Evaluation of the fruit-drop of Myrciaria dubia (H.B.K.) Mc Vaugh, camu-camu, in the "five River Basins" collection of the San Miguel experimental research station - IIAP, Loreto, Peru

Abstract

This study presents preliminary findings regarding the factors that cause fruit-drop in a collection of camu-camu originating from natural stands in five different river systems in Loreto, Peru. We evaluate the percentage of fruits attacked by insect pests, the retention of flowers and fruit according to branch diameter, and the influence of rainfall and temperature on fruit-drop. With respect to factors related to genetics and plant origin, plants from the Putumayo River Basin have the lowest fruit-drop, greatest yield and average weight per fruit, and the lowest rate of attack by insect pests. During the reproductive period, which lasts twelve weeks, the critical phase in which the majority of flower and fruit-drop occurs is during the first seven weeks. The total retention of flowers through to mature harvestable fruit was 5.1% and on average only 25% of the formed fruit reached a mature harvestable state. Our results show that insect pests caused 9.27% of the fruit-drop; of these, Edessasp. caused 98.7% of pest related fruit-drop and Conotrachellus dubiae caused 1.3%. Undetermined factors, potentially including hormonal, nutritional, and climatic (wind, rain, and temperature), caused the remaining 90.73% of fruit-drop. While higher environmental temperatures corresponded to higher fruit-drop, greater pluvial precipitation corresponded to lower levels of fruit-drop. Key words: Myrciaria dubia, fruit culture, camu-camugenetic, improvement, fruit-drop, physiology.