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%.
Correlation of Factors Affecting Yield in Hard Red Spring Wheat 1
In planning for the production of an improved variety, the smalI grain, breeder may cross two or more varieties with the hope of combining in a single variety the desirable characters of several. It is a common practice to use as one parent, at least, a variety which excels in yielding ability as determined by yield trials. The other parent should be selected because it contains a certain desired character or characters which are lacking in the standard variety! Yield in small grains is apparently a complex character influenced .by such factors as plumpness of grain, number of kernels per spike or panicle, reaction to disease, lodging, number of spikes or panicles per unit area, and period of maturity. Insufficient information is available concerning the extent to which various characters influence yielding ability and the extent to which two or more of these agronomic characteristics are conditioned by the same genetic factor or factors. This report comprises a statistical study of the relation between various plant characteristics and yielding ability of hard red spring wheat grown in rod rows at the Morris, Minnesota, Branch Experiment Station during the crop season of ~929.
Investigations on the rôle of organic matter in plant nutrition
1. As the result of decomposition of green manure in a swamp soil, the coarse fractions (including coarse and fine sand) of the surface layer (first 3 inches) decreased by 11·2 per cent. while the fine ones (silt+clay) increased by 9·8 per cent. in the course of 43 days. The effect was less pronounced in the manured soil maintained at 60 per cent. saturation, while no alteration was to be noticed in the case of the unmanured specimens. 2. Treatment with dilute hydrochloric acid prior to dispersion had no appreciable effect on the estimates of mechanical composition obtained in the different cases. Loss in solution was also comparatively small. 3. The silica-sesquioxide ratio increased slightly as the result of decomposition of green manure in swamp soil. The composition of the fine fractions was also altered, the total percentages of the oxides of iron, aluminium and silicon increasing from 90·5 to 99·3 in the course of 71 days. 4. The practical significance of the above and related observations has been discussed.