Irrigation and Zn fertilizer management improves Zn phyto‐availability in various rice production systems

Zinc (Zn) is an important micronutrient for rice (Oryza sativa L.) production and its deficiency has been observed in various production systems. High grain Zn concentration is equally important for high rice yield and human health. In this work, the effects of Zn fertilization on seedling growth, grain yield, grain Zn concentration, and their association with root traits were studied under alternate wetting and drying (AWD), aerobic rice (AR), system of rice intensification (SRI), and continuous flooding (CF). Zinc fertilization (15 kg ha^?1) improved nursery seedlings chlorophyll and Zn concentrations, root length, and number of roots with highest values observed in CF. At harvesting, maximum plant height, panicle length, total and panicle bearing tillers, and kernel yield were found with Zn addition in AWD and CF rice systems. Mid season drainage provided at maximum tillering and Zn fertilization increased its concentration in leaves, culms, panicles, and grains under CF and AR at physiological maturity. Most of Zn applied was allocated into culms and panicles, nevertheless, a significant increase in grain Zn concentration was also observed in all production systems. Association of leaf Zn with grain Zn concentration was stronger than with culm and panicle Zn. The results indicate that Zn application after rice nursery transplanting is more important for grain Zn enrichment in all rice systems than for increase in grain yield in all systems except AWD where grain yield was also increased. More grain yield in CF and AWD as compared to SRI and AR can also be attributed to decreased spikelet sterility and to better Zn phyto‐availability in these rice systems at physiological maturity.     

大豆耐低磷胁迫研究进展

磷是作物生长发育不可缺少的营养元素之一,但它在土壤中有效性是非常低的.缺磷是限制目前农业产量的一个重要因子,传统的农业生产主要通过施肥和土壤改良来满足植物对磷的需求,近年来人们开始发掘磷高效利用植物来替代传统方法提高磷的利用效率.在缺磷胁迫下,植物会产生一系列的包括根系形态及生理方面的适应性变化.本文综述了低磷胁迫对大豆根系、光合作用等影响的研究进展,大豆耐低磷胁迫的遗传学研究进展,以及讨论当前大豆磷效率遗传研究中存在的主要问题.     

基于B/S模式的奶牛日粮诊断系统的实现

针对现有奶牛日粮诊断过程中只考虑日粮营养组分方面的因素造成的局限性,本文首次提出了将奶牛日粮营养组分与营养代谢性病两个因素综合考虑,并以此结果对日粮配方优化设计。基于web2.0技术,采用JSP+Tomcat+MySQL架构,建立了B/S（浏览器/服务器）模式的奶牛日粮诊断系统。该系统先进实用,能有效地解决奶牛日粮配方针对性不强、难以规避奶牛营养性疾病等问题。     

基于深度学习的大豆生长期叶片缺素症状检测方法

为了检测作物叶片缺素,提出了一种基于神经网络的大豆叶片缺素视觉检测方法。在对大豆缺素叶片进行特征分析后,采用深度学习技术,利用Mask R-CNN模型对固定摄像头采集的叶片图像进行分割,以去除背景特征,并利用VGG16模型进行缺素分类。首先通过摄像头采集水培大豆叶片图像,对大豆叶片图像进行人工标记,建立大豆叶片图像分割任务的训练集和测试集,通过预训练确定模型的初始参数,并使用较低的学习率训练Mask RCNN模型,训练后的模型在测试集上对背景遮挡的大豆单叶片和多叶片分割的马修斯相关系数分别达到了0.847和0.788。通过预训练确定模型的初始参数,使用训练全连接层的方法训练VGG16模型,训练的模型在测试集上的分类准确率为89.42%。通过将特征明显的叶片归类为两类缺氮特征和4类缺磷特征,分析讨论了模型的不足之处。本文算法检测一幅100万像素的图像平均运行时间为0.8 s,且对复杂背景下大豆叶片缺素分类有较好的检测效果,可为农业自动化生产中植株缺素情况估计提供技术支持。     

Supplemental iron and phosphorus increase dietary inclusion of cottonseed and soybean meal in olive flounder (Paralichthys olivaceus)

A long‐term feeding experiment was conducted to investigate the use of cottonseed and soybean meal (CS) with iron and phosphorus supplements in diets for olive flounder (Paralichthys olivaceus). Olive flounder with an initial average size of 28.5 ± 0.35 g (mean ± SD) were divided into 15 groups (three tanks per dietary treatment) and fed 480 g kg^?1 crude protein diets in which each of five isonitrogenous diets was formulated to contain different levels of cottonseed/soybean meal (1 : 1) to replace fish meal (FM) with iron and phosphorus supplementations. The five experimental diets were as follows: diet 1 (control), 0%CS; diet 2, 20%CS; diet 3, 30%CS; diet 4, 30%CS + Fe&P; and diet 5, 40%CS + Fe&P. After 26 weeks of feeding trial, no significant differences were observed in weight gain, feed utilization and survival among all the treatments. The total gossypol accumulation in liver of fish fed diets supplemented with iron was significantly lower than that of fish fed diets without supplementation of iron. The results indicate that the addition of iron in diets could prevent the absorption of free gossypol. The findings in this study suggest that dietary supplements of iron and phosphorus could increase the inclusion of cottonseed and soybean meal for FM replacement in diets for marine fish species.     

