Supplementation of citric acid in plant protein‐based diets for juvenile tambaqui,Colossoma macropomum

We evaluated citric acid supplementation (0, 10, 20, and 30 g/kg) in plant protein‐based diets for juvenile tambaqui, Colossoma macropomum. In Experiment 1, fish (n = 160; 27.56 ± 2.73 g) were distributed in 310 L tanks (n = 16) for 80 days. Zootechnical performance, hematological parameters, and mineral composition (muscle and bones) did not differ significantly (p > .05). The inclusion of citric acid‐reduced pH of diets (p = .001) and stomach (p = .035). In Experiment 2, fish (n = 60; 48.00 ± 1.98 g) were distributed in fecal collection aquaria (200 L) for 21 days. The following were observed: a linear effect for the crude protein (p = .0004) and crude fat (p = .0037) digestibility coefficients; a quadratic effect for crude energy (p = .0037) and dry matter (p = .0004); an optimal supplementation level of 18.5 g/kg. Calcium (p = .0060) and magnesium (p = .0222) showed a linear effect, while phosphorus (p = .0001) had a quadratic effect with the 20 g/kg optimum supplementation level. To conclude, the supplementation of this organic acid in diets does not negatively affect fish nutritional status, health or welfare, and increases nutrient and mineral availability.     

基于叶片SPAD的棉花氮营养指数估算研究

为了探究不同施氮处理对棉花叶片SPAD值、生物量和氮营养指数(NNI)的影响,通过两年田间试验,设置5个施氮水平（即0、120、240、360、480 kg/hm²）,开展棉花叶片SPAD值、氮素吸收分配规律和生物量变化的研究。研究结果发现：棉叶SPAD值随施氮量增加呈增加趋势,在N4处理下获得最大值;建立棉花氮浓度稀释模型：N_c=3.02W_max^-0.24,分析表明棉叶SPAD与NNI之间呈正相关关系,相关系数R²为0.05~0.74;经验证,棉花不同生育时期的模型模拟性能较好,出苗后97天时相关系数达到最大。棉花叶片SPAD值与临界氮浓度存在显著的正相关关系,可以作为棉花氮营养诊断的指标。     

配方施肥对红锥幼林生理及叶片养分含量的影响

以红锥幼林为研究对象，采用N、P、K 3因素3水平正交设计，探究N、P、K配方施肥对红锥幼龄人工林生理和叶片养分的影响，为红锥幼林提供施肥依据。结果表明，T3(N1P3K3)处理下，叶绿素a和b的含量均最高，分别为0.71 mg·g^-1和0.38 mg·g^-1；T4(N2P1K2）和T5(N2P2K3)处理下红锥叶片的可溶性糖和可溶性蛋白含量最高，不足或者过量施肥均会降低可溶性糖和可溶性蛋白的含量；增加N肥施用量可使叶片N、P、K含量显著提高，但过量施N导致叶片N含量显著下降，增加P肥施用量会使叶片K含量下降，增加K肥施用量可使叶片N、P、K含量显著提高；主成分分析表明，T4和T5处理下红锥的生长质量最高。T4(N2P1K2)即尿素、过磷酸钙、KCl施用量分别为187.6、148.1、83.3 g/株(N:87.5 g/株,P₂O₅:81.3 g/株,K₂O:50.0 g/株)时，对3 a树龄的红锥幼林生长的促进作用最大。     

源调节对移栽玉米物质生产及子粒养分含量的影响

以辽单566为试材,2017年进行基质育苗,长至5叶1心进行剪叶、断根处理,剪叶处理设置0、15%、30%3个水平,断根处理设置未断根与断根2个水平,7月1日移栽至大田。结果表明,在剪叶15%处理下,叶片、茎秆转运量、转运率以及子粒的贡献率显著增加,果穗的穗粗和千粒重也显著上升。同时,剪叶断根显著降低了吐丝至成熟期叶片、茎秆中干物质转运率及子粒贡献率,使得干物质积累量减少。随着剪叶面积的增加,可以在一定程度上缓解断根造成的不良影响。移栽玉米进行源调节后,对子粒淀粉、蛋白质、氨基酸和脂肪含量的效应不同,子粒脂肪含量不易受源库关系改变的影响,无明显变化。蛋白质含量和氨基酸含量在苗期移栽后减少15%叶源时达到最大;同时去除植株的叶源和根源,会显著降低子粒中蛋白质和氨基酸的百分含量。淀粉百分含量表现在苗期移栽后减少15%叶源和根源时达到最大。     

