Enhancing the mineral and vitamin content of wheat and maize through plant breeding

More than half of the world's population suffers micronutrient undernourishment. The main sources of vitamins and minerals (iron, zinc, and vitamin A) for low-income rural and urban populations are staple foods of plant origin that often contain low levels or low bioavailability of these micronutrients. Biofortification aims to develop micronutrient-enhanced crop varieties through conventional plant breeding. HarvestPlus, the CGIAR's biofortification initiative, seeks to breed and disseminate crop varieties with enhanced micronutrient content that can improve the nutrition of the “hard to reach” (by fortification or supplementation programmes) rural and urban poor in targeted countries/regions. In attempting to enhance micronutrient levels in maize and wheat through conventional plant breeding, it is important to identify genetic resources with high levels of the targeted micronutrients, to consider the heritability of the targeted traits, to explore the availability of high throughput screening tools and to gain a better understanding of genotype by environment interactions. Biofortified maize and wheat varieties must have the trait combinations which encourage adoption such as high yield potential, disease resistance, and consumer acceptability. When defining breeding strategies and targeting micronutrient levels, researchers need to consider the desired micronutrient increases, food intake and retention and bioavailability as they relate to food processing, anti-nutritional factors and promoters. Finally, ex ante studies are required to quantify the burden of micronutrient deficiency and the potential of biofortification to achieve a significant improvement in human micronutrient status in the deficient target population in order to determine whether a biofortification program is cost-effective.     

Relationship Between the First Base of the Donor Splice Site of Waxy Gene Intron 1 and Amylose Content in Yunnan Indigenous Rice Varieties

There exists a single nucleotide polymorphism, G or T, at the first base of the donor splice site of waxy gene intron 1 in rice. In order to study the relationship between the first base of the donor splice site of waxy gene intron 1 and amylose content in rice, the one-step PCR method was used to determine whether it is G or T in 220 Yunnan indigenous rice varieties from 14 districts, 55 towns/counties of Yunnan Province, and 101 varieties of which were validated by the PCR-Acc I method. According to the G/T polymorphism, 164 rice varieties showed GG-genotype, while the other 56 fell into TT-genotype, accounting for 74.5% and 25.5% of all the test varieties, respectively. When all the rice varieties were divided into indica and japonica subspecies, it was found that 80.5% of indica rice and 67.0% of japonica rice belonged to GG-genotype. The rice varieties with GG-genotype had significantly higher amylose content (18.95% on average) than those with TT-genotype (all below 16%), but 33 rice varieties with GG-genotype still had low amylose content ranging from 3.91% to 15.93%, and most of them came from the Dai minority area in the Southwest of Yunnan Province. However, there was no significant difference in the mean amylose content of the same GG or TT genotypes between indica and japonica rice, suggesting that different genetic backgrounds, indica or japonica, had no effect on amylose content. The coefficient of correlation between the genotype and amylose content was 0.733 (P<0.01).     

花期干旱胁迫后限源疏库对玉米光合性能和茎流的影响

开展玉米花期干旱限源疏库试验,探索减轻花期干旱胁迫的技术途径。结果表明,去根叶组叶片可显著减少植株前期茎流,抑制叶片蒸腾,对穗5叶的叶绿素相对含量、光系统Ⅱ最大光化学效率(Fv/Fm)和潜在活性(Fv/Fo)影响不显著,正常灌溉情况下还有利于延缓玉米花后穗5叶的衰老,并促进后期茎流超补偿;去耕作层1/4根系会加剧前期植株水分的散失,干旱时浅中耕的措施是不可取的,并抑制后期茎流,增大Fv/Fm;去穗虽然可以显著减少茎流,抑制叶片蒸腾,但是因缺少库需求而加速花后穗5叶的叶绿素相对含量、Fv/Fm和Fv/Fo下降,促使叶片衰老。品种间对花期干旱胁迫后不同的限源疏库处理表现出显著差异,这是生物节水和作物补偿生长的生理基础。     

响应曲面法优化美拉德反应以制备蘑菇酪氨酸酶活性抑制组分

MRPs作为天然抗褐变剂,可抑制引起果蔬酶促褐变的酪氨酸酶的酶活。为进一步优化美拉德反应以制备酪氨酸酶活性抑制组分,本研究采用响应面法对MRPs制备工艺进行研究。在单因素实验基础上,确定美拉德反应初始pH、反应温度、反应时间、底物浓度比(糖∶氨基酸)4个因素,设计4因素5水平的二次回归中心组合试验。经响应面法分析,为方便实际操作,确定最佳工艺条件为:初始pH为2.94,反应时间为1.9 h,反应温度为110.09℃,底物浓度比(糖∶氨基酸)为0.57。经实验验证,得出结果与理论值相对误差较小,故采用二次回归中心组合设计得到的最优MRPs制备条件参数准确可靠。     

