In vitro growth of immature peach [Prunus persica (L.) Batsch] embryos as related to carbohydrate source and pH

Abstract

Carbohydrate source and pH of peach embryo culture media affect embryo growth and survival. The objectives of this study were to 1) determine the effect of five carbohydrates (fructose, glucose, maltose, sorbitol, and sucrose) at different levels and combinations on the germination and survival of peach embryos in-vitro, 2) determine the effect of MES buyer at three concentrations (0.0 mM, 4.5 mM, and 9.0 mM) and two pH levels (5.7 and 6.0) on peach embryo germination and survival in vitro. Use of fructose, glucose, maltose, and sucrose resulted in better embryo germination and survival than either glucose or sorbitol. Glucose gave intermediate and sorbitol gave very poor embryo germination and survival. Fructose (2% and 3%) produced better survival than did sucrose (2% and 3%) in smaller embryos (< 10% ovule dry weight). However, sucrose produced better survival than did fructose in the larger embryos ([]10% ovule dry weight). In sucrose combination experiments, sucrose at 1% in combination with either 1% fructose or 1% maltose produced greater survival than 2% sucrose although not different from 3% sucrose. In combined sucrose and fructose experiments, only 1% fructose with either 1% glucose or 1% maltose was better than 2% and 3% sucrose. However, fructose at 1% combined with either glucose, maltose, sorbitol, or sucrose at 1% had equivalent or higher survival than did either 1% or 2% sucrose in conjunction with the same sugars. Survival on differing carbohydrates was found to vary with genotype. Differences in molarity (48.1 mM to 166.5 mM) did not seem to be as important as carbohydrate energy source used. In experiments with MES buffer the 0.0 mM and 4.5 mM levels produced better embryo survival than the 9.0 mM level. Although the pH stability was better at the higher MES level (9.0 mM) survival decreased. In immature peach embryo culture, the increased pH stability is not as important as the level of the buffer.