Growth characteristics of spring barley and selected weeds. I. Effect of irradiance in growth chambers

Abstract

SummaryA study in growth chambers with three irradiance levels was carried out over a four‐week period on individual seedlings of spring barley (Hordeum vulgare L.) and five weed species (Brassica rapa L. ssp. oleifera (DC.) Metzger, Chenopodium album L., Galeopsis tetrahit L., Stellaria media (L.) Vill., and Viola arvensis Murray). Increased irradiance resulted in larger dry weight, net photosynthetic rate, relative growth rate (RGR), net assimilation rate (NAR), and lower leaf area ratio (LAR). The number of leaves per plant, plant length, leaf area, and shoot/root ratio were unaffected by irradiance levels, During the experimental period the net photosynthetic rate increased, while NAR remained the same, and RGR, LAR, and shoot/ root ratio decreased. On the basis of leaf area and dry weight, especially at the high irradiance level during the last part of the experimental period, barley, B. rapa, and C. tetrahit had the largest values, followed by C. album and S. media with medium values, and V. arvensis with the smallest values. As for leaf area and dry weight, S. media took more advantage of the low than the high irradiance level compared with C. album. Species differences are discussed with regard to competitive ability.