In the present study, the effect of weather on maize yields in northern China was examined using data from 10 districts in Inner Mongolia and two in Shaanxi province. A regression model with a flexible functional form was specified on the basis of agronomic considerations. Explanatory variables included in the model were seasonal growing degree days, precipitation, technological change (e.g. adoption of new crop varieties, improved equipment, better management, etc.) and dummy variables to account for regional fixed effects. Results indicated that a fractional polynomial model in growing degree days could explain variability in maize yields better than a linear or quadratic model. Growing degree days, precipitation in July, August and September, and technological changes were important determinants of maize yields. The results could be used to predict potential maize yields under future climate change scenarios, to construct financial weather products and for policy makers to incentivize technological changes and construction of infrastructure (e.g. irrigation works) that facilitate adaptation to climate change in the agricultural sector.

To evaluate the effects of a modern cultivation system of plastic film mulching with drip irrigation (MD) on soil greenhouse gas fluxes, methane (CH4) and nitrous oxide (N2O) fluxes were quantified and contrasted in an MD system and a traditional system of mulch-free flood-irrigated (MFF) cotton (Gossypium hirsutum L.) in fields of northwest China. The results showed that soil N2O flux and the absorption rate of CH4 were lower in the MD than the MFF sites. A possible reason for the higher CH4 emissions at MD sites was that the relatively low gaseous oxygen (O2) availability and high ammonium (NH4+) content in the MD soil increased CH4 generation by methanogens and decreased CH4 oxidation by methanotrophs. The lower N2O in the MD sites may be due to an increase of soil denitrification by Thiobacillus denitrificans that reduced some nitrous compounds further into nitrogen gas (N2). Taking into account the global warming potentials of CH4 and N2O in a 100-year time horizon, during the entire growth period, the contribution of CH4 to the greenhouse effect was significantly lower than N2O in these two treatments. Considering these two greenhouse gas fluxes together, a transition from non-mulching cultivation to mulching cultivation could reduce atmospheric emissions by c. 20 g CO2 e m2/season. Based on these findings and previous studies, it can be concluded that mulched-drip irrigation cultivation is a good way to decrease the emission of greenhouse gases and reduce the global warming impact of arid farmlands.

The objective of the present paper is to use CLIMEX software to project how climate change might impact the future distribution of date palm (Phoenix dactylifera L.) in Iran. Although the outputs of this software are only based on the response of a species to climate, the CLIMEX results were refined in the present study using two non-climatic parameters: (a) the location of soils containing suitable physicochemical properties and (b) the spatial distribution of soil types having suitable soil taxonomy for dates, as unsuitable soil types impose problems in air permeability, hydraulic conductivity and root development. Here, two different Global climate models (GCMs), CSIRO-Mk3.0 (CS) and MIROC-H (MR), were employed with the A2 emission scenario to model the potential date palm distribution under current and future climates in Iran for the years 2030, 2050, 2070 and 2100. The results showed that only c. 0·30 of the area identified as suitable by CLIMEX will actually be suitable for date palm cultivation: the rest of the area comprises soil types that are not favourable for date palm cultivation. Moreover, the refined outputs indicate that the total area suitable for date palm cultivation will increase to 31·3 million ha by 2100, compared with 4·8 million ha for current date palm cultivation. The present results also indicate that only heat stress will have an impact on date palm distribution in Iran by 2100, with the areas currently impacted by cold stress diminishing by 2100.

