Agriculture is a largely technical endeavour involving complicated managerial decision-making that affects crop performance. Farm-level modelling integrates crop models with agent behaviour to account for farmer decision-making and complete the representation of agricultural systems. To replicate an important part of agriculture in Central Europe a crop model was calibrated for a unique region's predominant crops: winter wheat, winter and spring barley, silage maize and winter rapeseed. Their cultivation was then simulated over multiple decades at daily resolution to test validity and stability, while adding the dimension of agent behaviour in relation to environmental and economic conditions. After validation against regional statistics, simulated future weather scenarios were used to forecast crop management and performance under anticipated global change. Farm management and crop genetics were treated as adaptive variables in the milieu of shifting climatic conditions to allow projections of agriculture in the study region into the coming decades.

Analyses of the geographic patterns of wild species abundance have been carried out in studies ranging from those interested in hot-spots for biodiversity and conservation to basic ecological analyses. Based on the methodological approaches used, the present study searched for areas of higher yield among native races of maize in Mexico, its centre of origin and diversification. Ecological theory suggests that population fitness, and thus abundance, is maximal at the centroid of the multi-dimensional ecological niche of a particular species, and decreases progressively as distance from it increases. In the present study, yield was used instead of abundance, assuming it to be higher under optimal environmental conditions. It was assessed whether nine Mexican maize races exhibited higher yields in areas that are ecologically closer to their niche centroid (NC), or a niche optimum (NO) that did not always coincide with the geometric centroid. Environmental and geographical clusters for each race were also created to identify additional NOs in widely distributed races. All races showed significant correlations between yield and distance, both to the NC or NOs, but in only six of them was the chosen model better than the null model. Three races and two sub-groups were selected for projection under climate change conditions: Celaya (R2 = 0·288), Celaya 3 (R2 = 0·774), Vandeño (R2 = 0·277) and Vandeño 2 (R2 = 0·466) and Tepecintle (R2 = 0·537). The Celaya race improved with environmental clustering, while Vandeño improved under geographical clustering. Finally, Tepecintle was projected at a race level. Projections under climate change suggested some potential areas for high yields in the future. It was concluded that the approach used in the present paper, considering the distance to NC/NO as a predictor of maize landrace yield, may contribute important information to agro-ecological projects.

Many studies have highlighted the continuously increasing need for genetic diversity in the field; nonetheless, plant breeding is still predominantly generating uniform cultivars. Evolutionary plant breeding offers the possibility of reconciling agro-biodiversity, high yields and adaptation to climate change. However, the diversity that can be conserved in heterogeneous populations, its evolution and the potential of ‘evolutionary breeding’ in the actual scenario of climate change is still a matter of debate. In the present study, a total of 147 barley individuals, 56 from seven parental populations (PPs) and 91 from the composite cross-derived population (CCP) resulting from their inter-crossing were genotyped at 22 Simple Sequence Repeat (SSR) loci with the objective of obtaining insights into how genetic diversity evolved in the field during 13 years of multiplication. A total of 92 different alleles were detected in the PP and 100 in the CCP. Results showed that the composite individuals are grouped into five major clusters differing for both the number of individuals and the relative level of genetic diversity. The mean values of the most common descriptors of genetic diversity were not significantly different between the parental and the composite populations. However, analysis of molecular variance showed some degree of differentiation between the two populations suggesting that evolution occurred during the years of multiplication and selection effects were detected for some loci. The SSR loci detected as putatively under selection in the present study have already been reported as co-localized with quantitative trait loci for adaptedness traits or tagging genes related to abiotic stress response. According to the current results, evolving crop populations, which have the capability of adapting to the conditions under which they are grown, can be useful in conserving genetic diversity and as sources of genes for breeding purposes in particular in the actual scenario of climate change.

