Translocation of Foliar-applied Urea 15N to Reproductive and Vegetative Sinks of Avocado and Its Effect on Initial Fruit Set

Abstract

Translocation of 15N from foliar-applied urea to vegetative and reproductive sinks of avocado (Persea americana Mill, cvs. Fuerte and Hass) was evaluated during inflorescence development and the early stages of fruit set. Urea (2%) increased the number and the total dry weight of the lateral inflorescence per shoot. The concentration of 15N in avocado inflorescences increased proportionately to the concentration of urea applied to the old leaf surface. The amount of 15N translocated was not affected by the proximity of the source leaf to the “terminal” inflorescence. 15N translocated to developing fruit and to new sprouting leaves in similar amount. Urea N was translocated basipetally from current flush leaves to developing fruit. Removing the vegetative sink reduced N influx to the reproductive tissue and increased initial fruit set by a factor of 1.7 to 2.1 in urea-treated and -untreated shoots, respectively. These data indicate that shoot growth does not limit fruit set in avocado via competition for N.

Flowering and Photosynthetic Responses of Phalaenopsis under Elevated CO2 and Nutrient Supply

“…In Cho et al (2019), CO 2 enrichment during the reproductive stage did not affect the growth of leaves. It is assumed that phalaenopsis is a slow-growing plant, and carbohydrates are allocated more to the flowers as well as fruit set during the reproductive stage (Zilkah et al, 1987).…”