Volume 39, 129-139

Tropical Grasslands (2005) Volume 39, 129–139

Influence of storage conditions on survival and sowing value of seed of tropical pasture grasses. 1. Longevity

J.M. HOPKINSON AND B.H. ENGLISH

Department of Primary Industries, Queensland Beef Industry Institute, Walkamin Research Station, Walkamin, Queensland, Australia

Abstract

To find ways of improving the sowing value of seed of tropical pasture grasses through attention to the storage environment used commercially, fresh seed lots of Panicum maximum, Brachiaria decumbens, Brachiaria humidicola, Setaria sphacelata and Chloris gayana were stored under different conditions and sampled periodically for laboratory, greenhouse and field testing. Comparisons were made between seed lots stored in bags of open weave in a cool-room at 10°C and 50% RH and in an open store-room at ambient temperature. Seed lots of P. maximum in moisture-proof packets at 5 different moisture contents between 7.3 and 12.9% were compared. One seed lot was also freezer-stored at −12°C. Part 1 reports their viability and dormancy loss.
Viability loss of seed in woven bags in open storage was complete within 3 years while barely detectable in similar cool-stored seed. Rates of loss in sealed packets increased with moisture content at ambient temperatures. They were much higher in seed in woven bags at comparable average moisture contents, an effect attributed largely to spatial moisture content gradients. Cool storage temperatures and low seed moisture contents appeared to prolong dormancy, while freezer storage retained and even intensified it.