Dairy farms are under pressure to increase productivity while reducing environmental impacts. Effective fertilizer management practices are critical to achieve this. In the present study the effect of timing and rate of nitrogen (N) fertilizer application on pasture production and N losses, either via direct leaching of fertilizer N or indirectly through consumption of N in pasture and subsequent excretion via dairy cow grazing, was modelled. The Agricultural Production Systems Simulator (APSIM) was first tested with experimental data from N fertilizer response experiments conducted on a well-drained soil in the Waikato region of New Zealand. The model was then used in a 20-year simulation to investigate the effect of fertilizer management on the impacts on potential N leaching losses. Year-to-year variability was assessed by incorporating 20 years of climate data into the model. Modelling indicated that N fertilization at rates of 140 and 220 kg N/ha/year, applied in four split applications and avoiding application in winter months, could increase pasture yield on average by 2·2–3·0 t dry matter (DM)/ha (25–38%). There were some significant amounts of direct leaching in some years, related to environmental conditions. The maximum loss was as high as 61 kg N/ha at an N application rate of 220 kg N/ha/year, in a year with low pasture production and high rainfall following fertilizer application. In general, however, the risk of direct N leaching from applied fertilizer was low. It seems the main effect of N fertilization is to increase the risk of indirect N leaching, due to increased N intake and excretion. The modelling indicated that the major contribution to increased indirect N leaching risk was from the extra DM grown (more urine deposited per ha). Increased N concentration in the pasture due to fertilization and the resultant extra partitioning of excretal N to urine had only a minor effect on indirect leaching losses. The exception was N fertilizer applied in late winter/early spring (July), where fertilizer N (55 kg/ha) increased pasture N concentration by c. 25%, suggesting that the N concentration in urine patch areas could increase from c. 550 to 840 kg N/ha. Further measurements are required to test the hypothesis developed from the modelling that the main effect of N fertilizer on urinary N leaching is by increasing DM production rather than increasing pasture N concentration.

The effects of planting pattern and irrigation on the soil water content, stomatal conductance, leaf relative water content, leaf water potential and leaf water use efficiency of winter wheat were investigated in North China during the 2008/09 and 2009/10 growing seasons. A field experiment was conducted using a randomized complete block design that consisted of three planting patterns: (i) a uniform row spacing of 25 cm, and alternating wide–narrow row spacing of 40 and 20 cm tested as (ii) flat and (iii) furrow–ridge seedbeds. In addition, irrigation treatments of 90, 135 and 180 mm were used. The planting pattern, irrigation treatments and interactions between them significantly affected soil water content, stomatal conductance, leaf relative water content, leaf water potential and leaf water use efficiency. The soil water content, stomatal conductance, leaf relative water content, leaf water potential, grains/spike, thousand grain weight, leaf water use efficiency and yield were highest in the furrow–ridge seedbed planting pattern and increased with increasing irrigation (except for the leaf water use efficiency). The leaf water use efficiency in the 135 mm irrigation treatment was significantly greater than in the other treatments. In addition, soil water content, stomatal conductance, leaf relative water content, leaf water potential, grains/spike and thousand grain weight were positively correlated with leaf water use efficiency and yield of winter wheat. The interaction between the furrow–ridge seedbed planting pattern and 135 mm irrigation increased soil water content, leaf water indices, grains/spike, thousand grain weight, leaf water use efficiency and yield. These results indicated that a beneficial response occurred for wheat yield. The furrow–ridge seedbed planting pattern combined with 135 mm of irrigation improved the soil and leaf water status and could increase wheat yield while using less water.

