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Abstract
From 3600 bean cultivars, lines and single plant selections grown at Rancocas, New Jersey, in 1968, 82 were selected as having greater than 33% higher microbiologically available methionine in the mature seed than the ‘Sanilac’ standard. Of these, 63 again assayed more than 33% higher in 1969. Methionine levels varied more within lines of mixed lots than pure lines. A highly significant correlation existed between methionine levels in seed from 2 or 3 crop years. Commercial cultivars, regardless of the seed source, tended to have relatively uniform levels of available methionine. The level of methionine in mature seeds of the common bean is determined genetically and sufficient variation exists within the species to permit improvement through hybridization and selection.
Abstract
During the past two years as Presidentelect and President of ASHS, I have heard from many of our Members relative to what some have labeled, “The Demise of Horticulture Departments”. Feature articles, editorials, and letters to editors have addressed the subject. Although we cannot deny that many changes have occurred in our applied science units—both private and public, academic and nonacademic—the vast majority of these changes represent progress.
At Michigan State Univ., the Dept. of Horticulture curriculum has been restructured simultaneously both toward and away from specialization. The traditional commodity orientation has been eliminated in the main track Horticulture option. At the same time, a new highly structured Landscape Design–Construction and Management option has been created. Both of these changes were made in response to industry needs. Additional optional Specializations in Environmental Studies, Agribusiness, and Biotechnology also are available. These require students to take 18–20 credits from specified course lists. These credits may be part of the required courses for the Horticulture major, or may be in addition to that requirement.
Abstract
Michigan State Univ. (MSU) has a long history of rendering outstanding service to the citizens of Michigan, the nation, and the world. Founded in 1855 as the Agricultural College of the State of Michigan, the teaching institution soon began its tripartite mission of instruction, research, and public service. In 1862, the college became a prototype for the 68 land-grant colleges established under the Morrill Act. Now, 132 years later, MSU has 11 baccalaureate-granting colleges that offer more than 125 programs, many of these offering multiple fields of concentration, and an enrollment of ≈42,000 students.
Net photosynthesis from whole plants of eight asparagus (Asparagus officinalis L.) genotypes was measured at two locations in an open infrared gas analysis system. Measurements started at about the completion of full fern growth, which occurred at the end of July and lasted through the season until fern senescence in late September. Net photosynthesis of the eight genotypes ranged from 15.67 to 27.79 μmol·m-2·s-1. Significant differences (P < 0.1) in net photosynthesis were found among the eight genotypes. Both yield and specific leaf mass (SLM) were correlated significantly with net photosynthesis. We suggest that specific leaf mass can be used as a criterion for selecting genotype of high photosynthetic ability. Daily photosynthetic rate patterns were studied and appear to be related to daily changes of stomatal conductance. Seasonal changes of asparagus' photosynthetic activity were studied. High photosynthetic activity was observed from July through August. Photosynthetic activity decreased greatly in September along with the fern maturation and unfavorable changes in environmental conditions.
Over the past few years, studies have been conducted exploring the variability in iron nutritional quality from a tropical vegetable, Amaranthus. In order to confirm previous iron bioavailability data, A. cruentus, A. hypochondriacus and A. tricolor lines were grown at the MSU Horticulture Research Center and then analyzed for total and in vitro bioavailable iron. Leaves were harvested 39 days after transplanting, washed, lyophilized and ground. Total iron levels were determined using atomic absorption spectroscopy and bioavailable iron estimates derived using an in vitro assay simulating gastrointestinal digestion. Among the lines tested, total iron concentrations ranged from 145 to 506 ppm. Bioavailable iron ranged from 44 to 70 ppm. Both the total and bioavailable iron measured were highest in A. tricolor, similar to results of previous years. Total iron values were lower for all of the lines than detected previously, but the range of bioavailable iron was similar to earlier work. Bioavailable iron estimated using the in vitro procedure does not appear to be greatly influenced by fluctuations in total iron content. Amaranth could provide between 44 and 70 mg Fe/100 gm fresh weight, equal to 20-35% of the daily Fe requirement for women, and 40-70% for men. Future experiments will utilize an animal bioassay to verify differences detected in bioavailable iron.
The process of fertilizer diffusion was examined using KBr and NaBr salts placed at the top of columns filled with a container medium at an initial water content of 4.0, 2.5, or 1.0 g·g-1 (mass of water/mass of medium). Columns were sealed to create a protected diffusion zone (PDZ) shielding the system from water infiltration and evaporation. Bromide and water distributions were determined after 5, 10, 25, and 120 days. Using a Fickian diffusion model, effective diffusion coefficients calculated for Br- in the medium at 2.5 g·g-1 ranged from 2.7 to 4.6 × 10-6 cm2·s-1, which is 3 to 9 times less than the diffusion coefficient in water alone. Diffusion rates increased with increasing medium water content. Differences in the hygroscopicity and solubility of KBr and NaBr affected the distribution of water and diffusion rates in the columns. Redistribution of water was driven to a significant degree by vapor-phase transport, caused by large gradients in osmotic potential, and was most apparent at low water content. At high water content, water redistribution was affected by solution density gradients in the system. This significantly complicates the mathematical modeling of the system, which renders a simple Fickian diffusion model of limited predictive value in high and low water content media.
Studies have been underway to evaluate the genetic variation in iron nutritional quality of the green leafy vegetable Amaranthus. Initial screening of 35 lines of amaranth from 12 species indicated wide variation in total iron, and small, but significant, differences in bioavailable iron, as determined by an in vitro assay. To verify if the differences in bioavailable iron detected by the in vitro assay were biologically significant, two lines of amaranth, A. tricolor Ames 5113 and A. hypochondriacus Ames 2171, were evaluated using a hemoglobin repletion assay in rats. Weanling Sprague-Dawley rats were made anemic by feeding an ironfree casein-based diet for 4 weeks. The anemic animals were fed treatment diets in which all Fe was provided by the amaranth lines. Hemoglobin levels were measured at the start and end of the treatment period to determine bioavailability. Although A. tricolor contained a higher concentration of total iron (670 ppm), the bioavailability of this iron to rats was lower than from the A. hypochondnacus line (total Fe = 210 ppm). Similar amounts of either amaranth line added to the diet produced similar changes in hemoglobin, although total iron concentrations were significantly different, confirming results observed with in vitro assays.
Actinomycetes were isolated from asparagus field soil and bioassayed against Fusarium spp. in petri dishes. Extracts of the active organisms were bioassayed to determine if inhibition was caused by competition or antibiosis. The most active, antibiotic-producing organism was inoculated into test tubes with asparagus and Fusarium and evaluated for disease control. Asparagus seedlings were dipped in actinomycete suspension before planting in Fusarium-infested soil. These seedlings were evaluated for disease incidence after 8 weeks. Asparagus crowns could be dipped in actinomycete suspension before planting in the field.