Relation of seed weight to grain yields in oats, Avena sativa L.
SummaryWe measured yielding ability and weight per 100 seeds in 7 populations of oat lines, each derived from a different cross. The association between these two traits was curvilinear, with maximum yields occurring when 100-seed weights were between 2.75 and 3.10 g.In a simulated selection experiment conducted on a bulk population of 150 oat lines (i.e. only lines with seed weight between 2.75 and 3.10 g per 100 seeds were saved), the proportion of superior yielding lines was increased from 16% in the original to 32% in the new one. In the 100-seed weight class below 2.75 g, the proportion of high yielding lines was only 5%.
Intra- and intergeneration relationships among yield, its components and other related characteristics in spring wheat
SummaryThe relationships between yield, its components and other associated characteristics, both within and across generations, were studied in the F2, F3 and F4 of two Hard Red Spring wheat (Triticum aestivum) crosses using simple correlation, path coefficient and step-wise multiple regression analyses. In the F2 and F3 the plants were grown 50 cm apart from each other while in the F4 they were grown under the usual farm practices. Selection was practiced for high and low yield in the F2 and F3 mainly on the basis of individual plant yield. Statistically significant, but not always practically useful, correlations were found between yield and its components and other associated characters. The relationship between yield and protein content was negative and significant within all generations but not so between F2 (and F3) and F4. The intergeneration correlation coefficients between F4 grain yields and grain yields measured in the F2 and F3 were all positive and highly significant. These coefficients, which are also heritability estimates in standard units, were small in magnitude.Stepwise multiple regression analysis identified plant yield as the most significant factor in determining F4 line yield, followed by its components in the order of 1000-kernel weight, grain yield per plant and number of tillers per plant.Path coefficient analysis identified tiller number per plant and grain yield per spike as having strong positive direct effects on single plant yield. Harvest index of individual F2 plants can be used as an indirect selection criterion for yield.
Studies on the breeding of self pollinating cereals
A survey of the genetic control of seven aspects of wheat quality shows the presence of complex genotype x environment interactions. The demonstration of these interactions emphasises the need for an effective sampling of environments during the testing of breeding material and the importance of consistency of performance of selections over the range of environments.