Phenological models are considered key tools for the short-term planning of viticultural activities and long-term impact assessment of climate change. In the present study, statistical phenological models were developed for budburst (BUD), flowering (FLO) and veraison (VER) of 16 grapevine varieties (autochthonous and international) from the Portuguese wine-making regions of Douro, Lisbon and Vinhos Verdes. For model calibration, monthly averages of daily minimum (Tmin), maximum (Tmax) and mean (Tmean) temperatures were selected as potential regressors by a stepwise methodology. Significant predictors included Tmin in January–February–March for BUD, Tmax in March–April for FLO, and Tmin, Tmax and Tmean in March–July for VER. Developed models showed a high degree of accuracy after validation, representing 0·71 of total variance for BUD, 0·83 for FLO and 0·78 for VER. Model errors were in most cases < 5 days, outperforming classic growing degree-day models, including models based on optimized temperature thresholds for each variety. Applied to the future scenarios RCP4·5/8·5, projections indicate earlier phenophase onset and shorter interphases for all varieties. These changes may bring significant challenges to the Portuguese wine-making sector, highlighting the need for suitable adaptation/mitigation strategies, to ensure its future sustainability.

Estimating crop nutrient requirements for winter oilseed rape (Brassica napus L.) is a crucial step in optimizing fertilization to enhance seed yield and improve fertilizer use efficiency. In the present paper, a database composed of 1035 on-farm observations collected from 2005 to 2010 across the major winter oilseed rape production regions in China was used to evaluate internal nutrient efficiencies (kg seed per kg nutrient in plant dry matter); then the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model for winter oilseed rape was developed to describe the nutrient uptake-yield relationship of oilseed rape over a wide range of environmental conditions and predict the nutrient requirements for a target yield. After excluding observations with low harvest index values, <0·20, and excluding 0·025 of the highest and lowest internal nutrient efficiencies, the minimum and maximum internal nutrient efficiencies were estimated as 13·1 and 31·6 kg seed/kg nitrogen (N), 68·9 and 200·3 kg seed/kg phosphorus (P) and 8·9 and 31·1 kg seed/kg potassium (K), respectively. On the basis of the data settings, the balanced N, P and K uptake at different yield potential levels was calculated using a linear–parabolic–plateau curve with the QUEFTS model. Crop nutrient requirements increased linearly until the yield reached approximately 0·60–0·70 of the potential yield, and 46·0 kg N, 8·0 kg P and 57·1 kg K were found to be needed to produce 1000 kg of seed. The corresponding internal nutrient efficiencies were 21·8, 125·1 and 17·5 kg seed/kg N, P and K, respectively. However, when the target yields approached the yield potential, a decrease in internal nutrient efficiencies was detected in the model. The predicted nutrient requirement values simulated by the QUEFTS model compared well with observed values across a range of conditions. To conclude, the QUEFTS model was shown to be a practical and robust tool for assessing the crop nutrient requirements of winter oilseed rape.

Crop production in the Northeast Farming Region of China (NFR) is affected considerably by variation in climatic conditions. Data on crop yield and weather conditions from a number of agro-meteorological stations in NFR were used in a mixed linear model to evaluate the impacts of climatic variables on the yield of maize (Zea mays L.), rice (Oryza sativa L.), soybean (Glycine max L. Merr.) and spring wheat (Triticum aestivum L.) in different crop growth phases. The crop growing season was divided into three growth phases based on the average crop phenological dates from records covering 1981 and 2010 at each station, comprising pre-flowering (from sowing to just prior to flowering), flowering (20 days around flowering) and post-flowering (10 days after flowering to maturity). The climatic variables were mean minimum temperature, thermal time (which is used to indicate changes in the length of growth cycles), average daily solar radiation, accumulated precipitation, aridity index (which is used to assess drought stress) and heat degree-days index (HDD) (which is used to indicate heat stress) were calculated for each growth phase and year. Over the 1961–2010 period, the minimum temperature increased significantly in each crop growth phase, the thermal time increased significantly in the pre-flowering phase of each crop and in the post-flowering phases of maize, rice and soybean, and HDD increased significantly in the pre-flowering phase of soybean and wheat. Average solar radiation decreased significantly in the pre-flowering phase of all four crops and in the flowering phase of soybean and wheat. Precipitation increased during the pre-flowering phase leading to less aridity, whereas reduced precipitation in the flowering and post-flowering phases enhanced aridity. Statistical analyses indicated that higher minimum temperature was beneficial for maize, rice and soybean yields, whereas increased temperature reduced wheat yield. Higher solar radiation in the pre-flowering phase was beneficial for maize yield, in the post-flowering phase for wheat yield, whereas higher solar radiation in the flowering phase reduced rice yield. Increased aridity in the pre-flowering and flowering phases severely reduced maize yield, higher aridity in the flowering and post-flowering phases reduced rice yield, and aridity in all growth phases reduced soybean and wheat yields. Higher HDD in all growth phases reduced maize and soybean yield and HDD in the pre-flowering phase reduced rice yield. Such effects suggest that projected future climate change may have marked effects on crop yield through effects of several climatic variables, calling for adaptation measures such as breeding and changes in crop, soil and agricultural water management.

