Determination of wheat bug (Eurygaster spp.) damage in durum wheat (Triticum durum L.) by electrophoresis and rapid visco analyser

The degradation effects of wheat bug protease(s) on glutenin proteins of durum wheat cultivars were investigated by electrophoresis and modified rapid visco analyser (RVA) test. Glutenin patterns of the bug damaged durum wheats changed substantially due to bug protease(s). Although high molecular weight glutenin subunits (HMW-GS) of three cultivars (Ege, Svevo, and Zenith) disappeared after 60 min of incubation, the HMW-GS of other two cultivars (Diyarbakir and Firat) were still visible even after the longest incubation period at medium damage level. It shows that there was an intercultivar variation in susceptibility to hydrolysis by bug proteolytic enzymes. Low molecular weight glutenin subunits of all cultivars decreased substantially after 30 min of incubation. The RVA curves indicated a clear reduction in viscosity in semolina samples with both medium and high damage levels as compared to their respective undamaged (control) samples. There were significant correlations (p < 0.001) between bug damage level and viscosities at 3 min (r = −0.765), at 4.5 min (r = −0.549) and at 10 min (r = −0.835), breakdown value (r = −0.534) and decay rate (r = 0.600). Consequently, hydrolysis rate of wheat bug protease(s) can be determined by modified RVA technique without much more chemicals, procedures and expensive equipments.     

Barley (1→3; 1→4)-β-glucan and arabinoxylan content are related to kernel hardness and water uptake

Harder kernels in barley are thought to be a factor affecting the modification of the endosperm during malting by restricting water and enzyme movement within the endosperm. The objective of this study was to investigate the relationship between kernel hardness, water uptake and the endosperm composition in barley. A range of barley samples from 2003 and 2004 crops were analyzed for kernel hardness by the Single Kernel Characterization System, water uptake during steeping and chemical composition of the endosperm including (1→3; 1→4)-β-glucan, arabinoxylan and total protein. Both (1→3; 1→4)-β-glucan and arabinoxylan content of the endosperm were correlated significantly with kernel hardness in barley samples from both 2003 (r=0.873 and 0.601, respectively, p<0.01) and 2004 seasons (r=0.764 and 0.501, respectively, p<0.01). Hardness of the kernel was highly correlated with its water uptake in both 2003 and 2004 samples (r=−0.853 and −0.752, respectively, p<0.01). β-Glucan content of the endosperm was also correlated significantly with the kernel water uptake for both years (2003: r=−0.752, p<0.01; 2004: r=−0.551, p<0.01). Arabinoxylan content of the endosperm was correlated significantly with the kernel water uptake for the 2003 barley but not for 2004 barley (2003: r=−0.523, p<0.01; 2004: r=−0.151, p>0.01). Protein content of the endosperm was not correlated with the kernel hardness in either year. These results demonstrate that endosperm cell wall components may have significant impact on kernel hardness as well as water uptake of barley.     

Potato Late Blight and Tuber Yield: Results from 30 Years of Field Trials

During 1983–2012, three field trials per year were performed in each of the three southernmost counties in Sweden to test different fungicide programmes aiming to control late blight, primarily in the very susceptible potato cultivar Bintje. A dataset with results from these field trials was used (i) to examine possible changes in the appearance and behaviour of late blight attack over the years, (ii) to investigate the relationship between late blight in foliage and tuber blight, (iii) to investigate the relationship between late blight and tuber yield and (iv) to identify any correlations between different variables in the dataset. Late blight reached epidemic proportions, i.e. 75% disease severity in the untreated control, in the majority of the field trials. The estimated first attack of late blight was earlier in many field trials after 1998. Differences between years and regions were great in terms of date of the first attack and how the attack developed during the season. For example, in 2002–2005 and 2007, the first attack occurred 40–55 days after planting (DAP), compared with 95–108 DAP in 1994 and 1996. In 1994, 2006 and 2009–2011, the attacks increased from first symptoms to 65% disease severity in the untreated control within 16–21 days, compared with 35–40 days in 1995, 1999 and 2002. The relationship between foliage late blight and tuber blight was weak with the best match found at high disease severity late in the growing season (r?=?0.33; p?<?0.001). The relationship between blight-free tuber yield and start of the first attack indicated a yield increase of 287 kg/day (R ²?=?0.27) for every day’s delay in first attack. Using the DAP for 65% disease severity in the untreated control improved the correlation (R ²?=?0.64) and indicated a yield increase of 534 kg/day for every day’s delay in first attack. The later the onset of attack, the higher the blight-free tuber yield in treated plots. In general, significant correlations were found between blight-free tuber yield, size fractions of tuber yield, date of first late blight attack, date of different degrees of disease severity, disease severity, date of treatment, treatment measures and maintenance.     

