Desiccation and germination of grain sorghum as affected by glufosinate

Preharvest desiccants are needed to reduce moisture content of grain sorghu m [Sorghum bicolor (L.) Moench] for earlier harvest to preserve seed qualit y and quantity, Objectives of this study were (i) to examine the desiccant activity of glufosinate [2-amino-4-(hydroxy-methylphosphinyl)butanoic acid] applied at several rates to grain sorghum at different seed moisture level s in contrasting environments and (ii) to determine the effect of glufosina te on germination and seedling growth of the treated crop. The soil at Coll ege Station (east-central Texas), was a Ships clay (very-fine, mixed, activ e, thermic, Chromic Hapludert); at Mayaguez, PR, a Coto clay (very-fine, ka olinitic, isohyperthermic Typic Hapludox). Glufosinate was evaluated becaus e of its contact herbicidal properties and limited systemic activity. In bo th Texas and Puerto Rico, glufosinate was applied at 0, 0.56, 1.1, or 2.2 k g ha(-1) to grain sorghum, Leaves and seed were sampled at 0, 1, 2, and 3 w k after treatment (WAT) for grain and leaf moisture. Seed was collected at 2 and 3 WAT for germination and growth studies. Glufosinate at all three tr eatment rates dried seed of the grain sorghum hybrid ATx638/Tx2783 in Texas from >350 g kg(-1) grain moisture at application to a storable moisture of <120 g kg(-1) at 2 WAT, at which time untreated grain moisture was 150 g k g(-1). Glufosinate rate did not affect grain moisture except at the high gl ufosinate rate at 1 WAT. Leaf moisture reduction was glufosinate rate-depen dent, but all treatments significantly reduced leaf moisture content at 1 W AT. Germination and seedling growth were not affected by glufosinate treatm ent. Grain desiccation rate under a tropical environment (Puerto Rico) was slightly slower than in Texas, but leaf moisture reduction was rapid and re ached <300 g kg(-1) by 1 WAT from initial leaf moisture contents of 500 or 770 g kg(-1). Germination was not adversely affected by glufosinate.