土壤游离氧化铁高光谱特征与定量反演

【目的】建立基于可见-近红外光谱的土壤游离铁精确预测模型,简单、快速、经济地预测土壤游离铁,有助于研究土壤发生和分类。【方法】采集广西壮族自治区的铁铝土、富铁土、淋溶土和雏形土等82个旱地土壤剖面的B层土壤,进行室内土壤化学分析、光谱测定,分析不同光谱变换后的光谱反射率与土壤游离铁含量的相关性。基于特征波段利用偏最小二乘回归(PLSR)和逐步多元线性回归(SMLR)法建立土壤游离铁含量光谱预测模型,通过决定系数(R2)、均方根误差(RMSE)和相对预测偏差(PRD)确定最优模型。【结果】土壤光谱曲线分别在457、800和900 nm波段附近有明显的游离铁吸收和反射峰特征;土壤游离铁含量与原始光谱反射率呈负相关;原始光谱经过微分变换后,游离铁含量与光谱反射率相关性显著提高;基于400～580和760～1 300 nm特征波段和一阶微分光谱变换的SMLR模型预测精度最高,其验证集的R2和RPD分别为0.85和2.62,RMSE为8.41 g·kg~(-1)。【结论】将可见近红外光谱技术应用于土壤游离铁含量高效快速地预测具有良好的可行性。广西旱地土壤光谱反射率与土壤游离铁含量具有高度的相关性,应用逐步多元线性回归方法可以很好地建立土壤游离铁含量反演模型。     

开食料中性洗涤纤维水平对犊牛生长性能、血清生化指标和抗氧化功能的影响

【目的】探究开食料中性洗涤纤维（NDF）含量对犊牛生长发育、血清生化指标及抗氧化性能的影响,为犊牛开食料的合理配制提供试验依据。【方法】选取平均体重为（42±2.5）kg 的60头（包括36头公犊牛,24头母犊牛）新生荷斯坦犊牛,随机分为4个试验组,每组15头（9头公犊牛+6头母犊牛）,15日龄起依次饲喂10%（10N）、15%（15N）、20%（20N）和25%（25N）NDF水平的开食料。试验犊牛单个饲养于犊牛岛,70日龄断奶,饲喂至112 日龄。每日记录开食料采食量,每两周称量犊牛的体重,于35和112日龄测量犊牛的体尺,35、70、90和112日龄空腹颈静脉抽血测定血液生化和抗氧化指标。【结果】（1）70—112日龄,犊牛开食料采食量10N组显著低于25N组（P＜0.5）;42—70日龄,20N和25N组NDF采食量显著高于10N和15N组（P＜0.05）;70—112日龄,NDF采食量随开食料NDF水平升高而显著增加（P＜0.05）; （2）70—112和15—112日龄,15N组犊牛体增重显著高于其他三组（P＜0.05）,分别高出12.67%、43.56%、30.17%和6.16%、18.09%、15.16%;15N组体高显著高于20N和25N组（P＜0.05）,体斜长和胸围显著高于25N组。（3）90日龄,15N组血清球蛋白含量显著高于其他三组,白球比显著低于其他三组（P＜0.05）;112日龄,血清谷丙转氨酶、谷草转氨酶和碱性磷酸酶含量随NDF水平的提高而显著降低（P＜0.05）。（4）35、70和112日龄,15N、20N和25N组血清超氧化物歧化酶浓度显著高于10N（P＜0.05）组,血清丙二醛浓度低于10N组。【结论】犊牛开食料中NDF水平直接影响进食量和体增重,15—112日龄荷斯坦犊牛开食料中NDF的适宜水平为15%。     

壮秧影响不同节氮水平下早稻产量及氮肥吸收利用

【目的】培育壮秧和施用分蘖肥是促进水稻早发的重要措施,但增施分蘖肥易导致水稻无效分蘖增加和氮素流失。研究双季稻区早稻壮秧和分蘖肥节氮条件下产量形成和氮素吸收利用特性,以期为早稻节氮控污和丰产栽培提供科学依据。【方法】以超级杂交早稻‘淦鑫203’为材料,采用壮苗育秧(状秧)和普通育秧(普秧)两种方式培育秧苗。于2014-2015年进行大田试验,设置壮秧常规施氮(VS+100%N)、节氮10%(VS–10%N)、节氮20%(VS–20%N)、节氮30%(VS–30%N) 4个处理,以普秧常规施氮(NS+100%N)处理和不施氮空白(NS+0N)处理分别作对照,共6个处理。减施的氮肥均在分蘖肥中扣除,除不施氮对照外,各处理基肥氮(72 kg/hm^2)和穗肥氮(54 kg/hm^2)均保持不变。分析早稻拔节期、齐穗期和成熟期SPAD值、光合速率、硝酸还原酶活性和各器官氮素含量,并测定成熟期水稻产量及其构成,明确了植株总氮积累量、氮素转运量、氮表观转运率、氮素利用效率等。【结果】与NS+100%N处理相比,壮秧条件下分蘖肥节氮10%~30%对叶片SPAD值和光合速率无显著影响,但壮秧能促进分蘖发生和成穗,在生育中后期可逐渐弥补分蘖肥节氮对分蘖期干物质积累的不利影响,成熟期VS–10%N和VS–20%N处理干物质积累量较对照NS+100%N增加,产量分别增加了8.5%和1.5%;VS–30%N处理干物质积累量和产量则呈下降趋势。同时,壮秧有利于提高早稻叶片硝酸还原酶活性、各器官氮含量和氮积累量,与NS+100%N处理相比,VS+100%N处理成熟期氮素积累量显著增加了6.9%,VS–10%N和VS–20%N处理无显著变化,VS–30%N处理显著下降了9.7%。壮秧处理氮素回收率和氮素农学效率较NS+100%N处理分别显著提高了12.1%~22.4%和9.9%~24.7%(P <0.05)。【结论】双季稻区早稻壮秧可以促进分蘖早发,提高叶片的干物质生产能力和氮代谢性能,弥补分蘖肥减氮后对水稻前期生长的不利影响,提高后期的干物质生产量和氮运转量。通过培育壮秧,分蘖肥减施总施氮量的20%以内,早稻产量不会下降,可实现水稻的节氮、丰产和节本栽培,有利于提高氮素利用效率和减少氮素流失对环境的污染。     

