Mechanisms associated with tiller suppression under stagnant flooding in rice

Stagnant flooding (SF) during vegetative growth triggers stem elongation usually at the cost of tiller production in rice, reducing grain yield. To explore physiological mechanisms associated with tillering suppression under SF, three contrasting genotypes (Swarna and Swarna‐Sub1, both sensitive and IRRI154, tolerant) were evaluated under standing water depths of 0, 5, 30 and 50 cm. SF significantly suppressed tiller formation but increased plant height, root biomass, shoot elongation (ratio of plant height before and after flooding), leaf emergency and non‐structural carbohydrate (NSC) concentration (in root–shoot junction) in all genotypes at the early stage of development. Chlorophyll concentration in the upper leaves (upper most fully expanded leaf at top) was higher than in lower leaves (lowest green leaf at base), but decreased under SF in both. SF increased hydrogen peroxide (H₂O₂) at the early stage of treatment, with concomitant increase in malondialdehyde (MDA) production by stems and leaves. MDA concentration in root–shoot junction increased but delayed. Tiller number correlated negatively with plant height, shoot elongation, leaf emergency, MDA concentration in leaves and root–shoot junction, root biomass, and NSC concentration in the root–shoot junction. The results suggested existence of compensatory mechanisms between tiller growth and shoot elongation in rice for resilience under SF, where energy is mainly diverted for shoot elongation to escape flooding. The SF‐tolerant genotype produced less H₂O₂ and maintained energy balance for higher survival and better growth under stagnant flooding.     

Seasonal and Diurnal Variation in Water-Soluble Carbohydrate Concentrations of Repeatedly Defoliated Red and White Clovers in Central Kentucky

Nonstructural carbohydrates of pasture plants, comprising water-soluble carbohydrates (WSCs) and starch, may contribute to excessive consumption of rapidly fermentable carbohydrates by grazing horses. Seasonal and diurnal variation in WSCs were studied in red (Trifolium pratense L.) and white clovers (Trifolium repens L.) subjected to a typical management regime of rotationally grazed horse pastures. Two red and two white clover cultivars from monoculture plots were harvested after 4 weeks of growth from April to October of 2015, in the morning and afternoon of each harvest date. Water-soluble carbohydrates were quantified for each harvest, and starch was quantified for two harvests. Mean monthly WSC concentrations ranged from 80 to 99 mg/g (freeze-dried weight basis), whereas mean starch concentrations were 31 and 40 mg/g. In September, white clover had 14% more WSCs than red clover (P < .0001). Water-soluble carbohydrate concentrations were 10% higher in the afternoon than in the morning (P < .0001). Starch concentrations were 290% higher in the afternoon than in the morning (P < .0001), and nonstructural carbohydrate concentrations in the afternoon averaged 150 mg/g. Further studies are needed to determine whether the mixed grass-legume pastures of central Kentucky accumulate enough nonstructural carbohydrates to present risk factors for equine metabolic or digestive dysfunction.     

Using vibrational molecular spectroscopy to detect moist heating induced carbohydrates structure changes in cool-climate adapted barley grain

There is limited research to study how moist heating affects internal structure of barley grain on a molecular basis. The objectives of this study were to use vibrational molecular spectroscopy: 1) to determine the moist heating induced changes of barley carbohydrate (CHO) structure on a molecular basis, 2) to study the effects of moist heating on CHO chemical profiles, Cornell Net Carbohydrate and Protein System (CNCPS) subfractions, in situ rumen degradation, and predicted intestinal carbohydrate supply of barley grain; and 3) to reveal the association between molecular structure spectral features and CHO related metabolic characteristics. Barley samples (CDC cowboy) were collected from Kernen Crop Research Farm (Saskatoon, Canada) during two consecutive years. Half of each sample was kept as raw barley and the other half underwent moist heating (autoclaving at 120 °C for 60 min). The molecular spectroscopy (attenuated total reflectance-fourier transform infrared, ATR-FTIR) was used to detect the barley CHO related molecular structure spectral features. Moist heating did not affect carbohydrate related chemical profiles and CNCPS subfractions but it decreased rumen degradable carbohydrate. Rumen undegradable and intestinal digestion of CHO subfractions were not affected by moist heating. The advanced vibrational molecular spectroscopy can be used to detect carbohydrate molecular spectral features. Nutrient utilization prediction using molecular spectral characteristics is warranted and further investigation is encouraged.     

能量溢出与储备碳水化合物合成对瘤胃微生物生长效率影响的研究进展

瘤胃微生物将一些ATP用来维持代谢,剩余的ATP用来进行储备碳水化合物合成和能量溢出（进行无效循环并产热）,因此,瘤胃微生物蛋白质合成效率较低。瘤胃原虫贮存的碳水化合物占绝大部分。在一些细菌纯培养实验中发现有能量溢出,最近研究发现在混合瘤胃菌群中也能发生能量溢出。通过精确测定碳水化合物贮存和能量溢出的量,以及二者对微生物生长效率的影响,可以预测微生物蛋白质产量,制定提高瘤胃微生物蛋白质生产效率的措施。综述了瘤胃微生物能量溢出和糖原储备规律方面的研究进展,以期为估测微生物蛋白质合成量,提高饲料蛋白质利用效率提供参考。     

伊犁绢蒿体内可塑性营养物质动态变化及分配特征的研究(简报)