Chamber sampling is a common method for measuring nitrous oxide (N2O) emissions from agricultural soils. However, for grazed pastures, the patchy nature of urine deposition results in very high levels of spatial variability in N2O emissions. In the present study, the behaviour of the sample mean was examined by simulating a large number (9999) of random N2O chamber samples under different assumptions regarding the underlying N2O distribution. Using sample sizes of up to 100 chambers, the Central Limit Theorem did not apply. The distribution of the sample mean was always right-skewed with a standard deviation varying between 12·5 and 135% of the true mean. However, the arithmetic mean was an unbiased estimator and the mean of the sample mean distribution was close to the true mean of the simulated N2O distribution. The properties of the sample mean distribution (variance, skewness) were affected significantly by the assumed distribution of the emission factor, but not by distribution of the urine patch concentration. The geometric mean was also investigated as a potential alternative estimator. However, although its distribution had lower variance, it was also biased. Two methods for bias correcting the mean were investigated. These methods reduced the bias, but at the cost of increasing the variance. Neither of the bias-corrected estimators were consistently better than the arithmetic mean in terms of skewness and variance. To improve the estimation of N2O emissions from a grazed pasture using chambers, techniques need to be developed to identify urine patch and non-urine patch areas before sampling.

The present study was designed to estimate the effects of the mutant su1 on the genetic regulation of fitness-related traits when introgressed into field maize backgrounds. Estimated genetic effects of agronomic traits in Su1 v. su1 plants were monitored in two separate mean generation designs. The first involved unrelated inbred lines EP42 and A631, while two Corn Belt inbred lines, A619 and A632, were used for the second design. Parents, F1s, F2s and backcrosses were crossed to the su1 inbred P39 as the donor of su1 and the 12 crosses were successively self-pollinated for 5 years. For each cross, Su1 and su1 kernels were evaluated separately in a growth chamber under controlled environmental conditions following a randomized complete block design. In addition, the genotypes were evaluated in field trials in 10 × 10 triple lattice designs during 2010 and 2011 at Pontevedra in north-western Spain; and in 2010 at Algiers, located in the sub-humid North of Algeria. The performance of su1 plants was lower when compared to the Su1 plants for all traits evaluated in both designs and across environments. The estimates of genetic effects of Su1 v. su1 plants were strongly affected by genotype and environment. The results suggest that, depending on specific sweet × field maize interaction, seedling vigour and, particularly, chlorophyll content (CCM) were the most critical traits in determining su1 viability. However, the complexity of the genetic regulation of emergence and the great heterogeneity of environmental conditions in the field evaluation prevent the estimation of the genetic regulation on sugary1 fitness.

