Predicting spring barley yield from variety-specific yield potential, disease resistance and straw length, and from environment-specific disease loads and weed pressure

Abstract For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential and quantifying the impact of susceptibility grouping and straw length scores (as a measure for weed competitiveness) for predicting spring barley grain yield under variable biotic stress levels. The study comprised 52 spring barley varieties and 17 environments, i.e., combinations of location, growing system and year. Individual varieties and their interactions with environments were analysed by factorial regression of grain yield on external variety information combined with observed environmental disease loads and weed pressure. The external information was based on the official Danish VCU testing. The most parsimonious models explained about 50% of the yield variation among varieties including genotypeenvironment interactions. Disease resistance characteristics of varieties, weighted with disease loads of powdery mildew, leaf rust and net blotch, respectively, had a highly significant influence on grain yield. The extend to which increased susceptibility resulted in increased yield losses in environments with high disease loads of the respective diseases was predicted. The effect of externally determined straw length scores, weighted with weed pressure, was weaker although significant for weeds with creeping growth habit. Higher grain yield was thus predicted for taller plants under weed pressure. The results are discussed in relation to the model ramework, impact of the considered traits and use of information from conventional variety testing in organic cropping systems

Influence of grass mulch application on tubers size and yield of ware potatoes

The aim of the experiment was to investigate the effect of grass mulch and the term of its application on the yield and quality of potatoes and weed biomass under organic system. The experiment with 2 varieties of early potatoes (Finka and Katka), 2 row spacings (28 000 and 38 000 tubers per hectare) and 2 terms of grass mulch application (after planting and after second hoeing) was carried out in the Czech Republic in 2008. Results showed that the yield was influenced mostly by mulching (55.9 %), then by variety (39.2 %) and by growth structure (4.9 %). The highest yield was reached in the variant with grass mulch applicated after planting. The yield of this variant increased statistically about 9.3 t/ha in comparison with control variant (bare soil). Results of the weed control showed a positive effect of grass mulch on weed biomass, where the lowest weed biomass was found out in variant with grass mulch applicated after planting (weed biomass was lower by 67.6 % in comparison with the control variant - bare soil)

Nitrogen and weed management in transplanted tomato in the Nigerian forest-savanna transition zone

Weed infestation and inherent low soil fertility are among primary reasons for low yields of tomato in Nigeria. Field trials were carried out during the wet season of 2015 and 2016 to evaluate yield response of tomato to nitrogen (N) application and weed control methods in the forest-savanna transition zone of Abeokuta, Nigeria. Positive relationship exists between growth of weed species and increase in N application. Across the years of study, increase in N up to 90 kg/ha increased weed density by 11–25%, however, the increased N gave the transplanted tomato competitive advantage and thus enhanced weed smothering. Pre-transplant application of butachlor (50% w/v) or probaben® (metolachlor 20% w/v+prometryn 20% w/v) each at 2.0 kg a.i/ha followed by supplementary hoe weeding at 6 weeks after transplanting (WAT) significantly reduced weed density by at least 15% and increased fruit yield of tomato by at least 32%, compared to use of the pre-transplant herbicides alone, across both years of study. The greatest tomato fruit yield of 12.2 t/ha was obtained with pre-transplant application of butachlor at 2.0 kg a.i/ha followed by supplementary hoe weeding at 6 WAT, averaged for both years. In general, this study suggests that increased application of N up to 90 kg/ha, and complementary weed control by pre-transplant herbicide and hoe weeding at 6 WAT would improve yield of tomato in the forestsavanna transition zone of Nigeria

Tolerance of four spring barley (Hordeum vulgare L.) varieties to weed harrowing

We investigated the tolerance to weed harrowing of four spring barley varieties and examined the possible interactions between varietal weed suppressive ability and two nutrient levels. Tolerance was defined as the combined effect of crop resistance (ability to resist soil covering) and crop recovery (the ability to recover in terms of yield). The weed harrowing strategy was a combination of one pre- and one post-emergence weed harrowing. In terms of yield, the four varieties responded significantly differently to weed harrowing and the response depended on nutrient level. At the lower nutrient level, weed harrowing caused an increase in yield of 4.4 hkg ha-1 for a strong competitor (cv. Otira), while there was no effect on yield at the higher nutrient level. For a weaker competitor (cv. Brazil), weed harrowing caused no change in yield at the lower nutrient level, whereas yield decreased by 6.0 hkg ha-1 at the higher nutrient level. There were marked differences between the weed suppressive ability of the four varieties when not harrowed, with less pronounced but significant differences when harrowed. Weed harrowing did not change the weed suppressive ability of a variety. Varieties that are tall at post-emergence harrowing and have increased density after pre-emergence harrowing, are the ones that benefit most from weed harrowing

