The Effect of Fruit Shading on Yield in Pisum sativum L.

Fruits of Pisum sativum L. cv. Feltham First which initiates only one flower per flowering node, were selectively shaded under varying levels of defoliation. The purpose of the experiments was to ascertain whether the foliage could compensate for loss of the fruit's contribution to its own growth. There was evidence of this, but fruit and seed weight per fruit and per plant were reduced by fruit shading at all levels of defoliation. The loss in yield due to shading suggested that the contribution from the fruit was at least 12 per cent. The number of seeds which developed to maturity was the yield component most affected by treatment. There was no evidence to suggest that shading had a different quantitative effect on final weight at different nodes, but it did increase flower abscission at the first fowering node in an experiment done at low radiant exposure. In an experiment at higher radiant exposure, very few flowers abscised at the earlier nodes, but leaflet removal reduced final fruit yield at the first flowering node to a greater degree than at the second. These differential responses could contribute to variability of seed size in a crop of vining peas.