Natural outcrossing in common buckwheat

Common buckwheat is an obligate cross pollinating crop because of its sporophytic self-incompatibility system. Therefore a study to assess the extent of natural outcrossing was undertaken for two years at Morden and Portage la Prairie, Manitoba using the semi-dwarf character, which is due to a homozygous genotype with regard to a single recessive gene, as a marker. The semi-dwarf genotype was grown in 100 m rows running in four directions at 90 ° from a central 36 m² plot of a normal, tall variety. At maturity, seed samples were taken from the semi-dwarf population at designated intervals. At least 200 F₁ seeds from each sample were grown in the greenhouse to the 3-4 leaf stage and the proportion of tall plants was used to determine the percentage of outcrossing. Approximately 50% outcrossing occurred where the semi-dwarf plants were immediately next to the normal plants and then the proportion decreased with increasing distance. Although outcrossing occurred throughout the distance tested, there were no significant differences from 12 m onward from the pollen source. Lack of directional influence in outcrossing and a sharp reduction in the proportion of tall plants within a 3 m distance from the pollen source suggested that wind was not a major factor in dispersing the buckwheat pollen over long distances. Although a substantial cross pollination was limited to a few metres from the pollen source, nearly 1% outcrossing occurred even at 100 m. Since the distance in this experiment was limited to 100 m from the pollen source, the present results do not allow us to recommend the minimum isolation distance required to meet certain standards for buckwheat seed production. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of conservation measures on groundwater regime in a semi arid tract of South India

A study was conducted in peninsular India in a predominantly agricultural watershed treated with soil and water conservation measures such as diversion drains and staggered contour trenches in nonarable land, terraces of trapezoidal cross section with graded channel on the upstream side (locally termed as graded bund) and stone checks in arable lands and rockfill dams, archweir and nala bund (a local term used for earthen embankment across the drainage channel) across the gully. Hydrological analysis has revealed that integrated management of land and water resources has consistently improved the groundwater regime. Surface runoff from the treated forest and agricultural catchment were only 27.4 and 57.4% of the untreated agricultural catchment, reflecting in high infiltration of rain water due to enhanced opportunity time. Consequently, water levels in the open wells rose by 0.5 to 1.0 m, thereby increasing the area irrigated by the wells by 172% when compared to the preproject period, which in turn improved crop yields by 70%. Hypssometric analysis indicated that water surface levels do not follow the trend of land surface levels due to the nature of the underground geological formation.     

Mayweed chamomile (Anthemis cotula L.) biology and management—A review of an emerging global invader

The globally invasive weed, mayweed chamomile (Anthemis cotula L.) is an annual, bushy, ill-scented herb, originating in Eurasia. It is aggressively weedy in croplands, field-side ditches, wet areas and along roadsides, especially in slightly acidic, nitrogen-rich, clay-loam soils. In addition to interfering with crop growth, the weed causes dermatitis and eye irritation in humans, skin rashes and sour mouth in domesticated mammals, and off-flavours in cow's milk through forage contamination. Although A. cotula may be managed effectively with some broadleaf herbicides in cereal crops, it is much more difficult to manage in broadleaved crops and cover crops. In some regions, aggressive use of relatively few herbicides has selected for acetolactate synthase herbicide resistance in A. cotula. Therefore, A. cotula poses serious ecological and economic challenges in many regions. Despite this threat, the details of A. cotula biology and ecology in the context of environmental change remain relatively unknown. For example, the reason for the invasiveness of A. cotula remains uncertain, but is presumed to be due to abundant seed production, allelochemicals, mycorrhizal associations, minimal herbivory in invaded ranges, ability to attract generalist pollinators through an extended flowering period and adaptive capacity in a wide range of soil types and conditions. In this paper, we comprehensively review the literature and ongoing work on A. cotula and provide a research agenda to improve understanding and management of this species.     

Evaluating smallholder farmers’ demand for rice variety attributes in Nepal

Despite the release of many modern varieties of rice (Oryza sativa), farmers in Nepal have been cultivating relatively few rice varieties. The objective of this study is to estimate farmers’ demand for rice variety attributes and to identify the factors that influence their decision regarding varietal choice. Yield increase is considered jointly with other attributes, such as cooking and eating quality, drought tolerance, and maturity period. Choice experiments were conducted and results showed that there was significant demand from farming households for yield increase, improvement in cooking and eating quality, tolerant to drought, and short maturing varieties. The choice data were analyzed using a multinomial and random parameter logit model. From a policy perspective, results showed that for broader adoption of crop varieties, variety development programs should give priority to aforementioned attributes rather than solely on increased crop productivity.     

Walkable Neighborhood Systems

This essay defines walkable neighborhood systems, summarizes the negative impacts of suburbia on the economy as a whole, and presents indirect pricing as a major cause of suburbia. The paper proposes several pricing reforms and green mobility as solutions based on prices that reflect full costs. Several hypotheses are presented concerning the performance of walkable neighborhood systems and the concept of an inflection point for the takeoff of non‐auto modes when density within a walkable area reaches economies of scale. It proposes research on old neighborhoods as a way to quantify relationships in the absence of pricing reforms. The paper discusses building types and high rise, and how at highest densities there may be diminishing returns. While it is natural for most scholars to study dominant land uses, there is a need to understand better dense walking neighborhoods as solutions to the costs of suburbia and to enhance their functioning to show a path to a sustainable future.     

