Nutrient uptake in cotton in relation to plant architecture
SummaryThe studies on uptake of nitrogen, phosphorus and potassium by two morphologically contrasting varieties of cotton MCU-1 and PRS-72 (bothGossypium hirsutum L.) at weekly intervals, showed that till the bursting of early formed bolls, the former type accumulated these nutrients in larger quantities in leaves and stem than in the fruiting parts unlike the latter type where differences in nutrient contents of these organs were very narrow till the active bolling phase. From flowering onwards, the fruiting parts of PRS-72 contained more phosphorus. Because of its bushy habit more dry matter accumulated and more nutrients remained unutilised in leaves and stem of MCU-1 at harvest compared with the short-branch variety PRS-72. Though both the varieties gave the same yield of seed cotton per unit area, PRS-72 removed considerably less quantities of nitrogen, phosphorus and pottassium. The short fruiting branch character in cotton therefore appears to contribute substantially towards balanced and economic utilization of nutrients.
Plant architecture influences growth and yield response of upland cotton to population density
Abstract Plant architectural characteristics directly affect inter-plant interactions and cotton crop management. Field studies were conducted in the 2010 and 2011 growing seasons at the University of Arizona Maricopa Agricultural Center to investigate the influence of plant architecture on the crop growth, biomass partitioning, and lint yield response of upland cotton to population density under irrigated desert conditions. Two cotton varieties of contrasting architecture, a tall stature columnar type, Delta and Pine 164B2RF (DP164), and a short stature bush type, Stoneville 4498B2F (ST4498), were evaluated under three plant population densities: low density (LD, 57,300–66,500 plants ha−1), medium density (MD, 77,300–109,800 plants ha−1), and high density (HD, 126,700–146,000 plants ha−1). While high population densities significantly increased plant height of both varieties at early growth stages, plant height at late growth stages were not significantly different. High plant population reduced main stem node number of both varieties. However, the effect was more pronounced with ST4498 where the HD treatment had 2.9 and 2.5 nodes less than the LD treatments in 2010 and 2011, respectively. Plant population affected the height to node ratio of DP164 more than ST4498. The taller, columnar type DP164 partitioned more biomass into stems than the bush type ST4498 at all three plant populations. The LD treatment significantly reduced cotton growth and yield of DP164 in 2010. This study suggests the existence of differences in responses to plant population density among upland cotton varieties, attributable to canopy architecture. Additionally, results indicate that shorter bush type varieties might have higher growth plasticity and thus accommodate a broader range of plant densities than taller stature columnar type varieties.
Effect of Soybean Cyst Nematode (Heterodera glycines) on Yield of Resistant and Susceptible Soybean Cultivars Grown in Ohio.
Soybean (Glycine max) producers in Ohio rarely use soybean cyst nematode (Heterodera glycines, SCN)-resistant cultivars because of concerns over limited yield potential and lack of resistance to Phytophthora sojae. A two-year study was initiated to determine grain yield and nematode population increase on soybean cyst nematode-resistant cultivars in maturity groups II and III in production fields. Sites differed in soil texture, nematode densities, and P. sojae infestation at a number of locations in Ohio. Soil was assayed for nematode densities before planting and at harvest. Yields of resistant cultivars averaged 0% to 18% higher than those of susceptible cultivars in fine-textured soils with average preplant populations ranging from 463 to 14,330 SCN eggs/100 cm(3) soil. In coarse-textured soils, yields of susceptible cultivars were 21% to 56% less than the resistant cultivars with average preplant densities ranging from 1,661 to 15,558 SCN eggs/100 cm(3) soil. The reproductive index ranged from 0.1 to 5.5 for resistant cultivars and 0.4 to 112 for susceptible cultivars. In 1993, yield of P. sojae-susceptible, nematode-resistant 'Asgrow A 3431' was as high as yield of the P. sojae-resistant, nematode-susceptible cultivar 'Resnik' in a Phytophthora-infested field. The nematode-resistant cultivars Madison Experimental 131527 and Asgrow A3431 had higher yields than AgVenture AV1341 and susceptible cultivars Resnik and Kenwood when compared over five nematode-infested sites. Nematode-resistant cultivars were found to be excellent alternatives to currently grown susceptible cultivars for managing SCN where group III cultivars are used. However, better cultivar alternatives may be needed for sites with combined Phytophthora root rot and cyst nematode problems.