基于堆叠沙漏网络的单分蘖水稻植株骨架提取

针对水稻栽培和遗传育种研究中单分蘖性状高通量无损提取的实际需求,该研究提出了一种基于沙漏网络模型的单分蘖水稻关键点预测和骨架提取方法。首先,对原始图像进行批量裁剪、gamma校正和锐化卷积等预处理,获取单色背景下的水稻单分蘖图像数据集;设计水稻单分蘖各器官关键点数据标注策略,构建监督数据集。然后,构建堆叠沙漏网络架构实现叶片数固定和不固定的水稻关键点检测,引入沙漏结构整合图像的多尺度特征,结合中间监督机制整合不同沙漏模块信息。叶片数一致的情况,模型预测准确率最高可达96.48%;叶片数不一致的情况,预测准确率达到82.09%。最后,根据预测关键点及其对应的语义信息连接形成植株骨架,选取茎秆长、叶片长、穗长、叶片-茎秆夹角和茎节点位置5个表型参数对生成骨架模型的实际意义进行评估,其均方根误差依次为5.82 cm、3.09 cm、1.71 cm、3.22°和2.04 cm,证明了该方法能较好地识别水稻单分蘖关键点,为水稻骨架提取提供了一种新思路,有助于加快水稻育种速度。     

海口地区高密度叠层笼养蛋鸡舍内热湿环境的实验研究

针对高密度蛋鸡叠层笼养工艺在海口地区的实际应用，从环境工程角度对舍内温度、湿度等诸多环境因子进行了实验研究。发现舍内环境状况良好，基本满足生产需要，为进一步在全国大中城市推广该工艺提供了宝贵经验。     

海口地区高密度叠层笼养蛋鸡舍内热湿环境的实验研究

针对高密度蛋鸡叠层笼养工艺在海口地区的实际应用，从环境工程角度对舍内温度、湿度等诸多环境因子进行了实验研究。发现舍内环境状况良好，基本满足生产需要，为进一步在全国大中城市推广该工艺提供了宝贵经验。     

蛋鸡高密度叠层笼养工艺的初步研究

蛋鸡叠层笼养工艺具有节约土地、减少环境污染、降低饲养成本、提高投资利用率和劳动生产率等优点，饲养密度达４８．３～６０只／ｍ²，料蛋比２．２～２．５∶１，死淘率低于１５％，与三层全阶梯笼养相比，可节约土地６３．４８％，提高劳动生产率１６０％～２９０％。     

蛋鸡高密度叠层笼养工艺的初步研究

蛋鸡叠层笼养工艺具有节约土地、减少环境污染、降低饲养成本、提高投资利用率和劳动生产率等优点，饲养密度达４８．３～６０只／ｍ２，料蛋比２．２～２．５∶１，死淘率低于１５％，与三层全阶梯笼养相比，可节约土地６３．４８％，提高劳动生产率１６０％～２９０％。     

海口地区蛋鸡高密度叠层笼养工艺饲养效果的实验研究

结合高密度蛋鸡叠层笼养工艺在海口地区的实际应用，对实验舍蛋鸡的产蛋率、死淘率等生产性能指标进行了研究。结果表明：产蛋率接近于标准生产性能，但蛋重明显减小，次蛋率＜０．４％，料蛋比≤２．３∶１，死淘率＜１０％，总体生产性能指标优良。     

Evaluation of Chilo partellus and Busseola fusca susceptibility to δ-endotoxins in Bt maize

Susceptibility of Chilo partellus (Lepidoptera, Crambidae) and Busseola fusca (Lepidoptera, Noctuidae) populations to Cry proteins from the bacterium, Bacillus thuringiensis (Bt), the δ-endotoxins Cry1Ab and Cry1Ba in Bt-maize, were evaluated under biosafety greenhouse conditions. Larval feeding on Bt-maize was adjusted to deliver sub-lethal doses of δ-endotoxins from the two events; survivors were reared on artificial diet to obtain successive generations. Eight generations of three C. partellus populations and five generations of a B. fusca population were screened for susceptibility on each event. Mean proportion of surviving larvae from Bt-maize plants, and the corresponding pupal weights of survivors for each population, were lower for individuals exposed to δ-endotoxins. Both Bt Cry proteins expressed in maize leaves controlled C. partellus and showed stability in control, with no indication of a change in susceptibility among generations. Neither toxin, however, provided complete control of B. fusca, but no changes in susceptibility were observed after five generations of selection. Implications for development of future transgenic Bt maize events, and research for East Africa are discussed.     