Cultivation offers effective management of subterranean clover damping‐off and root disease

Soil cultivation studies involving subterranean clover pastures were undertaken utilizing field cores from five farms and two in‐field trials. Tap and lateral root disease in cores was less (p < .001) severe and root and shoot weights greater (p < .001) following simulated cultivation. Germination and severity of root disease were both affected (p < .005) by three‐way interactions with cultivation, cultivar and field site. Cultivation in cores suppressed tap root disease for cultivars Meteora and Riverina across the five sites and Seaton Park for two sites. In‐field trials confirmed cultivation reduces root disease severity and increases germination and plant productivity. The best in‐field treatment was cultivation + fumigation that reduced (p < .05) tap and lateral root disease and increased nodulation and root and shoot weights for Riverina, Seaton Park and Woogenellup. Cultivation + fumigation also increased (p < .05) germination for Woogenellup and Seaton Park. There were negative correlations (all p < .001) between tap and lateral root disease with nodulation (R² = .85, R² = .58, respectively); tap root disease with root and shoot weight (R² = .58, R² = .854, respectively); and lateral root disease with root and shoot weight (R² = .83, R² = .64 respectively). This study highlights the close relationship between severe root disease and reduced nodulation, likely explaining much of the widespread poor nodulation in subterranean clover pastures. This study confirms that damping‐off and root disease can be mitigated by cultivation, offering producers flexibility in disease management, especially where autumn–winter feed shortages occur on a regular basis.     

An SNP downstream of the OsBEIIb gene is significantly associated with amylose content and viscosity properties in rice (Oryza sativa L.)

Allele mining in starch synthesis-related genes (SSRGs) has facilitated the discovery of desired natural sequence variations for eating quality in rice. This study investigated the sequence variations from 10 SSRGs, and further evaluated their relationship with the amylose content (AC) and rapid viscosity analysis profiles in a global collection of rice accessions by association mapping (AM). In total, 83 sequence variations were found in 10 sequenced amplicons, including 73 single nucleotide polymorphisms (SNPs), eight insertion-deletions (InDels) and two polymorphic simple sequence repeats (SSRs). Four subpopulations were identified by population structure analysis based on 170 genome-wide SSR genotypes. AM revealed 11 significant associations between three phenotypic indices and three sequence variations. One SNP with a g/c transversion at the 63rd nucleotide downstream of the OsBEIIb gene termination codon on rice chromosome 2 was significantly associated with multiple trait indices in both the general linear and mixed linear models (GLM and MLM), including the final viscosity (p < 0.001, R² = 23.87%) in both 2009 and 2010, and AC (p < 0.01, R² = 11.25%) and trough viscosity (p < 0.01, R² = 20.43) in 2010. This study provides a new perspective of allele mining for breeding strategies based on marker-assisted selection.     

Effect of green-belly stink bug,Dichelops furcatus (F.) on wheat yield and development

The green belly stink bug, Dichelops furcatus (F.) (Hemiptera: Heteroptera: Pentatomidae) is a pest of corn and soybean in southern Brazil. It also occurs on wheat, but information on its damage to this crop is limited. To determine the need for sustainable IPM programs, the impact of this bug on wheat production should be determined. Studies were conducted in the screenhouse with 1, 2 and 4 bugs caged for 16 days on single plants, cv. ‘BRS Parrudo’. During the vegetative period (plants ca. 25 cm tall), all infestation levels significantly reduced plant height and ear head length, but did not reduce grain yield. Feeding damage caused tissue necrosis on leaves. During the booting stage, grain yield was significantly reduced with 2 and 4 bugs per plant; ear heads were small, discolored and abnormally developed. In 2013 and 2014 field trials, plants were infested for 18 days with 2, 4 and 8 bugs per m² at vegetative, booting, and milky grain stage. At these infestation levels, there was no significant reduction in grain yield. There was a significant decrease in the number of normal seedlings resulting from seeds exposed to 8 bugs per m² at the milky grain stage. Results suggest that, in general, there is no need to control D. furcatus on wheat, unless numbers are ≥8 bugs per m² during reproductive period.     

