The results from three types of study with broilers, namely nitrogen (N) balance, bioassays and growth experiments, provided the data used herein. Sets of data on N balance and protein accretion (bioassay studies) were used to assess the ability of the monomolecular equation to describe the relationship between (i) N balance and amino acid (AA) intake and (ii) protein accretion and AA intake. The model estimated the levels of isoleucine, lysine, valine, threonine, methionine, total sulphur AAs and tryptophan resulting in zero balance to be 58, 59, 80, 96, 23, 85 and 32 mg/kg live weight (LW)/day, respectively. These estimates show good agreement with those obtained in previous studies. For the growth experiments, four models, specifically re-parameterized for analysing energy balance data, were evaluated for their ability to determine crude protein (CP) intake at maintenance and efficiency of utilization of CP intake for producing gain. They were: a straight line, two equations representing diminishing returns behaviour (monomolecular and rectangular hyperbola) and one equation describing smooth sigmoidal behaviour with a fixed point of inflexion (Gompertz). The estimates of CP requirement for maintenance and efficiency of utilization of CP intake for producing gain varied from 5·4 to 5·9 g/kg LW/day and 0·60 to 0·76, respectively, depending on the models.

During spring, perennial ryegrass tillers change from vegetative to reproductive growth in response to photoperiod and undergo irreversible morphological changes. The effect of latitude and meteorological factors on the timing of reproductive initiation and ear emergence (EE) were measured in the field on 40 vernalized spaced plants for each of eight cultivars. The measurements were made at two latitudes in Ireland (Moorepark 52°N, Crossnacreevy 54°N). There was a significant effect of site and cultivar on all the variables measured. Cultivar initiation responded to a specific photoperiod but detection through apical development incurred a small variation due to growing conditions affecting the time taken for a visible change in apical morphology to occur. When converted from photoperiod to initiation date this variance was minimal (±6 min). Timing of EE was dependent on growing conditions not photoperiod and so was specific to the studied conditions. As cultivar rank order for EE date was largely retained, there was a very strong correlation with published UK Plant Breeders Rights (PBR) heading dates for these cultivars, which in turn had a strong relationship with the ear initiation (EI) dates (R2=0·95). The latter relationship was sufficiently robust to allow estimation of photoperiod for any cultivar on the EU Common Catalogue based on its published heading date from Crossnacreevy, where the UK PBR trials are conducted. As photoperiod can be converted to calendar date by reference to latitude, this relationship can also be used to estimate the EI date for sites at latitudes other than those in the current study.

The effects of various gibberellin-insensitive semi-dwarfing (Rht) alleles and background genotypes on the growth response of wheat seedlings to simulated low water potential were investigated. Four sets of near-isogenic lines, each consisting of six members (Rht-B1a+Rht-D1a (rht), Rht-B1b, Rht-B1c, Rht-D1b, Rht-B1b+Rht-D1b and Rht-B1c+Rht-D1b), and one set of five members (rht, Rht-B1b, Rht-B1c, Rht-B1d and Rht-D1b) were germinated in the presence of polyethylene glycol (PEG). The growth responses were assessed by measuring the lengths of the longest root, coleoptile and longest leaf (shoot) and calculating the root length:shoot length ratio and a tolerance index (TI). Seedling growth was significantly affected by the allelic status at the Rht loci, background genes and the water potential. The PEG treatment had major effects on root and shoot growth. Coleoptile growth was mainly affected by the Rht alleles. There were significant interactions of the Rht allele and variety on the growth response to low water potential. Genotypes with longer roots, coleoptiles and shoots when grown in water, as determined by the Rht allelic status (rht, Rht-B1b and Rht-D1b) and varietal background, had the highest TI and maintained this advantage under stress, while genotypes with smaller seedlings (Rht-B1c and Rht-B1c+Rht-D1b) when grown in water were more strongly affected.

