Seasonal Changes in Mineral Content of Different Organs in the Alternate Bearing of Pistachio Trees
2007
Baninasab, B. | Rahemi, M. | Shariatmadari, H.
The alternation of heavy and light crops in pistachio (Pistacia vera L.) results from the abscission of flower buds on heavily cropping trees during the summer. The actual mechanisms involved in this bud abscission remain unclear. This study was conducted to examine the role of nutrients in flower bud abscission and alternate bearing. For this reason, 30-year old eight lightly cropping (OFF) and eight heavily cropping (ON) pistachio trees, cv. Owhadi, were selected and used for nutrient measurements. Nutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were measured in flower buds, leaves, fruits, current shoots, 1-yr-old shoots and roots of both OFF and ON trees at monthly intervals from 10 days after full bloom until harvest. The flower bud abscission percentage was recorded every 15 days, beginning 70 days after full bloom until the end of experiment. Time and fruiting state had a significant effect on the nutrient contents in many organs of alternate bearing pistachio trees. N and P concentrations declined during the period that coincides with that of seed development in most organs, in both OFF and ON trees. N and P concentrations in many organs from ON trees were most times lower than that of OFF ones. In contrast to N and P, in many organs concentrations of K, Ca, and Mg increased throughout the growing season. Ca and Mg concentrations of most organs were greater in ON trees than in OFF trees. There was a significant negative correlation between N and K concentrations in flower bud and leaf, and P concentration in flower bud, leaf, and 1-yr-old shoot with flower bud abscission. It was concluded that nutrients could have an important role in the alternate bearing in pistachio.
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