Summer drought decreases Leymus chinensis productivity through constraining the bud,tiller and shoot production

Extreme drought events can directly decrease productivity in perennial grasslands. However, for rhizomatous perennial grasses it remains unknown how drought events influence the belowground bud bank which determines future productivity. Ninety‐day‐long drought events imposed on Leymus chinensis, a rhizomatous perennial grass, caused a 41% decrease in the aboveground biomass and a 28% decrease in belowground biomass. Aboveground biomass decreased due to decrease in both the parent and the daughter shoot biomass. The decreases in daughter shoot biomass were due to reductions in both the shoot number and each individual shoot weight. Most importantly, drought decreased the bud bank density by 56%. In addition, drought induced a bud allocation change that decreased by 41% the proportion of buds that developed into shoots and a 41% increase in the buds that developed into rhizomes. Above results were supported by our field experiment with watering treatments. Thus, a 90‐day‐long summer drought event decreases not only current productivity but also future productivity, because the drought reduces the absolute bud number. However, plasticity in plant development does partly compensate for this reduction in bud number by increasing bud development into rhizomes, which increases the relative allocation of buds into future shoots, at the cost of a decrease in current shoots.     

茶园种植紫花苜蓿对节肢动物群落结构的影响

在崂山茶区采用网捕法和植株拍打法研究了种草和清耕茶园节肢动物数量的变化规律。结果表明,种植紫花苜蓿的第2年,节肢动物数量增加明显,种群结构趋于稳定。共调查到节肢动物12目,44科,81种,类群最大的为蜘蛛目,有27种,其次是同翅目,有12种,鞘翅目有10种,膜翅目有9种,其他23种。种草园与清耕园相比,节肢动物种类增加18.0%～19.0%,害虫数量平均减少75.6%,天敌种类增加10.3%～17.1%,个体数增加64.0%～77.1%,节肢动物数量在一年中的变化幅度平缓。茶园使用化学农药,是影响节肢动物数量的主要因素。在种植紫花苜蓿的茶园,不使用任何化学农药也不致造成害虫危害。     

低温胁迫下草坪草抗寒性的研究进展

通过介绍低温对草坪草的影响和作用机理,系统地综述了在低温胁迫下草坪草的光合特性、水分生理代谢、细胞质膜相对透性、保护酶系变化、碳水化合物贮藏、可溶性蛋白质含量、以及脂肪酸的变化在低温胁迫方面的研究进展,提出了今后进行草坪草抗寒性研究的趋势和建议。     

Field Evaluation of Cocksfoot,Tall Fescue and Phalaris for Dry Marginal Environments of South‐Eastern Australia. 1. Establishment and Herbage Production

Newly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south‐eastern Australia known to be marginally too dry for these grass species. The five locations were ‐ representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); ‐ representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern ‐ Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer‐autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release.     

白三叶返园对苹果园土壤微生物群落的影响

为了解苹果(Malus pumila)园中覆盖和埋置白三叶(Trifolium repens)对土壤微生物群落的影响,采用尼龙袋法将新鲜的白三叶覆盖和埋置到苹果园中,分别在白三叶降解1、3、6个月时,利用Biolog微平板法检测土壤微生物群落的功能多样性。结果表明,覆盖和埋置白三叶均可使苹果园土壤微生物代谢活性显著提高(P0.05),微生物的多样性除6个月外显著增加、丰富度显著增加,均匀度显著降低(P0.05),群落结构发生变化,且覆草处理大于埋草,同时,白三叶降解时间的长短也影响土壤微生物群落。土壤微生物群落主成分分析结果显示,不同返园方式间主要对羧酸类碳源的利用有差异,而导致不同降解时间土壤微生物群落代谢差异的主要是糖类。说明在苹果园覆盖和埋置白三叶可改变土壤微生物群落,而覆盖白三叶对微生物群落结构的改善情况显著优于埋置白三叶。     

大通县长宁镇退耕还林(草)后续产业探讨

分析了退耕还林(草)现状,结果表明,退耕还林草的后续产业发展不足,提出发展退耕还林草的后续产业对策。     

青海省优良牧草种质资源

青海省天然草地分布广、草地类型多样，草地植物以禾本科、莎草科、豆科、蓼科、藜科等植物为主，且绝大多数植物家畜可食，是一个丰富的优良牧草种质资源库。尤其是莎草科的植物其牧草品质良好，营养成分含量高，极具开发利用的潜力。因此，在积极保护天然草地上极具挖掘潜力的牧草种质资源的基础上，进一步深入研究和合理开发利用优质牧草资源是十分必要的。     

