Breeding trials for swede (Brassica napus var. napobrassica) in 2000–2010 showed that 0·85 of the incidence of brown heart (BH) in the trials was associated with genotypes that are progeny of Ag31, Or13 and Me77c. In order to investigate this and the effect of treatment with boron (B), established varieties and improved parent lines carrying male sterility (ms), and their F1 hybrids (test hybrids), were grown in a field trial in the UK in 2011 and subjected to four B treatments (0·00, 1·35, 1·80 and 2·70 kg B/ha). The results confirmed that BH incidence and severity was affected by genotype but could be ameliorated by B application. Genotype Ag31 was very susceptible while Or13 and Me77c were of intermediate susceptibility and the hybrids between susceptible parents were also sensitive. Genotypes Gr19 and Ly01 were highly resistant even in the absence of B application. Hybrids between resistant and susceptible lines were highly resistant. The use of ms had no influence on BH. Resistance to BH was a dominant trait: homozygous dominant (BHBH) or heterozygous (BHbh) genotypes confer this trait, while susceptibility is recessive (bhbh). Some quantitative variation existed, suggesting that resistance was not a single gene effect. There was a significant negative correlation (r=−0·632) between root B content and the severity of BH in susceptible genotypes. Severe BH was associated with 12–21·5 μg B/g of root dry weight at zero B applied. Moderate discolouration was associated with 19·5–24·8 μg B/g recorded at moderate B applied and only Ag31 showed BH at 2·70 kg B/ha. Resistant varieties had root contents of 23 μg B/g or more while susceptible varieties required a minimum of 31 μg B/g to offset BH.

Increasing human occupation of the Brazilian Amazon has led to the intensification of deforestation over the last 50 years. The present study is aimed at analysing the impacts of the first year of slash-and-burn cultivation on soil physicochemical properties. Sampling was done in 26 small-scale farms of the Tapajós River basin. In August 2004, soil samples were collected from primary forest plots planned for slash-and-burn cultivation. In September 2005, 1 year after the initial burning and the beginning of cultivation, the same sites were re-sampled. The results indicated that soil fertility after burning was relatively moderate, as the increase of base cations was not particularly marked. Moreover, although an increase of some nutrients (such as exchangeable phosphorus) was observed at soil surface, total carbon and nitrogen (N) pools did not change significantly. Nutrient leaching was also detected through the accumulation of both forms of available nitrogen (NO3 and NH4) as well as potassium in subsoil horizons. In addition, signs of erosion were seen, as a significant increase surface density occurred, coupled with up to 25% fine particle loss at the surface. The present study draws attention to the early impacts of slash-and-burn agriculture on soil properties within a year of cultivation. Furthermore, its regional dimension highlights undisturbed soils natural variability as well as differentiated responses to deforestation according to soil texture.

Cultivation of winter turnip rape (Brassica rapa L. ssp. oleifera (DC.) Metzg.) in Finland has been limited because of its reputation as an unreliable crop and its mid-season sowing time of July, when fields are already sown to other crops. An alternative management practice for winter turnip rape is proposed whereby it would be sown as a mixed crop simultaneously with spring cereals. The growth and yield formation of winter turnip rape grown in mixed stands with four different spring cereals was studied in two field experiments conducted in 2009–11. Pure and mixed stands of winter turnip rape and spring cereals were established in May at two different cereal and winter turnip rape stand densities. Subsequent to cereal harvest, one-third of each winter turnip rape plot was harvested for biomass in autumn, before cessation of growth. Three plant stand types, May- and July-sown monocrops and a mixed crop with oat (Avena sativa L.) were sampled for forage analysis. Plant stand densities were monitored from establishment until maturity. Winter turnip rape yield and its quality, including oil content, protein content and thousand seed weight, were determined. Following favourable overwintering conditions, winter turnip rape established with cereals yielded comparably to that of pure stands in terms of both quantity and quality. However, a pure stand of winter turnip rape out-yielded mixed crop stands after unfavourable overwintering conditions. Leaf removal decreased plant survival and seed yield. Establishing winter turnip rape with a cereal in May is an alternative to sowing it as a monocrop in July. A higher seeding rate is needed for under-sown winter turnip rape. Furthermore, autumn-harvested winter turnip rape monocrop forage potentially represents a high-protein supplement for ruminants.