Previous work has shown that the national average quality of the UK wheat crop from 1974 to 1999 was associated with the preceding winter North Atlantic Oscillation (NAO). The association of the winter NAO with the grain quality measure, specific weight, was shown to be mediated by sunshine duration during grain filling and unconditional wet day probability during grain ripening (the probability of a wet day following either a dry or a wet day). The present study tests the hypothesis that the association between specific weight and the winter NAO can be detected in data from 158 years of the Broadbalk Wheat Experiment at Rothamsted in south-east England. Specific weight from the Broadbalk Experiment responded to sunshine duration during grain filling and unconditional wet day probability during grain ripening in a similar way to the national average data. An association with the winter NAO was found in the Broadbalk data from 1956 to 2001, but not in the previous 112 years (1844–1955). This finding is consistent with other work showing significant correlations between the winter NAO and summer climate only in recent decades. It is concluded that the association between wheat quality and the NAO is a recent phenomenon.

Field experiments were conducted between 2003 and 2005 to compare the efficacy of five interactive decision support systems (DSSs) (DESSAC, PLANT-Plus, proPLANT Expert, CerDis and Crop Protection Online (CPO)) and an in-crop system (Septoria Timer) to schedule fungicide applications to winter wheat cultivars (Madrigal and Claire) for the control of Mycosphaerella graminicola. The effectiveness of the crop management programmes proposed by the DSSs was compared with that of standard 2-spray programmes applied at GS 37 and 65 and 3-spray programmes applied at GS 32, 39 and 65. Compared with the 3-spray programme, the programme scheduled by CPO advised application of the least active ingredient to the six trials over three seasons, while together with the Septoria Timer it also advised the least number of applications (average 2·3 per crop). The PLANT-Plus system advised the highest input of active ingredient and the highest number of applications (average of 4·0 per crop). The interactive DSSs responded to cultivar susceptibility to M. graminicola by scheduling more applications to the susceptible cv. Madrigal compared with the moderately resistant cv. Claire. Whether control of M. graminicola is expressed as reduction in the proportion of necrosis per leaf or a reduction of the area under the disease progress curve, the 3-spray programme provided the most effective control. The Septoria Timer provided a similar level of control. For the remaining programmes, the effectiveness of control varied with observation date, leaf and cultivar. The 2-spray programme provided the least successful control. Fungicide application significantly increased grain yield each season. The fungicide scheduling programme that provided the highest grain yield varied by cultivar and season. Grain specific weight was enhanced by fungicide application compared with the untreated control, except for cv. Claire in 2004. The fungicide scheduling programme that provided the highest specific weight varied with cultivar and season. The highest average margin over fungicide cost was provided by the Septoria Timer.

The use of secondary traits such as number of ears per plant, grains per ear, the interval from anthesis to silking, leaf senescence and leaf rolling, together with management of water stress and recurrent selection, have permitted a considerable increase in drought tolerance in the CIMMYT maize source germplasm populations Drought Tolerant Population (DTP) and La Posta Sequía (LPS). Inbred lines were extracted from DTP C9 and LPS C7 cycles and then used for generating single and three-ways hybrids. These were evaluated under normal irrigation and managed drought conditions. A weak, and in some cases no longer significant, correlation was found between grain yield and the traits initially used for selection. Most prominently, the relationship between anthesis-silking interval and grain yield became much weaker in these hybrids. Conversely, significant negative correlations were found between tassel dry weight and grain yield. Three-way hybrids involving two DTP lines yielded more than those involving one only, indicating the feasibility of gene pyramiding for drought tolerance. Overall, the results suggested that the relationship between grain yield and secondary traits has been modified due to continuous selection in the LPS and DTP populations. Some long-established secondary traits have become less important, while others have become more relevant. Mean grain weight, previously not used within a drought selection index, was strongly correlated with yield in the present study. The importance of traits related to the availability in C products for the development of ears and grains are discussed. The results indicate that the traits of source organs contribute marginally to drought tolerance; variation of leaf or root traits seems to be less important than variation in tassel parameters for increasing drought tolerance. For ensuring further progress in drought tolerance in maize, the solution might reside in the manipulation of sink organs. It is therefore suggested that selection for even greater number of ears, bigger grains and smaller tassels may help to increase grain yield under water limited environments in the near future. A short discussion on the optimal choice of parental lines for developing hybrids with maximum expression of drought tolerance concludes the paper.

