SEED SIZE EFFECTS ON EMERGENCE, HEAD NUMBER, AND GRAIN-YIELD OF WINTER-WHEAT

There is little information on the effect of seed size on grain yield of soft red winter wheat (Triticum aestivum L.) in the eastern USA, and research elsewhere has produced inconclusive results. This study was conducted during two growing seasons (1988-1989 and 1989-1990) to examine the effect of three seed sizes-produced by harvesting at intervals after anthesis- and two seed rates-19 and 38 seeds/sq ft-on emergence, head number, and yield of three wheat cultivars. All seed sizes emerged equally well, and compensated equally well for low plant stands under the low seed rate, by producing larger numbers of heads/plant. There was little effect of seed size on yield, though in 1989 the small seeds produced higher yield due to less lodging. Thus, it appears that over a considerable range, seed size has little effect on emergence, number of heads per unit area, and yield of these soft red winter wheat cultivars. While there may be instances where the cause of small seeds (e.g., disease) may affect plant health or stands, we have shown small size alone to have little effect on seed performance under Midwest growing conditions.