Fertilizer application can play an important role in soil organic carbon (SOC) retention and dynamics. The mechanisms underlying long-term accumulation and protection of SOC in intensive maize cropping systems, however, have not been well documented for cool high-latitude rainfed areas. Based on a 23-year fertilization experiment under a continuous maize cropping system at Gongzhuling, Jilin Province, China, the effects of fertilization regimes on SOC content and soil aggregate-associated carbon (C) composition were investigated. Results showed that, within the 0–1·0 m soil profile, SOC contents decreased significantly with soil depth in all treatments. In the topsoil layer (0–0·2 m), SOC concentrations in balanced inorganic fertilizers plus farmyard manure (MNPK), fallow system (FAL) and balanced inorganic fertilizers plus maize straw residue (SNPK) treatments were significantly greater than initial levels by 61·0, 34·1 and 20·1%, respectively. The MNPK and SNPK treatments increased SOC content by 50·7 and 12·4% compared to the unfertilized control in the topsoil layer, whereas no significant differences were found between balanced inorganic nitrogen, phosphorus and potassium fertilizers (NPK) and the unfertilized control treatment. There were no significant differences in aggregate-size distribution among the unfertilized control, NPK and MNPK treatments, whereas the SNPK treatment significantly enhanced the formation of micro-aggregates (53–250 μm) and decreased the formation of silt+clay aggregates (<53 μm) compared to the unfertilized control, NPK and MNPK treatments. Moreover, SOC concentrations in all aggregate fractions in the MNPK treatment were the highest among treatments. Furthermore, the MNPK treatment significantly increased SOC stock in micro- and silt+clay aggregates, which may slow down C decomposition in the soil. These results indicate that long-term manure amendment can benefit SOC sequestration and stability in the black soil of Northeast China.

Agroecosystem decision support systems typically rely on some types of weather data. Although many new digital weather and forecast datasets are gridded data, the current authors feel that evaluating previous methods with data of increased archive length is critical in aiding the transition to new datasets that lack extensive archives. To that end, the present paper reviews the improvements made to an artificial neural network for forecasting weather-based potato late blight (Phytophthora infestans) risk at 26 locations in the Great Lakes region. Accuracies of predictions made using an early model, developed in 2007, are compared with accuracies of predictions made using a new 10-year hourly optimized model. In nearly every comparison by month, forecast lead time and spatial region, the newly optimized model is more accurate, especially when the weather is conducive to high disease levels.

Although the grey forecasting model has been successfully employed in various fields and demonstrates promising results, the literature shows that its performance could still be improved. Therefore, the aim of the present study was to continue the investigation and derive three hybrid models to predict grain production in China by combining particle swarm optimization (PSO) with the grey linear power index model, the grey logarithm power model and the grey parabola power model. In grey modelling, the use of PSO had the ability to search optimum grey parameters to construct three improved derivative grey models. The results concluded that the improved optimization models with high precision were superior to the traditional models, and PSO contributed more to precision improvement of the three grey models. Furthermore, results from the experiments demonstrated that the optimized models were reliable and valid.

The present work built on a previous study of tillage trials, which found the effectiveness of least limiting water range (LLWR) as an indicator of soil organic carbon (SOC) mineralization under different tillage practices in a black soil of Northeast China in 2009. To improve the understanding of soil structure controls over SOC dynamics, a study was conducted to explore the relationship between LLWR, which was calculated based on soil bulk density and soil pore-size distribution, and the effects of LLWR, which was calculated based on soil bulk density and soil pore-size distribution on SOC mineralization following no tillage (NT) and mouldboard ploughing (MP). In contrast to MP, NT had a significantly greater volume of large macropores (>100 μm) at depths of 0–0·05 and 0·2–0·3 m, but a significantly lower volume of small macropores (30–100 μm) at depths of 0–0·05, 0·05–0·1, 0·1–0·2 and 0·2–0·3 m. The volume of meso- (0·2–30 μm) and micro-pores (<0·2 μm) at different depths under the two tillage practices were similar. Tillage-induced changes in soil bulk density and pore-size volumes affected the ability of soil to fulfil essential soil functions in relation to organic matter turnover. Soil pore-size distribution, especially small macropores greatly affected LLWR and there was a significant correlation between LLWR, which was calculated based on soil bulk density, and the proportion of small macropores. The proportion of small macropores were used to calculate LLWR instead of soil bulk density and the values for NT and MP soils ranged from 0·073 to 0·148 m3 water/m3 soil. Using the proportion of small macropores rather than bulk density in the calculation of LLWR resulted in more sensitive indications of SOC mineralization. Variation in the proportion of small macropores can help characterize the impacts of tillage practices on dynamics of LLWR and SOC sequestration.