The increase of ultraviolet (UV-B) radiation could be a challenge for wheat production systems in Southern Chile, as in other areas. Previous reports have shown that increased UV-B radiation decreases wheat yield by affecting both grain number and grain weight. However, contrasting results have also been published showing no effect on wheat biomass and grain yield. In addition, little is known about the effect of higher UV-B radiation at particular periods of the crop cycle on grain quality traits. The objective of the present study was to evaluate grain yield, yield components and grain quality in response to increased UV-B radiation during key periods of yield component determination. Two experiments were carried out under field conditions in the Universidad Austral de Chile (latitude 39°62′S). Two spring wheat cultivars were exposed to two periods of supplemented UV-B radiation (280–320 nm): (i) between booting and anthesis, c. 20 days, and (ii) from 10 days after anthesis until physiological maturity, c. 40 days. Ultraviolet radiation was increased to levels of 3·8 and 4·9 kJ/m2/day in experimental years 1 and 2, respectively, by using UV-B lamps. At harvest, plants were sampled to quantify aboveground biomass, grain yield, grain number and average grain weight. In addition, protein and gluten concentration of grains were measured. Grain yield was not affected (P>0·05) by the UV-B increase at pre- or at post-anthesis treatments. Similar results were found for each yield component. In addition, grain protein and gluten concentration showed similar values in the increased UV-B and control treatments. Therefore, if increases in UV-B radiation take place during the latter stages of the crop cycle as is expected, the present results do not support the speculation that increases of UV-B radiation in Southern Chile will compromise wheat production systems.

Seed composition in soybean [Glycine max (L) Merr.] has not been well investigated under charcoal rot infestation under irrigated and non-irrigated conditions. The objective of the present experiment was to assess seed composition and nitrogen fixation under these conditions. No significant differences in protein levels in the moderately resistant germplasm line DT97-4290 were observed under these conditions. Under irrigation, protein concentration was significantly (P⩽0·05) higher for the susceptible cultivars Egyptian and Pharaoh under non-infested than infested conditions. The opposite response for protein was observed under non-irrigated conditions for Pharaoh. Oleic acid concentration was significantly (P⩽0·001) higher in susceptible cultivars under infested conditions. The concentration of linolenic acid in susceptible cultivars was significantly lower under infested conditions. The enrichment of Delta 15N in susceptible cultivars under infested conditions indicated that nitrogen fixation was substantially inhibited, but soil nitrogen was used for compensating for atmospheric nitrogen inhibition. These results indicate that charcoal rot infection may alter seed composition and nitrogen fixation in soybean. The alteration in seed composition depended on cultivar susceptibility to charcoal rot and irrigation management.

Hard endosperm maize (Zea mays L.) is useful for industry and for human consumption. The objective of the present work was to study the inheritance of quality traits in hard endosperm maize. Three flint and three dent inbreds, F1 of their diallel crosses, F2s and backcrosses to each parent were evaluated for grain yield and quality traits (flotation test, flour-milling test, grain damage (GD) index and grain density). Genotypes and genotype×environment interactions were significant for most traits. A genetic model including additive, dominance and epistatic effects explained most of the genetic variation for the traits. Additive effect mean squares were larger than those due to dominance effects, except for grain yield and GD. Partition of the dominance variance into average, general, and specific dominance components revealed that the average dominance related to heterosis was the most important. Additive×additive epistatic variation was smaller than additive and dominance variation for quality traits. Some inbreds displayed sufficient potential to be used in hard endosperm maize breeding programmes. The average dominance effect was favourable for most of the quality and agronomic traits. Breeding programmes for improving quality in hard endosperm maize would be most efficient if both additive and dominant effects are capitalized on.

