Effect of nitrogen root zone fertilization on rice yield,uptake and utilization of macronutrient in lower reaches of Yangtze River,China

Improper application of nitrogen (N) has led to high N losses and low N use efficiency in the lower reaches of Yangtze River in China. An effective method to solve such problems is the deep fertilized N in root zone (RZF). Limited information is available on the effect of RZF on the uptake of macronutrients (N, P and K) and rice yield. Field experiments, conducted from 2014 to 2015, compared the farmer fertilizer practice (FFP, with 225 kg ha^?1 of N, split into three doses) and RZF using the same rate but placing N 5 cm away from rice roots in holes 10 cm deep (RZF10) or 5 cm deep (RZF5) as a single application. The highest mean yield (10.0 t ha^?1) was obtained in RZF10, which was 19.5% more than that in FFP. Root zone fertilization of urea (whether 10 cm deep or 5 cm deep) resulted in greater accumulation of N, P and K in stem, leaf sheaths, leaf blades and grains compared to that in FFP in sandy and in loam soils. The uptake of N, P and K was the highest in RZF10 (average at 176.7, 66.2 and 179.1 kg ha^?1, respectively), higher than that in FFP by 45.0, 17.0 and 22.6%, respectively. N apparent recovery efficiency was markedly higher in RZF10 (53.1%) than in FFP (27.5%). RZF10 significantly increased the N, P, K uptake compared with FFP under different N rates in both sandy and loam soils. These results suggest that the N, P and K input amount should be re-determined under RZF.     

机采籽棉储运技术质量成本分析

阐述了4种不同籽棉储运技术的原理，采用回归分析法分析了机采散状籽棉储运技术、压模车田间压模储运技术、散状籽棉运输场地压模储运技术、采棉机直接压模储运技术的经济性和优点，并建立起质量成本分析模型，为轧花厂籽棉储存技术应用和改进提供依据。     

Semisynthetic ferulic acid derivative: an efficient feed additive for Genetically Improved Farmed Tilapia (Oreochromis niloticus)

Ferulic acid (FA) derivative was synthesized by modifying the functional groups of FA as dietary additive in the feeding of Genetically Improved Farmed Tilapia (GIFT) juveniles. Structural confirmation of this compound was based on IR, ¹H and ¹³C NMR techniques. This study was conducted to evaluate the effects of dietary FA derivative supplementation on growth performance, antioxidant status and serum biochemical parameters of GIFT juveniles compared with that of FA. A total of 675 fish with an average initial weight of 10.73 ± 0.40 g were fed nine diets supplemented with 0, 0.26, 0.52, 1.04 and 2.08 mmol kg^?1 FA, or 0.26, 0.52, 1.04 and 2.08 mmol kg^?1 FA derivative. Each diet was assigned to three replicate groups of 25 experimental tilapia for 56 days. Weight gain (WG) in groups of fish fed FA derivative was much higher than that of fish fed FA diet (P < 0.05). The antioxidant enzyme activities (SOD, CAT and GPx) in serum and liver of tilapia fed the FA derivative diets were significantly higher, while the malondialdehyde values were significantly lower than those of the fish fed the FA diets (P < 0.05). The serum biochemical parameters of GIFT were significantly improved by the FA derivative supplement. Moreover, feed conversion ratio, hepatosomatic index and viscerosomatic index were significantly decreased in fish fed FA or FA derivative diet at 0.52 mmol kg^?1 feed (P < 0.05). The investigation on the semisynthetic FA derivative provides a new way for developing safe and efficient feed additives.     

基于双圆盘覆土的种肥分施装置设计与试验

【目的】针对免耕条件下玉米播种施肥时,采用自然回土方式存在的种肥间距不稳定、种子覆土量不足等问题,采用主动覆土方法,设计一种基于双圆盘覆土的种肥分施装置。【方法】设计基于双圆盘覆土的种肥分施装置,利用EDEM对该装置的作业性能进行离散元仿真,研究圆盘直径、圆盘入土深度、圆盘张角、排种管前后间距及圆盘后方开口间距对种肥间距和种子覆土厚度的影响,并在此基础上选取圆盘直径(150,175,200,225,250 mm)、排种管前后间距(60,80,100,120,140 mm)及圆盘后方开口间距(110,135,160, 185,210 mm)为试验因素,利用3因素5水平二次正交回归试验,分析各关键因素对种子覆土厚度的影响。与不加覆土圆盘的装置进行田间对比试验,对基于双圆盘覆土的种肥分施装置作业效果进行验证。【结果】利用Design-Expert软件得出了影响种子覆土厚度的主次因素:圆盘后方开口间距、排种管前后间距、圆盘直径;最优组合是圆盘直径201 mm,圆盘后方开口间距103 mm,排种管前后间距115 mm。田间试验表明,设计的装置种肥间距与种子覆土厚度与仿真优化结果的相对误差分别为7.63%和11.45%;设计的装置种肥间距和种子覆土厚度较不加覆土圆盘的装置分别增加了14.30%和19.30%,种肥间距与种子覆土厚度的变异系数分别为5.21%和7.26%。【结论】所设计的基于双圆盘覆土的种肥分施装置作业效果满足种肥分施要求,为后续种肥分施技术与装置的研发提供了依据。     