基于NRC模型下不同程度热处理豆渣的营养价值与分子结构功能团特征的相关关系

本试验旨在研究基于NRC模型下不同程度热处理豆渣的营养价值与分子结构功能团特征的相关关系。利用烘箱对豆渣进行不同温度(100、115、130℃)下不同时间(2、4、6 h)的热处理,采用NRC(2001)模型预测不同程度热处理豆渣的代谢蛋白质产量、可消化养分含量和能值,同时利用傅里叶变换红外光谱(FTIR)技术分析不同程度热处理豆渣的分子结构功能团特征,并分析它们之间的相关关系。结果表明:1)随着温度的升高以及加热时间的延长,豆渣的代谢蛋白质产量、可消化养分含量和能值呈现出降低的趋势。2)温度和时间对豆渣的分子结构功能团存在显著的互作效应(P<0.05)。3)酰胺Ⅰ带与结构性碳水化合物峰面积比值(AmideⅠ_STCHO)和酰胺Ⅰ带与总碳水化合物峰面积比值(AmideⅠ_CHO)可以共同作为预测因子估测瘤胃可降解蛋白质(R^2=0.35,P<0.05)、过瘤胃蛋白质(R^2=0.35,P<0.05)、小肠可吸收过瘤胃蛋白质(R^2=0.33,P<0.05)和瘤胃可降解蛋白质可合成菌体蛋白质(R^2=0.35,P<0.05)含量。综上所述,不同程度热处理豆渣的分子结构功能团与其代谢蛋白质产量、可消化养分含量和能值之间存在相关关系,初步证明可以利用分子结构功能团对热处理豆渣的营养价值进行快速分析和估测。     

2种紫花苜蓿耐盐生理特性的初步研究

为研究2种紫花苜蓿(Medicagosativa L.)“阿迪娜”(耐盐基因型)和“秘鲁”(敏盐基因型)在盐胁迫处理下的生理特性与耐盐机理,采用150mmol/LNaCl胁迫处理2种紫花苜蓿幼苗,分别测定盐处理前和处理后2,4,6,8,16h的过氧化氢酶(CAT)、过氧化物酶(POD)、丙二醛(MDA)、脯氨酸(PRO)、相对含水量(RWC)和叶绿素(Chl)含量。结果表明:2种紫花苜蓿的过氧化氢酶活性、过氧化物酶活性和丙二醛含量在盐胁迫下总体呈上升趋势,脯氨酸含量和相对含水量表现出相反的趋势。叶绿素含量在盐胁迫前期稳定不变,但在胁迫后期显著性下降;2种紫花苜蓿的相对含水量和叶绿素含量的变化趋势与植株表型变化相对应。主成分分析表明,过氧化氢酶和丙二醛的贡献率最大,能更好地为苜蓿耐盐机理及分子育种研究提供理论依据。     

Deep neural network algorithm for estimating maize biomass based on simulated Sentinel 2A vegetation indices and leaf area index

Accurate estimation of biomass is necessary for evaluating crop growth and predicting crop yield.Biomass is also a key trait in increasing grain yield by crop breeding.The aims of this study were(i)to identify the best vegetation indices for estimating maize biomass,(ii)to investigate the relationship between biomass and leaf area index(LAI)at several growth stages,and(iii)to evaluate a biomass model using measured vegetation indices or simulated vegetation indices of Sentinel 2A and LAI using a deep neural network(DNN)algorithm.The results showed that biomass was associated with all vegetation indices.The three-band water index(TBWI)was the best vegetation index for estimating biomass and the corresponding R2,RMSE,and RRMSE were 0.76,2.84 t ha−1,and 38.22%respectively.LAI was highly correlated with biomass(R2=0.89,RMSE=2.27 t ha−1,and RRMSE=30.55%).Estimated biomass based on 15 hyperspectral vegetation indices was in a high agreement with measured biomass using the DNN algorithm(R2=0.83,RMSE=1.96 t ha−1,and RRMSE=26.43%).Biomass estimation accuracy was further increased when LAI was combined with the 15 vegetation indices(R2=0.91,RMSE=1.49 t ha−1,and RRMSE=20.05%).Relationships between the hyperspectral vegetation indices and biomass differed from relationships between simulated Sentinel 2A vegetation indices and biomass.Biomass estimation from the hyperspectral vegetation indices was more accurate than that from the simulated Sentinel 2A vegetation indices(R2=0.87,RMSE=1.84 t ha−1,and RRMSE=24.76%).The DNN algorithm was effective in improving the estimation accuracy of biomass.It provides a guideline for estimating biomass of maize using remote sensing technology and the DNN algorithm in this region.     