Enhanced kernel set promoted by synchronous pollination determines a tradeoff between kernel number and kernel weight in temperate maize hybrids

Maize (Zea mays L.) grain yield is strongly related to the number of harvested kernels, where kernel number can be increased by synchronously pollinating silks rather than allowing them to be progressively pollinated as they naturally appear from the husks. However, there is scarce evidence on how this practice affects kernel weight (KW) and plant grain yield (PGY), and no report exists on its effects when combined with treatments aimed to reduce apical dominance, like male sterility and detasseling. Field experiments were conducted in two growing seasons (Exp₁ and Exp₂) using two hybrids, cropped at contrasting stand densities (3 and 9 plants per m²) and including (i) male-fertile and male-sterile versions, (ii) tasseled and detasseled plants, and (iii) natural (NP) and synchronous pollination (SP; pollen added manually to ears bagged 5 days after initial silking) systems. Tassel growth of sterile and fertile versions was also evaluated in a separate experiment (Exp₃). Detasseling increased the number of ears per plant reaching silking (P < 0.001) of NP plants, but this beneficial effect of reduced apical dominance did not improve kernel number per plant (KNP) or PGY. Similarly, the early arrest of anther growth in male-sterile plants had no clear benefit on KNP. In contrast, KNP was enhanced by synchronous pollination (range between −13% and +71%; average of +15.4% in Exp₁ and +3.9% in Exp₂). However, this pollination system promoted a decreased in KW (range between −30% and +4%; average of −11.8% in Exp₁ and −7.8 in Exp₂) such that the treatment had no effect on PGY (range between −19% and +37%; average of +1% in Exp₁ and −4% in Exp₂). Because plant growth rate around flowering was not different between pollination treatments, assimilate availability per kernel was reduced from ovary fertilization onwards in synchronously pollinated plants when compared to open pollinated plants. This explains the reduced KW when increasing KNP by synchronous pollination. In summary, none of the imposed treatments allowed grain yield to be increased at the plant level.     

马铃薯高产施肥措施研究

试验采用 311改良饱和D设计方法 ,对青海省新育成的青薯 2号 (32 8)品种进行了氮、磷、钾三大要素的施肥水平研究。其结果表明 :三种化肥对产量影响的大小程度依次排序为N >K >P。经计算机模拟寻优 ,获得了施肥的高产数学模型和最佳农艺措施组合方案。 6 6 7m2 产量高于2 6 0 0kg的最优方案有 18套 ,最佳农艺措施是 :氮肥用量为 2 8 97～ 2 9 15kg ,钾肥用量为 16 5 4～17 11kg ,磷肥用量为 5 34～ 5 88kg。     

城市住宅小区绿化设计初探

为了增进人与自然和谐以及社会、经济、生态的可持续发展,阐述了园林植物在城市住宅小区绿化中的重要作用,对当前中国城市住宅小区绿化设计现状及存在问题进行了综合分析,提出了城市住宅小区绿化设计与自然生态环境的关系,以及通过植物配置的最佳方式来提高城市住宅小区园林绿化的综合效益。     

Loss of and damage to scallops due to storms in the Sea of Okhotsk

In the coastal zone of the Sea of Okhotsk off Hokkaido, Japan, the giant ezo scallop ( Patinopecten yessoensis ) is widely cultivated on the sea bed, making its fishery a major industry. However, the area experiences intense cyclones, including typhoons, about once a decade and the scallop resources appear to have received severe damage from the storms. Such an event occurred on 29 October 1988. The storm caused 12-m-high wind waves, which appeared to be fully developed sea waves. The water above the sea bed repeatedly moved back and forth at speeds of 1∼2 m s^-1 causing damage to the scallops due to collisions and rubbing with gravel and other scallops. From a comparison of wind data with the annual catch of scallops, intense cyclones seem to play an important role on the year-to-year fluctuations in the scallop fishery.     

对虾病毒病的研究现状

主要依据９０年代关于对虾病毒病的资料,就对虾病毒的病原、诊断技术、预防进行综合述评,总结概括了对虾病毒病的研究现状。