Antifungal proteins and grain mold resistance in sorghum with nonpigmented testa.

Levels of four antifungal proteins (AFPs) were determined in mature caryopses (40-45 days after anthesis) of eight grain mold resistant (GMR) and eight susceptible (GMS) sorghum lines using the immunoblot technique. These 16 lines came from the same cross and were selected for high and low grain mold resistance. The 16 lines were grown in eight environments over three years. In the environments with grain mold incidence, levels of sormatin, chitinases, and ribosomal inactivating proteins (RIP) in the GMR group were higher than those in the GMS group. In a grain mold-free environment, the GMR group had higher RIP and lower beta-1,3-glucanase levels than the GMS group. Unlike the GMS group, chitinase, sormatin, and RIP levels in the GMR group were higher in the environments with grain mold than in the mold-free environment. AFPs correlated among themselves and with grain mold resistance. Grain mold infection pressure caused GMR lines to induce and/or retain more AFPs compared to GMS lines. The coexpression of these four AFPs may be a necessary prerequisite for resistance to grain mold in sorghums without a pigmented testa.     

Lower fumonisin mycotoxin levels in the grain of Bt corn grown in the United States in 2000-2002

Fumonisins were monitored in corn grain collected from Bt hybrids grown in 107 locations across the United States in 2000-2002. Bt corn hybrids contain the Cry1Ab protein from Bacillus thuringiensis that controls European corn borers and other stalk-boring pests. Fumonisin levels were frequently lower in grain from Bt hybrids grown in field trials under conditions of natural (FACT trials) or manual insect infestation (university trials). Over three years of FACT trials, there were 126/210 comparisons when fumonisin levels in grain from control hybrids were >2 ppm, exceeding U.S. FDA guidance levels of 2 ppm for human food. Grain from Bt hybrids was at or below 2 ppm of fumonisins for 58 of the 126 comparisons. The use of Bt hybrids can increase the percentage of corn grain that would be suitable for use in food and feed.     

Activity of antifungal proteins against mold in sorghum caryopses in the field

Sorghums were stressed with pathogenic fungi and sprinkling to determine relationships between changes in chitinase and sormatin in caryopses and grain mold resistance. Panicles of 10 cultivars differing in mold resistance and accumulation of antifungal proteins (AFPs) were inoculated at anthesis with Fusarium moniliforme and Curvularia lunata spores. Panicles were sampled at 30 and 50 days after anthesis, and caryopses were evaluated for chitinase and sormatin using western blots. Sprinkling panicles (to mimic rainfall) decreased sormatin and chitinase in most cultivars. Inoculation decreased AFPs in susceptible cultivars, but resistant cultivars maintained or increased AFPs in caryopses. Grain mold resistance corresponded to induction of AFP synthesis in response to sprinkling, fungal stress, and/or adverse field conditions. Sormatin and chitinase appear to be an active part of the defense mechanism of the caryopsis against grain mold.     

Response of nitrogen use efficient sorghums to nitrogen fertilizer

Little information is available on the response of grain sorghum [Sorghum bicolor (L.) Moench] genotypes differing in nitrogen (N) use efficiency (NUE) (g DM g N^‐1) to added N fertilizer. Such knowledge is important for reducing the reliance upon fertilizer N. A dryland field experiment was conducted in 1993 and 1994 at Mead, NE evaluating the agronomic responsiveness of 13 sorghum genotypes differing in NUE to three N rates (0, 50 and 100 kg N ha^‐1) and also to determine physiological factors that contribute to improved NUE. The experiment was conducted on a fine montmorillonitic, mesic, Typic Argiudoll soil. Total N at maturity, dry matter, and grain yield were used to calculate NUE terms. Genotype differences were found for all measured variables both years, but no N rate by genotype effects were significant. Nitrogen fertilizer enhanced plant N contents and grain yield, but decreased NUE for total biomass and grain production. An early freeze in 1993 markedly reduced the later maturing genotype grain yields which, in turn, influenced NUE group comparisons. All genotypes in the study attained their full yield potential in 1994. The linear response to N rate of the N non‐responsive group was significantly less than the moderately responsive or N responsive group. High NUE sorghums had greater yields than low NUE types averaged over N levels only in 1994 since Naga White, a high NUE type, did not reach maturity in 1993. There was no difference in the linear response to N between these two groups. A linear increase in grain yield with increasing N rate was significantly greater for hybrids than lines. The results suggest that specific selection for high NUE sorghums will not diminish responsiveness to applied N.     

