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%.
A Partial Analysis of Yield of Certain Common and Durum Wheats 1
In this article an analysis is made of certain plant characters of spring wheat varieties grown at two localities in North Dakota. The characters have to do mainly with prolificacy. Correlation coefficients are presented between yield and certain other characters, and these are discussed. A discussion of means of these characters between certain variety-groups is also taken up. It is shown that many varieties of common spring wheat do not possess one character of prolificacy, kernels per spike, in a degree sufficient to prevent lessened yields in comparison with other varieties possessing this character. It is evident, then, that full consideration must be given to breeding for high yields.per se, in addition to breeding for disease resistance. The analyses given indicate that something has already been accomplished in this direction. An increase of yield in farm crops is held desirable provided that the cost of increasing the yield is less than the value of the increased return. Particular stress is being laid upon elimination of disease by hybridization and subsequent selection. Evidently the introduction of new varieties, resistant or immune, relative to certain diseases, will result in increased yields in so far as previous yield deficiencies may have been. caused by these diseases. Moreover, .the cost of gains in yield increases of this nature will be relatively low. In breeding thns for increased Yield attention must be paid not only to disease elimination, but also to the production of varieties possessing an inherently high-yielding capacity. In the enthusiasm attendant upon disease elimination there is danger of neglecting hlgh-yielding capacity. In an analyt-ical stndy of parents proposed, for the production of new varieties, it is possible to anticipate, m a measure, the probable outcome o~ the hybrid offspring as to their prolificacy, particularly number of kernels per spike. Nillson-Ehle (4)3, in a thought-provoking article, has discussed the possibility of breeding for much higher cereal yields in northern regions than are now secured by using as one series of parents varieties of high-yielding capacity grown in southern regions. Percival (5) states that bearded .wheats, .especially those
Water Quality Aspects of Irrigation and Drainage: Past History and Future Challenges for Civil Engineers
This paper presents a brief history of irrigation and drainage related to ASCE activities on its Jubilee. This paper discusses legislation and policies that affect irrigation and drainage practices, water quality constituents of increasing concern in irrigation and drainage practices, and presents a prognosis on the future of declining freshwater resources available for irrigated agriculture and growing water quality problems in irrigation and drainage. Civil engineers in ASCE’s Irrigation and Drainage Division have compiled an 80-year history of highly meritorious service and accomplishments. In the next millennium, civil engineers will face a formidable challenge in managing and protecting the precious freshwater resources in the U.S.