Floral organ development influences plant reproduction and crop yield. The mechanism of floral organ specification is generally conserved in angiosperms as demonstrated by the ‘ABC’ model. However, mechanisms underlying the development of floral organs in specific groups of species such as grasses remain unclear. In the genus Oryza (rice), a spikelet consists of a fertile floret sub-tended by a lemma, a palea, two sterile lemmas and rudimentary glumes. To understand how the lemma is formed, a curve-shaped lemma-distortion1 (ld1) mutant was identified. Genetic analysis confirmed that the ld1 mutant phenotype was due to a single recessive gene mutation. Using a large F2 population, the LD1 gene was mapped between markers Indel-7-15 and Indel-7-18, which encompassed a region of 15·6 kilo base pairs (kbp). According to rice genome annotations, two putative genes, LOC_Os07g32510 and LOC_Os07g32520, were located in this candidate region. However, DNA sequencing results indicated only 1 base pair (bp) substitution (T⇨C) was found in LOC_Os07g32510 between the wild-type and the ld1 mutant. Thus LOC_Os07g32510, encoding a DNA binding with one zinc finger (DoF) containing protein, was the candidate gene for LD1. Further analysis showed that mutation of the amino acid cysteine (C) to arginine (R) was likely to lead to zinc finger protein deactivation. Phylogenetic and conservation analysis of the gene from different species revealed that cysteine was critical to LD1 function. As a new gene controlling lemma development, the study of LD1 could provide insights into rice floral organ formation mechanisms.

Understanding the effect of genetic factors controlling flowering time is essential to fine-tune crop development to each target environment and to maximize yield. A set of 35 durum wheat genotypes of spring growth-habit involving different allelic combinations at Ppd-A1 and Ppd-B1 genes was grown for 2 years at four sites at latitudes ranging from 19°N to 41°N. The emergence-flowering period was reduced from north to south. The frequency in the collection of the insensitive allele GS-105 at Ppd-A1 was greater (34%) than that of allele GS-100 (20%). Genotypes that flowered earlier due to the presence of alleles causing photoperiod insensitivity extended their grain-filling period, but less than the shortening in flowering time. The effect of the allele conferring photoperiod sensitivity at Ppd-A1 was stronger than that at Ppd-B1 (Ppd-A1b > Ppd-B1b). The effect of photoperiod insensitivity alleles was classified as GS-100 > GS-105 > Ppd-B1a. The phenotypic expression of alleles conferring photoperiod insensitivity at Ppd-A1 increased at sites with average day length from emergence to flowering lower than 12 h. An interaction effect was found between Ppd-A1 and Ppd-B1. Differences between allelic combinations in flowering time accounted for c. 66% of the variability induced by the genotype effect, with the remaining 34% being explained by genes controlling earliness per se. The shortest flowering time across sites corresponded to the allelic combination GS-100/Ppd-B1a, which reduced flowering time by 11 days irrespective of the Ppd-A1b/Ppd-B1b combination. The current study marks a further step towards elucidation of the phenotypic expression of genes regulating photoperiod sensitivity and their interaction with the environment.

Cassava (Manihot esculenta Crantz) is an economically important root crop in Thailand, which is ranked the world's top cassava exporting country. Production of cassava can be hampered by several pathogens and pests. Cassava anthracnose disease (CAD) is an important disease caused by the fungus Colletotrichum gloeosporioides f. sp. manihotis. The pathogen causes severe stem damage resulting in yield reductions and lack of stem cuttings available for planting. Molecular studies of cassava response to CAD will provide useful information for cassava breeders to develop new varieties with resistance to the disease. The current study aimed to identify quantitative trait loci (QTL) and DNA markers associated with resistance to CAD. A total of 200 lines of two F1 mapping populations were generated by reciprocal crosses between the varieties Huabong60 and Hanatee. The F1 samples were genotyped based on simple sequence repeat (SSR) and expressed sequence tag-SSR markers and a genetic linkage map was constructed using the JoinMap®/version3·0 program. The results showed that the map consisted of 512 marker loci distributed on 24 linkage groups with a map length of 1771·9 centimorgan (cM) and a mean interval between markers of 5·7 cM. The genetic linkage map was integrated with phenotypic data for the response to CAD infection generated by a detached leaf assay test. A total of three QTL underlying the trait were identified on three linkage groups using the MapQTL®/version4·0 program. Those DNA markers linked to the QTL that showed high statistically significant values with the CAD resistance trait were identified for gene annotation analysis and 23 candidate resistance genes to CAD infection were identified.