Logistic regression modeling of cropping systems to predict fumonisin contamination in maize

The aims of this research were to monitor the presence of fumonisins in maize crops in northern Italy over a 6 year period, to study the role of the cropping system on fumonisin levels, and to contribute to the development of a predictive system for fumonisin contamination. In the 6 year period from 2002 to 2007, 438 maize samples were collected in five regions, supported by agronomic data, and analyzed for fumonisin content. Fumonisin was detected in almost all of the grain samples, but 2007 was less and 2005 more contaminated compared to the other years. Preceding crop, maturity class of hybrids, nitrogen fertilization, sowing and harvest week, and grain moisture significantly affected the level of contamination. The logistic regression developed explained around 60% of variability with major roles for longitude, maturity class, and growing weeks. The function can be used to quantify the effect of these factors in a predictive system.     

Steam Flaking Characteristics of Sorghum Hybrids and Lines with Differing Endosperm Characteristics

Commercial and food-type sorghum hybrids with differing kernel and endosperm characteristics were grown under comparable conditions and steam flaked in each of three years. The raw-grain kernel characteristics and proximate analyses were homogenous over the three-year period. The waxy hybrid produced large, translucent, durable flakes that had significantly higher enzyme-susceptible starch values for all years compared to the other varieties. Flakes with lower amylose contents (waxy endosperm) were positively correlated with percent whole flakes (r² = 0.509), flake diameter (r² = 0.846), and enzyme-susceptible starches (r² = 0.564) and negatively correlated with higher flake fragility (r² = -0.647), test weight (r² = -0.626), and flake breakage (r² = -0.560). The heterowaxy flakes had a good appearance and were generally comparable in quality to the nonwaxy commercial and experimental hybrids. Heterowaxy sorghum hybrids with good grain yields can provide improved quality grain and flakes without sacrificing agronomic performance and yields. No difference in flaking performance was detectable among the kernels with different pericarp colors; flakes from the white food-type sorghums had excellent appearance. Nontempered control samples were inferior in quality to all conditioned treatments.     

Compositional changes of Australia-grown Western Schley pecans [Carya illinoinensis (Wangenh.) K. Koch] during maturation

Changes in composition during the maturation of Western Schley pecans [Carya illinoinensis(Wangenh.) K. Koch] grown in Australia were investigated. Pecans of different maturity levels were collected at monthly intervals between March and June in 1999 and 2000 and analyzed for the concentrations of moisture, total lipid, sucrose, raffinose, protein, and the minerals aluminum, boron, calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, sulfur, and zinc. Moisture, total lipid, and calcium contents changed significantly (p < 0.05) with harvest time and maturity, whereas the other components did not. Western Schley pecans grown in Australia should be harvested after the shuck has opened and it is either green or brown in color to maximize total lipid content and quality. This occurred after May 11 in 1999 and after May 17 in 2000.     

不同降雨年型下水分处理对大穗型小麦品种籽粒灌浆及产量的影响

在大田条件下，探讨了不同降水年型不同水分处理条件下大穗型小麦品种籽粒灌浆及产量的变化。结果表明：通过用不同方程对籽粒生长动态进行拟合，Cubic方程最精确。2000～2001干早年型W和Ws与两个灌浆持续期参数(Se、S)相关性显著．2001～2002丰雨年型W和Ws与3个灌浆速率参数(V、Vs、Vmax)间相关性达显著水平。两年度相比，2000～2001年度籽粒灌浆持续期短，灌浆速率小，导致粒重降低。灌水对灌浆参数的效应年际间存在差异，2000～2001年度随灌水次数增多，S和Se延长，灌浆速率降低；而2001～2002年度随灌水次数增多，S和Se缩短，灌浆速率以灌—水处理最小．灌两水处理最高。灌水对产量的影响，2000～2001年度显著增产，2001～2002年度处理间无显著差异，灌三水处理较灌两水处理反而减产。     