Compost use is increasingly proposed as a sustainable strategy to restore the fertility of degraded agricultural soils and to reduce landfill disposal or incineration of organic wastes. The effects of compost application on many soil physico-chemical and biological properties, as well as on soil contamination, have been investigated widely, but a model for the ecological interactions among them has never been developed. The aim of the present paper was to provide an integrated view of the causal processes induced by repeated compost amendments on agricultural soil properties. For this purpose, a confirmatory path analysis was performed to enable inferences to be drawn about the causal processes involving compost amendment, soil organic matter content, nutrient concentrations, microbial activity and soil contamination. The path analysis was performed on a dataset derived from a 3-year field trial carried out by the current authors in a Mediterranean intensive agricultural system, where 0, 15, 30 or 45 t/ha of certified compost from municipal solid wastes were annually applied. A script (‘cpa’) was developed using the R programming language and used to test 13 hypothetical models, expressed as directed acyclic graphs, against the observed data. Within the above-mentioned dataset, potassium and zinc available concentrations, microbial respiration and total polycyclic aromatic hydrocarbon (PAH) concentrations were selected as indicative of soil nutrient availability, microbial activity and organic contamination. The applied approach highlights that compost amendment directly influences all the other variables considered in the study and is the main determinant of the observed trends. Other important relationships are those among organic matter, nutrient availabilities, respiration and PAHs, as well as their temporal dynamics.

Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum, is one of the limiting factors for watermelon production in Taiwan. In recent research, the phenylalanine ammonia lyase (PAL) gene expressed in the shoot base of the Fusarium wilt resistant line JSB was related to Fusarium wilt resistance. Phenylalanine ammonia lyase is the key regulatory enzyme in the phenylpropanoid metabolic pathway. The downstream products of phenolic compounds are considered to be involved in the complicated plant defence mechanisms. They could act as signal molecules, antimicrobial substances and/or structural barriers. To study the resistant mechanisms of Fusarium wilt, the resistant JSB line was examined for comparison of F. oxysporum-watermelon interactions with the susceptible Grand Baby (GB) cultivar. Unlike infected GB, which was seriously colonized by F. oxysporum in the whole plant, the pathogen was limited below the shoot base of inoculated JSB, suggesting that the shoot base of JSB may contribute to Fusarium resistance. The data indicated that a significant increase in PAL activity was found in shoot bases of the resistant JSB line at 3, 9, 12 and 15 days after inoculation (DAI). Shoot bases of resistant watermelons accumulated higher amounts of soluble and cell wall-bound phenolics at 3–9 DAI; the susceptible GB cultivar, however, only increased the cell wall-bound phenolics in shoot bases at 3 DAI. High lignin deposition in the cell walls of vascular bundles was observed in the shoot bases of JSB but not of GB seedlings at 6 and 9 DAI. In the roots and shoot bases of JSB seedlings at 6 DAI, peroxidase enzyme activity increased significantly. In summary, the results suggest that accumulation of cell wall-bound phenolics and increase of peroxidase activity in shoot bases of JSB seedlings during F. oxysporum inoculation, together with the rapid deposition of lignin in the cell walls of vascular bundles, may have provided structural barriers in resistant JSB line to defend against F. oxysporum invasion.

