Controlling sprouting in potato tubers using ultraviolet-C irradiance

Legislation limiting the use of chlorpropham (CIPC), the major potato sprout suppressant, has led to a need for new technologies to extend storage life of tubers. Ultra violet C (UV-C) has been used postharvest to reduce disease incidence on many crops, yet its use and efficacy as a sprout suppressant has not been investigated. The aim of this project was to identify the optimum dose and treatment timing of UV-C treatment on potato tubers as an alternative method of sprout suppression to reduce the dependence on chemical sprout suppressants. Up to six potato cultivars over two seasons were treated with varying doses of UV-C ranging from 0 to 30 kJ m⁻² either at harvest or at first indication of dormancy break. The tubers were stored at 9 °C and sprout growth and incidence assessed. Treatment with moderate UV-C doses (5–20 kJ m⁻²) suppressed sprout length and sprout incidence in a range of cultivars. Periderm DNA damage and programmed cell death were not detected in response to any of the UV-C doses. The inactive ABA metabolite, ABA-GE, increased in response to 10 or 20 kJ m⁻² within 72 h of treatment. Multivariate analysis showed a negative relationship between ABA metabolites and sprout growth/incidence during storage. This study found that UV-C reduced sprout growth in potato with no deleterious effects on tuber quality. This suggests potential for further development as an alternative or supplement to conventional sprout suppressant technologies.     

鸡脚重性状的全基因组关联分析

鸡(Gallus gallus)脚重性状为鸡产业中的重要经济性状.为了揭示鸡脚重性状的遗传基础,寻找可用于鸡脚改良的分子标记,本研究以核心群京海黄鸡为实验动物,测定其脚重,利用简化基因组测序技术在整个基因组范围内检测与脚重相关的SNPs.共检测到16个与脚重相关的SNPs位点,其中13个集中分布在4号染色体上72.8～77.9 Mb区域;2个SNP位点rs475641139和rs475548810达到5％ Bonferroni全基因组显著水平(P＜5.5E-07),其余位点达到全基因组潜在显著水平(P＜1.1E-05).筛选每个SNP周围1 Mb区域内的基因,共找到9个可能的候选基因,并使用基因本体论(Gene Ontology,GO)数据库对9个候选基因的细胞组分、分子功能和参与的生物学进程进行了分析.结果表明二氢蝶啶还原酶(dihydropteridine deductase,QDPR)基因、LIM域结合蛋白2(LIM domain-binding protein 2,LDB2)基因、类184B家族(family with sequence similarity 184 memberB,FAM184B)基因、复合信号免疫球蛋白J结合蛋白(recombination signal binding protein for immunoglobulin kappa J region,RBPJ)基因、纤维母细胞生长因子结合蛋白2(fibroblast growth factor-binding protein 2,FGFBP2)基因、富亮氨酸重复蛋白5(F-box and leucine-rich repeat protein 5,FBXL5)基因、胆囊收缩素受体A(cholecystokinin receptor type A,CCK1R)基因、肌动蛋白互作蛋白1 (WD repeat containing protein 1,WDR1)基因和类桶状蛋白4(tubby like protein 4,TULP4)9个基因和4号染色体72.8～77.9 Mb区域可能为影响鸡脚重性状的重要候选基因和潜在功能区域.本研究为鸡脚重性状的标记辅助选择提供了理论依据.     

Effects of Different Nitrogen Treatments on N use Efficiency and Grain Yield of Mechanically-transplanted Hybrid Rice

In order to investigate effects of topdressing on grain yield and N use efficiency of mechanically-transplanted hybrid rice,this experiment was conducted with 2-line hybrid rice cultivars,Quanliangyou 1 and Quanliangyou 681 with 3 application levels of N fertilizer,No,N1,N2,respectively.The results showed that there were no significant differences in grain yields of the 2 varieties between treatments N1 and N2.It was indicated that N is not the factor which could limit grain yield within limited application levels of N fertilizer.High N fertilizer treatment could contribute to the formation of effective panicles and spikelets per panicle,but it could also lead to the decline in grain filling rate.It was suggested that lowering the amount of Nfertilizer could facilitate improvement of N-use efficiency.     

