Effects of early harvest times on nut quality and physiological characteristics of pistachio (Pistacia vera) trees

Abstract

Introduction - Pistachio harvesting at the appropriate time is one of the key factors affecting the product quality. The effects of early harvest time on quantitative and qualitative properties of pistachio nuts were investigated. Materials and methods - The 'Ohadi' pistachio cultivar was used as the market reference in Iran. Five harvest times (July 27, August 6, August 16, August 27 and September 6) were studied over four consecutive years (2008-2011) as treatments in the field experiment. Nut weight parameters, hull discoloration, hulling, cracked nuts, early-split nuts, kernel protein, mineral and chlorophyll contents were evaluated at each harvest time. Results and discussion - The fresh and dry nut weights showed the maximum and the minimum nut production rates for the last (September 6) and the first (July 27) harvest times, respectively. Percentages of hull discoloration, cracked nuts and immature nuts were significantly influenced by harvest time. The early-split nut percentage was not significantly different at the various harvest times. The maximum potassium, calcium, magnesium and nitrogen, protein and chlorophyll contents were obtained at the first harvest time. The growth of current year shoots, leaf area, percentages of vegetative and reproductive buds were not influenced by the harvest time, whereas the abscission of reproductive buds was minimum at the first harvest time and significantly different from all other times. Conclusion - Early harvesting of pistachio is preferable in terms of crop health indicators, nutritional value and color of the kernels. However, it is not preferable in terms of yield (nut and kernel production per hectare) for the producers, although potentially more sustainable.