The Cornell-Penn-Miner (CPM) Dairy is an applied mathematical nutrition model that computes dairy cattle requirements and the supply of energy and nutrients based on characteristics of the animal, the environment and the physicochemical composition of the feeds under diverse production scenarios. The CPM Dairy was designed as a steady-state model to use rates of degradation of feed carbohydrate and protein and the rate of passage to estimate the extent of ruminal fermentation, microbial growth, and intestinal digestibility of carbohydrate and protein fractions in computing energy and protein post-rumen absorption, and the supply of metabolizable energy and protein to the animal. The CPM Dairy version 3.0 (CPM Dairy 3.0) includes an expanded carbohydrate fractionation scheme to facilitate the characterization of individual feeds and a sub-model to predict ruminal metabolism and intestinal absorption of long chain fatty acids. The CPM Dairy includes a non-linear optimization algorithm that allows for least-cost formulation of diets while meeting animal performance, feed availability and environmental restrictions of modern dairy cattle production. When the CPM Dairy 3.0 was evaluated with data of 228 individual lactating dairy cows containing appropriate information including observed dry matter intake, the linear regression between observed and model-predicted milk production values indicated the model was able to account for 79·8% of the variation. The concordance correlation coefficient (CCC) was high (rc=0·89) without a significant mean bias (0·52 kg/d; P=0·12). The accuracy estimated by the CCC was 0·997. The root of mean square error of prediction (MSEP) was 5·14 kg/d (0·16 of the observed mean) and 87·3% of the MSEP was due to random errors, suggesting little systematic bias in predicting milk production of high-producing dairy cattle. Based upon these evaluations, it was concluded the CPM Dairy 3.0 model adequately predicts milk production at the farm level when appropriate animal characterization, feed composition and feed intake are provided; however, further improvements are needed to account for individual animal variation.

The potassium (K) and sodium (Na) requirements of sugar beet were re-examined in a 6-year series of experiments between 2000 and 2005 using reference plots with a wide range of long-established differences in exchangeable topsoil K (Kex). Two groups of plots with a topsoil concentration Kex range of 40–550 mg/kg were used, each situated within an individual field, one on a silty clay loam at Rothamsted and the other on a contrasting sandy loam at Woburn. The interactions between topsoil Kex and applied N, K and Na fertilizers were studied at Rothamsted. Under these well-defined conditions, maximum yields of 55–71 t/ha of adjusted clean beet were achieved with a topsoil Kex concentration of 120–150 mg/kg, i.e. at Soil K Index 2–, with a small difference between the two soils being accounted for by differences in exchangeable soil Na and subsoil Kex. There were no yield responses to freshly applied fertilizer K, even on low K plots where responses might be expected. It is concluded that the existing recommendations for K fertilizer use on UK sugar beet do not need to be adjusted to allow for the higher yields of modern crops.

There were no yield responses to NaCl fertilizer at any level of topsoil Kex at Rothamsted (where the soil contained 15–20 mg Na/kg), but yields were increased on low Kex plots at Woburn whose sandy loam contained only 5–10 mg Na/kg. The uptake of Na from the applied NaCl fertilizer was strongly influenced by the exchangeable K and Na status of the soil. On the low Na soil at Woburn, almost all of the applied Na was taken up by sugar beet grown on plots with low concentrations of topsoil Kex and half of it on plots with adequate concentrations of topsoil Kex compared with two-thirds and one-fifth, respectively, on the higher Na-content soil at Rothamsted.

Plants partitioned 0·75 of their K and 0·95 of their Na to the shoot and the balance to the storage root. This pattern of distribution was consistent across sites, seasons and soil K supply. The physiological interactions between K and Na were studied by examining their millimolar concentrations in the tissue-water (mmol/kg) of the shoots and storage roots. The tissue-water concentrations of K in the shoot increased asymptotically with the concentration of Kex in the topsoil, and the increase in K concentration was accompanied by a corresponding decrease in the tissue-water concentration of Na. Maximum concentrations of K in shoot tissue-water (and minimum concentrations of Na) were achieved when the topsoil contained a minimum of 200 mg Kex/kg. The optimal physiological tissue-water concentration of Na in shoots was estimated to be c. 90–100 mmol/kg; maintenance of this level required a minimum of 25 mg/kg of exchangeable Na in the topsoil. When not limited by soil Kex, plants maintained a total tissue-water concentration of c. 300–350 mmol/kg of K+Na within the shoot. This was achieved with 80 mmol of Na and 230 mmol of K/kg of tissue water on the high Na-content soil at Rothamsted, and with 40 mmol of Na and 275 mmol of K/kg tissue water on the low-Na soil at Woburn.

Significant correlations were established between measurements of beet K made in the factory tarehouse and those made using standard laboratory chemical analyses and between factory estimates of the concentrations of K in the tissue-water of delivered beet and the topsoil Kex. The uses of these relationships to estimate the off-takes of K in the harvested beet and provide feedback to growers on the K status of their soils, and the implications of the study for the use of K and Na fertilizers on UK sugar beet are discussed.

