To gain protection under the International Convention for the Protection of New Varieties of Plant, new plant varieties must be distinguishable from existing varieties in at least one important characteristic. Assessment of quantitative characteristics often uses a procedure based on analysis of variance of variety-by-year means for 2 years of trials. In the current paper, a new method is described that can identify those reference varieties that are so different from a candidate that there would be no reason to compare them in the subsequent year, resulting in potential cost savings. It is more objective and transparent than existing practice for quantitative characteristics based on expert opinion. The method calculates thresholds for quantitative characteristics. The thresholds are defined so that if in the first year the difference between two varieties in a characteristic is larger than the characteristic's threshold then it is highly likely that the varieties would be distinct after 2 years. Thresholds were derived based on statistical predictions of the full decision after 2 years using the first year results combined with historical data. It is shown that these thresholds are sensitive to yearly heterogeneity in the variety-by-year variation. The method accommodates this heterogeneity by modelling yearly residual variances with the inverse gamma distribution. This extension meant that exact analytical formulae were not available so an approximation was suggested. Using simulation it was found that the approximation was reasonable; for thresholds corresponding to a high probability of distinctness, the approximate thresholds were a little higher than required. The method was evaluated on a 19-year data set for field pea, comparing decisions based on first year thresholds with those based on the full 2 years. It was found that with the probability of distinctness set at 0·99, the calculated thresholds were generally lower than the existing expert-set thresholds but had acceptable levels of false positives and false negatives.

In search of a suitable resource conservation technology under pigeonpea (Cajanus cajan L.)–wheat (Triticum aestivum L.) system in the Indo-Gangetic Plains, the effects of conservation agriculture (CA) on crop productivity and water-use efficiency (WUE) were evaluated during a 3-year study. The treatments were: conventional tillage (CT), zero tillage (ZT) with planting on permanent narrow beds (PNB), PNB with residue (PNB + R), ZT with planting on permanent broad beds (PBB) and PBB + R. The PBB + R plots had higher pigeonpea grain yield than the CT plots in all 3 years. However, wheat grain yields under all plots were similar in all years except for PBB + R plots in the second year, which had higher wheat yield than CT plots. The contrast analysis showed that pigeonpea grain yield of CA plots was significantly higher than CT plots in the first year. However, both pigeonpea and wheat grain yields during the last 2 years under CA and CT plots were similar. The PBB + R plots had higher system WUE than the CT plots in the second and third years. Plots under CA had significantly higher WUE and significantly lower water use than CT plots in these years. The PBB + R plots had higher WUE than PNB + R and PNB plots. Also, the PBB plots had higher WUE than PNB in the second and third years, despite similar water use. The interactions of bed width and residue management for all parameters in the second and third years were not significant. Those positive impacts under PBB + R plots over CT plots were perceived to be due to no tillage and significantly higher amount of estimated residue retention. Thus, both PBB and PBB + R technologies would be very useful under a pigeonpea–wheat cropping system in this region.

A comparative study of the effect of organic fertilization at different times and doses on soil fertility and crop yield was performed over 3 years in a calcareous loamy soil. Nutrient availability in the soil and macronutrient concentration in leaves and in the edible part of the plants was examined in plots that were previously handled conventionally and ecologically for several years. The organic fertilizers used were manure compost at two doses in plots after 4 years of organic management treatment, and green residues of previous crops in plots with 10 years of organic management. In general, soil organic carbon (C), nitrogen (N), phosphorous (P) and magnesium (Mg) contents were found to be considerably greater in organically fertilized soils in comparison with soil receiving mineral fertilizer (conventional treatment (CT)). For C and N, the highest contents were observed in the long-term organic treatment (OR). However, few differences were found for potassium (K) and sodium (Na). The results obtained for electrical conductivity and pH indicated that, in general, there were no significant differences between treatments. The differences in the values of EC and pH occurred among cultivation cycles irrespective of the type of fertilization, but there was a contradictory trend for each of the above parameters. The results obtained for leaves and the edible part of the plant indicated that, in general, there were no significant differences between treatments, except for P with a trend for higher P content in organic crops. The nitrate values in leaves showed great variability, making it difficult to draw conclusions. The associations of fertilization and the chemical properties of soil with nutrient content in crops were checked by principal component analysis (PCA). For soil data, different clusters were observed between CT and OR treatments. However, PCA showed that the influence of crop type on plant nutrient concentrations was greater than type of fertilization. The effect of fertilization on crop yield was variable depending on plant species. The results indicated that organic fertilization did not cause deficiencies in the nutrient content and yield of vegetables when compared with conventional fertilization, showing that ecological management can be used effectively.

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.

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.