An SNP downstream of the OsBEIIb gene is significantly associated with amylose content and viscosity properties in rice (Oryza sativa L.)

Allele mining in starch synthesis-related genes (SSRGs) has facilitated the discovery of desired natural sequence variations for eating quality in rice. This study investigated the sequence variations from 10 SSRGs, and further evaluated their relationship with the amylose content (AC) and rapid viscosity analysis profiles in a global collection of rice accessions by association mapping (AM). In total, 83 sequence variations were found in 10 sequenced amplicons, including 73 single nucleotide polymorphisms (SNPs), eight insertion-deletions (InDels) and two polymorphic simple sequence repeats (SSRs). Four subpopulations were identified by population structure analysis based on 170 genome-wide SSR genotypes. AM revealed 11 significant associations between three phenotypic indices and three sequence variations. One SNP with a g/c transversion at the 63rd nucleotide downstream of the OsBEIIb gene termination codon on rice chromosome 2 was significantly associated with multiple trait indices in both the general linear and mixed linear models (GLM and MLM), including the final viscosity (p < 0.001, R² = 23.87%) in both 2009 and 2010, and AC (p < 0.01, R² = 11.25%) and trough viscosity (p < 0.01, R² = 20.43) in 2010. This study provides a new perspective of allele mining for breeding strategies based on marker-assisted selection.     

Evaluating cultivars in unbalanced on-farm participatory trials

Data from on-farm participatory varietal trials are often highly unbalanced. Using statistically robust techniques we showed that such data are amenable to sophisticated analyses. Data from 38 varieties of wheat tested in 44 mother trials (all test varieties compared) and 663 baby trials (single entries compared with local checks) over 6 years in Lunawada, Gujarat, India, were analysed. Two combined analyses for grain yield were performed by using either a fixed effects model within general linear modelling (GLM) or a mixed effects model using the restricted maximum likelihood (REML) procedure. Both analyses made substantial adjustments over the raw means and the estimated mean values from the two analyses for the fixed set of tested varieties were highly correlated (R² = 0.89) as were the t-value that compared test cultivars with the check variety (R² = 0.96). The GLM detected 15 varieties and REML detected 12 varieties that were significantly superior to the check cultivar with 11 varieties in common. Both methods were similar in identifying the top-most promising varieties but REML was more conservative (i.e. more subject to Type II error) with larger standard errors (S.E.s) of variety means for n > 17. However, for both procedures the S.E.s increased sharply when the number of trials decreased below 17.     

Genetic gains in grain yield, net photosynthesis and stomatal conductance achieved in Henan Province of China between 1981 and 2008

Knowledge of the changes in agronomic and photosynthetic traits associated with genetic gains in grain yield potential is essential for an improved understanding of yield-limiting factors and for determining future breeding strategies. The objectives of this study were to identify agronomic and photosynthetic traits associated with genetic gains in grain yield of facultative wheat (Triticum aestivum L.) between 1981 and 2008 in Henan Province, the most important wheat producing area in China. During the 2006-2007 and 2007-2008 crop seasons, a yield potential trial comprising 18 leading and new cultivars released between 1981 and 2008 was conducted at two locations, using a completely randomised block design of three replicates. Results showed that average annual genetic gain in grain yield was 0.60% or 51.30 kg ha⁻¹ yr⁻¹, and the significant genetic improvement in grain yield was directly attributed to increased thousand grain weight which also contributed to the significant increase in harvest index. The genetic gains in rates of net photosynthesis at 10, 20 and 30 days after anthesis were 1.10% (R² = 0.46, P < 0.01), 0.68% (R² = 0.31, P < 0.05) and 6.77% (R² = 0.34, P < 0.05), respectively. The rates of net photosynthesis at 10 (r = 0.58, P < 0.05), 20 (r = 0.59, P < 0.05) and 30 (r = 0.65, P < 0.01) days after anthesis were closely and positively correlated with grain yield. A slight decrease in leaf temperature and an increase in stomatal conductance after anthesis were also observed. Grain yield was closely and positively associated with stomatal conductance (r = 0.69, P < 0.01) and transpiration rate (r = 0.63, P < 0.01) at 30 days after anthesis. Therefore, improvement of those traits was the likely basis of increasing grain yield in Henan Province between 1981 and 2008. The genetic improvement in yield was primarily attributed to the utilization of two elite parents Yumai 2 and Zhou 8425B. The future challenge of wheat breeding in this region is to maintain the genetic gain in grain yield and to improve grain quality, without increasing inputs for the wheat-maize double cropping system.     

