Plant Density Effects on Main Culm and Tiller Development of Grain Sorghum1
- T. J. Gerik and
- C. L. Neely2
The development of tillers represent as an important yield compensation mechanism for many cereals. A 2-yr irrigated field study was conducted at Temple, TX, on a Houston Black clay (fine, montmorillonitic, thermic Udic Pellusterts) using two recently developed low tillering sorghum hybrids [Sorghum bicolor (L.) Moench], ATx623 ✕ RTx430 and ATx378 ✕ RTx430, to compare tiller phenological development to that of the main culm, and determine the impact of tillering on crop phenology and grain yield. Planting dates and plant densities were varied to determine the elasticity of tillering for these hybrids. Tillering occurred early in ontogeny and tillers originated from the axillary buds on the basal nodes on the main calm. Tillers extended the flowering interval from 7 to 10 days, depending upon year and planting date, but variability among the tiller and main culm flowering dates resulted in numerous instances when flowering by tillers and main culms occurred simultaneously. On average, four more leaves were produced on main culms than on tillers. Environments with cool temperatures/short daylength and high temperatures/long daylength retarded tiller development. Tillers had little effect on grain yield when plant densities were ≥ 12.5 plants m−2. A precipitous decline in number of grain forming tillers was found at densities >2.5 plants mm−2. This suggests that sorghum tillering maybe controlled by a biophysical mechanism similar to the light-mediated tillering control reported for wheat (Triticum aestivium L.) and deserves further study.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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