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No description available.

The objective of the study was to determine if and how grain sorghum hybrids (Sorghum bicolor (L.) Moench) of different maturity dates compete with one another when planted in adjacent rows under different moisture levels. Five sorghum varieties differing in their maturity were used: Taylor Evans Y-101-G coming to mid-bloom in 71 days, RS 610, Asgrow Corral, DK 64 and DK 69 coming to mid-bloom in 56.9 days, 61 days, 69.3 days and 75.6 days respectively. Six agronomic characters were measured to determine the effect and extent of competition. They included the number of days to mid-bloom, tiller ratio, grain yield, grain test weight and 300-seed weight. According to the results, adjacent row competition took place due to differences in maturity date for grain yield and 300-seed weight. An almost equilibrium appeared between loss or gain of border rows compared to the loss or gain of the middle row. Also the length of time between day to mid-bloom of the border rows hybrids and the center row genotype was important in the extent of competition effects.

This study evaluated relative responses of two grain sorghum (Sorghum bicolor (L.) Moench) hybrids to moisture stress treatments imposed during the seedling, early boot, flowering and grain-filling stages. The two hybrids, T.E. Y77 and FUNK HW6125, are high and low yielding respectively, having similar maturity periods. Twelve phenological characters were measured. The height to upper leaf collar, peduncle exsertion, panicle length, total plant height and total leaf area showed significant differences between the hybrids. Early boot stage stress was most sensitive to vegetative characters. T.E. Y77 produced more heads/m², grains, panicle, 500 grain weight (seed size), and grain yield/ha than FUNK HW 6125 across all treatments. Seed size was the most important determinant of grain yield in both hybrids. Moisture stress during the seedling and early boot stages enhanced grain yield, whereas during the grain-filling stage it was detrimental to grain yield in both hybrids.

Please read the abstract in the 00front part of this document Copyright 2004, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bayu, W 2004, Growth, development and yield responses of sorghum to water deficit stress, nitrogen fertilizer, organic fertilizer, and planting density, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-09202006-093510 / > / Thesis (PhD (Agronomy))--University of Pretoria, 2004. / Plant Production and Soil Science / unrestricted