Safety evaluation of a genetically modified crop entails assessing its equivalence to conventional crops under multi-site randomized block field designs. Despite mounting petitions for regulatory approval, there lack a scientifically sound and powerful statistical method for establishing equivalence. The current paper develops and validates two procedures for testing a recently identified class of equivalence uniquely suited to crop safety. One procedure employs the modified large sample (MLS) method; the other is based on generalized pivotal quantities (GPQs). Because both methods were originally created under balanced designs, common issues associated with incomplete and unbalanced field designs were addressed by first identifying unfulfilled theoretical assumptions and then replacing them with user-friendly approximations. Simulation indicated that the MLS procedure could be very conservative in many occasions irrespective of the balance of the design; the GPQ procedure was mildly liberal with its type I error rate near the nominal level when the design is balanced. Additional pros and cons of these two procedures are also discussed. Their utility is demonstrated in a case study using summary statistics derived from a real-world dataset.

A study was performed in controlled conditions to reproduce cold and warm spring regimes in the east Po valley, northern Italy with a temperate subcontinental climate, to evaluate whether and to what extent spring weather regimes favour the attack of Rhizoctonia solani or Colletotrichum coccodes on potato, in view of predicted climate change. The main experiment, preceded by a controlled chamber set of tests to quantify response to temperatures of R. solani anastomosis group (AG)-3 and C. coccodes strains, showed that limit temperatures (minimum, maximum and optimum of colony radial growth) of R. solani AG-3 are 6 °C lower than those of C. coccodes. Then, a trial to reproduce early growth stages of potato was performed in phytotrons with sprouts of cvar Hermes to simulate cold and warm spring regimes with two different relative soil moisture contents. That simulation was carried out on native non-sterilized soil samples which were co-inoculated artificially with R. solani AG-3 and C. coccodes. Species-abundance findings of fungal root colonization in potato roots and molecular quantification (quantitative polymerase chain reaction) of C. coccodes and R. solani AG-3 inoculum growth in soil showed that: (i) C. coccodes is more competitive than R. solani AG-3 in colonizing potato root both in warm and cold spring regimes; (ii) R. solani AG-3 infected potato roots only in the coldest spring regimes regardless of soil moisture content; (iii) soil temperature is the greatest factor that influences root colonization of C. coccodes and R. solani as well as that of soil inhabiting fungi including some potential antagonists; (iv) R. solani AG-3 and C. coccodes seem to greatly increase in soil under the relative driest and warmest spring weather regimes expected according to the mean scenarios of climate changing in northern Italy; (v) binucleate Rhizoctonia AG-A, a common non-pathogenic fungus indigenous to agricultural soil of that area, appears to be antagonistic towards root fungal pathogens of potato.

Biased assessment of tillage impacts on soil organic carbon (SOC) sequestration are often associated with a lack of information on the initial level of SOC stocks. The present study reported the changes in SOC concentrations and stocks following 10-year different tillage practices relative to the initial SOC levels. The tillage trial included no tillage (NT), ridge tillage (RT) and mouldboard plough (MP) on a Black soil (Hapludolls) in Northeast China. Results showed that tillage, soil depth and time significantly affected SOC concentration and SOC stock. Tillage and crop residue retention had great impacts on the SOC concentrations in the top 0·1 m layer. Compared with MP and NT, RT resulted in higher SOC concentration and SOC stock in the plough layer (0–0·2 m), which became more obvious with time. The soil under NT and RT had higher stratification ratios (SR) of SOC (SR, the ratio of SOC concentration in 0–0·05 m to that in 0·1–0·2 m) than under MP. Significant positive and nearly identical linear relationships between the SR of SOC and the duration of tillage practices occurred for both NT and RT soils; the increased SR in NT resulted from both SOC increase in surface and SOC decrease in subsurface soils, but in RT, the increased SR was only from a substantial SOC increase in surface soil. Accordingly, the present study highlights that RT was more helpful than NT in carbon sequestration for the studied Black soil in Northeast China.