Partitioning of phosphorus in different height isolines of winter wheat

Wheat (Triticum aestivum L.) grain yields and composition are influenced greatly by P and its interactions with other nutrients. Because most P in grain, like N, is remobilized from vegetative parts, high harvest index of dwarf wheats may adversely influence partitioning of P to grain. Isogenic tall, single semidwarf, and double dwarf ‘Pawnee’ wheat lines were used to characterize P partitioning, P nutrition before and after anthesis, and relationship between P and N. Plants were grown in hydroponic cultures with three P levels; the first study determined P, N, and dry matter accumulation from anthesis to maturity, the second study determined the effect of withholding P after anthesis on P, N, and dry matter partitioning during grain development. Plants continued to absorb P when it was available after anthesis, but grain growth was influenced more by P nutrition before anthesis than after anthesis. Leaf blades, sheaths, and stems were major sources of P for grain growth when the nutrient was withheld and major sites of P accumulation when the nutrient was supplied after anthesis. Content of N in plants was favored by ample P levels. Dwarfing genes increased harvest index, but had little effect on P partitioning because of differences in dry matter accumulation.     

Reduction of Aflatoxin and Fumonisin Contamination in Yellow Corn by High‐Speed Dual‐Wavelength Sorting

A high‐speed dual‐wavelength sorter was tested for removing corn contaminated in the field with aflatoxin and fumonisin. To achieve accurate sorting, single kernel reflectance spectra (500–1,700 nm) were analyzed to select the optimal pair of optical filters to detect mycotoxin‐contaminated corn during high‐speed sorting. A routine, based on discriminant analysis, was developed to select the two absorbance bands in the spectra that would give the greatest classification accuracy. In a laboratory setting, and with the kernels stationary, absorbances at 750 and 1,200 nm could correctly identify >99% of the kernels as aflatoxin‐contaminated (>100 ppb) or uncontaminated. A high‐speed sorter was tested using the selected filter pair for corn samples inoculated with Aspergillus flavus; naturally infested corn grown in central Illinois; and naturally infested, commercially grown and harvested corn from eastern Kansas (2002 harvest). For the Kansas corn, the sorter was able to reduce aflatoxin levels by 81% from an initial average of 53 ppb, while fumonisin levels in the same grain samples were reduced an average of 85% from an initial level of 17 ppm. Similar reductions in mycotoxin levels were observed after high‐speed sorting of A. flavus inoculated and naturally mold‐infested corn grown in Illinois.     

Effects of supplemental nitrogen on nitrogen‐assimilation enzymes,free amino nitrogen,soluble sugars,and crude protein of rice

Abstract

An upland rice variety IAC‐47 was grown in a greenhouse to determine the effect of foliar nitrogen (N) supplementation during grain development on the activity of the N assimilation enzymes, nitrate reductase (NR) and glutamine synthetase (GS), on free amino‐N content and leaf soluble sugars, and on grain crude protein content. At 10 and 20 days after anthesis (DAA), the leaves were fertilized with a liquid fertilizer containing 32% N as 12.8% urea, 9.6% ammonium (NH₄), and 9.6% nitrate (NO₃) in increasing rates corresponding to 0,20+20, 40+40, and 60+60 kg N ha^‐1. Leaves were collected twice (at 12 DAA and 14 DAA for GS activity, sugar and amino‐N content, and at 11 and 13 DAA for NRA) after each application of leaf N. The late foliar application of N increased significantly grain crude protein without a corresponding decrease in grain weight. The NR activity (NRA) increased after the foliar application of N. In the flag leaf, 60+60 kg N ha^‐1 (21 DAA) resulted in higher NRA (20x over the control), while GS activity was smaller than the control. At 22 DAA there was an increase in GS activity in the flag leaf at 20+20 N level. However, the GS activity decreased as applied N levels increased. Also at the 20+20 level, there were increases in free amino‐N in the flag leaf and second leaf at the final harvest. Throughout the experiment, plants at the 60+60 N level had the lowest levels of soluble sugars. Increases in crude protein were highest at 40+40 N level (27.9%), followed by 60+60 (18.7%).     