Canola (Brassica napus L.) meal is widely used in animal feed as a protein source, and its quality relies on protein and amino acid content. However, little information is available regarding amino acid regulation in canola seed with nitrogen (N) application. The present study is aimed to evaluate the effect of N rate and genotype on canola seed amino acid concentrations under field conditions. A split-plot design comprising four N rates (0, 120, 240 and 360 kg N/ha) and three genotypes differing in seed protein content were used in 2010/11 and 2011/12. The results showed that increasing N rate decreased seed oil content linearly but increased seed protein content in all of the genotypes. The total amino acid concentration and absolute concentrations of individual amino acids in canola seed also improved significantly with the N rates in all of the genotypes. Regarding the proportions of amino acids, a group that included glutamic acid (Glu), proline (Pro) and arginine (Arg) dominated and occupied > 0·30 compared with other amino acids. The ratio of amino acids in this group increased by 8·3% with 360 kg N/ha compared with the control. However, the proportions of the other amino acids showed negative responses to the N rates. The results of regression analysis of the responses of individual amino acids to N rate indicated that Glu, Pro and Arg had a greater improvement potential with application of N fertilizer, as revealed by higher slopes in the linear equations compared with the other amino acids. Additionally, the concentrations of sulphur-containing amino acids, methionine and cysteine, were also a potential target for improving with N application because these are always deficient in major crops. In conclusion, N application cannot only improve seed protein content but also enhance deposition of amino acids such as Glu, Pro and Arg.

Saline-sodic soils are widely distributed in the western Songnen Plain of Northeast China and planting rice has been found to be an effective and feasible approach for improving saline-sodic soil and increasing food production. Assessment of the effectiveness and sustainability of this method requires monitoring of the changes in soil salinity and nutrient content. The objective of the current study was to investigate the changes of soil salinity and nitrogen (N) contents over 1, 3, 6 and 9 years of cultivation, four application rates of N (N0: no N, N1: 100 kg N/ha, N2: 200 kg N/ha and N3: 300 kg N/ha) and two irrigation water types: ground water irrigation (GWI) and river water irrigation (RWI). Salinity and N contents of soil and water samples were analysed before planting and after harvest throughout the experiments. Soil pH and electrical conductivity (EC), especially in the surface layer of 0–40 cm depth, decreased with years of cultivation with both GWI and RWI, while soil inorganic N and total N contents increased. Moreover, with increasing N application rates, soil inorganic N and total N contents increased significantly in the 0–20 cm soil layer. Increasing N application had little effect on soil pH and EC. Reclaiming and planting rice promoted desalination of the surface and formation of a fertile tillage layer in saline-sodic paddy fields. In terms of irrigation and drainage in saline-sodic paddy fields, both soil salinity and N contents increased. Soil total salinity increased annually by 34 and 12·8 kg/ha, and inorganic N contents increased annually by 9 and 13·5 kg/ha with GWI and RWI, respectively. Therefore, comprehensive agricultural practices should be adopted for improving and cropping rice in saline-sodic paddy fields.