Effects of soil tillage systems and nitrogen (N) fertilizer management on spring wheat yield components, grain yield and N-use efficiency (NUE) were evaluated in contrasting weather of 2013 and 2014 on a clay soil at the Royal Agricultural University's Harnhill Manor Farm, Cirencester, UK. Three tillage systems – conventional plough tillage (CT), high intensity non-inversion tillage (HINiT) and low intensity non-inversion tillage (LINiT) for seedbed preparation – were compared at four rates of N fertilizer (0, 70, 140 and 210 kg N/ha). Responses to the effects of the management practices were strongly influenced by weather conditions and varied across seasons. Grain yields were similar between LINiT and CT in 2013, while CT produced higher yields in 2014. Nitrogen fertilization effects also varied across the years with no significant effects observed on grain yield in 2013, while in 2014 applications up to 140 kg N/ha increased yield. Grain protein ranged from 10·1 to 14·5% and increased with N rate in both years. Nitrogen-use efficiency ranged from 12·6 to 49·1 kg grain per kg N fertilizer and decreased as N fertilization rate increased in both years. There was no tillage effect on NUE in 2013, while in 2014 NUE under CT was similar to LINiT and higher than HINiT. The effect of tillage and N fertilization on soil moisture and soil mineral N (SMN) fluctuated across years. In 2013, LINiT showed significantly higher soil moisture than CT, while soil moisture did not differ between tillage systems in 2014. Conventional tillage had significantly higher SMN at harvest time in 2014, while no significant differences on SMN were observed between tillage systems in 2013. These results indicate that LINiT can be used to produce similar spring wheat yield to CT on this particular soil type, if a dry cropping season is expected. Crop response to N fertilization is limited when soil residual N is higher, while in conditions of lower residual SMN, a higher N supply is needed to increase yield and improve grain protein content.

Following the surface application of granulated urea to grassland, high ammonia (NH3) losses of up to 30% have been reported. The addition of a urease inhibitor (UI) to urea granules could be a way to abate these losses. Field experiments were conducted at two intensive grassland sites in 2007 and 2008 to evaluate the potential of the new UI N-(2-nitrophenyl) phosphoric triamide (2-NPT; concentrations of 0·75, 1·0 and 1·5 g N/kg) to reduce NH3 emissions resulting from the application of granulated urea. Ammonia losses were continuously measured on plots fertilized with urea, urea + 2-NPT, calcium ammonium nitrate and a control (0N). The measurements were made with a dynamic chamber system. All measurement periods were started after a period of precipitation with a following rainless period being forecasted. Results over measurement periods of 10 days following fertilization are presented. Ammonia losses following the application of granulated urea varied between 4·6 and 11·8 kg N/ha, corresponding to 4·2 up to 14·0% of the applied nitrogen. The addition of 2-NPT to urea granules at three concentrations significantly reduced NH3 losses by 69–100%. Comparable losses of NH3 were observed for urea containing the UI 2-NPT as well as calcium ammonium nitrate, and were not significantly different from the control treatment. No relationships between losses, meteorological factors and soil moisture were observed. The addition of the UI 2-NPT to urea granules applied on grassland effectively reduced NH3 losses.

Most acid sulphate soils (ASSs) in the Pearl River Delta of South China have been traditionally reclaimed for rice cultivation, but the rice yield in most of these paddy fields is lower than the average rice yield in China due to extremely high soil acidity. In the present study, a range of sulphate and acidity parameters were investigated in ASS profiles in three types of paddy fields in Taishan City (Guangdong Province, China) divided based on the local rice productivity (4500, 3000 and 1500 kg/ha) using an abandoned ASS (uncultivated) as the control treatment to ascertain key yield constraining parameters. Soluble acidity (SA), exchangeable acidity (ExA), soluble sulphate (SS) and net acid-soluble sulphate (NAS) increased with increasing soil depths from 0 to 100 cm and then decreased abruptly with further increases in the depth. However, the depth distribution of exchangeable sulphate (ES) was uniform. The soil acidity and sulphate contents differed significantly in three sampled paddy fields. The values of SA and SS in the soils at depths of 0–100 cm in the studied ASS were lower compared with those in the uncultivated ASS and the ExA in soils at depths of 0–40 cm in ASS were lower compared with those observed in the uncultivated ASS. A correlation analysis revealed that SA was strongly correlated with SS and ExA with NAS. Soluble acidity, ExA, SS and NAS in the ASS were significantly associated with rice yield. Exchangeable acidity in the plough layer (0–20 cm) of soils was the most sensitive indicator of soil quality affecting rice yield among those in soils from 0 to 140 cm depth. It is interesting to note that SA, SS and NAS were more sensitive indicators of soil quality affecting rice yield at 60–100 cm than at 0–40 cm depth. Principal component analysis showed that pH value, ExA and ES in soils at depths of 0–40 cm and SA, SS and NAS in soils at depths of 60–100 cm constituted the critical soil acidity and sulphate characteristics that were strongly correlated with rice yields. This finding implies that controlling the ExA in the plough layer and the SA and NAS in the Jarosite layer should be the major focus of studies aimed at the amelioration of ASSs.

