| dc.description.abstract | Field studies were conducted at the Botswana University of Agriculture and Natural Resources,
Sebele, Gaborone, to determine the effects of planting densities, nitrogen application rate, and
planting time, on two wheat genotypes during the winter planting seasons of 2015 and 2016,
under irrigated conditions. The experiment was laid out in a Randomised Complete Block
Design (RCBD) in a split-plot arrangement, with three replications. The main plot consisted of
two wheat genotypes, Baviaans and 14SAWYT308, and subplots comprised of two plant
density treatments, being (0.2m x 0.15m) 333,333 plants/ha and (0.2m * 0.2m) 250 000
plants/ha, sub-sub plots of five nitrogen doses, being 0 kg/ha (No), 50 kg/ha (Nso), 75 kg/ha
(N75), 125 kg/ha (N 125) and 200 kg/ha (N200), and sub-sub-sub plots of two planting dates being
21st April and 05th May. Plant density of 333,333 plants/ha gave higher grain yield and
enhanced most yield components than the 250 000 plants/ha density. Plant density of 333,333
plants/ha increased grain yield of wheat by 11.2% (2015) and 13.6% (2016) over the density
of 250 000 plants/ha. Nitrogen input had positive effects on grain yield and yield components
of wheat as it improved them. Grain yield increased up to 125 kg/ha of N, thereafter N did not
increase yield further. Grain yield was increased by 64.0% (2015) and 66.1% (2016) at 125
kg/ha nitrogen rate over the control. Planting date of 21s1 April produced significantly more
grain yield (about 23% higher) compared to 5th May date over the two years. The genotype
14SAWYT308 exhibited better yield and yield components characters than Baviaans in some
treatment factors. It was found that wheat genotypes 14SAWYT308 and Baviaans produced
maximum yield when planted on the 21“ April at 333,333 plants/ha and nitrogen application
rate of 125 kg/ha to maximize yield under South Eastern part of Botswana.
Pertaining to protein profiling, the presence or absence of protein bands revealed variations
among sizes of protein bands. Grain from treatments showed the presence of proteins with
vimolecular weight ranging from 17 kDa to 75 kDa, with protein bands of 22 kDa, 32 kDa, and
58 kDa identified to be most contributors to variability in treatments clustering. The results
showed that the presence of glutenins of both high molecular weight and low molecular weight
arc likely to contain genes that supports good baking quality of flour, and also indicate a
considerable amount of genetic diversity between studied treatments. With respect to protein
profiling, the interaction of plant population, planting time and N at 125 kg/ha contributed more
protein bands with low and high molecular weight glutenins and could produce wheat flour
with good baking qualities. Grain protein bands seem to have been influenced mainly by
addition of N, genotype and planting date rather than population. | en_US |
