两个特用稻的营养供应水平与~(32)P、~(14)C分布和谷产量的关系

香稻(竹香粘)的分蘖数多,其分蘖期根系吸收~(32)P和~(32)P分布到分蘖,以高、中肥和高N,高K肥处理的为高;~(14)C-葡萄糖同化物分布在分蘖比黑米稻(黑优粘)和常规稻“双桂36”的高,但灌浆期和黄熟期~(14)C分布在稻穗较少.低肥处理的稻谷产量较高.而在高、中肥条件下结实率降低,实粒数减少,成穗率稍低,谷产量也比“黑优粘”和“双桂36”低. “黑优粘”在高肥、高N条件下的分蘖多,成穗率高、结实粒数也较多,稻谷产量比“竹香粘”高,在高、中肥、高 N高 P条件下,~(32)P分布于分蘖多,分蘖的~(14)C分布则以高 N,高 K肥条件下的多;开花和灌浆用稻穗的~(14)C分布皆以高 K肥水平的为高。“黑优粘”是耐肥和需钾肥品种,高肥、高K可提高其稻谷产量,但仍比“双桂36”低.     

The effect of temperature shock and grain morphology on alpha-amylase in developing wheat grain

Background and Aims

The premature production of alpha-amylase without visible germination has been observed in developing grain of many cereals. The phenomenon is associated with cool temperatures in the late stages of grain growth but the mechanisms behind it are largely unknown. The aim of this study was to replicate the phenomenon under controlled conditions and investigate the possibility of a mechanistic link with grain size or endosperm cavity size.

Methods

Five wheat (Triticum aestivum) genotypes differing in their susceptibility to premature alpha-amylase were subjected to a range of temperature shocks in controlled environments. A comparison was then made with plants grown under ambient conditions but with grain size altered by using degraining to increase the assimilate supply. At maturity, alpha-amylase, grain area and endosperm cavity area were measured in individual grains.

Key Results

Both cold and heat shocks were successful in inducing premature alpha-amylase in susceptible genotypes, with cold shocks the most effective. Cold shocks also increased grain area. Degraining resulted in increased grain area overall, but the larger grain did not have higher alpha-amylase. Analysis of individual grain found that instances of high alpha-amylase were not associated with differences in grain area or endosperm cavity area.

Conclusions

Pre-maturity alpha-amylase is associated with temperature shocks during grain filling. In some cases this coincides with an increase in grain area, but there is no evidence of a mechanistic link between high alpha-amylase and grain or endosperm cavity area.Key words: Alpha-amylase, pre-maturity alpha-amylase, late maturity alpha amylase, temperature, grain size, endosperm cavity, wheat, Triticum aestivum     

Experimental research on the feeding of bream (Abramis brama L.) and white bream (Blicca bjoerkna L.)

Summary The feeding efficiency (the amount of food organisms (chironomids) eaten per unit time and weight raised to the power 0.8) of bream and white bream was determined in relation to the grain size of the substrate, in which the food was presented. Sand was used as substrate with a grain size up to 1500 , divided in eight fractions. The bream used had lengths of 14 and 33 cm and the white bream had a length of 21 cm.The experiments showed quite clearly that the grain size of the substrate influenced the feeding efficiency of all these fishes. An increasing grain size resulted in an decreasing feeding efficiency, because only up to a definite grain size the substrate can be filtered through the gill rakers. If the grain size is larger, the substrate cannot be sieved and is spit out. The size at which this switch occurred was different for all the fishes. For the small bream it was 350 , for the large bream 500 , and for the white bream 600 .Comparing the feeding efficiencies for a grain size which can be sieved by all these fishes, no significant difference was found between large bream and white bream. The small bream, however, was less efficient. Probably this difference is caused by the different sucking capacities of small and large fish. The small bream cannot in one time suck in the chironomids presented at 1 cm depth, while large bream and white bream can. So both grain size and depth at which the food was presented differentially determined the feeding efficiency of these fishes.     