2006年3-11月,在新疆阿什里乡对新疆蒿类荒漠草地建群种伊犁绢蒿可溶性碳水化合物、蔗糖、淀粉和粗蛋白进行动态监测。结果表明,伊犁绢蒿中粗蛋白和蔗糖含量居前2位,淀粉含量低,还原糖仅在茎中存在。5月4日-11月14日,可溶性碳水化合物、蔗糖含量呈"升高-降低-再升高-再降低"特征,叶片粗蛋白和淀粉均呈"单峰"曲线,最高为234.05和3.55 mg/g;根粗蛋白基本不变,为67.26 mg/g,茎中呈下降趋势。可塑性营养物质均在10月17日前完成根内贮存。不同生长阶段伊犁绢蒿营养物质在根、茎、叶上分配差异较大。     

施钾对草地早熟禾根部可溶性碳水化合物及叶片氮，磷和钾含量的影响

以草地早熟禾（Poapratensis）品种男爵（Baronie）为试验材料,研究了不同施钾处理对根部0～10cm可溶性碳水化合物和叶片氮,磷和钾含量的影响。结果表明：在单施钾肥的情况下,随着施钾量的增加,越冬前草地早熟禾根系可溶性碳水化合物的含量也显著提高（P〈0．05）,这可能有助于提高植株越冬率,促进返青生长,而在同时施有氮、磷的情况下,碳水化合物含量间的差异并不显著,草地早熟禾叶片氮、钾含量也随着施钾量的增加呈显著增加的趋势（P〈0．05）。通过碳水化合物及叶片氮,磷和钾含量的测定,以N5g／m^2＋P20s3．33g／m^2＋K2O 6．68g／m^2处理对草坪返青及分蘖最佳。     

结晶纤维素的降解

随着化石能源的日益消耗及其对环境的污染加重,寻求可再生的清洁能源已成为各国关注的焦点。木质纤维素是地球上最多的有机聚合物,对于解决能源危机具有巨大的潜力,但没有得到有效的利用,纤维素结晶区的存在是阻碍其降解的重大难题。本文介绍了结晶纤维素的结构、解结晶方法及优良的降解菌种;纤维素酶的结构和功能;降解结晶纤维素的机制;纤维素酶的基因工程和酶工程改造。突出应加大对耐热、高效的结晶纤维素降解菌株的挖掘,并深入探究碳水化合物结合结构域的相关作用机理,这对结晶纤维素的高效降解具有重要意义。     

小麦午睡原因的研究——Ⅲ.形成小麦午睡生态生理因素作用的综合分析

结合田间生态条件研究了各因素在形成小麦午睡中的作用。并且在人工控制的恒定适温、恒定 CO_2浓度、相对稳定的叶片水势和叶片可溶性醣含量的条件下基本上克服了午睡。研究认为高产麦田 CO_2浓度下降、叶片水势下降以及其所引起的气孔开度减低是形成午睡的主要原因;超过小麦光合适温的高气温和叶片可溶性醣含量过量积累是形     

Protein to carbohydrate ratio in high-energy diets for Atlantic salmon (Salmo salar L.)

The effect of dietary protein to carbohydrate ratios (P/CH, weight percentage) of P34/CH21, P39/CH15 and P44/CH10 was studied in Atlantic salmon (Salmo salar L.) with respect to growth and feed conversion ratio (FCR) in one medium-scale experiment (Experiment 1) and to slaughter quality in two production scale experiments (Experiments 2A and 2B). The dietary fat was maintained at 290 g kg⁻¹ whereas the protein (fish meal) was exchanged with carbohydrate (wheat). Fish grown from approximately 1 to 4 kg were fed a restricted diet (iso-energetic on gross energy basis) or to satiation. Nitrogen, fat, starch and energy digestibilities were measured in a separate experiment. There were slight tendencies for lower growth (P = 0.06) and for higher FCRs (P = 0.06) in Experiment 1, and a slight tendency for a lower dress-out percentage in Experiments 2A and 2B (P = 0.10 and 0.20 respectively) with decreasing P/CH. The P/CH had no effect on the fat concentration of fillets, flesh colour or sexual maturation. The digestibility of starch decreased from 62.1% to 46.1% and the digestibility of energy from 84.9% to 79.5% when P/CH decreased from P44/CH10 to P34/CH21. Growth per unit digestible protein increased with decreasing P/CH. Feeding to satiation improved the growth but the FCR was higher than it was for restricted feeding. The calculated starch load per kg of fish growth increased with decreasing P/CH, whereas the effluent nitrogen decreased.     

Effect of supplemental dietary zinc sources on the growth and carbohydrate utilization of tilapia Smith 1840, Oreochromis niloticus × Oreochromis aureus

An 8‐week feeding trial was conducted to investigate the effect of supplemental dietary zinc sources on the growth performance and carbohydrate utilization of juvenile tilapia Smith 1840, Oreochromis niloticus × O. aureus. The goal was to compare the bioavailability of two zinc sources, zinc sulphate (ZnSO₄) or zinc methionine (ZnMet), by using two practical basal diets with 350 g kg^?1 (C350) or 400 g kg^?1 (C400) carbohydrates based on wheat as the carbohydrate source. The results showed that fish fed with a diet supplemented with 60 mg kg^?1 Zn from either ZnSO₄ or ZnMet had a significantly (P < 0.05) greater specific growth rate and protein efficiency ratio than those fed with the diets of ≤30 mg kg^?1 Zn. The composition of tilapia carcass was also found to be influenced by various levels of dietary zinc from the two zinc sources. The G6P‐DH in fish fed with the 20 mg kg^?1 ZnMet diet and the PK levels in fish fed with 20 mg kg^?1 ZnSO₄ and 30 mg kg^?1 ZnMet diet were significantly (P < 0.05) higher than those in fish fed with the C400 diet. The data suggest that supplemental dietary zinc from either ZnMet or ZnSO₄ significantly affects the growth performance and carbohydrate utilization of tilapia.