Cultivated tomato has a narrow germplasm base because of several population bottlenecks in the form of founder events, as well as natural and artificial selections that occurred during domestication and evolution of modern cultivars. The F2 of commercial single-cross hybrids, as well as locally well-adapted varieties, provide germplasm for developing recombinant lines and exploiting genetic variability, respectively. The present study aims to discriminate the breeding value of tomato source material, i.e. commercial hybrids or well-adapted varieties, by (i) estimating tolerance to inbreeding of hybrids or estimating heterosis of diallel hybrids between varieties, (ii) determining undesirable traits and (iii) determining general combining ability (GCA) and specific combining ability (SCA) effects from diallel crosses between hybrids and between varieties. Two hybrids and four varieties were assessed. One hybrid showed 0·03 inbreeding vigour, which was not combined with undesirable traits in the F2 generation. However, negative GCA and positive SCA values did not support the hybrid as source material, provided that hybrids with low inbreeding depression, positive GCA and negative SCA correspond to an F2 capable of developing recombinant lines. The assessment of the varieties showed positive GCA and 0·34 heterosis in one variety, indicating agreement between yield and GCA, and that high-yielding varieties may produce high-yielding hybrids. In conclusion, the proposed mating design, taking into account the tolerance to inbreeding for hybrids and the heritability of general worth for both resources, provides a mechanism for ensuring continued improvement in plant performance through plant selection programmes.

A deterministic model for the spread of an important animal disease, bovine spongiform encephalopathy (BSE), is described. It is a sparse three-pool model, the pools corresponding to susceptible, infected and sick animals. Simulations illustrate the biological meaning of the parameters, and pinpoint how parameters affect epidemic characteristics: infectivity impacts on the leading edge of the epidemic and its intensity. The times when infection is introduced and when control is exercised determine the length and possibly the intensity of the epidemic. Finally, the (single) incubation rate influences the trailing edge of the epidemic. It is applied to data describing the recent UK BSE outbreak, with reasonable success. Apart from a scaling factor, only these four quantities were adjusted to achieve this. The contributions from greater modelling complexity are discussed. It is concluded that the simple model is well suited for grasping the essentials, whereas further detail is needed for a more mechanistic representation, in particular concerning incubation delays in developing infectiousness and clinical sickness.

Genetic manipulation of leaf architecture may be a useful breeding objective in cotton (Gossypium spp.). The present study reports quantitative genetic analysis of leaf traits from two intraspecific crosses of inbred lines in upland cotton (Gossypium hirsutum L.) viz. Kang3×Chaoji463 and Han109×Ji98. Six leaf morphological traits (leaf area (LA), leaf perimeter (LP), main lobe length (LL) and width (LW), petiole length (PL), and main LL/LW ratio) were recorded from multiple generations (P1, F1, P2, BC1, BC2, and F2) in the two crosses. Generation mean analyses were conducted to explain the inheritance of each leaf morphological trait. The six-parameter model showed a better fit to an additive-dominance model for LA, main LW, PL, and main LL/LW ratio in the two crosses, suggesting the relative importance of epistatic effects controlling leaf morphology. A simple additive-dominance model accounted for the genetic variation of the main LL in the Kang3×Chaoji463 cross. Different models were selected as appropriate to explain LP in the two crosses. The differences between broad- and narrow-sense heritability values for the same trait were not constant in the two crosses. The estimated minimum number of genes controlling each leaf morphological trait ranged from 0 to 2 for both the crosses. Moreover, the sums of the minimum number of genes controlling leaf morphology were 6 and 2 in the Kang3×Chaoji463 and Han109×Ji98 populations, respectively. Most data suggested that there existed a substantial opportunity to breed cottons that transgress the present range of leaf phenotypes found.

The transition from conventional to organic farming is accompanied by changes in soil chemical properties and processes that could affect soil fertility. The organic system is very complex and the present work carries out a short-term comparison of the effects of organic and conventional agriculture on the chemical properties of a silty loam soil (Xerofluvent) located in the Guadalquivir River Valley, Seville, Spain, through a succession of five crop cycles over a 3-year period. Crop rotation and varieties were compared in a conventional system using inorganic fertilizer and two organic systems using either plant compost or manure. At the end of the study, organic farming management resulted in higher soil organic carbon (OC), N and available P, K, Fe and Zn. The available Mn and especially Cu values did not show significant differences. In general, treatment with manure resulted in more rapid increases in soil nutrient values than did plant compost, which had an effect on several crop cycles later. The present study demonstrated that the use of organic composts results in an increase in OC and the storage of nutrients, which can provide long-term fertility benefits. Nevertheless, at least 2–3 years of organic management are necessary, depending on compost characteristics, to observe significant differences. Average crop yields were 23% lower in organic crops. Nevertheless, only two crops showed statistically significant differences.