激光—^60Co—γ辐射诱变小麦生物学效应初步研究

研究小麦品种“绵阳21号”和“汉源小麦”及其~(60)Co—γ一代(γ_1)等四个材料,经N_2和He—Ne激光辐照的20种处理(包括对照)的辐射生物学效应。试验结果表明,激光一代(L_1)植株高度,单株分蘖数,单株有效分蘖数,穗长,小穗数,不实小穗数,退化小穗数,小穗密度,主穗粒数,主穗粒重,分蘖穗粒重,单株粒重,抽穗期,叶面积,穗下轴长,倒一节间长,倒一节间粗等17种性状,都表现出不同处理所引起的生物效应差异。同株高,单株分蘖数、单株有效穗数、主穗长度、不实小穗数,主穗粒数、主穗粒重,单株粒重等8个性关变异系数的比较看出:He—Ne激光(照射10分钟)辐照干种子,“汉源小麦—γ_1”比“汉源小麦”产生的变异大,比对照(未照射)的变异更大。同时,发现不同品种所引起的抽穗期、株高、穗长等14种性状的变异分别达显著或极显著,由剂量不同引起抽穗期、主穗粒重和不实小穗数等三种性状的变异显著。     

Relative efficiency of two mating systems and selection procedures for yield improvement in wheat (Triticum aestivum L.)

Summary The relative efficiences of the biparental mating systems and selfing series in connection with phenotypic and geno-phenotypic selection procedures were evaluated for yield improvement in a cross HP1102 X CPAN 1681 of wheat. Two selection cycles having a 4 per cent selection intensity for grain yield were carried out following both selection procedures under the two mating systems. Following these selection procedures, a greater improvement for grain yield could be achieved with the biparental mating system than with the selfing series. During the first selection cycle, the geno-phenotypic selection procedure had an edge over phenotypic selection procedure. The realized response due to the second cycle of selection and the predicted response for the third selection cycle indicated that the phenotypic selection procedure is more efficient than the geno-phenotypic selection procedure. It is suggested that selection following intermating in early segregating generations is able to overcome several inherent limitations of the simple pedigree method as it is possible to increase genetic variation and to concentrate favourable genes and gene combinations for grain yield. An increase in grain yield was, in general, accompanied by an increase in plant height, peduncle length, 100 grain weight, tiller number and biological yield. Therefore, it is suggested that an index comprised of grain yield, plant height, tiller number, grain weight and biological yield could be used for selecting high yielding genotypes of suitable height.     

Abscisic acid in developing wheat grains and its relationship to grain growth and maturation

Summary During the later stages of growth of grains of wheat (Triticum aestivum L. cvs. WW15 and Gabo) there is a dramatic increase (up to 40fold) in the content of abscisic acid (ABA) to 4–6 ng per grain. This level remains high from 25 to 40 days after anthesis. Then, in association with natural or forced drying of the grain, there is a rapid drop (5–10 fold) in the ABA content and a brief increase in the content of bound ABA. The bulk of ABA in an ear was in the grain (95%) and although the embryo contributed 19% of this ABA it was less than 5% of the grain by weight. There was no clear relationship between ABA content and the growth of grains in various spikelet or floret positions. Application of (±)-ABA to the ear had no effect on grain growth rate but led to an earlier cessation of grain growth and hastened the drying of the grain. Isolated embryos and whole grains were capable of germinating during the mid grain growth period (15–25 days), but germination capacity declined subsequently as ABA accumulated. Later, still, with grain drying and loss of ABA, embryo and grain became germinable again. At this time there was also a dramatic increase in the ability of the grain to synthesize -amylase. It is suggested that the accumulation of ABA at the later stages of grain growth prevents precocious germination and premature hydrolysis of starch reserves of the morphologically mature but still unripe grain. An inevitable consequence of such action may be in triggering grain maturation.     

