The development of the ‘Delmas’ pecan fruit, with special reference to growth phases and changes of lipids and potassium

Abstract

The morphological development of pecan nuts and the changes in lipids and potassium were investigated. The nut reached its full size at the beginning of September, while the shuck continued to grow for about four additional weeks. The liquid endosperm attained its maximal volume by the end of August and disappeared during the first week of September. At about this time, potassium and lipids started to accumulate. The rate of accumulation of potassium in the shucks and lipids in the kernel was exponential. The influx of potassium into the kernel was discontinuous. There exists a linear relationship between the level of potassium in the shucks and of the lipids in the kernel. Extrapolation of the regression line indicates a critical potassium level in the shuck of ca. 1.57% per dry weight. Potassium analysis of the shucks is proposed as a physiological indication of the potassium status of the tree. Possible functions of potassium in the biosynthesis of lipids in pecan nuts are discussed.