SOYBEAN OIL AS BLOOM DELAYER IN LOW CHILLING PEACHES

Abstract

A possible method to reduce or avoid frost damage during bloom in low chilling requirement peach cultivars (Prunus persica L.), is based on sprays of bioregulators to delay bloom, however the results have not been consistent. Oils from different plant species have been used with promising results, because they delay bloom at low rates on late blooming varieties. The objective of this research was to evaluate the effect of soybean oil concentration (0, 2.5, 5 and 10 %) and spraying dates (November 11 and 24 and December 7) on bloom season of CP 87-3, a low chilling peach under field conditions. The same concentrations were studied under controlled conditions to evaluate the metabolic activity, respiration and growth rate of flower buds at eight and twelve days after application. Response to soybean oil sprays was strongly conditioned to concentration and application date. A mortality of 19 % of buds was recorded when 10 % oil was used. Twelve days after the sprays with 5 and 10 % soybean oil, bud metabolic activity was significantly reduced, as well as in respiration and growth rates, evidencing their delay in bloom. Soybean oil at 5 % sprayed on December 7 advanced the appearance of the pink stage by two days, although it delayed full bloom in twelve days. Nevertheless such a delay was not enough to escape the late frosts at Montecillo, Mexico.