Effect of the accumulation of cold hours on the percentage of flowering of apple and peach cultivars in high valley áreas

Abstract

In the producing regions of the Cochabamba Valley, deciduous fruit trees begin their flowering period at the beginning of September, the result of having accumulated a certain number of cold-hours. Some varieties in apple, plum and peach trees, show a low percentage of flowering, possibly because they have not met the needs in "cold hours" (HF).  The objective of the work was to determine how many hours-cold required each of the varieties under study to bloom at 100%. In winter of 2018, were applied to various treatments of HF stakes from peach variety Gumucio Reyes, apple variety Princess, Gala, Fuji, Sayaca and plum varieties Santa Rosa, Black Beauty, Black Amber and Fortuna, in order to assess the percentage of flowering obtained at different treatments in "cold hours. As a result, it was determined that the variety Gumucio Reyes (peach tree) reaches a percentage of flowering of 100 % when it accumulates HF superior to 300, in apple tree the variety Princesa requires to accumulate HF between 300 and 400 to be able to flower until a 100 %, the other varieties its requirements are superior to 600 HF. In the plums the varieties Santa Rosa, Fortuna and Black Amber, achieve a flowering superior to 60 % when they manage to accumulate HF superior to 400. In conclusion, the variety Gumucio Reyes in peaches will flower intensely in regions where the accumulation of "cold hours" is superior to 350, like the variety Princesa in apple trees. In relation to the other varieties its requirements are high. In the case of plums, they require production areas where the accumulation of cold hours is higher than 600 HF to be a species with great potential.