Remotely sensed estimates of biochemical parameters of agricultural crops are central to the precision management of agricultural crops (precision farming). Past research using in situ and airborne spectral reflectance measurements of various vegetation species has proved the usefulness of hyperspectral data for the estimation of various biochemical parameters of vegetation. In order to exploit the vast spectral and radiometric resources offered by space-borne hyperspectral remote sensing for the improved estimation of plant biochemical parameters, the relationships observed between spectral reflectance and various biochemical parameters at in situ and airborne levels needed to be evaluated in order to establish the existence of a reliable and stable relationship between spectral reflectance and plant biochemical parameters at the pixel scale. The potential of the EO-1 Hyperion hyperspectral sensor was investigated for the estimation of total chlorophyll and nitrogen concentrations of cotton crops in India by developing regression models between hyperspectral reflectance and laboratory measurements of leaf total chlorophyll and nitrogen concentrations. A comprehensive and rigorous analysis was carried out to identify the spectral bands and spectral indices for accurate retrieval of leaf total chlorophyll and nitrogen concentrations of cotton crop. The performance of these critical spectral reflectance indices was validated using independent samples. A new vegetation index, named the plant biochemical index (PBI), is proposed for improved estimation of the plant biochemicals from space-borne hyperspectral data; it is simply the ratio of reflectance at 810 and 560 nm. Further, the applicability of PBI to a different crop and at a different geographical location was also assessed. The present results suggest the use of space-borne hyperspectral data for accurate retrieval of leaf total chlorophyll and nitrogen concentrations and the proposed PBI has the potential to retrieve leaf total chlorophyll and nitrogen concentrations of various crops and at different geographical locations.

Information on the interactions between genotypes and environments for physiological traits of peanut (Arachis hypogaea L.) is limited. The objective of the present study was to evaluate the effects of seasons and genotype×season (G×S) interactions for dynamic growth and development traits of peanut. Fifteen peanut lines varying in maturity duration, seed type and yield level were grown in a field experiment at the Khon Kaen University in Northeast Thailand during the 2002 and 2003 rainy seasons and the 2003 and 2004 dry seasons. Data were recorded on phenological development stages, pod yield and final biomass, and leaf area index (LAI), crop growth rate (CGR), pod growth rate (PGR), partitioning coefficient (PC), pod harvest index (HI), shelling percentage, and specific leaf area (SLA) were determined. Seasonal effects were found for all development and growth traits of the test peanut lines. Crop duration for the dry season was much longer than for the rainy season because of low temperatures during the early growth stage, causing a delay in flowering and a longer period of pod formation. The test peanut lines showed small differences in the duration of vegetative development and pod formation, but varied greatly in the seed filling duration. This period also showed the greatest differential responses to seasons between the peanut genotypes. Crop yields for the 2003 rainy and the 2004 dry seasons were much lower than for the other two seasons because of late leaf spot disease in the 2003 rainy season and cool temperatures at flowering in the 2004 dry season, resulting in poor pod setting, low PGR and low HI. The test peanut lines differed considerably in pod and biomass yields and all the growth traits measured. Significant G×S interactions were also found for all of these traits, though were much smaller than season effect. Regression analyses identified PGR as the dominant physiological trait determining the G×S interaction for pod yield. Exploring marker-assisted selection for this trait is suggested.