Free and protein amino acids,and nutrient concentrations in wheat grain as affected by phosphorus nutrition at various salinity levels

Summary The effects of P nutrition under various salinity levels on the protein, amino acids, and nutrients in mature wheat grain were studied. Mexican dwarf wheat (Triticum aestivum L. var Inia) was grown to maturity in solution cultures with variable concentrations of P (0.5-, 5-, 25- and 50 mg P/l) in combination with NaCl at concentrations producing osmotic potentials (_s) of –0.4-, –1.4-, –2.4- and –4.4-bars. All other essential nutrients were present in adequate concentrations for vigorous plant growth.Increasing levels of P in the nutrient solutions tended to decrease the grain yield, N, Cl, protein-glutamic acid,-proline,-leucine,-glycine, and-serine, while P, K, Mg, Zn, Mn and Cu in the grain were increased. The sum of all protein amino acids in the grain decreased as the concentration of P increased in the nutrient solution. The effect of P on the individual and sum of amino acids tended to show peak amounts at the 5.0 mg P/l treatment level.Increased levels of salinity significantly reduced grain yield, N, proteinglutamic acid,-proline,-leucine,-glycine,-serine,-aspartic acid,-alanine, and-phenylalanine in the grain. The sum of the protein amino acids (mol/g dry wt.) was decreased in the grain from plants grown at –4.4 bars salinity level, but not in the grain from plants receiving less saline treatments. The concentrations of free amino acids: serine, aspartic acid, glutamic acid, alanine, and arginine were lower in the grain produced at the –4.4 bars salinity than at –0.4 bars salinity level. The sum of free amino acids (mol/g dry wt.) in the grain were decreased at the highest salinity level as compared with concentrations found for grain produced at lower salinity levels.There were some interactions found between P and salinity on the protein amino acids and nutrients in the grains.The amounts of essential amino acids expressed in mg/g of protein were not significantly affected by the increasing levels of P and salinity in the nutrient solution and they were found in adequate or greater amounts than those recommended by the World Health Organization and FAO.     

The reduction in zinc concentration of wheat grain upon increased phosphorus-fertilization and its mitigation by foliar zinc application

Background and aims

Malnutrition resulting from zinc (Zn) and iron (Fe) deficiency has become a global issue. Excessive phosphorus (P) application may aggravate this issue due to the interactions of P and micronutrients in soil crop. Crop grain micronutrients associated with P applications and the increase of grain Zn by Zn fertilization were field-evaluated.

Methods

A field experiment with wheat was conducted to quantify the effect of P applications on grain micronutrient quality during two cropping seasons. The effect of foliar Zn applications on grain Zn quality with varied P applications was tested in 2011.

Results

Phosphorus applications decreased grain Zn concentration by 17–56%, while grain levels of Fe, manganese (Mn) and copper (Cu) either remained the same or increased. Although P applications increased grain yield, they restricted the accumulation of shoot Zn, but enhanced the accumulation of shoot Fe, Cu and especially Mn. In 2011, foliar Zn application restored the grain Zn to levels occurring without P and Zn application, and consequently reduced the grain P/Zn molar ratio by 19–53% than that without Zn application.

Conclusions

Foliar Zn application may be needed to achieve both favorable yield and grain Zn quality of wheat in production areas where soil P is building up.     

<Emphasis Type="Bold">Zinc nutrition in wheat-based cropping systems</Emphasis>

Background

Zinc (Zn) deficiency is one of the most important micronutrient disorders affecting human health. Wheat is the staple food for 35% of the world’s population and is inherently low in Zn, which increases the incidence of Zn deficiency in humans. Major wheat-based cropping systems viz. rice–wheat, cotton–wheat and maize–wheat are prone to Zn deficiency due to the high Zn demand of these crops.

Methods

This review highlights the role of Zn in plant biology and its effect on wheat-based cropping systems. Agronomic, breeding and molecular approaches to improve Zn nutrition and biofortification of wheat grain are discussed.

Results

Zinc is most often applied to crops through soil and foliar methods. The application of Zn through seed treatments has improved grain yield and grain Zn status in wheat. In cropping systems where legumes are cultivated in rotation with wheat, microorganisms can improve the available Zn pool in soil for the wheat crop. Breeding and molecular approaches have been used to develop wheat genotypes with high grain Zn density.