The water driven crop growth model AquaCrop was evaluated for predicting the yield of kharif maize (i.e. maize sown in the monsoon season) under future water availability scenarios. Future climatic data were generated using the climate data generator ClimGen, which was parameterized using 37 years (1972–2008) of historical data relating to the study area. The climatic data generated were used first in the CROPWAT model to estimate the irrigation schedule, which was then used in the validated AquaCrop model to predict grain yield for future years. Rainfall estimates generated by ClimGen for 2012 (739 mm) and 2014 (625 mm) resulted in yields of 1600 and 5670 kg/ha, respectively, under rainfed situation during these 2 years with full fertilization levels. This variation may be attributed to the depths of rainfall events and their distribution during the entire growing season in general and sensitive growth stages in particular pertaining to the same sowing date (22 July) in both years. Nonetheless, the use of ClimGen, CROPWAT and AquaCrop models can be standardized as a model-linking protocol to estimate future maize yield and irrigation water requirements for sustainable production and as an adaptation measure to climate change.

Identification of climate-smart nutrient management practices will overcome the ill effects of extreme climate variability on agricultural production under projected climate change scenarios. The rice–wheat cropping system is the major system used in India: using long-term yield data from Integrated Nutrient Management experiments on this system, the present study analysed trends in weather parameters and grain yield under different nutrient management practices. Twelve treatments with different combinations of inorganic (chemical fertilizer) and organic (farmyard manure (FYM), green manure (GM) and crop residue) sources of nutrients were compared with farmers’ conventional practices. A significant increasing trend was noticed for rainfall during the rice season at Kalyani and Navsari, of the order of 137·7 and 154·2 mm/decade, respectively. The highest increase in maximum temperature was seen at Palampur (1·62 °C/decade) followed by Ludhiana (1·14 °C/decade). At all the sites except Ludhiana and Kanpur, the yield of the rice–wheat system showed an increasing trend ranging from 0·08 t/ha/year in Jabalpur to 0·011 t/ha/year in Navsari, under the recommended dose of inorganic fertilizer application. A significant decreasing trend of 0·055 t/ha was found in Ludhiana. For most of the sites, a combination of half the recommended dose of inorganic fertilizer and either FYM or GM to provide the remainder of the N required was sufficient to maintain productivity. The top three climate-resilient integrated nutrient management practices were identified for all the study sites. Thus, the present study highlights the adaptive capacity of different integrated nutrient management practices to rainfall and temperature extremes under rice–wheat cropping system in distinctive agro-ecological zones of India.

Fungal infections of barley have tremendous agricultural significance, and can be detrimental or beneficial. Beneficial root infections often involve endophytic fungi, but endophytic associations do not always confer benefits on their hosts. Endophyte infection can be negative, positive or neutral for the host. Benefits to barley and other plants infected with endophytic root fungi include an increase in seed yield, enhanced resistance to pathogens and improved stress tolerance. Even if an endophyte is never pathogenic, it is not always beneficial. The most important factors that determine the nature of the relationship are the specific combination of partner genotypes and developmental stage, and the ecological and environmental setting. The nutrient status of the plant and the availability of soil nutrients may have little effect on the degree of beneficial endophyte colonization and, unlike mycorrhizae, there is no apparent increase in endophyte-associated phosphorous transfer. There are indications of an association between successful endophyte colonization and high soil pH and clay content. The greatest benefits to the barley plant resulting from the associations seem to be obtained in abiotically stressed environments. Fungal infection may give the plant a greater ability to cope with the stress if the partners are in a balanced relationship. Each new study reveals an increasing diversity of beneficial fungal root endophytes and the full potential of these organisms is still to be determined. Further studies are urgently required to develop specific beneficial root–endophyte associations, or combination of them, that are tailored to individual barley varieties for maximum impact in agriculture.

