Exploring pollination mechanisms in walnut: Production and breeding perspectives

Abstract

Pollination promotes both fruit production as well as genetic variations in fruit crops. Walnut belongs to the deciduous, monoecious, anemophilous and self-compatible fruit tree. Regardless of self-compatibility, due to dichogamous nature of crop it is hindering pollination, fruit set and breeding in walnut. Pollination mechanisms in walnut are not completely understood, and this unusually complex pollination behavior necessitates that we improve our mechanistic understanding of cytology, flower and pollen morphology, pollen collection, storage and germination and pollination process in walnut. A deeper understanding of pollination mechanisms is vital for fruit production as well as to reduce pistillate flower abortion (PFA) and to speed up future walnut breeding and varietal improvement by enhancing genetic diversity and developing hybrid verities targeted for having desirable traits like lateral bearing, precocity, batter fruit quality, high productivity, earlier harvest and resistance to late-spring frost, cherry leaf roll virus (CLRV), blight and pistillate flower abortion. A comprehensive grasp of walnut pollination mechanisms enables experts to offer more effective technical guidance to walnut growers. This article presents recent advancements in our understanding, consolidating pertinent and up-to-date information on walnut pollination mechanisms into a single resource for the first time. It serves as a valuable reference for researchers engaged in horticultural research, particularly in the domains of pollination, fruit production, and walnut tree breeding.