The effect of seed rate and growing season on four oat cultivars: II. Culm morphology and panicle conformation

Abstract

SUMMARYThe effects of low and high seed rates on height, culm and panicle morphology of four oat cultivars grown in field trials in two growing seasons were investigated. Significant differences were detected between cultivars in the number of extended culm internodes, panicle whorls initiated, total height, length of panicle and individual internodes. Differences in seed rate had no effect on the number of culm internodes, but high seed rate significantly reduced the whorl number in the panicle, total plant height, length of panicle and the three upper internodes. The fourth internode remained unaffected, but the lowermost internode showed a relative length increase at high seed rate. The interaction of cultivar x seed rate was significant for total height, and for the length of the central internodes, but the length of the panicle was similarly affected in all cultivars.Panicle conformation was markedly affected by seed rate; high population density caused a reduction in number of grain-bearing whorls, and reduced the number of spikelets and total grain weight per whorl, and 1000 grain weight particularly in the lowermost whorls. The percentage of husk in the grain was increased slightly at high seed rate. The effect of seed rate on culm and panicle morphology is discussed in relation to the development of stiffer-strawed oats.