Effect of Nitrogen Applications on Bloom Delay and Levels of Abscisic Acid, Carbohydrates, and Nitrogen in Peach Buds1

Abstract

Soil applications of nitrogen in February and August delayed bloom of trees of ‘Redglobe’ peach (Prunus persica (L.) Batsch) the following spring. Applications of 67 to 134 kg N/ha delayed bloom progressively from 12 to 72 hours when compared to trees receiving no N. Buds from trees that received high levels of N contained higher levels of abscisic acid (ABA) and N and lower levels of carbohydrates (CHO) than did those from trees receiving no soil-applied N. ABA levels decreased sharply and CHO levels increased in buds from all treatments upon completion of the chilling requirement (850 hours). Delays in bloom of more than 24 hours prevented significant spring freeze damage in 1975.