Although the effect of weather on crop growth has been studied widely, the contribution of other water sources has been less well studied, mainly due to data limitation. To address this gap, the current analysis considers the importance of water availability on crop growth by taking advantage of crop field boundaries and information on South Africa's four major grain producing provinces (Northwest, Mpumalanga, Free State and Gauteng) provided by the Agricultural Geo-referenced Information System dataset. To capture crop growth along the crop growing cycle at the plot level, the MODIS's MOD13Q1 dataset of 16-day normalized difference vegetation index (NDVI) was used. To estimate the determinants of crop growth, weather effects were considered and represented by rainfall and reference evapotranspiration satellite derived data provided by the National Oceanic and Atmospheric Administration's RFE and GDAS dataset, respectively. Hydrologic and irrigation determinants were estimated based on the HYDRO1K river network dataset produced by the US Geological Survey. The results show that although weather is an important explanatory factor, other sources of water, such as irrigation, proximity to perennial and ephemeral rivers, and stream flow are also influential. Taking into account the interaction effects between weather and water availability related factors is also important to determine the effect of water availability on crop growth.

The relationship between sheep diet selection and the vertical/horizontal availability of plant species on complex natural Leymus chinensis grassland was investigated. Two plots (low and high stocking rate plots) with different vegetation availabilities, created by adjusting sheep numbers, were studied for 3 months (June, July and August). In each month, the sheep's diet composition was estimated using n-alkanes in combination with long-chain alcohols and/or fatty acid markers. Vertical (sward surface height) and horizontal food availability (proportion cover of individual plant species) were determined simultaneously. The results revealed that sheep diet composition varied greatly according to seasonal variations in vegetation availability, and that sheep diet selection was related to the vertical and horizontal availability of plant species on both plots. Horizontal availability, which turned out to be the main influencing factor, was strongly and positively correlated with sheep diet composition in each month on both plots. On the low stocking rate plot, vertical availability affected sheep consumption in June, July and August. In contrast, a significant correlation between diet composition and vertical availability was only observed in July on the high stocking rate plot. These results suggest that the relative importance of vertical and horizontal availability differed between plots depending on vegetation availability. Horizontal availability played a more important role than vertical availability when sheep grazed freely on natural L. chinensis grassland. Finally, the changing selectivity index for each plant species in each grazing period on both plots indicated different grazing impacts on vegetation communities when vegetation availability differed.

The objective of the current study was to determine whether exposure to an artificial long-day photoperiod increases milk production in subtropical goats maintained under extensive grazing conditions, with or without the presence of a nutritional supplement. Forty-four lactating goats were exposed to a natural photoperiod (11 h light) with nutritional supplementation (NDS; natural day supplemented group; n=11) or without nutritional supplementation (NDN; natural day non-supplemented group; n=11) or to an artificial long-day photoperiod (16 h light) with nutritional supplementation (LDS; long-day supplemented group; n=11) or without nutritional supplementation (LDN; long-day non-supplemented group; n=11). Daily nutritional supplementation consisted of a mixture of 300 g rolled maize and 200 g soya bean per animal. During the suckling phase, milk yield was assessed at 10 and 20 days lactation and thereafter every 10 days up to 110 days lactation from day 40 of lactation. Plasma insulin-like growth factor 1 (IGF-I) concentration was determined at 20, 40, 60, 80 and 100 days of lactation. Mean milk yield was greater in goats from the LDN group than the NDN group. The difference in mean milk yield was greater when goats received a nutritional supplement. With nutritional supplementation, the plasma IGF-I concentrations were greater in goats exposed to long days than in those maintained under natural photoperiod. However, IGF-I concentrations were lower with long days when goats were not supplemented. In conclusion, exposure to an artificial long-day photoperiod increases milk yield in subtropical lactating goats maintained under extensive grazing conditions, and this increased milk production is more pronounced with a nutritional supplement. Furthermore, depending on nutritional status, exposure to artificial long days increases plasma IGF-I concentration in lactating goats.