大麦杂种优势利用研究,Ⅲ.大麦异棱型和同棱型F1杂种的杂种优势特征

研究了大麦4种杂交类型（含二棱×二棱、二棱×六棱、六棱×二棱和六棱×六棱）的F₁杂种的性状表现和优势特征，比较了同棱型相配组（二棱×二棱和六棱×六棱）和异棱型相配组（二棱×六棱和六棱×二棱）的超高亲优势（H_h）组合数及其出现率。研究性状包括株高、穗长、穗下节间长、穗数、粒数、粒重、籽粒产量、籽粒蛋白质含量和赖氨酸含量等13个.结果表明,(1)二棱×二棱杂种的穗长较长、每株穗数较多、千粒重较高；六棱×六棱杂种的每穗粒数、每株粒数较多、籽粒产量较高；而异棱型相配杂种则比同棱型相配组有较高的株高、穗下节间长和千粒重。（2）4种杂交类型杂种的类型内杂种间变异，在大多数性状上均为同质，仅有株高、穗长和主穗粒数在六棱×六棱杂种中变异增大，有较大的选择潜力。（3）在13个数量性状中，有9个性状的H_h优势出现率与杂交类型显著关联；株高、穗下节间长和千粒重的H_h优势出现率在二棱×六棱和/或六棱×二棱杂种中最高，而主穗粒数、每穗粒数、每株粒数、每粒重和每株干重的H_h优势出现率则在六棱×六棱和/或六棱×二棱杂种中最高。（4）异棱型相配组杂种的株高、穗下节间长和千粒重的Hh优势率显著高于同棱型相配组杂种，依次为20/30对8/33、30/30对18/33和22/30对5/33；但同棱型相配组杂种籽粒产量的H_h优势率显著高于异棱型相配组杂种，为10/33对2/30。说明异棱型杂种易产生生物量和千粒重优势，而同棱型杂种易产生籽粒产量优势。     

Sulfadiazine pharmacokinetics in grass carp (Ctenopharyngodon idellus) receiving oral and intravenous administrations

This study aimed to examine the bioavailability (BA) and pharmacokinetic (PK) characteristics of sulfadiazine (SDZ) in grass carp (Ctenopharyngodon idellus) after oral and intravenous administrations. Blood samples were collected at predetermined time points of 0.083, 0.17, 0.5, 1, 2, 4, 8, 16, 24, 48, 72, and 96 hr (n = 6). The samples were extracted and purified by organic reagents and determined by the ultra‐performance liquid chromatography. The software named 3P97 was used to calculate relevant PK parameters. The results demonstrated that the concentration–time profile of SDZ was best described by a one‐compartmental open model with first‐order absorption after a single oral dose. The main PK parameters of the absorption rate constant (K_α), the absorption half‐life (t_{1/2 Kα}), the elimination rate constant (K_e), the elimination half‐life (t_1/2Ke), and the area under concentration–time profile (AUC_0‐∞) were 0.3 1/h, 2.29 hr, 0.039 1/h, 17.64 hr, and 855.78 mg.h/L, respectively. Following intravenous administration, the concentration–time curve fitted to a two‐compartmental open model without absorption. The primary PK parameters of the distribution rate constant (α), the elimination rate constant (β), the distribution half‐life (t_1/2α), the elimination half‐life (t_1/2β), the apparent distribution volume (V_SS), the total clearance (CL), and AUC_0‐∞ were 9.62 1/hr, 0.039 1/hr, 0.072 hr, 17.71 hr, 0.33 L/kg, 0.013 L h^?1 kg^?1, and 386.23 mg.h/L, respectively. Finally, the BA was calculated to be 22.16%. Overall, this study will provide some fundamental information on PK properties in the development of a new formulation SDZ in the future and is partially beneficial for the appropriate usage of SDZ in aquaculture.     

种草养畜与草场建设综合配套技术

畜牧业快速发展,对于牧草资源需求量越来越大,为更好地满足畜牧业发展需求,我国提出“种草养畜”技术理念,加快草场建设,能在保障畜牧养殖业稳定发展的同时,达到良好的生态环保效益。该文分析种草养畜技术理念的意义,着重探讨种草养畜和草场建设综合配套技术。