Bt-maize effects on biological parameters of the non-target aphid Sitobion avenae (Homoptera: Aphididae) and Cry1Ab toxin detection

Bt-maize crop is increasingly used worldwide and the study of ecological side effects is a major subject in this domain. Under laboratory conditions, we determined Bt-maize effects on the non-target aphid Sitobion avenae (Fabricius) (Homoptera: Aphididae). We found no significant differences between S. avenae on MON810 and the near-isogenic line when alate offspring production, apterous survivorship, longevity, intrinsic rates of natural increase (r_m), finite rates of increase and doubling times were compared. No significant differences were found between treatments for apterous pre-reproductive and reproductive periods. Additionally, we used immunological tests (ELISA) to detect Cry1Ab protein in maize leaves and S. avenae nymphs. Results showed that Bt-maize leaves expressed 0.203 (±0.05) μg Cry1Ab/g leaf tissue (Mean ± SEM). No Cry1Ab protein was present in S. avenae nymphs developing on Bt or conventional maize. We conclude that Bt-maize does not affect the development of the non-target aphid S. avenae and that Cry1Ab toxin quantities in these aphids are nil, suggesting an inconsequential risk for natural enemies of this aphid species.     

Risk assessment of the cultivation of a stacked Bt-maize variety (MON89034 × MON88017) for nematode communities

Genetically modified Bt-maize MON89034 × MON88017 contains three different genes derived from Bacillus thuringiensis (Bt) which enable protection against insect pests, due to expression of three different insecticidal crystal proteins (Cry proteins), i.e., Cry1A.105 and Cry2Ab2 against the European corn borer and Cry3Bb1 against the Western corn root worm. Nematodes are important organisms in agricultural soil ecosystems, and on fields with Bt-maize cultivation they will be exposed to Cry proteins released into the soil from roots or plant residues. The objective of this study was to analyze in a field experiment the effect of Bt-maize MON89034 × MON88017 on nematodes as non-target organisms. Nematode communities from soil planted with the Bt-maize were compared to those from soil planted with the near-isogenic cultivar (with and without chemical insecticide treatment) and two conventional maize cultivars. The experimental field consisted of 40 plots in a completely randomized block design (eight plots for each treatment), which were monitored over two growing seasons (2008 and 2009) at six sampling dates for nematode diversity at the genus level in the rhizosphere soil. Physicochemical soil properties and Cry protein concentrations were also analyzed. Nematodes showed very high abundances, as well as a high diversity of taxa and functional guilds, indicating the relevance of maize fields as their habitat. Neither Bt-maize cultivation, nor insecticide treatment adversely affected abundance or community structure of nematode assemblages in field plots compared to several non-Bt cultivars including a near-isogenic cultivar. This confirmed the risk estimations based on the analyzed soil concentrations of extractable Cry protein, not exceeding 4.8 ng g⁻¹ soil dry weight and thus revealing a safe toxicity-exposure ratio of >20.     

Absolute quantitative detection of genetically modified soybean MON87708×MON89788 with stacked traits by digital polymerase chain reaction

The main advantage of digital PCR (dPCR) is that it facilitates absolute quantification of the target without reference to the standard/calibration curve. Crystal droplet dPCR has a three-color staining detection function, which enables multiplex PCR reaction. In this study, this technique was used to establish triple dPCR detection for the genetically modified soybean MON87708 ​× ​MON89788 with stacked traits. Specific absolute quantitative detection was accomplished for the genomic DNA extracted from the homogenized seeds of GM stack MON87708 ​× ​MON89788 soybean. Our results can serve as a reference for the absolute quantitative detection of stacked events of genetically modified crops.