Soil organic matter (SOM) is important for long-term crop productivity through maintenance of soil quality and is also now receiving attention due to its potential for climate change mitigation. The objectives of the present study were to investigate the effects of 9 years of fertilization on soil organic carbon (SOC) and total organic nitrogen (TON) and their fractions for the 0–50 cm profile in clayey (Luvisols) and sandy (Arenosols) soils in Murewa District, Zimbabwe. Three treatments were assessed: unfertilized (Control), nitrogen fertilizer (Nfert) and nitrogen fertilizer plus cattle manure (Nfert+manure). Density fractionation was used to assess the distribution of SOC and TON in three SOM fractions and their sensitivity to fertilization in fields 0–50 m away from homesteads (Homefields) and > 100 m away from homesteads (outfields). The relationship between light and heavy fraction organic carbon (C) were analysed to determine equilibrium levels that give an indication of carbon storage potential. In clayey soils total organic C under Nfert+manure was 4% higher than Nfert and 16% higher than the control. In sandy soils, SOC stocks were lowest in the control and highest in Nfert treatments at all depths. Nine years of fertilization significantly influenced SOC concentrations and storage up to 20 cm depth, below which stocks and concentrations of C and N were statistically insignificant. Distribution of C and N in density fractions showed greater stabilization under Nfert+manure in clayey soils, whereas it was greater under Nfert in sandy soils. Estimation of equilibrium levels suggested that homefields had potential to store more C, whereas outfields and control treatments had limited capacity due to attainment of lower equilibrium levels. Application of manure can be a low-cost alternative for enhancing soil quality and promoting soil C sequestration under conventionally tilled continuous maize cropping systems in Zimbabwe.

There is limited information about the influences of long-term fertilizer management on methane (CH4) and nitrous oxide (N2O) emissions from double-cropping paddy fields in Southern China. Therefore, the objective of the present study was to characterize the changes of CH4 and N2O related to different fertilizer treatments based on a long-term field experiment. The experiment was initiated in 1986 and consisted of five treatments: unfertilized (CK), mineral fertilizer alone (MF), rice residues plus mineral fertilizer (RF), low manure rate plus mineral fertilizer (M1 + F), and high manure rate plus mineral fertilizer (M2 + F). Investigations were conducted over 2 years, from 2013 to 2014, to examine the CH4 and N2O emissions from paddy field of Southern China. The results indicated that M2 + F plots had the largest CH4 emissions during the early rice and late cropped rice and that MF and RF had larger N2O emissions than CK in both early and late cropped rice. When compared with the control, total N2O emissions in both rice-growing seasons increased in both MF and RF in 2013 and 2014. The global warming potentials (GWP) from paddy fields were ranked as M2 + F > M1 + F > RF > MF > CK. Meanwhile, the results demonstrated that CH4 and N2O emissions were closely associated with the soil redox potential and soil temperature. In summary, the incorporation of rice residues in addition to the use of mineral fertilizer (RF treatment) may be an effective fertilizer management practice for mitigating total GWP per grain yield and maintaining rice grain yield in southern China.

Phenological development and its variation during reproductive growth have important effects on the yield and quality of forage grasses. In perennial ryegrass (Lolium perenne L.) genetic variation in heading date is well recognized, but there are no reliable studies about the variability in the length of the stem elongation phase. To determine the variation in phenological traits of single plants of perennial ryegrass genotypes, a field trial was conducted over three growing seasons (2011–2013) using plant material from eight different ecotype populations, sampled from old permanent grassland swards in Northern Germany. In addition to the phenological stages of jointing, heading and flowering, the critical phase of stem elongation was considered as a new phenological trait. It was hypothesized that the length of the critical phase between jointing and heading differs significantly among genotypes and thus offers a new tool for selecting for specific purposes, e.g. adaption to changing climatic conditions, cutting or grazing as well as yield and quality. The study revealed significant genotypic variation in the observed traits, which was highest for the critical phase (GCV = 0·21). Moderate heritability in jointing (h2 = 0·72) revealed a large environmental impact. In contrast, high heritability (h2 > 0·86) in heading, flowering and the critical phase imply a strong genetic effect. Moderate to high genotypic and phenotypic coefficients of correlation revealed a substantial linkage among the phenological traits. Results are discussed in the context of providing different approaches and strategies in forage crop production, especially with regard to regional weather conditions and future climate change. Significant differences among the tested ecotype populations indicate that existing diversity in permanent grassland can provide source material for further progress in grass breeding.

