Plant and nodule development and nitrogen fixation in climbing cultivars of Phaseolus vulgaris L. grown in monoculture, or associated with Zea mays L.

Abstract

SummaryPlant and nodule development and nitrogen fixation were studied in two climbing cultivars of Phaseolus vulgaris, grown in monoculture, or associated with two maize populations differing in growth characteristics.Bean cultivar P590 showed similar plant and pod fresh weight development in monoculture and when associated with a vigorous landrace maize, interspecific competition becoming significant only 92 days after planting. Nitrogen (C2H2) fixation in this cultivar was greatest 68 days after planting and declined rapidly thereafter, showing no significant differences between monoculture and associated plantings. When the bean cultivar P526 was associated with the landrace maize, plant development was depressed as early as 50 days after planting. While slight inhibition of nitrogen fixation, specific nodule activity (SNA) and nodule carbohydrate content was also observed at this time, it could not be concluded that such inhibition was definitely due to the associated planting.Association with an improved maize, amarillo subtropical, did not affect plant development in P590 but did decrease growth of P526 at the 80 and 92 day harvests.