Effects of γ‐aminobutyric acid supplementation on the growth performance,serum biochemical indices and antioxidant status of pharaoh cuttlefish,Sepia pharaonis

This study evaluated the effects of dietary γ‐aminobutyric acid (GABA) on the growth performance, serum biochemical indices and antioxidant status of pharaoh cuttlefish, Sepia pharaonis. Cuttlefish were cultured in open‐culturing cement pool systems for 8 weeks. Six practical diets supplemented with graded levels of GABA (0, 20, 40, 60, 80 and 100 mg/kg) were formulated. Each diet was randomly assigned to triplicate groups of 60 cuttlefish (mean weight: 10.33 g), the cuttlefish were fed two times per day to apparent satiation. The results showed that the specific growth rate (SGR), weight gain (WG) and feed efficiency (FE) significantly increased with dietary GABA supplementation (p < .05). The survival rate (SR) and protein content in muscle significantly increased when 58.9 mg/kg GABA supplied. Moreover, the nitric oxide (NO) content and acid phosphatase (ACP) activity in serum were significantly increased with dietary GABA supplementation (p < .05), while the activity of aspartate aminotransferase (AST) in serum decreased significantly when supplied with GABA at 58.9 mg/kg (p < .05). In addition, dietary GABA improved antioxidation activity by significantly increasing the activities of superoxide dismutase (SOD) and catalase (CAT) but decreasing malondialdehyde (MDA) levels in the liver and gill (p < .05). On the basis of the quadratic regression analysis of FE, the optimum content of dietary GABA in S. pharaonis was estimated to be 55.3 mg/kg. The findings of this study demonstrated that dietary GABA had a positive effect on the growth performance, serum biochemical indices and antioxidant status of S. pharaonis.     

基于机器学习算法的土壤有机质 质量比估算

为快速高效地估测干旱、半干旱地区土壤有机质(soil organic matter, SOM)质量比,提出了一种结合竞争适应重加权法(CARS)和随机森林(RF)的估测模型.以内陆干旱区艾比湖流域为研究区,测定土壤高光谱反射率和SOM质量比,经预处理后,利用CARS对原始光谱(R)、一阶导数(R′)、吸光度(log(1/R))及吸光度一阶导数［log(1/R)］′4种光谱变量的可见-近红外光谱进行筛选,并结合RF算法,建立全谱段RF模型与CARS-RF模型.结果表明,基于CARS方法对光谱进行变量筛选后,得出4种光谱变量的优选变量集个数分别为35,26,34和121;在4种光谱变量中,R′和［log(1/R)］′的SOM估测模型精度较高,以［log(1/R)］′为基础数据获得的模型精度最高;CARS-RF模型精度优于全谱段RF模型,模型验证集决定系数(R²)、均方根误差(RMSE)、相对分析误差(RPD)分别为0.881,6.438 g/kg和2.177.该研究在预处理的基础上通过变量优选,应用较少的变量个数获得较高的估测精度,为干旱、半干旱区SOM高光谱估测提供了适宜高效的方法.     

Relationships of Spectral Reflectance with Plant Tissue Mineral Elements of Common Bean (Phaseolus Vulgaris L.) Under Drought and Salinity Stresses

ABSTRACT

Salinity and drought stresses are critical for Phaseolus vulgaris L. growth and development. They affect plants in various ways, including tissue mineral element content. Micro- and macro-elements in leaves of Phaseolus vulgaris L. (cv. ‘Blue lake’ and cv. ‘Terli’) subjected to deficit irrigation and salinity treatments were investigated, both analytically and with regards to their effect on the leaves’ spectral reflectance. B (boron), K (potassium), Mn (manganese), Na (sodium), Si (silicon) and Zn (zinc) appeared to be influenced by stress factors, mainly responding to salinity increase. The leaf spectral reflectance of the plants appeared to be significantly correlated with most of the elements under investigation. Multivariate regression identified a relationship of the reflectance at particular regions of the spectrum with phosphorus and NDVI (normalized difference vegetation index) and indicated a significant correlation with B, Fe (iron), K, Mn, P (phosphorus) and Zn. Moreover, customized spectral indices, exhibiting significantly high correlation with B, Fe, K, Mg (magnesium), Mn, Na, P, Zn and N (nitrogen), were developed.