ISHS Acta Horticulturae 284: I International Symposium on Walnut Production
EFFECT OF FERTILITY AUTO-REGULATION ON PRODUCTIVITY OF WALNUT |
| Author: | P. SZENTIVÁNYI |
| Abstract:
Commercial walnut orchards are traditionally built up either of seedling trees or, more recently of grafted clone cultivars. The lack of fruiting capacity of walnut trees in plantations is caused by the autoregulation of fertility and not by the inadequate spacing or illumination as widely supposed. The mechanism of autoregulation is pollen dependent. If pollengrains are present on pistils in superflous amounts the pistils may turn brown soon, the female flowers may abort and the whole fruitlet falls down. Autoregulation of fertility exists in every closed plantation system, the quantity of aborted flowers rising with the number of trees however, an adequate choice of varieties may counter-balance the effect. The described behaviour is so much different from that of other domesticated plants, that most of experts refuse to admit the fact, unless convinced by own studies. The possibility of autoregulation has been investigated upon flowering data collected from Hungarian cultivars since 1954 and for foreign varieties since 1971. Comparision of the male - and female floering time - within and among varieties showed, that in collections of every walnut producing countries varieties and or variety pairs more ore less suitable as well as totally unsuitable for industrial production were to be found. | |
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