The acquisition and use of miombo litter by small-scale farmers in Masvingo,Zimbabwe

A questionnaire survey of fifty-two small-scale farmers was conducted to elucidate the practices associated with acquisition and use of miombo litter. On average, a household cropped 3.7 ha of land and owned ten head of cattle. Farmers collected, on average, 0.5 t of litter per household per annum with larger amounts collected by those with more cropland and more cattle. Cattle ownership is related to quantities of litter collected and the destination of the collected litter, most of the litter being cured in cattle pens. Farmers with less area of cropland applied greater quantities of litter per hectare of cropland than did farmers with more cropland. On average, five tons per hectare per season of the manure-litter mixture is applied to crop fields with litter contributing, on average, 0.12 t/ha to the mixture. Some crops, particularly maize and fingermillet, are more likely to receive litter than other crops.     

Can Australian farming systems be more sylvan?

This paper discusses the extent to which Australian agriculture is integrating trees into farming systems and concludes that while broad environmental awareness and concern may have increased, Australian agriculture exemplifies essentially the same attitudes to native vegetation as those held by the first European settlers. It is suggested that for real change to occur, land users require three key ingredients — commitment, knowledge and resources. The state of play with respect to each of these key factors is reviewed and suggestions for reform mooted.     

Farming systems research for agroforestry extension

Farming systems research and extension (FSRE), as used by the global Association for Farming Systems Research-Extension, applies to a family of methodologies used to generate, evaluate and disseminate agricultural technologies in association with farmer participation. FSRE shares many attributes with Diagnosis and Design as practiced in agroforestry. The history of FSRE is traced from 1965 to the present, showing the formalization of the methodology and its critical use in sustainable agricultural technology development. In on-farm research, a primary basis for FSRE, research and extension merge in practice. The definition of recommendation domains (a fundamental concept of FSRE) is based on analysis and interpretation of multi-environmental research results as evaluated by varied criteria.In this paper, we present the results of three research projects to demonstrate the nature of farmer criteria for evaluation. Modified Stability Analysis (MSA) is used to demonstrate the relationship of on-farm research to specific extension messages. Design of on-farm research to make it amenable to analysis by MSA is discussed.Florida Agricultural Experiment Station, Journal Series No. R-03113.     

Assessment of genotype × environment interactions for yield and fiber quality in cotton performance trials

Plant breeding programs involving a wide range of crop plants routinely practice selection (directly or indirectly) for genotypes that display stability for a given trait or set of traits across testing environments through the genotype evaluation process. Genotype stability for trait performance is a direct measure of the presence and effect of genotype × environment interactions, which result from the differential performance of a genotype or cultivar across environments. The genotype evaluation process also requires selection of the proper field trial locations that best represent the target environments the breeding program is directed toward. In this study, we assessed the extent to which genotype × environment interactions affected agronomic performance (lint yield, gin turnout) and fiber quality (fiber length, fiber strength, uniformity index, micronaire, fiber elongation) in a series of cotton (Gossypium hirsutum) performance trials in 12 location–year environments in South Carolina. Genotype × environment interactions affecting lint yield were larger in higher yielding environments, while interactions for fiber strength were greater for genotypes with lower mean fiber strength values. Two regions within the South Carolina cotton production areas were identified as proper testing locations for lint yield performance, while testing for fiber strength can be accomplished in any location within the statewide cotton production areas. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Comparisons of genetic and morphological distance with heterosis between Medicago sativa subsp. sativa and subsp. falcata

Biomass yield heterosis has been shown to exist between Medicago sativasubsp. sativa and Medica gosativa subsp. falcata. The objective of this study was to gain a better understanding of what morphological and genetic factors were most highly correlated with total biomass yield heterosis. We calculated genetic distances among nine sativa and five falcate genotypes based on amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) DNA markers. Genetic distance did not correlate with specific combining ability (SCA) or mid-parent heterosis. In contrast, a morphological distance matrix based on seventeen agronomic and forage quality traits was significantly correlated with heterosis; the agronomic traits of maturity, midseason regrowth, and autumn regrowth showed strong association with heterosis. Heterosis was also correlated with subspecies. We suggest that in many cases progeny heterosis can be accounted for by the interaction of genes controlling morphologically divergent traits between the parents. In other cases, progeny heterosis could also be due to divergence between the parents at particular genetic loci that do not control field-level phenotypic differences. Genetic distanceper se between parental genotypes, based on neutral molecular markers, however, does not reflect the potential of individual genotypes to produce heterosis in their progeny. This revised version was published online in August 2006 with corrections to the Cover Date.     

Association between resistance to Cercospora and yield in commercial sugarbeet hybrids

This report documents the difficulty breeders have experienced in combining resistance to Cercospora leaf spot (causal agent Cercospora beticola Sacc.) with high yield in sugarbeet (Beta vulgaris L.). Forty commercial hybrids, all recommended for Cercospora-threat areas, were grown in a Cercospora-free and a diseased (inoculated) environment in 1991 and 1992. A 2.9 Mg/ha decrease in root yield associated with each increment increase in susceptibility confirmed that under a severe epiphytotic (1991) Cercospora resistance provided substantial protection. Under less-severe disease conditions (1992) there was no apparent relationship between yield and resistance, suggesting that the benefits of resistance were similar to the yield potential sacrificed to obtain the resistance. In the absence of the disease, root yields increased 2.7 Mg/ha for each increment of increased susceptibility. There was no evidence of association between sucrose concentration and resistance in the Cercospora-free environment. Despite the limited efforts and/or success in developing resistant commercial hybrids, the demonstrated ability of Cercospora to produce fungicide-resistant strains and the possibility that effective fungicides will not be available provide incentives to seek genetic resistance through breeding efforts.     

Genetic Variability for Mineral Concentration in the Forage of Jerusalem Artichoke Cultivars

Summary One of the potential uses of Jerusalem artichoke (Helianthus tuberosus L.) is as a forage crop. Information on inherent differences in forage nutritional quality is essential if the quality of the forage is to be improved through breeding. The objectives of this study were to determine the genotypic variability among and within forage of Jerusalem artichoke cultivars for the concentration of N, P, Ca, Mg, K and the Ca/P ratio at flowering, to determine if selection among and within cultivars is feasible, to estimate the magnitude of the genotype × environment interaction, and to examine the relationships among mineral concentrations in the forage. Ten cultivated Jerusalem artichoke cultivars grown in an irrigated field nursery at Bushland, TX were evaluated for N, P, Ca, Mg, K, and the Ca/P ratio in the forage at flowering over a 2-yr period. Cultivars, cultivar × year, and error variances were estimated to calculate the phenotypic variance. Estimates of the within-population variances were also determined. The adequacy of Jerusalem artichoke forage at flowering for maintenance of a ruminant animal was classified as follows: N, Ca, Mg, K as adequate, P inadequate, and the Ca/P ratio as excessive. There were genotypic differences among the ten cultivars for N, P, Ca, Mg, K, and the Ca/P ratio for both years and averaged across years. The magnitude of the genotypic variance components indicated that a substantial proportion of the total variation for these elements was due to cultivar, indicating the possibility of improving these elements. However, further studies on heritability and response to selection will be required before conclusions can be reached concerning the likelihood of successfully breeding for these traits.