Sowing

About: Sowing is a research topic. Over the lifetime, 33888 publications have been published within this topic receiving 273438 citations. The topic is also known as: seeding.

Hessian Fly (Diptera: Cecidomyiidae) Injury and Loss of Winter Wheat Grain Yield and Quality

Abstract: The damage–yield-loss relationships of Hessian fly, Mayetiola destructor Say, in soft red winter wheat, Triticum aestivum L., were examined using results of studies on Hessian fly management and yield loss that were conducted over a 9-yr period with various cultivars and planting times and at various locations in Georgia. Differences in grain yield and test weight of susceptible and resistant cultivars with or without a systemic insecticide (disulfoton or phorate) at planting were compared with the percentage of infested tillers in autumn (vegetative stage) and the percentage of infested stems or the number of immatures per stem in spring during grain filling. Grain yield loss increased linearly with increasing percentage of autumn-infested tillers and spring-infested stems. Infestations had little effect on grain test weight until infestations exceeded 20% of autumn-infested tillers or 38% of spring-infested stems. Grain yield and test weight losses were exponentially related to number of immatures per stem during grain filling, with proportionate loss increasing as immature numbers increased up to 6 immatures per stem. Analysis of grain yield components of headed stems found that injury reduced seeds per spike, spikelets per spike, seeds per spikelet, and seed weight. Gain thresholds indicated that, depending on commodity price, an application of a systemic insecticide at planting provided positive marginal returns for 68–74% of plot-years ( n = 50) on susceptible cultivars but only provided positive returns for 23–27% of plot-years ( n = 26) on resistant cultivars. Depending on control cost, economic damage occurred when autumn infestations exceeded 5–8% of infested tillers or when spring infestations exceeded 13–20% of infested stems, or 0.4–1.0 immatures per stem. These results provide a quantitative basis for Hessian fly damage loss assessment in wheat.

On-Farm Evaluation of Winter Wheat Yield Response to Residual Soil Nitrate-N in North China Plain

Abstract: High soil nitrate-N accumulation has been observed in North China Plain (NCP), but it was seldom considered as a N source in N management due to the lack of data on crop response to soil nitrate-N accumulation. A total of 124 on-farm N-response experiments were conducted from 2003 to 2006 in seven key winter wheat (Triticum aestivum L.) production regions of NCP to evaluate wheat yield response to residual soil nitrate-N. High soil nitrate-N accumulation (≥172 kg N ha -1 in 90 cm soil depth) was observed during wheat growing season. Compared with 165 nitrate-N ha -1 in 0 to 90 soil layer before sowing, added fertilizer N did not increase wheat yield under 262 kg nitrate-N ha -1 condition, but increased residual nitrate-N and N losses and reduced recovery N efficiency (P < 0.05). Wheat yield response to residual soil nitrate-N could be fitted by a linear plus plateau model, and calculated minimum soil nitrate-N content for maximum grain yield was 211 kg N ha -1 (R 2 = 0.31) before sowing across all 223 zero-N plots in 124 sites. When two growth periods (before and after shooting stage) were analyzed separately, the coefficient of determination between yield and soil nitrate-N increased significantly. We conclude that winter wheat yield response to added N fertilizer was unlikely if soil nitrate-N content exceeded 72 (0-30 cm soil depth) and 175 kg N ha -1 (0-90 cm soil depth) before sowing and shooting stage, respectively. According to these thresholds, 55% and 37% of farmer's fields did not need to apply N fertilizer before sowing and at shooting stage, respectively.

Effect of sowing date and seed rate on crop development and grain production of winter wheat.

Abstract: In a field trial in 1973-5, winter wheat cv. Lely was sown on 3 dates at 3- to 4-wk intervals from end-Sept. at low (80-90 kg seed/ha) or high (160-180 kg seed/ha) sowing rates. Delaying the sowing date decreased grain yield. This decrease was caused by a smaller number of grains/ear and a lower grain wt. Sowing rate had a positive influence on the number of ears, but a negative effect on the number of grains/ear and the grain wt. With early sowing, sowing rate was found to have no effect on grain yield, due to mutual compensation of changes in yield components. With late sowing, a higher sowing rate increased the number of ears so much that a higher grain yield was achieved. The grain yield/ear depended on the age of the tiller. Tillers that emerged earlier produced more and heavier ears. The number of grains/ear and the grain wt. could be related to the rate of development of the ear-bearing shoot. The pattern of tillering was affected by the sowing date. With early sowing, most tillers emerged in autumn and winter, whereas the late-sown wheat tillered in spring. Also, the early-sown crop consisted largely of ears from early tillers, whereas the late-sown one had many ears from late-formed tillers. (Abstract retrieved from CAB Abstracts by CABI’s permission)