Contribution of large ear phenotypes to grain number improvement in advanced spring wheat (Triticum aestivum L.) CIMMYT lines
| MSI08P4300 | |
| Goburdhun, P. J. | |
| Contribution of large ear phenotypes to grain number improvement in advanced spring wheat (Triticum aestivum L.) CIMMYT lines | |
| Thesis, MSc in Crop Improvement, University of Nottingham | |
| Thesis | |
| 2008 | |
| 96 p.: 18 figs, 11 tbls | |
| En | |
| En | |
| Wheat (Triticum Aestivum L.) is one of the most important cereal crops grown in many countries around the world and there is a gap between the production and its global demand. The need to breed for high yielding wheat varieties has always been of utmost priority in worldwide. Previous studies on wheat have shown traits influencing the capacity of the grains to store assimilate (sink) to be better correlated with yield than traits influencing the potential assimilate production (source). In this respect, strategies to improve the ear fertility, defined as the number of grains per ear, are one of the most important objectives in the wheat breeding to improve yield potential. The University of Nottingham in collaboration with the International Maize and Wheat Improvement Centre (acronym in Spanish being CIMMYT) are currently examining the performance of novel high yielding CIMMYT spring wheat advanced lines bred in Mexico, under the UK environment. In this study, 36 novel spring wheat CIMMYT advanced lines (7 having rachis length comparable to a UK elite spring wheat check variety Ashby and 29 having longer rachis, hence large-ear phenotypes were investigated to test for improvement in grain number with respect to Ashby under UK conditions. The genotypes evaluated comprised 5 families as follows: (i) "F8 YC (Super wheat) - Big spikes/High yield", (ii) "F8 YCINT (Big spikes/High yield)", (iii) "YP-PRE IP F5'7 (High yield)", (iv) "F8 YC (Super wheat) - High yield", (v) "F8 YCINT (High yield)"; and one additional large-ear phenotype Mexican spring wheat referred to as L14 (for 'CMH79A.955/4/AGA/3/4'). They were compared in the field against an elite UK commercial spring variety 'Ashby'. The study consisted mainly of physiological measurements of yield-related characters. The research was supported with some molecular analyses to check the presence of important adaptive genes such as the photoperiod genes (Ppd-D1), vernalization (Vrn-A1), plant height or stature (Rht-B1) and tillering inhibition (tin-1A) within the 36 lines as well as the check variety. The field experiment was planted on 4 March, 2008 at the University of Nottingham Farm, Sutton Bonington, Nottinghamshire. Several physiological traits were measured at onset of booting, onset of flowering and during grain filling and growth analysis performed on all the genotypes under test. Research findings have shown that a number of novel high fertility ear phenotypes from CIMMYT do contribute to grain number improvement as a result of improved ear morphology (large ear phenotype) when expressed on a single shoot basis. Improved ear fertility was associated with restricted tillering, larger flag leaf area, higher number of grains per spikelet and a higher ear dry weight at anthesis compared to the check cultivar. . The study was based on plots with a very low plant population density broadly equivalent to spaced plants and therefore the findings would have direct relevance for early generation selection stage in wheat breeding programs. The traits related to grain number could serve as criteria for selection purposes in early generations of wheat breeding programs. In this respect, traits identified to correlate with grain number per ear were flag leaf green area (r=0.65), long rachis (r=0.53), grains per spikelet (r=0.90), and individual ear dry weight at anthesis (r=0.44). Further work is required to test how well these large-ear phenotypes are maintained at normal plant populations densities. The use of molecular tools can help in elucidating the genetic make-up of genotypes and for a better understanding of the physiological potential of genotypes. The physiological performance of CIMMYT spring wheat genotypes in the UK has previously been found to be related to pleiotropic effects of one or several genes. In this particular case the pleiotropic effect of the tin gene (restricted tillering) and the Rht-D1b and Rht-B1b genes (semi-dwarf stature) were the most evident ones that contributed to a relative increase in grain number per ear in the present study. | |
| Wheat Triticum Aestivum L yield potential yields ear fertility ear morphology large ear phenotypes grain number improvement genetics genomic DNA CIMMYT | |
| Wheat - Genetics | |
| 2008-10-08 | |
| En | |
| LIB BH | |
| CAT | |
| 1 | |
| PB |