Two in vitro experiments were conducted to analyse the effects of replacing dietary barley grain with wastes of tomato and cucumber fruits and a 1 : 1 tomato : cucumber mixture on rumen fermentation characteristics and microbial abundance. The control (CON) substrate contained 250 g/kg of barley grain on a dry matter (DM) basis, and another 15 substrates were formulated by replacing 50, 100, 150, 200 or 250 g of barley grain/kg with the same amount (DM basis) of tomato or cucumber fruits or 1 : 1 tomato : cucumber mixture. In Expt 1, all substrates were incubated in batch cultures with rumen micro-organisms from goats for 24 h. Increasing amounts of tomato, cucumber and the mixture of both fruits in the substrate increased final pH and gas production, without changes in final ammonia-nitrogen (NH3-N) concentrations, substrate degradability and total volatile fatty acid (VFA) production, indicating that there were no detrimental effects of any waste fruits on rumen fermentation. Therefore, in Expt 2 the substrates including 250 g of waste fruits (T250, C250 and M250 for tomato, cucumber and the mixture of both fruits, respectively) and the CON substrate were incubated in single-flow continuous-culture fermenters for 8 days. Total VFA production did not differ among substrates, but there were differences in VFA profile. Molar proportions of propionate, isobutyrate and isovalerate were lower and acetate : propionate ratio was greater for T250 compared with CON substrate. Fermentation of substrates containing cucumber (C250 and M250) resulted in lower proportions of acetate, isobutyrate and isovalerate and acetate : propionate ratio, but greater butyrate proportions than the CON substrate. Carbohydrate degradability and microbial N synthesis tended to be lower for substrates containing cucumber than for the CON substrate, but there were no differences between CON and T250 substrates. Abundance of total bacteria, Fibrobacter succinogenes and Ruminococcus flavefaciens, fungi, methanogenic archaea and protozoa were similar in fermenters fed T250 and CON substrates, but fermenters fed C250 and M250 substrates had lower abundances of R. flavefaciens, fungi and protozoa than those fed the CON substrate. Results indicated that tomato fruits could replace dietary barley grain up to 250 g/kg of substrate DM without noticeable effects on rumen fermentation and microbial populations, but the inclusion of cucumber fruits at 250 g/kg of substrate DM negatively affected some microbial populations as it tended to reduce microbial N synthesis and changed the VFA profile. More studies are needed to identify the dietary inclusion level of cucumber which produces no detrimental effects on rumen fermentation and microbial growth.

Two experiments were carried out to evaluate different dosing and sampling regimes for estimating the dry matter intake (DMI) of vegetation by grazing beef cattle. Experiment 1 compared the DMI of a perennial ryegrass pasture by 48 grazing beef cattle dosed with C32n-alkane and faecally sampled at different time intervals. The cattle, of dairy and suckler origin, were balanced by origin and allocated to one of three alkane-dosing treatments (n=16): T1, dosed once daily (10.30 h) with two 500 mg boluses of C32 alkanes; T2, dosed twice daily (09.00 and 16.00 h) with a 500 mg bolus of C32n-alkane; and T3, dosed twice daily (07.00 and 19.00 h) with a 500 mg bolus of C32n-alkane. Faecal samples were collected concurrently with dosing in each treatment. Dosing interval had no effect on estimated DMI, when calculated using the n-alkane content of faeces sampled concurrently with dosing, suggesting that once-daily dosing with concurrent faecal sampling is adequate to estimate DMI by beef cattle. The objective of Expt 2 was to compare the accuracy of herbage DMI estimated using a once-daily C32 alkane dosing regime and n-alkane concentrations in faeces sampled at 09.00, 13.00, 17.00 and 21.00 h, against DMI measured directly. Twelve Holstein-Friesian bulls (mean body weight 265 kg) were housed individually in digestibility stalls and offered harvested perennial ryegrass or harvested semi-natural upland vegetation, both ad libitum. The DMI estimated by once-daily dosing with n-alkane and concurrent per rectum faecal sampling did not differ significantly from the directly measured DMI for either herbage type. It is concluded that a once-daily alkane dosing and concurrent faecal sampling protocol is adequate to reliably estimate the DMI of both upland and lowland pasture vegetation by beef cattle.