Genotype by environment interaction of tomato blossom-end scar size

Summary Large blossom-end scar is a disorder in tomato fruit which reduces its marketability. The disorder is affected by genotype and by several environmental factors and therefore the genotype by environment interaction was studied by stability analysis. Blossom-end scar size was recorded for 4 tomato cultivars grown in 6 fields. The blossom-end scar size (BSC) was affected by the genotype, the field and their interaction. Stability analysis revealed that most of the interaction resulted from different stability of the cultivars. Heterogeneity of the slopes was significant (P<0.0013). The stability slopes were 0.29, 0.74, 1.11 and 1.85 for BR-214, FA-38, Hayslip and Suncoast, respectively. The stability slopes seemed to associate with the means of the cultivars over all environments, which were 1.57, 2.92, 3.84 and 5.43, respectively. Analysis of a blossom-end scar index (BSI), which also takes fruit size into account, revealed stability similar to BSC. It was concluded, that selection for small BSC under most conditions would yield cultivars with small and stable BSC under most growing environments, however differences between genotypes in non-inducing environments are expected to be small.     

The mechanism of preferential fertilization in tomatoes carrying the I-Allele for fusarium resistance

Summary Preferential fertilization of ovules by male gametes carrying the dominant I allele for Fusarium resistance occurred when heterozygous Ii plants served as male parent. Pollination with a mechanical l:l mixture of I and i pollen gave the normally expected Mendelian ratio.No significant differences were found in vivo in growth rate or in final length of pollen tubes of genotypes I and i. The experiments indicated that preferential fertilization was mainly caused by prepollination events leading to production of unequal amounts of fertile pollen grains of the two types.     

The genetic control of mildly restricted branching in narrow-leafed lupin (Lupinus angustifolius L.)

The indeterminate growth habit of most cultivars of narrow-leafed lupin(Lupinus angustifolius) results in undue competition between podgrowth and branch growth, and sometimes poor partitioning of dry massto grain. Selection of restricted-branching genotypes has been proposedas a method to overcome this problem. The restricted branching (RB)trait occurs in two forms, mild and severe. This paper reports the patternof genetic control of mild RB derived from a number of independentsources. The trait, as indicated by the number of leaves on the uppermostbranch, was found to be quantitative (quasi-continuous), but highlyheritable, and largely controlled by additive genetic effects. There was noconsistent correlation of this trait with the number of leaf nodes on themain stem or the time to flowering. It should therefore be possible toobtain different combinations of branching pattern and maturity datethrough plant breeding, and to assess their adaptation to a range ofenvironments.     

Trichothecene profiling and population genetic analysis of Gibberella zeae from barley in North Dakota and Minnesota

Gibberella zeae, the principal cause of Fusarium head blight (FHB) of barley, contaminates grains with several mycotoxins, which creates a serious problem for the malting barley industry in the United States, China, and Europe. However, limited studies have been conducted on the trichothecene profiles and population genetic structure of G. zeae isolates collected from barley in the United States. Trichothecene biosynthesis gene (TRI)-based polymerase chain reaction (PCR) assays and 10 variable number tandem repeat (VNTR) markers were used to determine the genetic diversity and compare the trichothecene profiles of an older population (n = 115 isolates) of G. zeae collected in 1997 to 2000 with a newer population (n = 147 isolates) collected in 2008. Samples were from across the major barley-growing regions in North Dakota and Minnesota. The results of TRI-based PCR assays were further validated using a subset of 32 and 28 isolates of G. zeae by sequence analysis and gas chromatography, respectively. TRI-based PCR assays revealed that all the G. zeae isolates in both populations had markers for deoxynivalenol (DON), and the frequencies of isolates with a 3-acetyldeoxynivalenol (3-ADON) marker in the newer population were ≈11-fold higher than those among isolates in the older population. G. zeae populations from barley in the Midwest of the United States showed no spatial structure, and all the isolates were solidly in clade 7 of G. zeae, which is quite different from other barley-growing areas of world, where multiple species of G. zeae are commonly found in close proximity and display spatial structure. VNTR analysis showed high gene diversity (H = 0.82 to 0.83) and genotypic diversity but low linkage disequilibrium (LD = 0.02 to 0.07) in both populations. Low genetic differentiation (F(ST) = 0.013) and high gene flow (Nm = 36.84) was observed between the two populations and among subpopulations within the same population (Nm = 12.77 to 29.97), suggesting that temporal and spatial variations had little influence on population differentiation in the Upper Midwest. Similarly, low F(ST) (0.02) was observed between 3-ADON and 15-acetyldeoxynivalenol populations, indicating minor influence of the chemotype of G. zeae isolates on population subdivision, although there was a rapid increase in the frequencies of isolates with the 3-ADON marker in the Upper Midwest between the older collection made in 1997 to 2000 and the newer collection made in 2008. This study provides information to barley-breeding programs for their selection of isolates of G. zeae for evaluating barley genotypes for resistance to FHB and DON accumulation.     

Cost-Benefit Analysis of a Community Forest in Nepal

Community forestry is an approach for mitigating deforestation and forest degradation by managing the forest resources for benefitting neighboring communities. Monetary benefits and costs are associated in a community forest during conservation and management of a forest. For sustainable forest management, the benefit should be more than cost which is a contesting issue of research. So, this study was conducted in a community forest of the central part of Nepal with the help of 80 household surveys and a focus group discussion. The firsthand information collected at the site is complimented by forest product harvest and cost-related secondary information. It was observed that the total annual harvest of timber was 60 cubic feet, pole was 8 cubic feet, firewood was 1,110 Bhari,¹ fodder was 4,388 Bhari, and leaf litter was 590 Bhari. To manage a forest, people were involved in fencing, thinning, and meetings. Management cost was six times higher than administration cost. The benefit from firewood and fodder was more due to the dependency of people in a forest for enhancing their livelihood. The higher value of benefit cost ratio indicates that the Community Forest User Group benefited from community forest management.