Canopy architecture, row spacing and plant density effects on yield of dry bean (Phaseolus vulgaris) in the absence and presence of hairy nightshade (Solanum sarrachoides)

Abstract

A field study was conducted to determine the combined effects of cultivar growth habit, row spacing and plant density on weed management and dry bean yield. In the absence of weeds, upright and viny cultivars expressed similar yield potentials and greater yields of both cultivars were attained by increasing density from 24 to 48 plants m−2. A reduction in row spacing from 69 to 23 cm apart increased dry bean yield in all years when grown at a density of 48 plants m−2 but only increased yield in 1 of 3 yr when grown at 24 plants m−2. In the presence of hairy nightshade (Solanum sarrachoides Sendt.), the upright cultivar always attained a greater yield than the viny cultivar. Upright dry beans were often 15–20 cm taller than viny beans, and this resulted in their being more competitive for light with hairy nightshade. Regardless of cultivar, an increase in plant density resulted in greater suppression of hairy nightshade and greater dry bean yield. Narrow compared with wide rows always resulted in less hairy nightshade biomass, and a concurrent increase in dry bean yield occurred in 2 of 3 yr. Despite the advantages conferred by an upright cultivar, narrow rows and high plant density, yield of weedy beans was always much less than that of weed-free beans. Further studies are required to integrate these desirable agronomic practices with herbicides or other weed control tactics to develop an improved weed management program for dry bean. Key words: cultural control, hairy nightshade, integrated weed management, upright dry beans, weed suppression, Solanum sarrachoides