An in vitro study was conducted to investigate the effects of condensed tannin (CT) structural properties, i.e. average polymer size (or mean degree of polymerization), percentage of cis flavan-3-ols and percentage of prodelphinidins in CT extracts on methane (CH4) production and fermentation characteristics. Condensed tannins were extracted from eight plants in order to obtain different CT types: blackcurrant leaves, goat willow leaves, goat willow twigs, pine bark, redcurrant leaves, sainfoin plants, weeping willow catkins and white clover flowers. They were analysed for CT content and CT composition by thiolytic degradation, followed by high performance liquid chromatography (HPLC) analysis. Grass silage was used as a control substrate. Condensed tannins were added to the substrate at a concentration of 40 g/kg, with or without polyethylene glycol (+ or −PEG 6000 treatment) to inactivate tannins, then incubated for 72 h in mixed buffered rumen fluid from three different lactating dairy cows per run. Total cumulative gas production (GP) was measured by an automated GP system. During the incubation, 12 gas samples (10 µl) were collected from each bottle headspace at 0, 2, 4, 6, 8, 12, 24, 30, 36, 48, 56 and 72 h of incubation and analysed for CH4. A modified Michaelis-Menten model was fitted to the CH4 concentration patterns and model estimates were used to calculate total cumulative CH4 production (GPCH4). Total cumulative GP and GPCH4 curves were fitted using biphasic and monophasic modified Michaelis-Menten models, respectively. Addition of PEG increased GP, GPCH4, and CH4 concentration compared with the −PEG treatment. All CT types reduced GPCH4 and CH4 concentration. All CT increased the half time of GP and GPCH4. Moreover, all CT decreased the maximum rate of fermentation for GPCH4 and rate of substrate degradation. The correlation between CT structure and GPCH4 and fermentation characteristics showed that the proportion of prodelphinidins within CT had the largest effect on fermentation characteristics, followed by average polymer size and percentage of cis flavan-3-ols.

The effect of feeding two levels of Saccharomyces cerevisiae on the performance of crossbred Friesian calves was investigated. Twenty-four neonatal male Friesian × Baladi calves (35·5 ± 0·25 kg of initial body weight) were randomly assigned in a completely randomized design into three experimental groups for 90 days (eight calves per group). Calves fed their diets without yeast (S. cerevisiae) were considered as Control, while the diets of other calves were supplemented daily either with 2·5 g (YL diet) or with 5 g (YH diet) of yeast per calf. Calves fed the YH diet showed increased feed intake, while dry matter and fibre digestibilities were increased in calves fed YH and YL diets. Calves fed YL and YH diets showed lower ruminal ammonia-N and higher total volatile fatty acids, acetate and propionate concentrations than Control calves. Both YH and YL calves showed increased plasma concentrations of total protein, globulin and glucose and decreased cholesterol and triglycerides concentrations. Calves’ final weight and daily gain were increased with S. cerevisiae yeast supplemented diets. After 42 days of experiment, Clostridium spp., Escherichia coli and Enterobacteria spp. counts were down to undetectable levels in the faeces of calves fed S. cerevisiae additive. It could be concluded that adding S. cerevisiae to milk-fed calves increased feed utilization and improved pre-weaned calf performance and health status, reducing faecal pathogenic bacteria.

The objective of the present study was to evaluate the effects of isovalerate supplementation on growth performance and ruminal fermentation in pre- and post-weaning dairy calves. Forty-eight Chinese Holstein male calves at 15 days of age and 45·1 ± 0·36 kg body weight (BW) were assigned randomly to four groups. The treatments were: control, low-isovalerate, moderate-isovalerate (MIV) and high-isovalerate (HIV) with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. Isovalerate was hand-mixed into milk in pre-weaning calves and the concentrate portion in post-weaning calves. The study lasted 75 days, including a 15-day adaptation period followed by a 60-day sampling period. Weaning was conducted when calves were 60 days old. Six calves were chosen from each treatment at random and slaughtered at 30 and 90 days of age. Average daily weight gain increased linearly whether during pre-weaning or post-weaning period with increasing isovalerate supplementation. Dry matter intake linearly increased at 90 days of age with increasing isovalerate supplementation. During weaning, ruminal pH and ammonia nitrogen (N) decreased linearly, whereas total ruminal volatile fatty acid concentration increased linearly with increasing isovalerate supplementation. The ratio of acetate to propionate increased linearly with increasing isovalerate supplementation due to increased acetate concentration and the unchanged propionate concentration. Activities of caboxymethyl-cellulase, cellobiase, xylanase and pectinase linearly increased at 90 days of age, α-amylase and β-amylase activities linearly increased at 30 and 90 days of age. Relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Fibrobacter succinogenes and Ruminococcus flavefaciens increased linearly with increasing isovalerate supplementation. Ruminal fermentation, enzyme activities and cellulolytic bacteria were higher for HIV and MIV than for the control. The present results indicate that isovalerate accelerated growth of calves by improving ruminal fermentation, microbial enzyme activities and cellulolytic bacteria growth during weaning. In the experimental conditions of the current trial, the optimum isovalerate dose was about 6·0 g isovalerate per calf per day.