Conclusions

Options for improving grain yield and grain Zn concentration in wheat include screening wheat genotypes for higher root Zn uptake and grain translocation efficiency, the inclusion of these Zn-efficient genotypes in breeding programs, and Zn fertilization through soil, foliar and seed treatments.

     

Genetic dissection of grain traits in Yamadanishiki,an excellent sake-brewing rice cultivar

Key message

The grain traits of Yamadanishiki, an excellent sake-brewing rice cultivar in Japan, are governed by multiple QTLs, namely, a total of 42 QTLs including six major QTLs.

Abstract

Japanese rice wine (sake) is produced using brewing rice (Oryza sativa L.) that carries traits desirable for sake-brewing, such as a larger grain size and higher white-core expression rate (WCE) compared to cooking rice cultivars. However, the genetic basis for these traits in brewing rice cultivars is still unclear. We performed analyses of quantitative trait locus (QTL) of grain and days to heading over 3 years on populations derived from crosses between Koshihikari, a cooking rice, and Yamadanishiki, an excellent sake-brewing rice. A total of 42 QTLs were detected for the grain traits, and the Yamadanishiki alleles at 16 QTLs contributed to larger grain size. Two major QTLs essential for regulating both 100-grain weight (GWt) and grain width (GWh) were harbored in the same regions on chromosomes 5 and 10. An interaction was noted between the environment and the QTL associated with WCE on chromosome 6, which was detected in two of 3 years. In addition, two QTLs for WCE on chromosomes 3 and 10 overlapped with the QTLs for GWt and GWh, suggesting that QTLs associated with grain size also play an important role in the formation of white-core. Despite differences in the rate of grain growth in both Koshihikari and Yamadanishiki across 2 years, the WCE in Yamadanishiki remained consistent, thus demonstrating that the formation of white-core does not depend on grain filling speed. These data can be informative for programs involved in breeding better cooking and brewing rice cultivars.

     

Expression of sorghum gene <Emphasis Type="Italic">SbSGL</Emphasis> enhances grain length and weight in rice

Grain weight is a major determining factor of rice (Oryza sativa L.) yield and the comprehensive embodiment of grain length, width, and thickness. Here, we describe the molecular and functional characterization of SbSGL (Sorghum bicolor L. stress tolerance and grain length), a sorghum gene that encodes a putative member of the DUF1645 protein family of unknown function. Expression of SbSGL in rice promoted cell division and grain filling, which affected an array of traits of rice, including grain length, grain weight, and seed setting rate. Expression of SbSGL also affected the expression of genes related to the plant cell cycle and grain size.     

Genetic dissection of sorghum grain quality traits using diverse and segregating populations

Key message

Coordinated association and linkage mapping identified 25 grain quality QTLs in multiple environments, and fine mapping of the Wx locus supports the use of high-density genetic markers in linkage mapping.

Abstract

There is a wide range of end-use products made from cereal grains, and these products often demand different grain characteristics. Fortunately, cereal crop species including sorghum [Sorghum bicolor (L.) Moench] contain high phenotypic variation for traits influencing grain quality. Identifying genetic variants underlying this phenotypic variation allows plant breeders to develop genotypes with grain attributes optimized for their intended usage. Multiple sorghum mapping populations were rigorously phenotyped across two environments (SC Coastal Plain and Central TX) in 2 years for five major grain quality traits: amylose, starch, crude protein, crude fat, and gross energy. Coordinated association and linkage mapping revealed several robust QTLs that make prime targets to improve grain quality for food, feed, and fuel products. Although the amylose QTL interval spanned many megabases, the marker with greatest significance was located just 12 kb from waxy (Wx), the primary gene regulating amylose production in cereal grains. This suggests higher resolution mapping in recombinant inbred line (RIL) populations can be obtained when genotyped at a high marker density. The major QTL for crude fat content, identified in both a RIL population and grain sorghum diversity panel, encompassed the DGAT1 locus, a critical gene involved in maize lipid biosynthesis. Another QTL on chromosome 1 was consistently mapped in both RIL populations for multiple grain quality traits including starch, crude protein, and gross energy. Collectively, these genetic regions offer excellent opportunities to manipulate grain composition and set up future studies for gene validation.