Influence of variety and nitrogen fertilizer on productivity and trait association of malting barley

Poor soil fertility is a major constraint to crop productivity in the highlands of Ethiopia. This study was conducted to evaluate the effects of nitrogen (N) fertilization, variety and growing season on grain yield and yield related traits, and determine relationships among agronomic traits of malting barley. The treatments studied were five N levels (0, 23, 46, 69 and 92?kg ha^?1) and two malting barley varieties (Miscal-21 and Holker) over three growing seasons (2012, 2013 and 2014) at Bekoji, south eastern Ethiopia. The results revealed that as N rates increased, grain yield, number of tillers and spikes per square meter, biomass yield at harvest, days to physiological maturity, spike length and number of kernels per spike increased, but harvest index decreased. Grain yield, harvest index, number of tillers and spikes per square meter, spike length and biomass yield at harvest were greater in Miscal-21, whilst days to maturity and number of kernels per spike were greater in Holker. Grain yield, harvest index, number of tillers and spikes per square meter, spike length, biomass yield at harvest and days to maturity were significantly affected by seasonal conditions, but spike length and kernels per spike were not affected. Grain yield was positively influenced by the number of tillers per square meter, biomass yield at harvest, spikes per square meter, spike length, kernels per spike and harvest index. However, the number of tillers per square meter followed by biomass yield and spikes per square meter largely determined grain yield. The results of the current study suggest that genetic improvement of those yield related traits is the likely basis of increasing grain yield in barley.     

Soil C and N dynamics and maize (Zea may L.) yield as affected by cropping systems and residue management in North-western Pakistan

This paper presents the results of irrigated rotation experiment, conducted in the North West Frontier Province (NWFP), Pakistan, during 1999–2002 to evaluate effects of residues retention, fertilizer N and legumes in crop rotation on yield of maize (Zea mays L.) and soil organic fertility. Chickpea (Cicer arietinum L) and wheat (Triticum aestivum L) were grown in the winters and mungbean (Vigna radiata) and maize in the summers. Immediately after grain harvest, above-ground residues of all crops were either completely removed (−residue), or spread across the plots and incorporated by chisel plough by disc harrow and rotavator (+residue). Fertlizer N rates were nil or 120 kg ha⁻¹ for wheat and nil or 160 kg ha⁻¹ for maize. Our results indicated that post-harvest incorporation of crop residues significantly (p < 0.05) increased the grain and stover yields of maize during both 2000 and 2001. On average, grain yield was increased by 23.7% and stover yield by 26.7% due to residue incorporation. Residue retention also enhanced N uptake by 28.3% in grain and 45.1% in stover of maize. The soil N fertility was improved by 29.2% due to residue retention. The maize grain and stover yields also responded significantly to the previous legume (chickpea) compared with the previous cereal (wheat) treatment. The legume treatment boosted grain yield of maize by 112% and stover yield by 133% with 64.4% increase in soil N fertility. Similarly, fertilizer N applied to previous wheat showed considerable carry over effect on grain (8.9%) and stover (40.7%) yields of the following maize. Application of fertilizer N to current maize substantially increased grain yield of maize by 110%, stover yield by 167% and soil N fertility by 9.8% over the nil N fertilizer treatment. We concluded from these experiments that returning of crop residues, application of fertilizer N and involvement of legumes in crop rotation greatly improves the N economy of the cropping systems and enhances crop productivity through additional N and other benefits in low N soils. The farmers who traditionally remove residues for fodder and fuel will require demonstration of the relative benefits of residues return to soil for sustainable crop productivity.     

Growth and Iron Uptake of Lowland and Aerobic Rice Genotypes under Flooded and Aerobic Cultivation

With increasing water shortages in China, rice (Oryza sativa L.) cultivation is gradually shifting away from continuously flooded conditions to partly or even completely aerobic conditions. The effects of this shift on the growth and iron (Fe) nutrition of different aerobic and lowland rice genotypes are poorly understood. A field experiment was conducted to determine the effects of cultivation system (aerobic vs. flooded), genotype (five aerobic rice varieties and one lowland rice variety), and Fe fertilization [no Fe and 30 kg ha^?1 ferrous sulfate (FeSO₄·7H₂O] on rice grain yield and Fe nutrition. Plants were sampled at tillering and physiological maturity. In both aerobic and flooded plots, Fe application significantly increased shoot dry weight, shoot Fe concentration, and shoot Fe content at tillering but not physiological maturity. At physiological maturity, grain yield and Fe and grain harvest indices were significantly lower in aerobic than in flooded plots. Shoot dry weight and shoot Fe content differed among genotypes at tillering and at physiological maturity. The grain harvest index of aerobic rice genotype 89B-271-17(hun) was significantly greater than that of the other five genotypes when no Fe was applied. Because soil Fe fertilization did not improve the Fe nutrition of rice in aerobic plots, the results indicate that the shift from flooded to aerobic cultivation will increase Fe deficiency in rice and will increase the problem of Fe deficiency in humans who depend on rice for nutrition.     