Sulphur (S) is one of the six main macroelements required to sustain the growth of plants. Sources include soil, fertilizer and atmospheric deposition, which has been reduced by 85% over the last three decades. Risks of S deficiencies are now recognized in high S-demanding species such as Brassica napus L. With the aims of evaluating the risk of excessive or insufficient fertilization and identifying robust relationships that may be used as plant S status indicators, 57 commercial crops of oilseed rape were selected among contrasting soils and along a rainfall gradient that may affect soil S availability. Cultivation practices were investigated and the S and nitrogen (N) concentrations of soil, senescing leaves, stems and seeds were analysed. Despite an excessive organic N supply and large variation in S supply (from 0 to 112 kg S/ha), principal component analysis using 43 parameters indicated that seed yield was poorly related to N and S fertilization rates. While the N and protein-N concentrations in seeds were inversely related to oil and glucosinolate concentrations, they were linked to S and sulphate (SO42−) accumulation in the seeds. Sulphate concentrations in senescing leaves, stems or seeds could be deduced from total S concentrations, as they were positively and highly correlated. Sulphate accounted for on average 0·69 of total S in senescing leaves with minimum and maximum values of 0·007 and 0·94, which revealed conditions of limited and excess supply of S, respectively. This high variation of SO42− concentration in leaves can be interpreted as the result of its mobilization triggered by S deficiency, but cannot be used alone as an indicator of plant S status. A comparison with plants grown in controlled conditions under different S supplies suggests that the intensity of S starvation affects N metabolism, leading to NO3− (nitrate) accumulation. It is further suggested that dual evaluation of SO42− and NO3− concentrations in senescing leaves could be used at the vegetative stage as a field indicator to adjust S fertilization.

Leaves of Nagafu No. 6 were transformed by the Agrobacterium tumefaciens-mediated method, and 158 hyg-resistant buds were obtained. Using fresh leaf tissue, seven positive lines were obtained by polymerase chain reaction (PCR) with total DNA, and four by reverse transcriptase–polymerase chain reaction (RT–PCR) with total RNA. The results showed that the MhTGA2 gene was successfully transformed into Nagafu No. 6 plants and expressed. At 4 months after transplanting, photosynthetic parameters of young leaves were determined using transgenic and control plants prior to the determination of leaf surface characteristics (epidermal structure and stomatal distribution) by scanning electronic microscopy. The results showed that the net photosynthesis rate, the instantaneous carboxylation rate and stomatal conductance of transgenic plants were higher than the control, whereas the internal carbon dioxide (CO2) concentrations of the transgenic plants were lower. Under non-saline conditions, the stomata of the transgenic plants were better distributed than in the control. Under saline conditions, the epidermal structure of the control leaves was severely hypohydrated and the quantity of stomata was significantly decreased. Conversely, the epidermal structure of transgenic leaves was not significantly altered, indicating salt-stress tolerance. The overall results suggested that MhTGA2 may play a crucial role in the response to salt stress in Nagafu No. 6.

The root and shoot characteristics of triticale grown in either a monoculture sequence of winter triticale (WT) and spring triticale or in rotation with sugar beet and faba bean (Norfolk rotation) were studied. Grain yield, root and shoot biomass as well as root morphometric parameters, were determined in a long-term field trial carried out in Poland. Spring triticale had lower root biomass and shorter root length than WT as observed at a soil depth of 5–20 cm and was related to the 0·1–0·5 mm root diameter fraction. Grain yields were affected by both crop rotation (Norfolk>monoculture) and the type of triticale grown (winter>spring). Straw yield was lower for the Norfolk rotation (7·16 t/ha) than for monoculture (8·47 t/ha). Consequently, the harvest index (HI) was higher in the Norfolk rotation (0·421 v. 0·324). In conclusion, when grown in monoculture, triticale showed lower biomass production and HI compared with triticale grown in a rotation with other non-cereal crops. These differences could be caused not only by deterioration in the physical, biological and/or chemical properties of the soil resulting from the use of a monoculture rotation, but also by the beneficial effects of the organic amendments applied and the legumes grown in the Norfolk rotation.

