The Effects of Shading and Cutting Treatments on the Photosynthetic Rate of Ryegrass Leaves

Publisher Website
Google Scholar
Abstract
As the leaf area of miniature simulated swards of S24 perennial reygrass (Lolium perenne L.) grown in controlled environment increased, successive leaves which expanded on the main stem of a sample plant within the sward had progressively lower photosynthetic capacities. When the plants surrounding the sample plant were cut, the photosynthetic capacity of the next leaf to expand was increased, whether or not other leaves on the sample plant had been removed. When all fully expanded leaves on the sample plant were removed but the surrounding plants left uncut, the photosynthetic capacity of successive leaves on the sample plant continued to decrease as in uncut swards. These results support the view that the changes in photosynthetic capacity in grass swards are consequences of changes in the light climate of the developing leaf rather than of changes in demand for assimilates or growth substance supply. The decline in photosynthetic capactiy was contributed to by both stomatal and residual diffusion resistances.