ISHS Acta Horticulturae 633: XXVI International Horticultural Congress: Protected Cultivation 2002: In Search of Structures, Systems and Plant Materials for Sustainable Greenhouse Production
HOW TO REDUCE YIELD FLUCTUATIONS IN SWEET PEPPER? |
| Authors: | E. Heuvelink, L.F.M. Marcelis, O. Körner |
| Keywords: | Capsicum annuum, yield flushing, fruit set, fruit abortion, parthenocarpy, planting dates, fruit pruning |
| Abstract:
Flushing, i.e. cyclic fluctuations in fruit yield, is an important problem in sweet pepper production. These fluctuations result from cyclic variations in fruit set. Therefore, the relationship between fruit set and plant sink and source strength was investigated in several greenhouse experiments. A decrease in plant source strength by decreasing inter-plant distance or light intensity or by leaf removal led to a decrease in fruit set. For example, the percentage of fruit that set was 32, 20 and 16% at a plant density of 1.6, 3.1 and 4.6 plants m-2, respectively. Plant sink strength was varied by the number and position of competing fruits on the plant. Fruit set decreased with increased plant sink strength, e.g. in plants with 0, 1, 2 or 4 early-formed fruits, fruit set of four later-formed flowers was 78, 56, 28 and 6%, respectively. Average rate of fruit set could be predicted from the ratio between plant source and sink strength. Removal of some flowers and/or young fruits in periods of abundant fruit set did reduce the cyclic fluctuations in fruit set and yield, but less than expected. When planting in late spring, as opposed to a winter planting, yield fluctuations at farm level could be substantially reduced by adopting two planting dates with four weeks in between. An increase in seed number, resulting from higher pollen load on the stigma of flowers, increased the inhibitory effect of a fruit on set and growth of later developing fruits. Variation in fruit set and yield was strongly reduced in plants with parthenocarpic fruit growth, obtained by preventing pollination through applying a lanolin-auxin paste onto the stigmas of all flowers on a plant. Hence, developing seeds in sweet pepper fruits are an important cause of the abortion of new flowers, and irregular fruit set and yield. | |
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