应用体外消化法评定不同生育期麦类作物营养价值

试验旨在探讨澳大利亚东南部玛瑞达令河沿岸平原地区小麦、青稞和燕麦这3种主要冬季麦类作物在不同生育期的营养价值变化规律.通过近红外光谱分析法测定这3种麦类作物在拔节期、扬花期和灌浆期的主要营养成分和体外消化率.结果表明:生长期对麦类作物的营养价值有显著影响;拔节期的CP含量、DMD、OMD显著高于扬花期(P＜0.05)和灌浆期(P＜0.05);而拔节期的NDF和ADF含量虽然与扬花期和灌浆期无显著差异(P＞0.05),但还是比后者含量要低.综上所述,拔节期的营养价值高于扬花期和灌浆期,建议作为饲草种植的冬播麦类作物的收获期以拔节期为宜.     

我国苗木培育水肥管理研究进展

本文从苗木营养诊断技术方面介绍了当前植株营养分析的进展;同时从苗木生长所需的水分、养分等方面阐述了苗木培育技术的研究进展,为苗木培育水肥管理提供一定思路。     

Feeding of juvenile cobia,Rachycentron canadum: Evaluation of practical feeds,comparison of commercial fishmeal replacers,and estimation of essential amino acid requirements

Three studies were conducted with juvenile cobia, Rachycentron canadum: (Study 1) a 10‐week feeding trial within floating net cages to test the nutritional efficacy of different dietary feeding regimes (trash‐fish control diet, a semimoist diet, an in‐house dry formulated diet, and a commercial cobia feed); (Study 2) a 10‐week feeding trial within an indoor water‐recirculating tank‐based system to test the nutritional efficiency of different potential dietary fishmeal replacers (poultry byproduct meal, soy protein concentrate, feather meal), a diet without taurine supplementation, and a commercial cobia feed; and (Study 3) estimation of the essential amino acid (EAA) requirements of cobia based on EAA whole‐body composition in fast‐growing cobia fed a trash‐fish‐based diet. Fish performance in terms of growth and feed efficiency was the greatest within the outdoor net‐cage feeding trial, with fish fed the control trash‐fish‐based diet exhibiting the best performance. Although fish growth was poorer within the indoor feeding trials, fish performance was similar for most diets, with apparent crude protein digestibility coefficients of over 75% being obtained in all experimental diets in both feeding trials. The estimated EAA requirements of cobia obtained during this study were similar to those reported for other similar marine carnivorous fish species.     

基于图像处理的作物营养诊断研究进展

近年来，随着农业化肥滥用问题的日益突出，图像处理技术在作物营养诊断上的应用研究越来越多。通过对作物营养诊断研究背景的阐述，指出图像处理技术在作物营养诊断上应用的重要意义，介绍作物图像营养诊断研究的总体情况和基本思路，论述作物图像采集、图像预处理、特征提取与优化、分类识别4个环节所用技术方法以及取得的成果，并分析作物图像营养诊断方面存在的问题。     

Differential response of corn inbreds to calcium

Abstract

Differential responses were noted among several corn (Zea mays L.) inbreds for Ca when grown in nutrient solutions at varied Ca stresses. Properties of one of the more “Ca‐efficient”; inbreds (Oh43) compared to one of the more “Ca‐inefficient”; inbreds (A251) are reported.

Oh43 produced more dry matter and developed fewer Ca stress symptoms when grown at both low and high Ca or with high Mg and K than A251. Comparable dry matter was produced by Oh43 at 4 times less Ca than A251. Oh43 also produced more dry matter per unit Ca than A251. Oh43 leaves and roots had lower Ca concentrations than A251 leaves and roots. With added Ca to solutions, Mg, K, Mn, Zn, and Cu concentrations decreased more in A251 than in Oh43. A251 contained higher P concentrations than Oh43. Functional and critical Ca concentrations appeared to be lower in Oh43 than in A251. Oh43 should grow and adapt better to Ca stress conditions than A251.