Mixed grazing is an alternative pasture management which can be used to increase ruminant performance and reduce gastro-intestinal nematodes. A meta-analysis was performed on the results of previous studies from the literature to quantify the benefit of mixed grazing with sheep and cattle and identify determinants and enhancing factors. The analysis focused on papers reporting measurements of average daily weight gain (ADG) of sheep and cattle, carried out simultaneously in mixed grazing and in mono-grazing. The meta-analysis used 179 observations from 16 experiments published in nine carefully selected papers. The benefits of mixed grazing were appraised using the individual ADG of sheep (ADGisheep), cattle (ADGicattle) and the overall performances (ADG per hectare (ADGha), g/day/ha). A theoretical production value (ADGha-Theo) was calculated from the ADGha in mixed and mono-grazing at similar stocking rates (SRs)/ha. The ADGisheep was greater in mixed treatments compared with control treatments (+14·5 g/day, P<0·001) and varied with physiological status and SR (P<0·001). The ADGicattle was similar in mixed and mono-grazing. At a global level ADGha in mixed treatments (ADGha-Mtrt) was higher by 28·6% compared with sheep alone and by 25·1% compared with cattle alone; also, ADGha-Mtrt was 8% higher than ADGha-Theo. The ADGha varied with physiological status and decreased with the proportion of sheep in association (P<0·01). The contribution of ADGha in mixed grazing due to each species was lower compared with gains for each species reared alone (1438 v. 2423 g/day/ha for sheep and 1687 v. 2491 g/day/ha for cattle, P<0·001).

The current research was carried out to evaluate the use of crude protein and fibre components in faeces for estimating intake and digestibility in sheep fed with pearl millet (Pennisetum americanum (L.) Leeke). The equations were developed from four trials in metabolism cages with 16 sheep in each trial. Each animal received a different quantity of millet leaves in the diet: 0·015, 0·020 and 0·025 dry matter (DM) as a proportion of live weight (LW) and ad libitum with at least 0·2 of daily feed refusals. Organic matter intake (OMI, g/day) was measured, through the difference between offer and refusals; total faeces were collected for 5 days, which was used to determine faecal crude protein (CPf, g/day and g/kg of organic matter (OM)), faecal neutral detergent fibre (NDFf, g/day and g/kg OM), faecal acid detergent fibre (ADFf, g/day and g/kg OM) and OM digestibility (OMD). Linear regression equations were calculated to determine the relationship between OMI and CPf (P<0·001, R2=0·90, relative prediction error (RPE=14·02%). A multiple linear equation was generated for OMI including CPf and NDFf (P<0·001, R2=0·94; RPE=9·25%). Hyperbolic (single and multiple) and exponential models were tested to estimate OMD, where the hyperbolic multiple model including CPf and NDFf showed lower RPE (3·90%). These equations for estimating OMI and OMD were evaluated on sheep grazing P. americanum fertilized with increasing levels of nitrogen (N) (50, 100, 200 and 400 kg N/ha), comparing measured and estimated OMI. The intake estimated by multiple regression (CP and NDFf) showed a higher R2 (0·98) and lower RPE (5·25%) than the simple (CPf only) linear equation (R2=0·94; RPE=20·45%). The results demonstrated the feasibility of using the faecal index generated in metabolism cages for estimating intake and digestibility in sheep grazing P. americanum.

