms, with little chlorosis. Within a day after first recognizable symptoms, interveinal areas collapse and leaflets died. Recovery of plants in early stages of Mo deficiency may be effected by appln. of molybdate soln. (100 ppm. Mo) to foliage or by addition of molybdate to the culture soln. Mo is unique among essential elements in that seeds may supply up to 10 times the mature plants'' nutritional need.