Studies were made in 1954, 1955, and 1956 of the effects of various quantities of normal sunlight, obtained by the use of shade structures, on growth and grain production of three corn hybrids: Illinois 972A, Hy2 ✕ Oh41 (tolerant of high rates of planting), and WF9 ✕ C103 (intolerant of high rates of planting). The light treatlnents in 1954 were 100% (control), 70, 40, and 10%; 1955 and 1956, additional treatments of 30 and 20% were used. Shading was initiated in 1954, 1955, and 1956 on July 2, July 5, and June 8 thus providing 90, 72, and 113 days of treatment, respectively.In general, there was a significant decrease in measured components (grain, stover, total protein, total oil, etc.) as light was decreased. With minor exceptions, e.g., height, reduction of light by even 30% caused a decrease in production of plant material. Of signal importance is the essentially linear reduction in total plant (grain and stover) protein with decrease in light.Based on grain yields, Hy2 ✕ Oh41 proved to be more tolerant of low light levels than did WF9 ✕ C103 when shade treatments were imposed in mid‐season at a time when mutual shading becomes intense in dense plant populations.

The purpose of this investigation is twofold: 1. to determine whether the nitrogen in the vegetative parts of the corn plant at pollination is adequate to supply the maturing grain, if not, the contribution of soil nitrogen to the overall nitrogen supply after pollination; 2. to determine to what extent certain nitrogen compounds in the stalks and leaves at pollination contribute to the nitrogen of the maturing grain. The plan was to study corn grown under field conditions on a naturally fertile soil in which there was no deficiency in the nutrient-supplying capacity for the crop. It was also hoped this investigation would disclose new facts about the nitrogen metabolism of the corn plant which might have a bearing on practical aspects of corn protein problems.There have been many investigations concerned with various phases of nitrogen metabolism of plants. The bulk of the recent work has dealt with the effect of changing environmental and nitrogen nutritional conditions on the composition of the plant (30,31,32,33,34,35). In view of the many excellent reviews on the subject (5, 17, 20, 27, 28) no attempt will be made to review the literature here. Methods PLANTING AND SAMPLINGTo accomplish the aims set forth in the introduction, two corn hybrids, U.S. 13 and Funk's G-80, were planted in a rich dark-colored soil classified as Drummer clay loam. No commercial fertilizer was applied for this crop, although a good crop of second-year mammoth clover was plowed under.The hybrids were planted June 1, 1945, and grown at the rate of three plants per hill. To provide for the sampling technique, each hybrid plot was divided into 10 blocks. Only the even-numbered hills were used for samples. At sampling, one from each block was chosen at random. The plants were examined and those showing too much deviation from the average stage of development were discarded. The remaining plants were used as a composite sample, which consisted of the above-ground parts of 14 to 26 plants.

Ethrel sprayed on corn plants at three rates and at several stages of development caused a reduction in plant height, leaf area, leaf efficiency, and yield of grain as compared to untreated plants. No beneficial effects were observed from the use of this chemical on corn under the conditions of this experiment.

No abstract

A 2‐year field study was conducted to determine the possibility of supplementing soil and symbiotically‐fixed nitrogen of soybeans with nitrogen fertilizer.In 1947, during a hot dry growing season marked responses were obtained from added nitrogen. The number of nodules per plant decreased 80 to 90%, there were appreciable increases in seed yields, nitrogen content of the seed increased, and oil content decreased.In 1949, with adequate rainfall, moderate temperatures, and 30 to 40 days additional growing season there was little to no response to added nitrogen. The number of nodules per plant on the untreated plots was larger than in 1947, and the largest application of ammonium nitrate resulted in only a 35% decrease in number of nodules. The yield of seed increased very little, and no change occurred in the nitrogen and oil contents of the seed.A comparison of three dates of side‐dressing with plow‐down treatments indicated that the most effective utilization occurred with plow‐down applications.This experiment helps explain some of the variation in response of soybeans to nitrogen fertilizers. Rainfall and temperature conditions during the growing season apparently have a direct influence on the sufficiency of symbiotically‐fixed nitrogen for maximum yields, thus indirectly influencing the response to added nitrogen.