     

Characterization of grain protein content gene (<Emphasis Type="Italic">GPC</Emphasis>-<Emphasis Type="Italic">B1</Emphasis>) introgression lines and its potential use in breeding for enhanced grain zinc and iron concentration in spring wheat

At least two billion people around the world suffer from micronutrient deficiency, or hidden hunger, which is characterized by iron-deficiency anemia, vitamin A and zinc deficiency. As a key staple food crop, wheat provides 20% of the world’s dietary energy and protein, therefore wheat is an ideal vehicle for biofortification. Developing biofortified wheat varieties with genetically enhanced levels of grain zinc (Zn) and iron (Fe) concentrations, and protein content provides a cost-effective and sustainable solution to the resource-poor wheat consumers. Large genetic variation for Fe and Zn were found in the primitive and wild relatives of wheat, the potential high Zn and Fe containing genetic resources were used as progenitors to breed high-yielding biofortified wheat varieties with 30–40% higher Zn content. Grain protein content (GPC) determines processing and end-use quality of wheat for making diverse food products. The GPC-B1 allele from Triticum turgidum L. var. dicoccoides have been well characterized for the increase in GPC and the associated pleiotropic effect on grain Zn and Fe concentrations in wheat. In this study effect of GPC-B1 allele on grain Zn and Fe concentrations in wheat were measured in different genetic backgrounds and two different agronomic management practices (with- and without foliar Zn fertilization). Six pairs of near-isogenic lines differing for GPC-B1 gene evaluated at CIMMYT, Mexico showed that GPC-B1 influenced marginal increase for grain Zn, Fe concentrations, grain protein content and slight reduction in kernel weight and grain yield. However, the magnitude of GPC and grain Zn and Fe reductions varied depending on the genetic background. Introgression of GPC-B1 functional allele in combination with normal or delayed maturity alleles in the CIMMYT elite wheat germplasm has the potential to improve GPC and grain Zn and Fe concentrations without the negative effect on grain yield due to early senescence and accelerated maturity.     

Contributions of root uptake and remobilization to grain zinc accumulation in wheat depending on post-anthesis zinc availability and nitrogen nutrition

Background and aims

Whether root Zn uptake during grain filling or remobilization from pre-anthesis Zn stores contributes more to grain Zn in wheat is subject to an on-going debate. This study investigated the effects of N nutrition and post-anthesis Zn availability on the relative importance of these sources.

Methods

Durum wheat plants were grown in nutrient solution containing adequate Zn (0.5?μM) and three different N levels (0.5; 1.5; 4.5?mM). One third of the plants were harvested when they reached anthesis. One half of the remaining plants were grown to maturity with adequate Zn, whereas the Zn supply to the other half was discontinued at anthesis. Roots, straw and grains were harvested separately and analyzed for Zn and N.

Results

Depending on the N supply, Zn remobilization from pre-anthesis sources provided almost all of grain Zn when the Zn supply was withheld at anthesis; otherwise up to 100?% of grain Zn could be accounted for by Zn taken up post-anthesis. By promoting tillering and grain yield and extending the grain filling, higher N supply favored the contribution of Zn uptake to grain Zn accumulation.

Conclusion

Remobilization is critical for grain Zn accumulation when Zn availability is restricted during grain filling. However, where root uptake can continue, concurrent Zn uptake during grain development, favored by higher N supply, overshadows net remobilization.     

