Relationship between visual colour rating and chlorophyll content, photosynthetic rate, and some growth characteristics in couchgrass (Cynodonspp. L.)

Abstract

SUMMARYChlorophyll contents per unit leaf area and unit dry weight, chlorophylla:bratio, visual colour rating, specific leaf area, and leaf fresh weight: dry weight ratios were estimated for 12 couch (bermudagrass) varieties (Cynodonspp. L.) in winter (July) and spring (October). Net photosynthetic and dark respiration rates were estimated in winter only.The chlorophyll contents per unit leaf area were higher in all varieties in spring than in winter, but per unit weight were more variable. The varieties differed substantially in the net photosynthetic and dark respiration rates. The specific leaf areas were greater in winter than in spring in five varieties: in others it changed little. The fresh: dry weight ratios of the leaves were almost constant between varieties in the spring but varied greatly during the winter. Visual colour ratings were well correlated with chlorophyll contents per unit area but not with weight. The net photosynthetic rate was closely correlated with chlorophyll content (per unit area) but not so closely with colour rating.