Variability in European Maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) Landraces under High and Low Nitrogen Inputs

An European maize (Zea mays L.) landrace core collection (EMLCC) was formed with samples from several countries. Evaluation of the EMLCC may contribute to broad the genetic base of maize breeding programs. The objective of this study was to assess the variability of EMLCC under low nitrogen (N) in relation to high N input. Eighty-five landraces of the EMLCC, grouped in four maturity groups, and three check hybrids were evaluated for response to low (0 kg ha⁻¹) and high (150 kg ha⁻¹) N in Spain and Greece. Five plant size traits (plant height, ear height, leaf length, leaf width and leaf area index), two grain traits (1000-kernel weight and grain yield), and two agronomic traits [growing degree units (GDU) and lodging] were studied. Overall means of plant size and grain traits increased when genotypes were grown at 150-N relative to 0-N input. The relative increase for grain traits was smaller in landraces than in hybrids. This suggests that landraces had lower grain yield response to N supply compared to hybrids. Linear regressions of plant size traits on GDU indicated that vegetative development was primarily associated with flowering lateness. The maturity group was the main source of variation for all traits. Landrace variability within maturity groups was significant for all traits across environments, despite significant landrace × environment interactions. Estimates of genetic and genotype × environment variances, and heritabilities at both high and low N inputs were not significantly different from each other. However estimates were generally larger at high N. Genetic and phenotypic correlation coefficients between the two N levels were very high for all traits.     

Grain filling pattern of Hordeum vulgare as affected by salicylic acid and salt stress

Although application of salicylic acid (SA) to various plants grown on saline soils has been examined adequately, the effect of SA on changes during grain filling period has not been studied in details. In this 2-year field study, the grain-filling pattern of barley has been monitored as affected by different SA concentrations (0, 0.5, 1.0, 1.5, and 2.0?mM) under varied irrigation salinity levels (2 and 12?dSm^?1) during 2012–2013 and 2013–2014 growing seasons. In both years, total soluble carbohydrates (TSC) increased up to 15?days after anthesis (DAA) and then decreased until the end of the grain-filling period. However, starch content (SC) and the mean grain weight (MGW) increased form the first sampling, and such increase was substantial between 15 and 25 DAA. The grain growth rate (GGR) and the absolute grain growth rate (AGGR) were enhanced up to 20 DAA and then were reduced until 30 DAA. The grain-filling pattern changed by salt stress, so that TSC was greater for the salt stressed plants from 15 or 10 DAA in the first and the second years, respectively. Throughout the grain-filling period, SC, MGW, and AGGR were lower under saline conditions in both years. Application of SA increased TSC, SC, MGW, GGR, and AGGR from 15 to 20 DAA, however, the effect of SA was obvious earlier under saline than the non-saline conditions. Generally, it can be concluded that SA foliar application might increase grain weight through modulating the negative impact of salt stress on carbohydrate and starch contents. It also appeared that the effect of SA was obvious earlier under salt stress conditions.     

Role of chitinase and sormatin accumulation in the resistance of sorghum cultivars to grain mold