Barley grain at Uppåkra,Sweden: evidence for selection in the Iron Age

A metric analysis on hulled barley grain from the Iron Age regional centre of Uppåkra and surrounding sites in southern Sweden has identified a variation in the size of the grain found on these archaeological sites. Large, high-quality grain was found more frequently at Uppåkra when compared to sites in the surrounding area, where smaller grain was more frequent. The observed large grain found at Uppåkra was, however, restricted to only a few house contexts, including hall-buildings, while other contexts on the site, such as areas dedicated to craft production, had barley assemblages containing smaller grain, similar to the size range found on the surrounding sites. The intra-site variation between different contexts at Uppåkra points to a degree of sorting for larger grain and that this variation between grain assemblages was the result of selection after the crop processing was completed. The distribution of grain size at Uppåkra shows a pattern that indicates that the high-quality barley grain was indented for specific individuals or households. The different contexts at Uppåkra have together produced a record spanning the first millennium ad, representing almost the whole existence of the site. The evidence for selection of larger grain can be seen in the hall-buildings throughout most of the first millennium ad, although less prominently during the Late Roman Iron Age (ad 200–400), while during the Migration Period (ad 400–550) several houses on the main site Uppåkra had assemblages of large grain size. The distribution of grain size at the regional centre Uppåkra shows a pattern that indicates that the handling of large high-quality barley grain was part of a spatial organization, and such organization is similar to other functions observed on the site. The long-term record of grain size patterns across time shows that a structure for handling grain was already in place during the early phase of the settlement and that it remained for centuries. This study indicates that the affluence otherwise seen at the regional centre Uppåkra from an abundance of high-status objects, could also include agricultural wealth, with extensive access to high-quality grain.     

Genetic control of grain yield and grain physical characteristics in a bread wheat population grown under a range of environmental conditions

Key message

Genetic analysis of the yield and physical quality of wheat revealed complex genetic control, including strong effects of photoperiod-sensitivity loci.

Abstract

Environmental conditions such as moisture deficit and high temperatures during the growing period affect the grain yield and grain characteristics of bread wheat (Triticum aestivum L.). The aim of this study was to map quantitative trait loci (QTL) for grain yield and grain quality traits using a Drysdale/Gladius bread wheat mapping population grown under a range of environmental conditions in Australia and Mexico. In general, yield and grain quality were reduced in environments exposed to drought and/or heat stress. Despite large effects of known photoperiod-sensitivity loci (Ppd-B1 and Ppd-D1) on crop development, grain yield and grain quality traits, it was possible to detect QTL elsewhere in the genome. Some of these QTL were detected consistently across environments. A locus on chromosome 6A (TaGW2) that is known to be associated with grain development was associated with grain width, thickness and roundness. The grain hardness (Ha) locus on chromosome 5D was associated with particle size index and flour extraction and a region on chromosome 3B was associated with grain width, thickness, thousand grain weight and yield. The genetic control of grain length appeared to be largely independent of the genetic control of the other grain dimensions. As expected, effects on grain yield were detected at loci that also affected yield components. Some QTL displayed QTL-by-environment interactions, with some having effects only in environments subject to water limitation and/or heat stress.     

Biofortification of zinc in wheat grain by the application of sewage sludge

Background and aims

Increasing the concentrations of the essential micronutrient Zn in staple crops like grain is desirable for human nutrition. We investigated the long-term ability of municipal treatment works sewage sludge, liquid sewage sludge and ZnCO₃ applied to soils to increase Zn in in wheat grain (Triticum aestivum L.) in a number of field experiments conducted on different soils.

Methods

We used six long-term field experiments that were set up on contrasting soils in England and the target applications were built up between 1994 and 1997. Topsoil samples and harvested grain samples were taken and air dried in 1999, 2001, 2003 and 2005. Relationships between grain Zn concentrations and soil properties and changes with time were examined.

Results

Wheat grain Zn concentrations increased with soil Zn concentrations in a similar log-log relationship with all of the Zn sources tested. Comparing total or extractable Zn in soil as explanatory factors showed little benefit of using extractable Zn measurements to predict grain concentrations over total Zn. Additional factors such as soil pH or organic carbon did not explain much more of the variation in grain Zn in our experiments. However, grain Zn concentrations did not respond at all at a site with pH 7.7.

Conclusions

Sewage sludge applications to soil can increase grain Zn concentrations for at least 2 to 8?years after application and has similar effectiveness to ZnCO₃.     