Wheat Cultivar Susceptibility to Grain Damage by the New Zealand Wheat Bug,Nysius huttoni,and Cultivar Susceptibility to the Effects of Bug Proteinase on Baking Quality

Immature wheat grain in New Zealand is attacked sporadically by the native insect (bug),Nysius huttoni.This ‘bug-damaged wheat’ contains a bug salivary proteinase, and bread made from this wheat has a characteristically poor loaf volume and texture. Historical baking data suggest variations in wheat cultivar susceptibility to bug damage. This suggestion was tested in two trials (1992/1993 and 1993/1994) on immature wheat using nine or seven New Zealand cultivars and breeding lines enclosed together in nylon mesh cages with and withoutN. huttoni.Visible damage, bug-proteinase levels, electrophoretic protein patterns, and baking properties of the grain were analysed. Both trials showed that susceptibility to bug damage was significantly different amongst cultivars and breeding lines. The ranking of cultivar susceptibility was the same for the two trials, except for cv. Arawa, which was one of the most susceptible cultivars in the first trial, but one of the least susceptible in the second trial. Cultivars Domino and Oroua consistently showed less susceptibility to bug attack. The breeding line WW378 and the cultivar Otane were the most susceptible to bug attack. The high quality bread wheats (Otane, Oroua, Domino and Batten) were less susceptible to the effects of bug proteinase in baking than the poor baking quality wheats (Karamu, WW378, ASPS9927 and ASPS9928). Batten was significantly less susceptible than any other cultivar in test baking. There was no relationship between bug-damage susceptibility and grain characters such as colour, hardness and texture, or head characters such as shape, awns and waxiness.     

Hyperspectral remote sensing of yellow mosaic severity and associated pigment losses in Vigna mungo using multinomial logistic regression models

Yellow mosaic disease (YMD) has been a serious threat to blackgram cultivation especially during post-monsoon season. Visual assessment of disease severity is qualitative and time consuming. Rapid and non-destructive estimation of YMD by hyperspectral remote sensing has not been attempted so far on any of its hosts. Field studies were conducted for two seasons with eight blackgram genotypes having differential response to YMD. Comparison of mean reflectance spectra of the healthy and YMD infested leaves showed changes in all the broad band regions. However, reflectance sensitivity analysis of the narrow-band hyperspectral data revealed a sharp increase in reflectance from the diseased leaves compare to healthy at 669 (red), 505 and 510 nm (blue). ANOVA showed a significant decrease in leaf chlorophyll (p < 0.0001) with increase in disease severity, while no such relationship was observed for relative water content. By plotting coefficients of determination (R²) between leaf chlorophyll and percent reflectance at one nm wavelength interval, two individual bands (R₅₇₁; R₇₀₅) and two band ratios (R₅₇₁/R₇₂₁; R₇₀₅/R₅₉₃) with highest R² values were selected. These bands showed a significant linear relationship with SPAD chlorophyll readings (R² range 0.781–0.814) and spectrometric estimates of total chlorophyll content (R² range 0.477–0.565). Further, the relationship was stronger for band ratios compared to single bands. With optimal spectral reflectance ratios as inputs, disease prediction models were built using multinomial logistic regression (MLR) technique. Based on model fit statistics, reflectance ratios R₅₇₁/R₇₂₁ and R₇₀₅/R₅₉₃ were found better than the individual bands R₅₇₁ and R₇₀₅. Validation of MLR models using an independent test data set showed that the overall percentage of correct classification of the plant into one of the diseased categories was essentially same for both the ratios (68.75%). However, the MLR model using R₇₀₅/R₅₉₃ as dependent variable was of greater accuracy as it gave lower values of standard errors for slopes (β_G range 9.79–36.73) and highly significant estimates of intercept and slope (p < 0.05). Thus the models developed in this study have potential use for rapid and non-destructive estimation of leaf chlorophyll and yellow mosaic disease severity in blackgram.     