崎岖山地环境履带机器人降维变系数控制方法研究

针对崎岖山地环境下自走式履带机器人自走姿态波动大、跟踪精度低等问题,研究了三维崎岖路面履带机器人控制方法。通过分析机器人在二维平整路面与三维崎岖路面的运动学模型,建立了降维运动学几何模型;设计了一种基于降维变系数的滑模控制方法,实现三维崎岖路面履带机器人的运动控制,并进行了平整路面与崎岖路面的路径跟踪仿真与试验。仿真结果表明,平整路面仿真中,行驶方向误差逐渐减小并趋近于0,侧向位置误差在±0. 2 m内波动,并可在1 s内完成姿态调整;崎岖路面仿真中,三轴位置误差均控制在±0. 1 m范围内,同样可在1 s内完成姿态调整。路径跟踪田间试验结果表明,平整路面和崎岖路面机器人跟踪稳定后的横向误差分别为-2. 9～8. 8 cm、-14. 3～21. 5 cm,姿态误差分别控制在±2°、±5°内,能够满足实际跟踪需求。     

Does the application of silvicultural management models drive the growth and stem quality of sweet chestnut coppices towards sustainability?

New Forests - The coppice is a very flexible cultural system producing several calibers adapting to the demands of the market. Small-caliber roundwood from sweet chestnut (Castanea sativa Mill.)...     

采后UV-C处理对树莓贮藏保鲜效果的影响

以"September"树莓果实为材料,采用0.43、2.15、4.3和6.45 kJ/m2的UV-C进行辐照处理,并在4℃下贮藏,通过测定贮藏期间果实腐烂指数、失重率、可溶性固形物含量、总酚含量和抗氧化能力,研究UV-C处理对树莓果实保鲜效果的影响。结果表明,UV-C处理能够显著抑制果实腐烂指数、失重率的上升,减缓果实可溶性固形物含量、总酚含量的下降,增强果实的抗氧化能力,维持果实较好的品质。在4个UV-C处理剂量中,4.3 kJ/m2UV-C处理组果实的腐烂指数、失重率最低,可溶性固形物含量和总酚含量最高,抗氧化能力最强。适宜剂量的UV-C处理(4.3 kJ/m2)能维持树莓果实采后品质,增强抗性,延缓衰老。     

基于转录组测序的槜李EST-SSR标记开发

为开发槜李EST-SSR标记,本研究利用MISA软件筛选了槜李花转录组测序获得的35584条Unigenes,对其SSR信息进行分析后,利用Primer Premier 3.0软件设计EST-SSR引物,并随机选取40对SSR引物对12个李品种进行EST-SSR引物筛选及多态性分析。结果发现,在槜李花转录组中共搜索到个10791个SSR位点,分布于8433条Unigenes,SSR发生频率为23.70%,平均每3.71 kb含有1个SSR;SSR重复基元中二核苷酸重复出现频率最高,占总SSR数量的52.98%,其次为三核苷酸重复(占24.00%)和单核苷酸重复(占20.95%);二核苷酸重复基元以AG/CT为主(85.95%),三核苷酸重复基元以AAG/CTT为主(31.24%)。利用Primer Premier 3.0软件共设计出9870对候选引物,随机选择40对引物对12个李品种进行SSR引物筛选及多态性分析。40对引物均能扩增出预期大小的条带,有效扩增效率为100%,40对引物中有5对引物在12个李品种中表现出多态性。本研究开发的EST-SSR标记可为李属植物遗传多样性分析提供丰富的候选标记,同时可为槜李发育相关功能基因定位、遗传图谱构建、及分子标记辅助育种等研究提供帮助。     

云南籽粒苋种质资源的表型多样性分析

为了系统分析云南籽粒苋种质资源的表型遗传多样性。采用遗传多样性指数、主成分分析、相关分析和聚类分析对104份云南籽粒苋种质资源的30个表型性状进行研究。结果表明,遗传多样性指数最高的质量性状和数量性状分别是主花序形状(1.68)和主花序长度(2.07)。前10个主成分累计贡献率达到73.944%,单株鲜体重与第3、第6、第9主成分极显著正相关,单株粒重与第9主成分极显著正相关。聚类分析将104份种质划分为5类,第Ⅰ类群可为间套种亲本材料,第Ⅱ和Ⅲ类群可为大粒亲本材料,第Ⅳ类群可为优质饲用亲本材料,第Ⅴ类群可为观赏类亲本材料。云南籽粒苋种质资源表型性状具有丰富的遗传多样性,有较大的开发利用潜力。