The objectives of the present study were to quantify the effects of contrasting methods for storing solid cattle manure on: (i) total carbon (C) and nitrogen (N) balances during storage, and (ii) crop apparent N recovery (ANR) following manure application to arable land, with maize as a test crop. Portions of 10 t of fresh solid cattle manure were stored for 5 months during 2009/10 in three replicates as: (i) stockpiled heaps, (ii) roofed heaps, (iii) covered heaps and (iv) turned heaps at Wageningen University, the Netherlands. Surface emissions of ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) were measured regularly using a static flux chamber connected to a photo-acoustic gas monitor. Total C and N losses during storage were determined through the mass balance method. After storage, the manures were surface-applied and incorporated into a sandy soil, and maize ANR was measured as a proportion of both N applied to the field (ANRF) and N collected from the barn (ANRB).

During the storage period, the average losses of initial total N (Ntotal) were 6% from the covered, 12% from the roofed, 21% from the stockpiled and 33% from the turned heaps. Of the total N losses, 2–9% was lost as NH3-N, 1–4% as N2O-N and 16–32% through leaching. However, the greatest part of the total N loss from the four storage methods was unaccounted for and constituted in all probability of harmless dinitrogen gas. Of the initial C content, c. 13, 14, 17 and 22% was lost from the covered, stockpiled, roofed and turned heaps, respectively. Maize ANRF was highest from covered (39% of the applied N) followed by roofed (31%), stockpiled (29%) and turned manure (20%). The respective values in case of maize ANRB were 37, 27, 23 and 13%. It is concluded that from a viewpoint of on-farm N recycling the storage of solid cattle manure under an impermeable plastic cover is much better than traditional stockpiling or turning heaps in the open air.

Increasing recognition of the extent to which nitrous oxide (N2O) contributes to climate change has resulted in greater demand to improve quantification of N2O emissions, identify emission sources and suggest mitigation options. Agriculture is by far the largest source and grasslands, occupying c. 0·22 of European agricultural land, are a major land-use within this sector. The application of mineral fertilizers to optimize pasture yields is a major source of N2O and with increasing pressure to increase agricultural productivity, options to quantify and reduce emissions whilst maintaining sufficient grassland for a given intensity of production are required. Identification of the source and extent of emissions will help to improve reporting in national inventories, with the most common approach using the IPCC emission factor (EF) default, where 0·01 of added nitrogen fertilizer is assumed to be emitted directly as N2O. The current experiment aimed to establish the suitability of applying this EF to fertilized Scottish grasslands and to identify variation in the EF depending on the application rate of ammonium nitrate (AN). Mitigation options to reduce N2O emissions were also investigated, including the use of urea fertilizer in place of AN, addition of a nitrification inhibitor dicyandiamide (DCD) and application of AN in smaller, more frequent doses. Nitrous oxide emissions were measured from a cut grassland in south-west Scotland from March 2011 to March 2012. Grass yield was also measured to establish the impact of mitigation options on grass production, along with soil and environmental variables to improve understanding of the controls on N2O emissions. A monotonic increase in annual cumulative N2O emissions was observed with increasing AN application rate. Emission factors ranging from 1·06–1·34% were measured for AN application rates between 80 and 320 kg N/ha, with a mean of 1·19%. A lack of any significant difference between these EFs indicates that use of a uniform EF is suitable over these application rates. The mean EF of 1·19% exceeds the IPCC default 1%, suggesting that use of the default value may underestimate emissions of AN-fertilizer-induced N2O loss from Scottish grasslands. The increase in emissions beyond an application rate of 320 kg N/ha produced an EF of 1·74%, significantly different to that from lower application rates and much greater than the 1% default. An EF of 0·89% for urea fertilizer and 0·59% for urea with DCD suggests that N2O quantification using the IPCC default EF will overestimate emissions for grasslands where these fertilizers are applied. Large rainfall shortly after fertilizer application appears to be the main trigger for N2O emissions, thus applicability of the 1% EF could vary and depend on the weather conditions at the time of fertilizer application.