Sodium sulphite is used in an optional way to remove insoluble proteins from neutral detergent fibre (NDF) residue. To determine whether the recovery of both NDF and insoluble nitrogen (N) in NDF solution (NDIN) are altered by its use, both parameters were measured in a set of 12 feeds, including cereal grains: maize (MG), rye (RG) and wheat (WG); cereal co-products: maize gluten feed (MGF), distilled dried grains from barley (DDGB) and wheat (DDGW) and wheat bran (WB); protein concentrates: rapeseed meal (RSM) and expeller palm kernel (EPK); dehydrated sugar beet pulp (DBP) and oat (OH) and ryegrass (RGH) hays. Associated effects on the in situ effective degradability (ED) of both NDF and NDIN were also studied in DDGW, WB, RSM, EPK, DBP, OH and RGH. Also, ED of acid detergent fibre (ADF) and its N (ADIN) were studied in hays. Errors due to microbial contamination in the rumen on the ED of NDF, ADF, NDIN and ADIN were also established in these last seven samples using 15N infusion methods. Three rumen and duodenum cannulated wethers were used in the study. The sulphite use in NDF solution led to reductions (DDGB, DDGW, RSM and OH) and increases (RG, WG, WB and DBP) of the NDIN proportion, as well as the contribution of crude protein to NDF. These variations were associated with irregular effects on NDF residues and on ED of both NDIN and NDF. As a consequence, sulphite use does not assure the reduction of the insoluble protein contamination and it may even increase it. This methodology may also alter the degradability estimates of NDIN or NDF. Mean ruminal microbial contamination in NDF was 7·0, 10·8, 13·3, 5·4, 12·0, 35·3 and 20·0 g/kg in WB, DDGW, RSM, EPK, DBP, OH and RGH, respectively. The associated contents of microbial N in NDIN were: 59·3, 29·9, 26·2, 19·8, 37·3, 441 and 150 g/kg, respectively. Microbial contamination in ADF and ADIN (g/kg) was 3·6 and 94·5 in OH and 1·7 and 41·2 in RGH. Not correcting this contamination led to consistent undervaluations of ED of NDIN and NDF in all tested feeds, although errors only reached significance for NDIN in hays and DBP. Microbial-corrected ED of NDIN was 0·685, 0·826, 0·481, 0·389, 0·166, 0·718 and 0·425 in WB, DDGW, RSM, EPK, DBP, OH and RGH, respectively, whereas values for ADIN were 0·504 (OH) and 0·469 (RGH).

Forage sorghum (FS) (Sorghum bicolor (L.) Moench) is a key feed source for ruminants owing to its high yield and drought tolerance. The present paper assessed the agronomic characteristics, silage quality, intake and digestibility of five new Brazilian sorghum cultivars (BRS Ponta Negra variety, BRS 655 hybrid, BR 601 hybrid, BRS 506 variety and BRS 610 hybrid). Forages were grown (randomized complete block design) in a typical Brazilian north-eastern semi-arid climate, irrigated with 267 mm water, harvested as plants reached the soft dough stage of grain maturity and ensiled under laboratory and farm conditions. Apparent digestibility of the silages was determined using 25 Santa Inês lambs. BRS 506 outperformed the other cultivars in dry matter (DM) and digestible DM yields/ha. BRS 506 exhibited the lowest neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents and the highest in vitro dry matter digestibility (IVDMD) of the cultivars examined. BRS 655 produced the lowest level of lactic acid and the highest pH and ammonia-N concentration. There was no difference in intake or digestibility of DM among cultivars. Silages produced from BRS Ponta Negra resulted in higher crude protein (CP) intake than BRS 655. Silages made from BRS 506 and BRS Ponta Negra resulted in a greater digestibility of CP than those produced from BRS 655. Intake of NDF in silages generated from BRS Ponta Negra and BRS 610 was higher than that found in other cultivars. Although an average Brazilian North-eastern FS exhibited similar characteristics to other cultivars grown in dry regions around the world, the results indicated that BRS 506 had a yield advantage and higher nutritive value under Brazilian semi-arid conditions as compared to the other cultivars examined.