不同生态环境下甘蔗组合的生长表现和适应性

以2017—2018年组配的119个甘蔗组合为材料,分别在广西的南宁、崇左、来宾同时开展组合评价试验,基于锤重性状进行联合方差分析和遗传参数估计,并采用回归分析和AMMI模型对组合进行稳定性分析。结果表明:不同的组合、环境及组合与环境互作在锤重间的差异均达到了极显著水平(P0.01);3个试验点锤重的广义遗传率均属于中等偏低水平;崇左、来宾试验点的锤重变异系数较大,南宁试验点的锤重变异系数较小;643、404、575、972、636、144、YC95、1470、755、409、701、832、YC37、579等组合表现出高产、稳产和适应性广的特性;结合锤重和组合入选率综合分析,组合449、YC127、796、YC44、533、570、YC123、391、546、403、YC90、252在南宁试验点的表现为锤重和组合入选率较高;组合643、212、YC61、432、903、YC95、YC44、368、YC83、YC127、YC112、701、411、YC90、YC123在崇左试验点的表现为锤重和组合入选率较高;组合643、404、449、144、403、YC48在来宾试验点的表现为锤重和组合入选率较高。     

Effect of feeding different sources of selenium on growth performance and antioxidant status of broilers

ABSTRACT

1. This study was conducted to determine the effect of different sources of selenium (Se) on breast and liver tissue deposition, apparent metabolisable energy (AME), growth performance and antioxidant status of broilers, measured as Se content in liver and breast tissues and glutathione peroxidase (GSH-Px) in blood, when used in 0–35 d broiler chicken diets.

2. A total of 200 male Ross 308 broilers were used in the feeding trial, which comprised two dietary phases, a starter from 0 to 21 d and finisher from 21 to 35 d of age. Four treatments with 10 replications each were used. A control diet (C) was formulated that was sufficient in protein and energy (230 and 215 g/kg of crude protein and 12.67 and 13.11 MJ/kg of metabolisable energy, respectively), for both phases, but contained background Se only from the feed ingredients. Diet 2 (IS) was supplemented with 10.35 g/t inorganic, elemental source of Se. Diet 3 (SY) was supplemented with 136.36 g/t selenised yeast, an organic source derived from Saccharomyces cerevisiae. Diet 4 (SS) was supplemented with 0.666 g/t sodium selenite, an inorganic source.

3. Birds fed the SY diet consumed less and weighed less than those fed IS or C (P < 0.05; 0–35 d of age), but there was no difference compared to birds fed SS diets. There were no differences in FCR or dietary AME between broilers fed different Se sources. All diets containing supplementary Se increased concentrations in the liver and breast muscle, and for GSH-Px levels in blood compared to birds fed the C diet (P < 0.001). Birds fed SY diets had greater Se levels in liver and breast tissues compared to birds fed any of the other diets (P < 0.001).

4. Diets supplemented with Se had variable effects on broiler growth performances and antioxidant status. Feeding Se from a yeast source has higher transfer into breast tissues. Feeding different sources and levels of Se to birds in a more challenging situation to induce oxidative stress may bring more conclusive results.     

Dynamic change of mineral nutrient content in different plant organs during the grain filling stage in maize grown under contrasting nitrogen supply

The introduction of new hybrids and integrated crop-soil management has been causing maize grain yield to increase. However, less attention has been paid on the nutrient concentration of the grain; this aspect is of great importance to supplying calories and nutrients in the diets of both humans and animals worldwide. Increasing the retranslocation of nutrients from vegetative organs to grain can effectively increase the nutrient concentration of grain and general nutrient use efficiency. The present study involved monitoring the dynamic change of macro- and micronutrients in different organs of maize during the grain filling stage. In addition, the mobility of different elements and their contribution to grain nutrient content were evaluated in a 2-year experiment under low (LN, no N supplied) and high N (HN, 180 kg N ha⁻¹) supply. Under HN supply, the net remobilization efficiency (RE) of the vegetative organs as a whole (calculated as nutrient remobilization amount divided by nutrient content at silking) of N, P, K, Mn, and Zn were 44%, 60%, 13%, 15%, and 25%, respectively. The other nutrients (Mg, Ca, Fe, Cu, and B) showed a net accumulation in the vegetative organs as a whole during the grain filling stage. Among the different organs, N, P, and Zn were remobilized more from the leaves (RE of 44%, 51% and 43%, respectively) and the stalks (including leaf sheaths and tassels) (RE of 48%, 71% and 43%, respectively). K was mainly remobilized from the leaves with RE of 51%. Mg, Ca, Fe, Mn, and Cu were mostly remobilized from the stalks with the RE of 23%, 9%, 10%, 42%, and 28%, respectively. However, most of the remobilized Mg, Ca, Fe, Mn, Cu, and Zn were translocated to the husk and cob, which seemingly served as the buffer sink for these nutrients. The REs of all the nutrients except for P, K, and Zn were vulnerable to variations in conditions annually and were reduced when the grain yield and harvest index were lower in 2014 compared with 2013. Under LN stress, the RE was reduced in P and Zn in 2013, increased in Cu and unchanged in other nutrients. The concentration of these nutrients in the grain was either unchanged (P, K, Ca, Zn, and B) or decreased (N, Mg, Fe, Mn, and Cu). It is concluded that grain N, P, K, Mn, and Zn, but not Mg, Ca, Fe, Cu, and B concentration, can be improved by increasing their remobilization from vegetative organs. However, enhancing the senescence of maize plant via LN stress seems unable to increase grain mineral nutrient concentration. Genetic improvement aiming to increase nutrient remobilization should take into account the organ-specific remobilization pattern of the target nutrient.     