大豆小肽螯合铁的制备工艺及光谱分析研究

通过铁源筛选比较得知,氯化亚铁比较适合与大豆小肽进行螯合反应制备大豆小肽螯合铁,利用响应面法优化了大豆小肽螯合铁的制备工艺,优化结果为:小肽与亚铁盐质量比4∶1,反应pH5.0,反应温度40℃,得到离子螯合率平均值为56.81%,经中试车间生产试制得到大豆小肽螯合铁的得率是78.3%,螯合率为82.39%,检测大豆小肽螯合铁的主要成分中的蛋白含量为78.94%,铁的含量为10.87%。红外和紫外光谱分析检测结果显示:大豆小肽和大豆小肽螯合铁(Fe~(2+))红外吸收峰的强度在不同波长位置上有明显的变化,大豆小肽螯合铁(Fe~(2+))在紫外波长上发生了明显的位移且宽化,表明大豆小肽螯合铁(Fe~(2+))形成了络合物。同时对大豆小肽螯合铁的结构进行了预测。     

花前氮亏缺对水稻叶片氮代谢酶活性的影响

以籼型杂交稻中浙优1号和籼粳型杂交稻甬优12为材料,试验分析了花前不同时期氮亏缺处理对水稻叶片氮代谢酶活性的影响。结果表明,花前氮亏缺导致植株上3叶氮浓度、NR、GS、GOGAT、GOT和GPT酶活性大幅下降,GDH活性显著增长,且各叶位对花前氮亏缺敏感度总体上表现为剑叶倒2叶倒3叶;破口期亏氮对籼型杂交稻中浙优1号上3叶氮同化酶活性的影响远小于减数分裂期处理,与之相比,籼粳杂交稻甬优12对破口期亏氮胁迫仍较敏感,表明中浙优1号植株氮代谢酶的亏氮敏感性由减数分裂期至破口期逐步下降,对土壤速效氮的需求同步降低,甬优12则对土壤供氮存在更高需求。     

铁氧化物-硅酸盐复合物的形成、性质及其对砷的固定

铁氧化物与硅酸盐矿物是土壤中最重要、最活跃的固相组分,它们之间的交互作用直接影响土壤物理化学特性,可有效地调控土壤(类)重金属的迁移、转化。本文以铁氧化物和硅酸盐矿物胶结过程中的一些表观特征变化为出发点,从宏观、表观到微观综述了二者交互作用的界面特性和机理、交互作用前后对土壤砷的固定与释放机制等内容。本文阐明层状硅酸盐与铁氧化物通过多种化学作用而发生表面复合,其中静电作用是作用力之一,带负电荷的硅酸盐与带正电荷的铁氧化物在静电引力的作用下迅速结合,在胶体表面双电层上形成二元团聚体;形成的二元团聚体可改变土壤矿物的表面积和孔性结构、表面电化学特性和物理性质。同时,铁氧化物-硅酸盐复合物表面的活性基团可以通过内层络合共氧的方式将土壤中AsO_4~(2-)络合,形成单核或双核表面络合物而固定砷。复合物对AsO_4~(2-)的吸附能力介于铁氧化物和硅酸盐矿物之间,并更接近铁氧化物的表面吸附特性。本文旨在为土壤砷的原位固定提供理论支撑。     

低比转速离心泵塑料叶轮设计

以一台低比转速离心泵铸铁叶轮水力模型为原型,将其材质替换为塑料.考虑泵效率提升和注塑工艺可行性对叶轮几何参数进行修改:减小叶轮外径,增加叶轮出口宽度;考虑塑料结构工艺对叶轮结构进行调整:后盖板外侧设置加强筋,轮毂处加铜嵌件,盖板与叶片结合处添加定位孔销和焊接用导熔线。将塑料叶轮和铸铁叶轮安装在同一泵体进行对比测试。测试结果表明:塑料叶轮设计工况点泵的效率由56%提高到60%,增加了4%,既达到国家节能效率指标,又为用户节省了用电费用。     

灰口铸铁电弧热焊法补焊工艺的研究

文章分析了灰口铸铁的焊接性和常用的焊接方法,阐述了电弧热焊法对灰口铸铁进行补焊时的焊接工艺。