The Association of Semisterile-1 in Maize with Two Linkage Groups.
In 1925 there appeared in one of the senior writer’s cultures of maize a few plants producing 50 percent aborted pollen. Subsequent examination of the ears borne by these individuals revealed that they likewise developed only one-half the normal number of seeds. Following BELLING’S (1914) application of the term to a similar condition in Stizolobium, the phenomenon was called semisterility. The pedigreed line to which the
Genetically Reduced Prolificacy in Rats.
A case of inherited partial sterility in rats, characterized by increased uterine embryonic resorptions and a corresponding decrease in average number of young born, has been described by WALETZKY and OWEN (1942). The genetically reduced prolificacy in these rats is of particular interest because it occurs in both sexes. This paper presents the results of five generations of tests of these partially sterile rats when mated inter se and with non-sterile controls.
Spatial distribution of root lesion nematodes (Pratylenchus spp.) in a long-term no-till cropping system and their relationship with soil and landscape properties
The Cook Agronomy Farm of Washington State University is a long-term precision agriculture study site. Since 2000, the farm has been in various three-year no-till rotations with winter wheat, spring wheat, and various rotation crops such as barley, canola, peas, lentils, and chickpea. The spatial distribution of root lesion nematodes (Pratylenchus spp.) and their relationships with soil and terrain variables were studied by collecting soil samples at 127 and 124 geo-referenced points in two 12-ha fields during the spring of 2010 and 2011, respectively. Pratylenchus spp. were detected in more than 85% of the sampled locations in both fields. Nematode densities spatially mapped using ArcGIS software occurred in an aggregated pattern. Previous rotation crops had no effect on the spatial distribution. Classification and regression tree analysis (CART) using soil and terrain variables, and nematode density, explained 61 and 34% of the variability associated with nematode density in 2010 and 2011, respectively. Soil edaphic factors, such as organic matter, were stronger predictors of nematode populations than rotation effects.