Stratification of sorghum hybrid testing sites in southern Africa based on grain yield

Sequential retrospective (SeqRet) pattern analysis technique was applied to classify sorghum hybrid testing sites in accordance with their similarity for yield differentiation among genotypes. Historical grain yield data from 150 multi-environment trials (METs) conducted at 23 sites in the Southern Africa Development Community (SADC) region during 1987/1988–1992/1993 was used. The sites were clustered into six major environment groups in the SADC region with a model fit of R² = 68%. Analysis of these 6 years’ data together with additional data from 1999/2000 stratified the 23 sites in the same six major groups (R² = 69%), the additional five sites in 1999/2000 classified with appropriate site groups. These results suggest that future sorghum hybrid testing could be cost-effectively conducted in a few representative sites selected from within each of the six identified site groups.     

Stratification of SADC regional sorghum testing sites based on grain yield of varieties

We applied sequential retrospective (SeqRet) pattern analysis to stratify sorghum variety testing sites according to their similarity for yield discrimination among genotypes using historical grain yield data from 147 multi-environment trials (METs). The trials were conducted at 38 sites in 10 countries of the Southern African Development Community (SADC) region during 1987/1988–1992/1993 and 1999/2000. The analysis for the 6 years 1987/1988–1992/1993, covering 34 sites, clustered these sites into 6 major groups with a model fit of R² = 0.75. With additional data from the year 1999/2000, the SeqRet pattern analysis delivered a very similar clustering of the 34 sites, with the additional four sites in 1999/2000 properly classified with appropriate site groups (R² = 0.74). The results suggest that future sorghum variety testing could be restricted to a few representative sites selected from within each of the six identified site-groups.     

Relationship between P and N concentrations in maize and wheat leaves

Simple plant-based diagnostic tools can be used to determine crop P status. Our objectives were to establish the relationships between P and N concentrations of the uppermost collared leaf (P_L and N_L) of spring wheat (Triticum aestivum L.) and maize (Zea mays L.) during the growing season and, in particular, to determine the critical leaf P concentrations required to diagnose P deficiencies. Various N applications were evaluated over six site-years for wheat and eight site-years for maize (2004-2006) with adequate soil P for growth. Phosphorus and N concentrations of the uppermost collared leaf were determined weekly and the relationships between leaf N and P concentrations were established using only the sampling dates from the stem elongation stage for wheat and from the V8 stage of development for maize. Leaf P concentration generally decreased with decreasing N fertilization. Relationships between P_L and N_L concentrations (mg g⁻¹ DM) using all site-years and sampling dates were described by significant linear-plateau functions in both maize (P_L = 0.82 + 0.089 N_L if N_L ≤ 32.1 and P_L = 3.7 if N_L > 32.1; R² = 0.41; P < 0.001) and wheat (P_L = 0.02 + 0.106 N_L if N_L ≤ 33.2 and P_L = 3.5 if N_L > 33.2; R² = 0.42; P < 0.001). Variation among sampling dates in the relationships were noted. By restricting the sampling dates [413-496 growing degree days (5 °C basis) in wheat (i.e., stem elongation) and 1494-1579 crop heat units in maize (i.e., silking), relationships for wheat (P_L = 0.29 + 0.073 N_L, R² = 0.66; P < 0.001) and maize (P_L = 1.04 + 0.084 N_L, R² = 0.66; P < 0.001) were improved. In maize, expressing P and N concentrations on a leaf area basis (P_LA and N_LA) at silking further improved the relationship (P_LA = 0.002 + 0.101 N_LA, R² = 0.80; P < 0.001). Predictive models of critical P concentration as a function of N concentration in the uppermost collared leaf of wheat and maize were established which could be used for diagnostic purposes.     

Ecophysiological determinants of biomass and grain yield of wheat under P deficiency

