Soybean Biomass Accumulation and Leaf Area Index in Early-Season Production Environments
1992
Savoy, B. R. | Cothren, J. T. | Shumway, C. R.
Some indeterminate soybean [Glycine max (L.) Merr.] cultivars are adaptable to early plantings in the southern USA (<35°N lat). The purpose of this study was to determine the effects of inter-row spacing and soil moisture level on dry matter accumulation, leaf area index, and plant height of an early-planted indeterminate soybean in southcentral Texas. Soybean (‘Williams 82’, Maturity Group III) was planted in mid-April in 1988 and 1989 near College Station, TX (30° 32'N lat). Harvest maturity occurred in late August. Soil moisture levels were irrigation and no irrigation; inter-row spacings were 0.36 and 1.02 m. Soil moisture level treatments did not affect any of the measured dry matter or leaf area traits. Reproductive (pod and seed) dry matter production was greater in 0.36-m rows near physiological maturity in both years. Total dry matter accumulation in 0.36-m rows was greater than in 1.02-m rows in 1988, but not in 1989. Leaflet, stem, and petiole dry matter accumulation was similar across soil moisture Levels and inter-row spacings. Maximum leaf area index was greater in 0.36-m rows than in 1.02-m rows in 1988, but not in 1989. Narrow rows had greater radiation use efficiencies (0.48 g MJ⁻¹ in 1988, 0.42 g MJ⁻¹ in 1989) than wide rows (0.35 g MJ⁻¹ in 1988, 0.37 g MJ⁻¹ in 1989). Mean plant height was greater in 1.02-m rows than in 0.36-m rows in 1989, but not in 1988. Adequate levels of dry matter accumulation, leaf area production, and plant height were obtained using an adaptable indeterminate soybean in an early-planted, early-maturing production environment in south-central Texas. Contribution of the Dep. of Soil and Crop Sciences, Texas A&M Univ. and the Texas Agric. Exp. Stn. Technical Article no. 30 111.
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