Maize (Zea mays L.) growth at low soil P levels is affected both by inherent physiological factors as well as interactions with soil microbes. The objectives of this study were (i) to quantify differences among maize inbred lines for growth at low P and response to mycorrhizal fungi, and (ii) to identify quantitative trait loci (QTL) controlling these traits in a B73 × Mo17 recombinant inbred population. Shoot dry weight and root volume were measured in the greenhouse after 6 wk of growth in a factorial experiment of 28 inbred maize lines using treatments of low vs. high P and mycorrhizal vs. nonmycorrhizal treatments. Shoot dry weight for the low P treatment in the absence of mycorrhizae ranged from 0.56 to 3.15 g. Mycorrhizal responsiveness based on shoot dry weight ranged from 106 to 800%. Shoot dry weight in the low P–nonmycorrhizal treatment was highly negatively correlated with mycorrhizal responsiveness. Plants grown at high P in the presence of mycorrhizae accumulated only 88% of the biomass of plants grown at high P in the absence of mycorrhizae, indicating that mycorrhizae can reduce plant growth when not contributing to the symbiosis. Percentage of root colonization was not correlated with mycorrhizal responsiveness. B73 and Mo17 were among the extremes for growth at low P and mycorrhizal responsiveness, and a B73 × Mo17 population of 197 recombinant inbred lines was used to detect QTL for growth at low P and mycorrhizal responsiveness. Three QTL were identified which controlled growth at low P in the absence of mycorrhizae based on shoot weight and one QTL which controlled mycorrhizal responsiveness. This study indicates that there is substantial variation among maize lines for growth at low P and response to mycorrhizal fungi. This variation could be harnessed to develop cultivars for regions of the world with P deficiency and for reduced‐input production systems.

effects of detasseling and tassel branch removal with detasseled plants having a 5% yield increase and deb-Light penetration into the canopy of maize (Zea mays L.) producranched tassels having a 2% yield increase over the tion fields is an important determinant of grain yield. Factors affecting light penetration include agricultural practices such as planting density control. and plant morphological factors such as leaf angle, leaf size, and Leaf angle effects on maize yield have also been docutassel size. The objectives of this experiment were to identify genomic mented. Pendleton et al. (1968) compared liguleless2 regions controlling the inheritance of leaf angle and tassel morphology and normal hybrids and showed up to a 41.2% yield 1902

We describe an efficient system for site-selected transposon mutagenesis in maize. A total of 43,776 F1 plants were generated by using Robertson's Mutator (Mu) pollen parents and self-pollinated to establish a library of transposon-mutagenized seed. The frequency of new seed mutants was between 10 ؊4 and 10 ؊5 per F1 plant. As a service to the maize community, maize-targeted mutagenesis selects insertions in genes of interest from this library by using the PCR. Pedigree, knockout, sequence, phenotype, and other information is stored in a powerful interactive database (maize-targeted mutagenesis database) that enables analysis of the entire population and the handling of knockout requests. By inhibiting Mu activity in most F 1 plants, we sought to reduce somatic insertions that may cause false positives selected from pooled tissue. By monitoring the remaining Mu activity in the F 2, however, we demonstrate that seed phenotypes depend on it, and false positives occur in lines that appear to lack it. We conclude that more than half of all mutations arising in this population are suppressed on losing Mu activity. These results have implications for epigenetic models of inbreeding and for functional genomics.

High Plains disease has the potential to cause significant yield loss in susceptible corn (Zea mays L.) and wheat (Triticnm aestivum L.) genotypes, especially in the central and western USA. The primary causal agent, High Plains virus (HPV), is vectored by wheat curl mite (WCM; Aceria tossicheila Keifer), which is also the vector of wheat streak mosaic virus (WSMV). In general, the two diseases occur together as a mixed infection in the field. The objective of this research was to characterize the inheritance of HPV and WSMV resistance using B73 (resistant to HPV and WSMV) × Mo17 (moderately susceptible to HPV and WSMV) recombinant inbred lines. A population of 129 recombinant inbred lines scored for 167 molecular markers was used to evaluate resistance to WSMV and to a mixed infection of WSMV and HPV. Loci conferring resistance to systemic movement of WSMV in plants mapped to chromosomes 3, 6, and 10, consistent with the map position of wsm2, wsml, and wsm3, respectively. Major genes for resistance to systemic spread of HPV in doubly infected plants mapped to chromosomes 3 and 6, coincident or tightly linked with the WSMV resistance loci. Analysis of doubly infected plants revealed that chromosome 6 had a major effect on HPV resistance, consistent with our previous analysis of B73 × W64A and B73 × Wf9 populations. Quantitative trait loci (QTL) affecting resistance to localized symptom development mapped to chromosomes 4 (umc66), 5 (bnl5.40), and 6 (umc85), and accounted for 24% of the phenotypic variation. Localized symptoms may reflect the amount of mite feeding or the extent of virus spread at the point of infection. Identification of cosegregating markers may facilitate selection for HPV and WSMV resistance in corn breeding programs.

Larvae of the green lacewing, Chrysoperla carnea (Stephens), were raised on immature stages of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Whitefly of all stages were consumed, but none of the lacewings survived to pupation. First instar lacewings fed on whitefly eggs survived longest. Eggs and first larval instar whitefly were eaten in the greatest quantities. In a second experiment, lacewing first instar larvae were fed on whitefly eggs plus a food supplement. They did not survive longer than those fed on whitefly eggs alone. It is concluded that although they would not survive to produce a stable population in the greenhouse, inundative releases of lacewing larvae might be effective as a supplementary control method.

This article reviews the impact of further education (FE) colleges – in particular, mixed economy colleges – on the surrounding environment and community, and attempts to answer the question of whether the mixed economy college can still be considered an anchor in the community. A mixed methods small-scale case study of a medium-sized mixed economy college was used to evaluate a range of issues that impact on the local community, considering the future and expansion of 16–19 education, against the backdrop of decreases in college provision in the East of England. The aim was to present the background and brief history of the mixed economy college’s impact on the surrounding community, particularly through associated financial, economic and environmental measurements. In conclusion, the authors argue that FE/mixed economy colleges can add significant value to the surrounding environment, community and wider society, and that they are still an anchor in the environment and local communities in which they are situated. They further posit that the goal is for all involved in the FE/mixed economy community to contribute to the shared aim of widening access to lifelong learning, thus further improving the communities and environment in which students and staff reside and work.

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