Carbohydrate and Nitrogen Levels in Pistachio Branches as Related to Shoot Extension and Yield1

Abstract

The pistachio ( Pistacia vera L.), characteristically a biennial bearer, produces its most extensive shoot growth in years of heavy crop production. Whereas levels of total sugars in bark and wood of bearing and nonbearing branches were similar throughout the year, starch levels tended generally to be higher in nonbearing than in bearing branches. Consequently, nonbearing branches one year gave rise to heavy crops the next and, beacuse of greater quantities of reserve foods, also produced extensive shoot growth. Bearing branches of that same year, .however, produced few or no nuts the next and, because of lesser quantities of reserve foods, produced markedly less shoot growth. No relationship between total nitrogen level and shoot growth or fruiting was evident.