Sowing Summer Grain Crops Early in Late Winter or Spring: Effects on Root Growth, Water Use, And Yield

Dr Dongxue Zhao1, Peter deVoil1, Prof Daniel Rodriguez1

1The University of Queensland, 2Department of Agriculture and Fisheries (DAF), 13 Holberton Street, Toowoomba, QLD 4350, Australia, 3Department of Agriculture and Fisheries (DAF), 203 Tor Str Toowoomba, QLD 4350, Australia,

Biography:

Dr Dongxue Zhao is a Research Fellow within the Queensland Alliance for Agriculture and Food Innovation at The University of Queensland, Australia. Her research aims to contribute to sustainable gains in crop productivity by improving our understanding of how crop-soil interactions determine crop and root growth, water and nutrient uptake, and final yield. In her research, she combines innovative proximal and remote sensing techniques of crops, soils and roots, with predictive modelling and artificial intelligence tools.

Abstract:

To research the effects of cold conditions in early sowing sorghum on crop and root growth and function (i.e., water use), and final grain yield, two years of field experiments were conducted in the Darling and Eastern Downs region of Qld, Australia. Each trial consisted of three times of sowing (late winter, spring, and summer), two levels of irrigation (i.e., rainfed and supplementary irrigated), four plant population densities (3, 6, 9 and 12 pl m-2), and six commercial sorghum hybrids. Roots and shoots were sampled at the flag leaf stage on three times of sowing, two levels of irrigation, and three replications, for a single hybrid and a single plant population density (9pl m-2). Crop water use and functional root traits were derived from consecutive electromagnetic induction (EMI) surveys around flowering.nEarly sowing increased yield by transferring water use from vegetative to reproductive stages and increasing grain numbers in tillers. Sowing sorghum, a summer crop, early in late winter or spring transferred water use from vegetative stages to flowering and post-flowering stages increasing crop water use later in the season. Root length and root length density were reduced by pre-flowering mean temperatures lower than 20C, indicating a need to increase cold tolerance for early sowing. The higher grain numbers in early sown crops were related to higher grain numbers in tillers. The EMI derived index of root activity has potential in the development of high throughput root phenotyping applications.