Experiments were conducted to determine the association between resistance to grain mold and the accumulations of chitinase and sormatin. Eight sorghum lines were treated at 50% bloom with Fusarium thapsinum, Curvularia lunata, a mixture of the two fungi, and a water-sprayed control. At maturity, percent disease severity, seed germination rates, and kernel weight were recorded. Chitinase and sormatin content (mg/g of dry weight) were measured in seed samples taken at 30 and 50 days after treatment (DAT). Seed chitinase content was moderately affected by sorghum line (P = 0.10) and significantly affected by the developmental stage of the kernels (P = 0.05). Cultivars Sureno, 98LB650, and 98LB723 exhibited larger negative changes in chitinase content at 50 DAT over water-sprayed control treatment at 30 DAT than the susceptible cultivars Dorado, RTx2536, and RTx430. In 2000, significant negative correlations were observed for percent disease severity and chitinase content at 30 DAT, seed germination and sormatin content at 50 DAT, and between seed germination and kernel weight. There also was a significant positive correlation between germination and chitinase content at 30 DAT. No association between disease severity and changes in chitinase content at 50 DAT was observed. Sormatin content also was significantly affected by the stage of kernel development. Sorghum cultivars inoculated with fungal pathogens responded differently as indicated by the significant sorghum line x treatment interaction for sormatin content in 2000. In both years, larger increases in sormatin content over the water-sprayed control treatments were observed on moderately susceptible to susceptible cultivars such as 98LB650, 98LB723, 98LB789, RTx430, and RTx2536 than on Sureno. Except for percent disease severity and germination, there was no significant association among all of the other parameters measured in 2001. The results of this study did not clearly demonstrate a strong association between resistance to grain mold and the accumulation of sormatin and chitinase. Thus, there is the possibility that certain moderately resistant to resistant sorghum cultivars, such as Sureno, may employ other strategies to eschew or restrict fungal invasion either before or after physiological maturity.     

Antifungal proteins and other mechanisms in the control of sorghum stalk rot and grain mold

Research on antifungal proteins and other mechanisms that provide the biochemical basis for host-plant resistance to stalk rot and grain molds is reviewed in this paper. Stalk rot caused by Fusarium species leads to substantial yield loss due to poor grain filling and/or lodging. A transgenic sorghum expressing high levels of chitinase exhibited less stalk rot development when exposed to conidia of F. thapsinum. Grain mold of sorghum is associated with warm humid environments and results from colonization by several fungi (F. thapsinum, Curvularia lunata, and Alternaria alternata) of the developing caryopsis. The roles of several biochemical mechanisms (tannins, phenolic compounds, red pericarp, proteins, hard endosperm, and antifungal proteins) on grain mold resistance are discussed. Resistance mechanisms related to these compounds appear to be additive, and pyramiding of genes is a feasible approach to limit grain deterioration. Several experimental approaches are proposed to extend current findings.     

Effects of Maturity on Grain Quality and Wet‐Milling Properties of Two Selected Corn Hybrids

The effects of maturity on grain quality and wet‐milling properties were investigated for two hybrids of corn. Significant differences for hybrid and maturity were observed for all grain quality parameters. Test weight, absolute density, and thousand‐grain weight all increased as the corn matured. Kernel hardness increased and breakage susceptibility varied with increased maturity. Water uptake parameters decreased with maturity of the grain. The starch yield results from wet milling showed that the starch yield increased significantly within each cultivar in the early stages of grain maturity, but there were no significant differences between hybrids. Mathematical models using selected grain quality parameters accurately predicted trends in starch yield for the immature and mature corn samples in this study.     

Patterns of Barley Grain Development in Spain and Scotland and Their Implications for Malting Quality

To determine whether patterns of grain filling were consistent between seasons and different between sites in northern and southern Europe, the cultivar Troubadour and TR49, a mutant derived from it, were grown, over two seasons, at sites in Scotland and northern Spain. Differences in sowing date and climate were reflected in different patterns of grain filling. Ear emergence in Scottish grown barley occurred around the time when daylight hours were maximal; optimal photosynthesis was the likely explanation for the rapid increase in grain size observed at the Scottish site. Differences between the sites in temperature and rainfall were most evident during the last month of the growing season. In Scotland, where ripening occurred in cooler, more humid conditions, synthesis of hordein and β-glucan followed the pattern of grain filling, reaching a peak at ~600 degree days after anthesis (the product of days after anthesis and average temperature). Levels then remained fairly constant until harvest ripeness was reached. In Spain, levels of hordein and β-glucan rose virtually throughout the growing season. Differences observed at maturity, between Scottish and Spanish grown grain, in total nitrogen and β-glucan levels were due to this accumulation in the later stages of growth. This was accompanied by a major change in the ratio of the constituent polypeptides of the storage protein and differences in the relative proportions of soluble and insoluble β-glucan.