Grain yield of crops can be expressed as a function of the intercepted radiation, the radiation use efficiency and the partitioning of above-ground biomass to grain yield (harvest index). When a wheat crop is grown under P deficiency the grain yield is reduced but it is not clear how these three components are affected. Our aim was (i) to identify which of these components were affected in spring bread wheat under P deficiency at field conditions and (ii) to relate the grain yield responses to processes of grain yield formation during the spike growth period. Three field experiments were conducted in the potentially high wheat yielding environment of southern Chile. All experiments had two levels of P availability: with (155 kg P ha⁻¹) or without P fertilization (average soil P-Olsen concentration of 10 ppm, a medium level of P availability). High wheat grain yields were obtained varying between 815 and 1222 g m⁻² with P applications. Experiments showed a grain yield reduction caused by P deficiencies of 35, 16 and 18% in experiments 1, 2 and 3, respectively. This was related (R² = 0.99, P < 0.01) to a reduction in the total above-ground biomass at harvest and not to the harvest index. Reductions in above-ground biomass were due to a reduction in radiation intercepted under P deficiency without effecting radiation use efficiency. Grain number per square meter was the main yield component (R² = 0.99, P < 0.01) that explained the grain yield reduction caused by the P deficiency which was due to low spike biomass at anthesis (R² = 0.96, P < 0.05). The reduction in spike biomass at anthesis was related (R² = 0.86, P < 0.01) to reductions in crop growth rate during the spike growth period as a consequence of a lower radiation intercepted during this period. This study showed that under high wheat yield conditions the main effect of a P deficiency on grain yield reduction was a negative impact on the total above-ground biomass due to the negative impact on intercepted radiation, particularly during the spike growth period, affecting negatively spike biomass at anthesis and consequently grain number and yield.     

Uptake and use efficiency of N, P, K, Ca and Al by Al-sensitive and Al-tolerant cultivars of wheat under a wide range of soil Al concentrations

The impacts of acidic soils and Al toxicity on wheat nutrient economy have been scarcely researched under field conditions even though these soils are widely spread in wheat production areas around the world. The main objective of this study was to quantitatively evaluate the element (N, P, K, Ca and Al) economy of an Al-sensitive and an Al-tolerant wheat cultivar growing under different soil Al concentrations at field conditions. To reach this objective, two field experiments were conducted in an Andisol in Valdivia (39°47′18″S, 73°14′05″W), Chile. Treatments were a factorial arrangement of: (i) two spring wheat cultivars (Al-sensitive, Domo.INIA and Al-tolerant, Dalcahue.INIA) and (ii) five exchangeable Al levels (0-2.7 cmol₍₊₎ kg⁻¹) with three replicates. At harvest, plant biomass was sampled and divided into 5 organ categories: ears, grains, blade leaves, stems plus sheath leaves and roots. The element content (N, P, K, Ca and Al) in each organ was measured to quantify element uptake and concentration, nutrient uptake efficiency (UPE) and nutrient utilization efficiency (UTE). Element uptake (N, P, K, Ca, and Al) was negatively affected by the increased soil Al concentration in above-ground and root biomass in both cultivars (R² = 0.61-0.98, p < 0.01), although clear differences were found between cultivars. On the contrary, the impact of soil exchangeable Al on the plant element concentration was minor, showing weak associations with soil Al levels. However, the Al concentration in above-ground tissues of the Al-sensitive cultivar was an exception because it increased exponentially with the Al soil concentration (R² = 0.96-0.99, p < 0.001). Nutrient uptake efficiencies, UPEs (N, P, K and Ca), were negatively affected by soil Al concentrations and were well described by linear equations in both cultivars (R² = 0.58-0.98, p < 0.05), with notable differences between them. Both nutrient uptake (capture) and UPE were the traits that best explained above-ground biomass production (R² = 0.82-0.99, p < 0.001, n = 20). Nutrient utilization efficiency, UTEs (N, P, K and Ca) responded more conservatively to the soil Al concentration, except for the Al sensitive cultivar under very high soil Al levels.     

Seed yield components,oil content,and fatty acid composition of two cultivars of moringa (Moringa oleifera Lam.) growing in the Arid Chaco of Argentina

Moringa oleifera Lam. (M. pterygosperma Gaertn [Moringaceae]) is a fast-growing small tree native to the sub-Himalayan tracts of Northern India. The recognition that moringa oil has value in cosmetics has increased interest in cultivating it for seed-oil. The experimental trials were conducted in a semi-commercial moringa plantation in the subtropical northwestern region of Argentina, considering the similar climate conditions to the plant native region. Pods per tree, seeds per pod, weight of seed per pod, kernel weight, kernels oil content and fatty acid composition of PKM-1 and African cultivars were determined. One individual, E₄-9, a PKM-1 plant, had significantly (P < 0.05) higher production than all other plants. In addition, this individual was the highest extrapolated oil producer in both 2003 and 2004, with 595 and 564 kg ha^?1, respectively (ave. 580 kg ha^?1). Seed weight (200-seed wt.) was significantly greater in 2003 than 2004; no other traits studied showed significant differences between years. Both cultivars produced-oil with practically identical fatty acid composition, and the monounsaturated ω-9 oleic fatty acid accounted for more than 70% of the total for both cultivars. The polyunsaturated ω-6 linoleic fatty acid content of the African cultivar was slightly, but significantly (P < 0.05), higher than that of PKM-1.     

