末次刈割时间和低温处理对苜蓿根颈抗寒性的影响

【目的】探究科尔沁沙地生境中不同末次刈割时间紫花苜蓿抗寒性及其与低温胁迫下糖类物质含量变化的关系,为科尔沁沙地苜蓿抗寒越冬提供理论依据和技术指导。【方法】以公农1号紫花苜蓿为材料,于2020年8月25日-11月5日进行不同末次刈割时间处理,每处理间隔10 d,以未刈割为对照;于封冻前期（11月15日）挖取不同处理苜蓿越冬器官(根颈)分别进行-10,-15,-20,-25,-30 ℃低温冷冻处理,以4 ℃处理为对照,测定各处理紫花苜蓿根颈的相对电导率及可溶性糖、蔗糖、果糖和淀粉含量,利用相对电导率根据logistic回归方程计算苜蓿的半致死温度,并对半致死温度与糖类物质含量进行相关性分析。【结果】未刈割和8月25日、9月5日、9月15日、9月25日、10月5日、10月15日、10月25日及11月5日末次刈割处理苜蓿的半致死温度分别为-18.03,-17.61,-17.03,-16.59,-15.80,-15.82,-16.83,-16.34和-17.12 ℃,表明在科尔沁沙地生境下不同末次刈割时间苜蓿的抗寒性表现为：未刈割＞8月25日刈割＞11月5日刈割＞9月5日刈割＞10月15日刈割＞9月15日刈割＞10月25日刈割＞10月5日刈割＞9月25日刈割;随着处理温度的降低,苜蓿根颈可溶性糖含量呈先升高后降低的变化趋势,蔗糖含量变化因刈割时间不同表现有别,果糖含量呈增加-降低-增加的双峰型变化趋势,淀粉含量呈逐渐降低的变化趋势;紫花苜蓿根颈的半致死温度与-10,-20,-30 ℃下的可溶性糖含量呈极显著负相关（P＜0.01）,与-15和-20 ℃下的蔗糖含量呈显著或极显著负相关（P＜0.05或P＜0.01）,与-15 ℃下果糖含量呈极显著负相关（P＜0.01）,与-15和-20 ℃下淀粉含量呈极显著正相关。【结论】末次刈割时间可调控苜蓿根颈淀粉向可溶性糖的转化,进而通过蔗糖和果糖等可溶性糖协同作用来维持细胞的渗透压,进而提高苜蓿的抗寒性。     

橡胶树树皮和木质部淀粉和可溶性糖含量测定

提出一种橡胶树树皮和木质部非结构性碳水化合物含量测定方法。取样测定范围为10~200 mg,利用80%乙醇浸提提取可溶性糖,硫酸蒽酮法测定可溶性糖含量,硝酸钙法提取淀粉,I2-KI法测定淀粉含量。本方法优点是:取样量小,对胶树伤害小,取样过程简单,测定结果准确。     

鲽形目鱼类营养需求的研究进展

文章综述了近年来国内外鲽形目鱼类的营养需求,包括蛋白质、脂肪、碳水化合物、维生素、矿物质和添加剂等方面。     

藏东南色季拉山急尖长苞冷杉非结构性碳水化合物时空动态特征

目的 为了验证高山林线的形成机理,探究树木分布上限的限制因素。 方法 本研究以色季拉山急尖长苞冷杉为研究对象,在其低海拔针阔叶混交林（3 500 m）、中海拔适生区（3 900 m）和高海拔林线过渡带（4 300 m）,分别于生长季（7月初）与非生长季（11月底）测定树木叶、枝、干和根的非结构性碳水化合物（NSC）及其组分含量,以及C、N、P含量。 结果 不同生长季节急尖长苞冷杉非结构性碳水化合物源与汇含量比较稳定,未出现碳供应不足现象;海拔对急尖长苞冷杉非结构性碳水化合物及其组分影响较小;器官间NSC含量差异显著,叶、枝、干和根在不同生长季节所侧重的生理活动和功能不同;非生长季急尖长苞冷杉非结构性碳水化合物及其组分显著高于生长季,非生长季较高的可溶性糖和NSC含量有利于抵御低温等恶劣环境;急尖长苞冷杉的NSC含量随海拔的上升呈现出递增的趋势,一定程度上支持了“生长抑制”假说。 结论 色季拉山急尖长苞冷杉的生长更多的受到了植物养分的限制,而非碳限制。     

Lignin and carbohydrates in soils under secondary forest,alley-cropping,and continuous farming,Thailand

This study was designed to investigate the impact of three land-use practices in Thailand on soil organic matter (SOM) composition. The land uses were continuous farming (till), alley-cropping, and secondary forest. Samples, taken from the top 10 cm soil surface, were fractionated into clay- (< 2 μm), silt- (2–20 μm), and sand-sized particles (20–2000 μm) prior to analyses of C, N, lignin-derived phenols and individual carbohydrates. As particle size increased, the C/N ratio and the concentration of lignin-derived phenols increased, whereas the degree of lignin oxidation as well as ratios of microbially derived hexoses to plant-derived pentoses decreased. Thus, the coarser the particle size, the less the SOM was altered by microbes. Seven years of alley-cropping increased SOM levels only little but considerably affected SOM composition by affecting the SOM of the sand fraction. The SOM concentration in the sand fraction increased in the order continuous farming < alley-cropping < secondary forest. In the same order, microbial alteration of lignin and carbohydrates of sand-sized SOM decreased. Both the different concentrations of SOM in the sand fractions as well as its different composition contributed, therefore, to different SOM among the sites. Increasing lignin-to-carbohydrate ratios for bulk soils and fractions in the order continuous farming < alley-cropping < secondary forest reflected such changes in SOM composition sensitively.     

