MSCAGR (Animal Science) / Department of Animal Science / Soya bean (Glycine max) is a legume that is mostly cultivated for food grain which can be used as high-protein forage for grazing, haying or ensiling. The use of forage soya bean by small holder farmers is currently very limited. The objective of the current study was to evaluate the nutritive value of three trifoliate forage Soya bean cultivars (Locally denoted as 4-LF, PAN, and TGX). The study was carried out at the University of Venda where the soya beans were planted in 63 25L pots (21 pots for each cultivar) which were randomly placed on the floor of an open, wire-net protected house. Forage harvested at three growth stages (pre-anthesis, anthesis and postanthesis). Samples of the forage were analyzed for dry matter (DM), ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) micro and macro minerals. Ruminal DM and CP degradability were evaluated in situ by incubation of samples within nylon bags (external dimension: 6 × 12 cm, pore size of 46 μm) in the rumen of three Bonsmara steers for 0, 6, 12, 16, 24, 48, 72, and 96 hours. Estimates of rapidly degradable fraction “a”, slowly degradable fraction “b”, constant outflow rate ‘c’ and the DM or CP degradability (p) at time (t) were estimated by fitting the degradability data into the exponential equation P = a + b (1 - e-ct) using the NEWAY computer programme. Parameters were subjected to ANOVA for a 3 X 3 factorial treatment arrangement using the General Linear Model procedures of MINITAB software (version 17 of 2014). Effective degradability ED) was estimated asED = a + bc at fractional outflow rates of k= (k +c) 2%, 5% and 8%. In vitro enzymatic DM and CP digestibility of rumen undegradable residues collected after 24 and 48-hour incubation was determined by simulating sequential gastro-small intestinal digestion. Cultivar PAN harvested post anthesis had significantly higher (p< 0.05) CP than other cultivars. The CP content increased with growth stage. Cultivar 4LF harvested preanthesis had significantly highest (p< 0.05) NDF. The cultivar had no significant effect (p> 0.05) on DM, ash, CP, NDF, ADF and minerals. Cultivar PAN harvested pre-anthesis had significantly highest (p< 0.05) Mg. The harvest stage significantly affected (p< 0.05) mineral content other than (p> 0.05) Zn and Cu. Cultivar TGX harvested pre-anthesis had significantly highest (p< 0.05) effective degradability of dry matter at k=0.08. Fraction ‘c’ and ED at k= 0.08 were lower (p> 0.05) in cultivar * growth stage interaction in dry matter degradability. Fraction ‘a’ for CP was highest (p< 0.05) for cultivar TGX harvested post-anthesis. Fraction ‘c’ was lower (p> 0.05) for cultivar 4LF harvested at anthesis stage. There was a significant effect (p< 0.05) on crude protein soluble fraction ‘c’ and effective degradability k=0.08 in cultivar and growth stage interaction. There was no significant interaction (p> 0.05) of the cultivar X growth stage on crude protein degradability at 48 hours, IVCPD at 24 and 48 hours with significant effect on crude protein degradation at 24 hours caused by cultivar TGX at pre-anthesis growth stage. In conclusion, growth stage increases the chemical composition of soya bean but does not affect digestibility. / NRF

In durum wheat (<i>Triticum turgidum</i> L. var <i>durum</i>), grain protein concentration (GPC) and gluten quality are among the important factors influencing pasta-making quality. Semolina with high protein content produces pasta with increased tolerance to overcooking and greater cooked firmness. However, genetic improvement of GPC is difficult largely because of its negative correlation with grain yield, and a strong genotype x environment interaction. Therefore, identification of quantitative trait loci (QTL) for high GPC and the associated markers is a priority to enhance selection efficiency in breeding durum wheat for elevated GPC. At a physiological level, GPC is influenced by several factors including nitrogen remobilization from vegetative organs and direct post-anthesis nitrogen uptake (NUP) from the soil. Understanding the relationship between elevated GPC and nitrogen remobilization, and post-anthesis NUP will enable durum wheat breeders to develop varieties that not only produce high yield and high GPC, but also exhibit better nitrogen use efficiency. The objectives of this study were: (1) to identify and validate QTL for elevated GPC in two durum wheat populations; and (2) to determine if elevated GPC is due to more efficient nitrogen remobilization and/or greater post-anthesis NUP. A genetic map was constructed with SSR and DArT® markers in a doubled haploid population from the cross Strongfield x DT695, and GPC data were collected in replicated trials in six Canadian environments from 