Assessing agricultural education: Agricultural economics at a crossroads

Colleges of agriculture are being forced to adapt to a changing world. The forces behind these changes affect all departments within the college. In this paper, the place of agricultural economics within the college and within the university is identified, the current situation facing the discipline is outlined, and strategies for responding to the forces of change are discussed. Three alternatives are available: continuation, termination, and metamorphosis. Different departments are likely to pursue different strategies. Some may disappear altogether or may be absorbed into the parent discipline, economics, or into the business school. Other departments may transform themselves into specialized sub-disciplines, such as natural resources or agribusiness departments. Still others may continue with little or no change. Whatever course is followed, strategic planning will surely be necessary.     

Genetic control of phaseolin protein expression in seeds of common bean,Phaseolus vulgaris L.

Phaseolin, the major globulin seed storage protein of common bean,Phaseolus vulgaris L., accounts for up to 50% of the total seed protein. The rapid accumulation of phaseolin in the maturing seeds begins about 14 days after flowering and continues for some 12–14 days longer. However, the amount and rate of phaseolin accumulation, related to variation in onset, length, termination, and rate of synthesis, have been shown to vary between genotypes.Only three phaseolin electrophoretic types, designated T, S, and C after the cultivars Tendergreen, Sanilac, and Contender, respectively, have been identified among over 100 cultivated accessions. The narrow ranges of molecular weights and isoelectric points of the 14 protein polypeptides of phaseolin, as well as the homology observed from peptide mapping, suggest that the phaseolin polypeptides are similar proteins. Based on the results of crosses among cultivars having the three electrophoretic patterns, the genes controlling the polypeptides of each of the phaseolin types appear to be tightly linked, inherited in a block and the alleles are codominant.Substantial variation in phaseolin content, based on estimations using rocket immunoelectrophoresis, has been found among bean lines. Although most segregating populations show continuous distributions and quantitative inheritance, some inbred backcross lines having enhanced phaseolin accumulation appear to carry a few genes with major effects. A single gene that reduces the amount of phaseolin to less than one-half of the normal levels has been identified recently in an accession of wildP. vulgaris.     

Assessing compensation for insect damage in mixed plantings of resistant and susceptible potatoes

Plant mixtures have been proposed for pesticidal transgenic potatoes as a means to reduce selection intensity favoring resistant insect genotypes. Colorado potato beetle,Leptinotarsa decemlineata (Say), defoliation was simulated in mixed plantings of susceptible and resistant potato “mimics” to evaluate yield compensation. Various mixtures of susceptible and resistant potato were planted at two densities and two locations in eastern North Carolina. Resistant plants were undamaged throughout the season whereas susceptible plants were completely defoliated by hand either during early or late bloom. The ability of non-defoliated plants to compensate for neighboring defoliated plants was investigated through single-plant and smallplot field experiments for 2 years. Yield compensation for defoliated plants by neighboring non-defoliated plants was not evident in our studies. Yield of two potato plants, positioned on either side of a defoliated plant, was not different from yield of two potato plants positioned on either side of a non-defoliated potato plant. Compensation in mixtures of resistant and susceptible potato was not evident using several non-linear regression analyses. A negative linear relationship existed between yield and an increasing percent of susceptible plants in the mixture for all planting densities, at each location, every year.     

A system for concurrent measurement of centripetal passage of eadiophosphorus and of water plow across hoots to the xylem

Methods are described for the concurrent measurement of water flow and of Centripetal Passage (CP)¹ of radiophosphorus across the root to the xylem. The amount of isotope which completed CP and reached the plant top served as a measure of CP. Comparison of this value with ³²P in the xylem stream served as a guide to water flow. This comparison was made by means of a double ratio function for check and treated plants, and conclusions were based on whether the final values were at, below, or above unity. Illustrations of these methods were given for various test variables including potassium supply, magnesium supply, root temperature, and root oxygen tension.     

The role of population and quantitative genetics and modern sequencing technologies to understand evolved herbicide resistance and weed fitness

Evolution of resistance to multiple herbicides with different sites of action and of nontarget site resistance (NTSR) often involves multiple genes. Thus, single‐gene analyses, typical in studies of target site resistance, are not sufficient for understanding the genetic architecture and dynamics of NTSR and multiple resistance. The genetics of weed adaptation to varied agricultural environments is also generally expected to be polygenic. Recent advances in whole‐genome sequencing as well as bioinformatic and statistical tools have made it possible to use population and quantitative genetics methods to expand our understanding of how resistance and other traits important for weed adaptation are genetically controlled at the individual and population levels, and to predict responses to selection pressure by herbicides and other environmental factors. The use of tools such as quantitative trait loci mapping, genome‐wide association studies, and genomic prediction will allow pest management scientists to better explain how pests adapt to control tools and how specific genotypes thrive and spread across agroecosystems and other human‐disturbed systems. The challenge will be to use this knowledge in developing integrated weed management systems that inhibit broad resistance to current and future weed‐control methods. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.