An improved method for extraction of sorghum polymeric protein complexes

A method for fractionating sorghum proteins using extraction solvents and techniques designed to obtain polymeric protein structures (especially disulfide linked) was developed. Extraction and separation conditions were optimized in terms of completeness of protein extraction, sample stability, and analytical resolution. After pre-extraction of albumins and globulins, a 3-step sequential procedure involving no reducing agents was applied to ground whole sorghum flour. The three fractions obtained represented proportionally different protein polymer contents and molecular weight distribution as evidenced by comparative size exclusion chromatography. Protein composition also varied among the extracts with differences in kafirin composition and non-kafirin proteins detected in the fractions by RP-HPLC and SDS-PAGE analysis. The ability to quantify and further characterize sorghum polymeric protein complexes will be useful for additional studies linking protein structures with functionality and digestibility and variations for these properties within diverse sorghum germplasm.     

Identification of CIMMYT spring bread wheat germplasm maintaining superior grain yield and quality under heat-stress

Unpredictable temperatures and rainfall associated with climate change are expected to affect wheat (Triticum aestivum L.) production in various countries. The development of climate-resilient spring wheat cultivars able to maintain grain yield and quality is essential to food security and economic returns. We tested 54 CIMMYT spring bread wheat genotypes, developed and/or released over a span of 50 years, in the field for two years under optimum sowing dates, as well as using two delayed sowing dates to expose crops to medium and severe heat-stress conditions. The grain yield and yield components were severely affected as the heat-stress increased. Two contrasting groups of 10 lines each were identified to determine the effect of heat-stress on bread-making quality. The first set included entries that produced high yields in optimal conditions and maintained higher yields under heat-stress (superior-yielding lines), while the second set included genotypes that did not perform well in the environment with high temperature (inferior-yielding lines). We identified genotypes exhibiting bread-making quality stability, as well as the quality traits that had higher correlation with the loaf volume in the environment without stress and under heat-stress. Of all the quality traits tested, dough extensibility (AlvL) and grain protein content had a significant influence in heat-stress adaptation. Most of the lines from the superior-yielding group were also able to maintain and even improve quality characteristics under heat-stress and therefore, could be used as parents in breeding to develop high-yielding and stable quality wheat varieties.     

不同燕麦基因型源库关系对穗粒数形成过程的影响

为了解燕麦穗粒数形成过程与源、库特征之间的关系，连续两年以10个不同来源、熟期、穗型、株型、小穗数的燕麦品种为试验材料，测定三叶期至拔节期的幼穗分化阶段及抽穗期源库特征，采用方差分析、聚类分析、逐步回归分析等方法，分析不同燕麦基因型源库特征及对穗粒数形成过程的影响。结果表明，燕麦穗粒数形成过程存在基因型差异，幼穗分化较好品种的穗粒数较全部品种平均值高11.22%~65.43%；幼穗分化较好品种的光合势、干物质量、粒数叶比、收获指数显著高于幼穗分化较差品种，其中粒数叶比和收获指数是影响穗粒数形成的主要因素，粒数叶比和收获指数较全部品种平均值分别高0.99%~68.74%和0.85%~13.80%。综上所述，源库协调是燕麦幼穗分化良好的生理基础，可通过提高光合势和干物质量达到增源的目的，进而提高穗粒数。