Genotype by environment (G×E) interaction effects are of special interest for breeding programmes to identify adaptation targets and test locations. Their assessment by additive main effect and multiplicative interaction (AMMI) model analysis is currently defined for this situation. A combined analysis of two former parametric measures and seven AMMI stability statistics was undertaken to assess G×E interactions and stability analysis to identify stable genotypes of 11 lentil genotypes across 20 environments. G×E interaction introduces inconsistency in the relative rating of genotypes across environments and plays a key role in formulating strategies for crop improvement. The combined analysis of variance for environments (E), genotypes (G) and G×E interaction was highly significant (P<0·01), suggesting differential responses of the genotypes and the need for stability analysis. The parametric stability measures of environmental variance showed that genotype ILL 6037 was the most stable genotype, whereas the priority index measure indicated genotype FLIP 82-1L to be the most stable genotype. The first seven principal component (PC) axes (PC1–PC7) were significant (P<0·01), but the first two PC axes cumulatively accounted for 71% of the total G×E interaction. In contrast, the AMMI stability statistics suggested different genotypes to be the most stable. Most of the AMMI stability statistics showed biological stability, but the SIPCF statistics of AMMI model had agronomical concept stability. The AMMI stability value (ASV) identified genotype FLIP 92-12L as a more stable genotype, which also had high mean performance. Such an outcome could be regularly employed in the future to delineate predictive, more rigorous recommendation strategies as well as to help define stability concepts for recommendations for lentil and other crops in the Middle East and other areas of the world.

In northwest (NW) Europe, oilseed rape (OSR) is often used as a preceding crop for winter wheat. Due to its low N harvest index (HI) and to favourable soil conditions after harvest, large amounts of mineral N remain in the soil, which cannot completely be taken up by the subsequent wheat crop. This increases the risk of N leaching into the groundwater during the following winter. Recently, semi-dwarf genotypes of OSR were developed and made commercially available that show similar yields but reduced height growth compared to conventional genotypes. The present authors hypothesized that the introduction of dwarfing genes leads to an increase in HI for dry matter (DM) and for N of OSR. As a consequence, semi-dwarf genotypes would accumulate less aerial biomass, return fewer plant residues to the soil and need less N to achieve yield maximum compared to conventional hybrids or open pollinating varieties. This may lead to a reduced risk of N leaching after growing OSR. In order to test this hypothesis, field trials conducted in 2003/04–2005/06 near Kiel in NW Germany combined four commercial varieties of OSR (Express, Talent, Trabant and Belcanto as semi-dwarf genotype), two seeding dates (mid-August and beginning of September) and eight mineral N fertilization rates (0–240 kg N/ha). On average in 2003/04–2004/05, the semi-dwarf genotype Belcanto achieved significantly less seed yield (4·44 t/ha) than the other varieties (4·65–4·88 t/ha). However, all varieties tested required similar N fertilization to achieve maximum yield. In addition, N offtake by the seeds did not differ. No interaction between genotype and N treatment was observed. Detailed analysis of DM accumulation and N uptake during the growth period revealed only small differences between the varieties in the averages of all N treatments and both years. At harvest, Belcanto produced more pods/m2 and a slightly higher 1000 seed weight. Nevertheless, HI and N HI were similar for all genotypes. It is concluded that, despite its lower plant height, the semi-dwarf genotype did not provide the opportunity to reduce the risk of N leaching after growing OSR.

Pearl millet [Pennisetum glaucum (L) R. Br.] is an important cereal crop in Niger, West Africa and a potential crop for the United States of America (USA). Only a few studies have been conducted in either country to identify the optimum planting dates for high and stable yields, in part because planting date experiments are resource-intensive. Crop simulation models can be an alternative research tool for determining optimum planting dates and other management practices. The objectives of the present study were to evaluate the performance of the Cropping System Simulation Model (CSM)–CERES-Millet model for two contrasting environments, including Mead, Nebraska, USA and Kollo, Niger, West Africa and to use the model for determining the optimum planting dates for these two environments. Field experiments were conducted in both environments to study the impact of nitrogen fertilizer on grain yield of three varieties in Kollo and three hybrids in Mead and their associated growth and development characteristics. The CSM–CERES-Millet model was able to accurately simulate growth, development and yield for millet grown in these two contrasting environments and under different management practices that included several genotypes and different nitrogen fertilizer application rates. For Kollo, the optimum planting date to obtain the maximum yield was between 13 and 23 May for variety Heini Kirei, while for the other varieties the planting dates were between 23 May and 2 June. For Mead, the planting date analysis showed that the highest simulated yield was obtained, on average, between 19 and 29 June for hybrid 59022A×89-083 and 1361M×6Rm. Further studies should focus on evaluation and application of the millet model for other agroclimatic regions where pearl millet is an important crop.