Long-term evolution and prediction of feed value for permanent mountain grassland hay: Analysis of a 32-year data set in relation to climate change

Elevation of mean air temperature related to climate change speeds up plant maturity, which influences mostly forage feed value. The objective of the study was to assess variation in hay quality harvested over 32 years at the same experimental site, and whether feed value is better predicted by combining agro-climatic variables with chemical composition. From 1979 to 2010, the in vivo digestibility (OMd) and voluntary dry matter intake (VDMI) of 271 hays, harvested during the first vegetation cycle on permanent grasslands, were measured in sheep. Over 32 years, the mean air temperature between February and August increased significantly by 1.34°C. Cutting date was advanced by 6 days, but the average sum of temperature at cutting (ST) increased significantly by 13%. Crude protein (CP) content declined (−22%, p < .001), crude fibre content increased (+8%, p < .001), OMd decreased (−3%, p = .012) and VDMI increased (+9%, p = .011). Changes in the chemical composition and OMd were consistent with the increase in ST. Finally, the prediction of OMd from CP and crude fibre contents (R² = .57, RMSE = 2.99) was slightly improved by the addition of ST and hay drying time (R² = .60, RMSE = 2.83). Climate change may have a negative indirect effect on hay quality if an earlier cutting date does not compensate for its effect on the faster maturation of the plants. Moreover, agro-climatic criteria could help to monitor and predict hay quality in relation to intra- and inter-annual climatic changes.     

Quantification of the cardinal temperatures and thermal time requirement of opium poppy (Papaver somniferum L.) seeds to germinate using non-linear regression models

The response of plant development rate (including germination rate) to temperature might be described as a non-linear function. We compared 3 non-linear regression models (Dent-like, segmented and beta) to describe the germination rate-temperature relationships of opium poppy (Papaver somniferum L.) over 6 constant temperatures to find cardinal temperatures and thermal time required to reach different germination percentiles. Two replicated experiments were performed with the same temperatures. An iterative optimization method was used to calibrate the models and different statistical indices (mean absolute error, coefficient of determination (R²), intercept and slope of the regression equation of predicted vs. observed germination rate) were applied to compare their performance. The segmented was found to be the best model to predict germination rate (R² = 0.92, MAE = 0.0011 and CV of 1.4-3.6%). Estimated cardinal temperatures were similar for different germination percentiles (P < 0.05). Base on the model outputs, the base, the optimum and the maximum temperatures for germination were estimated as 3.02, 27.36 and 36.31 °C. The thermal time required to reach 50 and 95% germination was 57.27 and 87.55 degree-days, respectively. Model predictions of the time required for seed germination agreed reasonably well with the observed times (MAE = 0.56 day, R² = 0.887). All model parameters may be readily used in crop simulation models.     

Dynamic of water activity in maize hybrids is crucial for fumonisin contamination in kernels

The dynamic of water activity (a_w) and humidity (h) of maize (Zea mays L.) kernels and their relevance for fumonisin (FUM) accumulation in kernels was studied in 10 commercial hybrids grown in 5 locations of North Italy, in 2007 and 2008. The dynamic of both a_w and h in maize kernels was different in diverse hybrids and was accurately described by monomolecular and linear regression, respectively, using degree-days (base 0 °C) accumulated between female flowering and harvest as an independent variable (R² = 0.61-0.96, depending on the hybrid). FUM contamination at harvest was predicted by using a_w as an independent variable in a logistic regression which provided 67% of correct prediction of cases with FUM ≥ 4000 μg/kg of kernel; accuracy of prediction increased to 72% by using both a_w and ECB severity as independent variables. The use of h as independent variable provided 71% correct predictions, but specific correction factors were necessary for each hybrid. Results showed that “slow dry down” hybrids were more prone to FUM accumulation, irrespective of their season length. The identification of factors able to drive a_w dynamic in maize kernels and their genetic bases may then provide a crucial contribution in breeding maize for resistance to FUM contamination.