Five lines of dry beans (Phaseolus vulgaris L.) were selected for differences in protein content and were used as parents in crosses. The F1, F2, and F3 mean crude protein contents were generally between the parents, but slightly closer to the low‐protein parent. Reciprocal differences in protein of F1 seeds and its absence in F2 seeds showed that the maternal genotype controlled seed protein content.Broad‐sense heritability estimates ranged from 30.7% to 63.7%. The narrow‐sense heritability estimates were 20.1% for backcrosses and 5.0% and 12% based on F3/F2 regression. These low values indicate high environmental influence on crude protein content and relatively low additive genetic variance.Yield and crude protein percentage were generally negatively correlated in F2 and F3 plants from crosses between low and high percent crude protein bean lines. Seed yield and protein yield were highly correlated. The highest total seed protein was produced by plants average or below average in percent crude protein. In breeding for total protein production per unit area, progress appears more likely if efforts are directed toward increased seed yield while maintaining percent crude protein near average levels rather than by selecting for high protein in the seeds alone.Generally, high‐yielding segregates tended to be relatively low in protein percentage. Among F2 and F3 progenies, however, there were plants that were high in seed yield and had above‐average percent crude protein.
Two years of field research were conducted to determine the additive effects of weed cover and insects on pepper production. When weeds covered less than 10% of test plots, the natural insect populations reduced the marketable fruit yield of bell peppers 32% in 1983 and 22% in 1984. When weeds covered 72 or 94% of the test plots, foliage damage due to insects was from 5.8 to 12.1%, respectively. The high percent weed cover and insects reduced yield 99%. The average fresh weight of pepper foliage approached zero as weed cover approached maximum. Foliar levels of iron and aluminum were reduced greatly in peppers grown in competition with a 100% weed cover. The level of boron, copper, phosphorus, and potassium in pepper foliage increased as percent weed cover increased.
The metabolism of malathion-C14 was studied in both bean seedlings and rats. The distribution of imbibed or ingested radioactivity in expired CO2, excrements, and certain tissues was determined. Chromatography was used to determine the distribution of metabolites in extracts of rat urine, rat stomach contents, and plant extracts at various in-
The major effects of the gibberellins (GA) on plants have been reviewed recently (13,14) but no definite linkage with any metabolic pathway has been established. In their study of photosynthesis in gibberellin treated leaves Haber and Tolbert (8) (7) suggested at possible action of gibberellin through an auxin-sparing mechanism by way of the formation of IAA oxidase inhibitor. It is the purpose of this paper to describe the results of experiments on the influence of GA on plant metabolism. In the method used, plant tissue was first pre-treated with GA and then incubated with a selected isotopically labeled substrate. Samples of the tissue were then harvested after several hours of incubation. The influence of GA on the metabolism of the material was determined by comparing the extents of the labeled atoms which have been metabolized and incorporated into other compounds between the control and treated tissues.
MATERIALS AND METHODSAlaska pea (Pisum sativum L.) and sweet corn (Zea mays L. var. GTolden Cross) were soaked in distilled water for 2 hours and were then germinated in the dark between two sheets of moist paper. Uniform seedlings were removed from the paper after two or three days and the roots were immersed in either 0.01 M phosphate buffer (pH 5.2) or buffer + 5 ppm GA. At the end of the 2 hours pre-treatment period, the seedlings were removed from the solution and then rinsed with water. The distal 2 cm of the roots was cut off, blotted dry, and weighed. Equal samples of roct tips were placed in 50 ml Erlenmeyer flasks which contained 10 ml of 0.01 M phosphate buffer, pH 5.2, along with Cit labeled substrates, and were allowed to incubate at 26 to 280 C. The respiratory C1402 was collected periodically as described previously (6). At the end of the incubation period, the tissues were removed from the medium, rinsed with water, and homogenized with ethyl alcohol. The radioactivities of the medium, alcohol extract of the tissues, and the residue of the tissue were also determined by the usual method.The incorporation of C14 in each isotopically labeled metabolite was studied by paper chromatographic and radioautographic techniques.
RESULTS AND DISCUSSION EFFECT OF GA ON METABOLISM OF IAA-1-C14The influence of GA on the metabolism of auxins in higher plants has always been of interest. This problem was approached by using C14 labeled indoleacetic acid. Corn root tissue has been chosen for this study because in addition to the decarboxylative oxidation, C-1 carbon of IAA has been found to incorporate into many metabolites. The root tips from control and GA treated seedlings were incubated separately at 26°C in 10 ml 0.01 M phosphate buffer (pH 5.2) containing 2.OX 10_-M IAA-1-C'4. Twvelve 40-watt fluorescent lights placed 3 ft from the flask, providing a light intensity of 800 ft-c, were used for illumination during the incubation period. Respiratory CO2 was collected periodically and precipitated as BaCO3.After a 6 hr period of incubation, the root tissues were removed, rinsed, and homogenized with 10 ml...
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