Contributions of <Emphasis Type="Italic">TaSUTs</Emphasis> to grain weight in wheat under drought

Key message

The homologous genes to OsSUT1-5 in wheat were identified and detailed analysed. TaSUT1 was the predominant sucrose transporter group and it illustrated the genotypic variations towards drought during grain filling.

Abstract

Sucrose transporters (SUT) play crucial roles in wheat stem water soluble carbohydrate (WSC) remobilization to grain. To determine the major functional SUT gene groups in shoot parts of wheat during grain development, drought tolerant varieties, Westonia and Kauz, were investigated in field drought experiments. Fourteen homologous genes to OsSUT1-5 were identified on five homeologous groups, namely TaSUT1_4A, TaSUT1_4B, TaSUT1_4D; TaSUT2_5A, TaSUT2_5B, TaSUT2_5D; TaSUT3_1A, TaSUT3_1D; TaSUT4_6A, TaSUT4_6B, TaSUT4_6D; TaSUT5_2A, TaSUT5_2B, and TaSUT5_2D, and their gene structures were analysed. Wheat plants above the ground were harvested from pre-anthesis to grain maturity and the stem, leaf sheath, rachis, lemma and developing grain were used for analysing TaSUT gene expression. Grain weight, thousand grain weight, kernel number per spike, biomass and stem WSC were characterized. The study showed that among the five TaSUT groups, TaSUT1 was the predominant sucrose transporting group in all organs sampled, and the expression was particularly high in the developing grain. In contrast to TaSUT1, the gene expression levels of TaSUT2, TaSUT3 and TaSUT4 were lower, except for TaSUT3 which showed preferential expression in the lemma before anthesis. The TaSUT5 gene group was very weakly expressed in all tissues. The upregulated gene expression of TaSUT1 Westonia type in stem and grain reveal a crucial role in stem WSC remobilization to grain under drought. The high TaSUT1 gene expression and the significant correlations with thousand grain weight (TGW) and kernel number per spike demonstrated the contribution in Kauz’s high grain yield in an irrigated environment and high TGW in Westonia under drought stress. Further molecular level identification is required for gene marker development.

     

Response of corn (Zea mays L.) to manganese application on Atlantic Coastal Plain soils

Field research was conducted on four Atlantic Coastal Plain soils in the United States to evaluate response of corn (Zea mays L.) plants to Mn application. The soils under study were classified as either Aeric or Typic Ochraquults. Manganese application increased corn grain yields by an average of 1195 kg ha^–1 on the four soils. The average grain yields on the soils were 7955 kg ha^–1 for the control and 9150 kg ha^–1 for the +Mn treatment. A Mitscherlich plant growth model was used to establish relationships between percent maximum grain yield and Mn concentration in the ear leaf at early silk (r=0.87, =0.01) and in the mature grain (r=0.58, =0.01). Based on 90% of maximum yield as the definition of the critical deficiency level, the critical Mn deficiency levels calculated with parameters from the Mitscherlich model were 10.6 mg kg^–1 in the ear leaf and 4.9 mg kg^–1 in the grain.     

Phenol oxidising enzymes in the grain aphid’s saliva

Sucrose-agarose gels and sucrose liquid diets were used to study the phenol oxidising enzymes in the salivary secretions of the grain aphid, Sitobion avenae (Fabricius). Activity indicating the presence of two oxidoreductases, polyphenol oxidase (PPO) and peroxidase (Px), was found. Both enzymes were present in the aphids stylet sheath (gelling saliva) but only polyphenol oxidase activity was found in the halos around sheaths and thus in watery saliva. Electrical penetration graphs (EPG) revealed that the secretion of these enzymes into the gels, by an individual aphid, was associated with its probing activity observed during penetration of the epidermal and mesophyll tissues. The grain aphids PPO, secreted in its saliva reacted with a range of phenolic compounds. As most of these phenolics occur naturally in cereals, the grain aphid could modify its host-plants phenolic composition. The importance of the grain aphids polyphenol oxidase and peroxidase in detoxifying cereal phenolics is discussed.