Tolerance to weed harrowing in spring barley genotypes

Controlling weeds in spring cereals grown under organic conditions is mostly done by post emergence weed harrowing, where spring tines of the weed harrow control weeds by uprooting and/or covering small weeds plants with soil. In situations with relatively large weed plants and relatively small crop plants, there are increased risks for crop damages by soil coverage or other mechanical damages of the crop leaves. These damages are increasing with increasing weed control intensity, and are resulting in reduced crop growth immediately after weed harrowing. There are risks that the reduced growth reduces final crop yield too. However, there is some evidence that there are varietal differences in the tolerance to weed harrowing. The aim of this study was to estimate the damages by weed harrowing in four pure genotypes and three two- or one three-component mixtures of spring barley, and to analyze if there were differences in tolerance to weed harrowing between the genotypes and mixtures. Results from a two-year field study showed that there were varietal differences in the tolerance to mechanical weed control in the immediate effect as well as the short term effect, however there were marked differences in the immediate and short term effect between the two years. Regarding the long term effect of weed harrowing on yield, there were no significant differences in 2003 but in 2004, Brazil and the three component mixture suffered significantly from weed harrowing while Modena, Otira and Modena+Orthega mixture, seems to benefit from weed harrowing. The reason for these differences is probably due to differences in growth habit at the time for weed harrowing

Organic Spring Wheat Weed Control Strategies Report

Many organic cereal grain growers struggle with weed issues, especially in spring wheat. Weed competition is one of the major issues in spring wheat due to many factors. Some of those factors include weed seed flushes from spring tillage and weed germination at the same time as crop germination. With this in mind, the University of Vermont Extension has begun conducting trials to evaluate the effects of different weed control methods in spring wheat. In 2012, the study was continued to develop strategies that will minimize weed competition while maintaining yield and quality parameters to successfully produce high-quality bread wheat. The management practices evaluated include variable row spacing and mechanical cultivation with a tineweeder or inter-row hoe

Reducing weed infestation in winter wheat by sowing technique

Hoeing can improve weed control in cereals but this requires wider row spacing of the crop. A spe-cific band row design may also ensure high crop yield and quality, especially at the conditions of organic farming. In order to study those effects two field experiments with winter wheat were con-ducted in 2005 and 2006 at the organic farming research area of the BBA. Three different row de-signs have been investigated: narrow (100 mm spacing), wide (400 mm) and band sowing (alternat-ing of crop band of 400 mm and a crop-free band of 300 mm width). All plots were harrowed whereas the wide and band sown plots have additionally been hoed. Also two cultivars differing in growth habit and competitiveness were tested (Ludwig, Pegassos). Neither harrowing nor the combination of harrowing and hoeing could reduce weed density (by analysing data before and after treatments). Also the different row spacing had no effect on weed density at late spring (257 weeds m-2). However, weed growth at the same time was clearly influenced by the row spacing: Weed biomass was significantly higher in the plots with wide rows (23.1 g m-2) compared to normal (8.3 g m-2 ) and band sowing (10.5 g m-2 ). Crop yield was highest at band sowing (7.09 t ha-1) whereas the wide sown crop stand was of significant lower yield (6.18 t ha-1) but highest protein content (10%). Regarding cultivar effects Pegassos was more competitive against weeds and provided also a higher yield than cultivar Ludwig. So far, band sowing has been proved as an easily applicable sowing technique which enables the use of hoes in cereals and ensure high crop yield especially at conditions of organic farming

Organic Spring Wheat Planting Date Trial

The local food movement has revived otherwise historical crops in Vermont including small-scale grains. As the demand for local organic wheat has risen over the last few years, University of Vermont Extension has been developing best agronomic practices for wheat production. In an organic system, weed management can be one of the biggest challenges. One strategy to manage weeds is to modify planting dates. Early planting dates can establish a crop prior to weed flushes, while a late-planted crop can avoid some weed species. Planting date can also have an overall impact on both grain yield and quality. Certain wheat varieties may respond better to earlier or later planting dates. At this time, there is minimal data to document optimum spring wheat planting dates for the Northeast. The objective of this project was to determine the effect of planting date on the yield and quality of multiple spring wheat varieties

Sowing time, false seedbed, row distance and mechanical weed control in organic winter wheat.

In organic farming, mechanical weed control in winter wheat is often difficult to carry out in the fall, and may damage the crop, and weed harrowing in the spring is not effective against erect, tap-rooted weeds such as Tripleurospermum inodorum, Papaver rhoeas, Brassica napus and others which have been established in the autumn. Some experiments concerning sowing strategy and intensity of mechanical weed control, which included row distance, were conducted. The results underline the importance of choosing weed control strategy, including preventive measures, according to the weed flora in the field. In the experiment with low weed pressure and without erect weeds, there was very little effect of sowing strategy and row distance. In such a case, the winter wheat might as well be sown early, in order to avoid possible yield loss by later sowing, and at normal row distance to enhance the competitiveness of the crop. In the experiments with high weed pressure and erect weeds, the weed control was better with late sowing and large row distance (high intensity control), even though this was not always reflected in the yield. However, the trade-off for lower input to the soil seed bank in organic systems should be enough to balance off the risk of smaller yield

Spring Wheat Planting Date Trial

Growing demand for local organic food has inspired new efforts to revive a staple element of the New England food system. Weed management is one of the foremost production related challenge for organic growers. The objective of this research was to determine the impact of spring wheat cultivar selection and planting date on weed biomass, Fusarium head blight incidence and grain yield and quality