温带12个树种新老树枝非结构性碳水化合物浓度比较

非结构性碳水化合物(NSC)是树木存活的重要碳储备。以温带12个树种(红松、樟子松、红皮云杉、兴安落叶松、蒙古栎、春榆、水曲柳、胡桃楸、山杨、大青杨、白桦和紫椴)为对象,在不同物候期取样7次以比较新枝和老枝的NSC浓度的季节动态,分析新枝和老枝的可溶性糖和淀粉浓度的关系,探索引起树枝NSC种间差异的原因。结果表明:除了山杨和大青杨之外,其它树种的新枝和老枝NSC浓度具有相似的季节动态,且新枝NSC浓度普遍高于老枝。常绿树种发芽前老枝TNC(总非结构性碳水化合物,即糖和淀粉之和)浓度快速上升,发芽后TNC变化较小,秋季TNC略有回升。落叶树种展叶前多数树种老枝TNC浓度下降;完全展叶后新枝和老枝TNC浓度均逐渐升高;秋季新枝和老枝的TNC大量积累,在休眠季节部分淀粉转化为可溶性糖。所有树种的新老枝中可溶性糖和淀粉均具有显著的线性关系;而可溶性糖、淀粉和TNC在新枝和老枝之间也均有显著的相关性。除了红皮云杉、春榆(缺乏数据)和蒙古栎(夏季出现两次生长)之外,其它9个树种老枝的TNC浓度的季节平均值、最大值和储存能力均随枝长生长期的延长而显著下降,说明枝长生长期与TNC存储功能之间相关联。     

Effects of Supplemental Carbohydrate Sources on Lactation Performance, Nitrogen Balance, and Ruminal Fermentation in Dairy Cows Fed Energy-Deficient Total Mixed Rations

The effects of supplemental carbohydrate (CHO) sources on milk yield and composition,nitrogen (N) balance,and ruminal fermentation were evaluated in lactating dairy cows fed energy-deficient total mixed rations (TMR).Fifty-six lactating Holstein cows (36.8 ±3.4 kg/d of milk yield; 152 ±26days in milk [ DIM ] ) were randomly assigned to one of four diets:( 1 ) basal TMR ( control ) ; ( 2 ) basal TMR + 1.25 kg/d sucrose (SUC) ; ( 3 ) basal TMR + 2.12 kg/d steam-flaked corn ( SFC ) ; ( 4 ) basal TMR + 2.23 kg/d wheat (WHE).The trial lasted 70 days,including the first 10 days of adaptation.Simultaneously,a 4 × 4 Latin square trial was conducted with four ruminally cannulated cows of similar DMI (Dry Matter Intake) fed on the above four diets.Each testing period lasted 18 days:15 days for adaptation and 3 days for sampling.Cows fed SUC-,SFC-,and WHE-supplemented diets produced 1.6,2.9,and 0.8 kg/d,respectively,more milk than those on the basal TMR control diet,but the difference was not significant (P =0.160).However,the production of energy-corrected milk of cows fed CHO-supplemented diets improved significantly (P =0.020),and the yield of 4％ fat-corrected milk tended to be higher (P =0.063 ) than in control animals.Percentages of milk protein,lactose and solidsnot-fat (SNF) increased significantly in cows fed CHO-supplemented diets ( P ＜ 0.05 ),and yields of milk protein and SNF were significantly higher (P＜0.05); yields of milk fat and lactose were somewhat higher ( P ＜ 0.10 ).Cows receiving supplementary CHO diets consumed more DM (Dry Matter) ( P =0.023 ) ; however,there was no significant difference in N retention,digestibility,or utilization efficiency among the treatments (P ＞ 0.10 ).The average ruminal pH was lowest in cows supplemented with SUC,while that in cows supplemented with SFC and WHE was only slightly reduced (P =0.025 ).Ruminal NH3-N concentration was highest with no supplementary CHO ( P =0.017 ),and changes in postfeeding time were similar across the diets.Total volatile fatty acid concentration was significantly lower in control animals than in those on SUC- and WHE-supplemented diets ( P =0.001 ) ; significant dietary responses were observed in the concentrations of acetate,butyrate,and branched-chain fatty acids and in the acetate-to-propionate ratio ( P ＜ 0.001 ).These results indicate that supplementation with different CHO sources in energy-deficient diets substantially improved the balance of energy and N in the rumen,altered ruminal fermentation,and improved lactation performance in dairy cows.     

粉状富淀粉传统保健食材碳水化合物体外消化特性

探讨焙烤后打粉冲糊方法对富淀粉保健食材碳水化合物消化特性的影响。采用体外模拟消化方法测定各样品快消化淀粉、慢消化淀粉和抗性淀粉的含量及水解率,并对淀粉糊化温度、糊化度等进行研究。试验结果表明：冲糊水量和温度显著影响样品的水解速率和淀粉类型,增加沸水量可使所有样品的水解指数超过蒸煮处理水平,蒸煮处理山药干、芡实、莲子、薏米和红小豆血糖负荷评估值分别为47．38、42．28、29．05、42．79和28．96;沸水量大冲糊方法的血糖负荷评估值分别为51．80、55．49、50．19、50．93和40．26。控制冲糊方法或可有效控制粉状淀粉食材的消化速度和淀粉类型比例,为不同生理状况的人群控制其血糖反应提供可能性。