2002 to 2005. Two stable QTL for high GPC, QGpc.usw-B3 on chromosome 2B and QGpc.usw-A3 on 7A, were identified. Strongfield, the high GPC parent, contributed the alleles for elevated GPC at both QTL. These two QTL were not associated with variation in grain weight (seed size) or grain yield. QGpc.usw-A3 was validated in a second Strongfield-derived population as that QTL was significant in all six testing environments. Averaged over five locations, selection for QGpc.usw-A3 resulted in a +0.4% to +1.0% increase in GPC, with only small effects on yield in most environments. A physiological study of grain protein accumulation revealed that regardless of the growing condition, nitrogen remobilization was the major contributor for grain nitrogen in durum genotypes evaluated, accounting for an average of 84.3% of total GPC. This study confirmed that introgression of Gpc-B1 into Langdon resulted in increased GPC, and this GPC increase was due to higher N remobilization. Strongfield expressed greater N remobilization than DT695 and the semi-dwarf cultivar Commander, but N remobilization was not the determining factor for Strongfields elevated GPC. Strongfield expressed greater post-anthesis NUP than DT695. Similarly, a selection of six high-GPC doubled haploid (DH) lines from the cross DT695 x Strongfield expressed significantly greater post-anthesis NUP than six low-GPC DH selections, supporting the hypothesis that elevated GPC in Strongfield is derived from greater post-anthesis NUP. All six high-GPC DH selections carried the Strongfield allele at QGpc.usw-A3, suggesting this QTL maybe associated with post-anthesis NUP.

In durum wheat (<i>Triticum turgidum</i> L. var <i>durum</i>), grain protein concentration (GPC) and gluten quality are among the important factors influencing pasta-making quality. Semolina with high protein content produces pasta with increased tolerance to overcooking and greater cooked firmness. However, genetic improvement of GPC is difficult largely because of its negative correlation with grain yield, and a strong genotype x environment interaction. Therefore, identification of quantitative trait loci (QTL) for high GPC and the associated markers is a priority to enhance selection efficiency in breeding durum wheat for elevated GPC. At a physiological level, GPC is influenced by several factors including nitrogen remobilization from vegetative organs and direct post-anthesis nitrogen uptake (NUP) from the soil. Understanding the relationship between elevated GPC and nitrogen remobilization, and post-anthesis NUP will enable durum wheat breeders to develop varieties that not only produce high yield and high GPC, but also exhibit better nitrogen use efficiency. The objectives of this study were: (1) to identify and validate QTL for elevated GPC in two durum wheat populations; and (2) to determine if elevated GPC is due to more efficient nitrogen remobilization and/or greater post-anthesis NUP. A genetic map was constructed with SSR and DArT® markers in a doubled haploid population from the cross Strongfield x DT695, and GPC data were collected in replicated trials in six Canadian environments from 2002 to 2005. Two stable QTL for high GPC, QGpc.usw-B3 on chromosome 2B and QGpc.usw-A3 on 7A, were identified. Strongfield, the high GPC parent, contributed the alleles for elevated GPC at both QTL. These two QTL were not associated with variation in grain weight (seed size) or grain yield. QGpc.usw-A3 was validated in a second Strongfield-derived population as that QTL was significant in all six testing environments. Averaged over five locations, selection for QGpc.usw-A3 resulted in a +0.4% to +1.0% increase in GPC, with only small effects on yield in most environments. A physiological study of grain protein accumulation revealed that regardless of the growing condition, nitrogen remobilization was the major contributor for grain nitrogen in durum genotypes evaluated, accounting for an average of 84.3% of total GPC. This study confirmed that introgression of Gpc-B1 into Langdon resulted in increased GPC, and this GPC increase was due to higher N remobilization. Strongfield expressed greater N remobilization than DT695 and the semi-dwarf cultivar Commander, but N remobilization was not the determining factor for Strongfields elevated GPC. Strongfield expressed greater post-anthesis NUP than DT695. Similarly, a selection of six high-GPC doubled haploid (DH) lines from the cross DT695 x Strongfield expressed significantly greater post-anthesis NUP than six low-GPC DH selections, supporting the hypothesis that elevated GPC in Strongfield is derived from greater post-anthesis NUP. All six high-GPC DH selections carried the Strongfield allele at QGpc.usw-A3, suggesting this QTL maybe associated with post-anthesis NUP.