Accumulation of Seed Vigour During Development and Maturation

Abstract

Physiological maturity (PM, maximum accumulation of dry seed weight) represents maximum yield in grain crops and is proposed to represent maximum seed quality (germination and vigour) for sowing purposes of all crops. The relationship of seed maturation to seed quality was investigated for 5 agronomic (rape, wheat, maize, soyabeans and tobacco) and 4 horticultural crops (lettuces, onions, tomatoes and Capsicum) in several field environments in California and Kentucky. Annual evaluations of several soyabean cultivars were made from 1982 to 1992, while one single cross hybrid of maize was tested from 1985 to 1994. All other crops were evaluated for 2 production years, except wheat (Triticum aestivum) with one year. High seed viability occurred first (early in development) for all crops and was followed by maximum standard germination at or before PM in all crops except tomatoes and Capsicum. Maximum seed vigour occurred at or slightly before PM in crops harvested as dry seeds, but after PM for crops with seed harvested from fleshy fruits (tomatoes, Capsicum). When soyabean and maize plants were stressed by defoliation, drought or high temperatures during seed development, seed maturation was accelerated, but maximum seed vigour occurred at or before PM. Thus, the maximum expression of seed vigour was closely related to the occurrence of PM in all crops harvested as dry seeds.