The current study was designed to determine the effect of roughage to concentrate ratio (R : C) on rumen pH, fermentation and bacterial population in dairy steers. Four rumen fistulated dairy steers (170±20 kg) were randomly assigned according to a 4×4 Latin square design, in which the steers were fed with four dietary treatments with different R : C ratios of 0·8 : 0·2, 0·6 : 0·4, 0·4 : 0·6 and 0·2 : 0·8, respectively. All animals were kept in individual pens and received feed according to the respective R : C ratios at 0·025 body weight (BW)/d; urea-treated rice straw (prepared using 3·5 kg urea+100 kg water sprayed onto 100 kg of rice straw) was used as a roughage source. The experiment was conducted for four periods of 21 days each. During the first 14 days, feed intake was measured and the animals were then moved to metabolism crates for total urine and faecal collection for 7 days. Total dry matter intake (DMI) was similar among treatments. Energy intake increased as the proportion of concentrate in the diet increased. Apparent digestibilities of dry matter (DM), organic matter (OM) and crude protein (CP) were improved, while neutral detergent fibre (NDF) and acid detergent fibre (ADF) were reduced when the levels of concentrate increased. A decreasing ratio of R : C reduced rumen pH linearly, from 6·4 to 5·9 at 0·2 : 0·8. High levels of concentrate impacted on volatile fatty acids (VFA) molar proportions and decreased acetate (C2) linearly, while propionate (C3) was increased, leading to decreased C2 : C3 ratio. Numbers of protozoa, fungi and proteolytic bacteria were not affected by R : C ratio. Cellulolytic bacteria decreased linearly while amylolytic bacteria increased linearly with 0·60 and 0·80 concentrates. Quantitative polymerase chain reaction (qPCR) based on 16S RNA revealed that Fibrobacter succinogenes numbers were increased when steers were fed with R : C ratio of 0·8 : 0·2. Conjugated linoleic acid (CLA)-producing bacteria, especially those of Butyrivibrio fibrisolvens, increased linearly with R : C ratios of 0·8 : 0·2 and 0·6 : 0·4, while Megasphaera elsdenii, a lactate-utilizing bacterium and reported producer of trans-10, cis-12 CLA increased linearly with R : C ratio of 0·8 : 0·2. In addition, microbial CP synthesis increased quadratically when steers were fed high levels of concentrate. However, the efficiency microbial N synthesis (EMNS) based on OM, truly digested in the rumen, was not affected by different R : C ratios. From the current study, it can be concluded that roughage to concentrate ratio of 0·4 : 0·6 had positive effects for the creation of healthy rumen (rumen pH and ecology), and improved energy intake and rumen fermentation, particularly propionic acid and microbial protein synthesis, in dairy steers fed urea-treated rice straw as a roughage source.

The effects of melamine on gas production (GP) kinetics, methane (CH4) production and fermentation of diets differing in forage content (low-forage (LF) diet: 200 g/kg and high-forage (HF) diet: 800 g/kg) by rumen micro-organisms in vitro were studied using batch cultures. Rumen contents were collected from three Simmental×Luxi crossbred beef cattle. Melamine was added to the incubation bottles to achieve final concentration of 0 (control), 2, 6, 18, 54, 162 and 484 mg/kg of each diet. Cumulative GP was continuously measured in an automated gas recording instrument during 72 h of incubation, while fermentation gas end-products were collected to determine molar proportions of carbon dioxide (CO2), CH4 and hydrogen gas (H2) in manually operated batch cultures. Differences in GP kinetics and fermentation gases were observed in response to the nature of the diets incubated. Although melamine addition did not affect GP kinetics and fermentation gas pattern compared to the control, the increase of melamine addition stimulated the yield of CH4 by decreasing CO2, especially during the fermentation of the HF diet. The concentrations of ammonia nitrogen (N), amino acid N and microbial N in culture fluids were greater in the fermentation of LF- than HF diets, and these concentrations were increased by the increase of melamine addition after 72-h fermentation. The concentrations of total volatile fatty acids (VFA) were greater in HF than LF diets. The addition of melamine decreased total VFA concentrations and this response was greater in HF than LF diet fermentations. Melamine addition did not affect molar proportions of acetate, butyrate, propionate and valerate compared with the control; however, branched-chain VFA production, which was lower in the HF than the LF diet, was increased by the melamine addition, especially in the HF diet fermentation. The ratio of non-glucogenic to glucogenic acids was lower in the HF than the LF diet, but it was not affected by melamine addition. In brief, the greater reduction in the rate and extent of rumen fermentation found for the HF diet in comparison with the LF diet suggested that rumen fermentation rate and extent in vitro depended mainly on the nature of the incubated substrate, and that they could be further inhibited by the increase of melamine addition.