几种常见桑树病害的识别与防治

桑树是蚕桑产业的重要物质基础。为确保桑树健康成长,促进产业发展,桑树病害的有效识别与及时防控尤为重要。真核微生物、原核微生物及非细胞类病毒中均存在能引发桑树传染性病害的病原微生物。其中由真核微生物引起的桑里白粉病与桑椹菌核病,原核微生物引起的桑青枯病与桑疫病是爆发频繁、危害极大的桑树病害。本文就这四种桑树病害的病原、侵染循环、病害识别及防治方法等进行系统梳理,并简要介绍几种非细胞类微生物引起的桑树病害,以期为生产上防治相关病害提供参考。     

Feeding value of enset (Ensete ventricosum), Desmodium intortum hay and untreated or urea and calcium oxide treated wheat straw for sheep

Feed intake, in vivo nutrient digestibility and nitrogen utilization were evaluated in male sheep fed different fractions (leaf, pseudostem, corm, whole plant) of enset, untreated or 2% urea‐ and 3% calcium oxide‐ (CaO or lime) treated wheat straw and Desmodium intortum hay as sole diets. All feeds, except D. intortum hay and enset leaf had low crude protein (CP) content. Non‐fiber carbohydrate contents were higher in enset fractions, especially in pseudostem and corm relative to other feeds. Enset leaf and pseudostem had high calcium, phosphorus and manganese contents. Corm, whole enset and D. intortum hay were rich sources of zinc. Daily dry matter and CP intakes were higher (p < 0.05) in sheep fed D. intortum hay (830 and 133 g, respectively) than those fed pseudostem (92 and 7.8 g, respectively). Organic matter digestibilities were highest for corm (0.780) and whole enset (0.776) and lowest for D. intortum hay (0.534) and untreated wheat straw (0.522). The CP digestibility ranged from 0.636 in D. intortum hay to 0.408 in corm. Nitrogen (N) balance was highest (p < 0.05) in D. intortum hay (10.4 g/day) and lowest in corm (?1.3 g/day). Enset leaf could be a useful protein supplement whereas the pseudostem and corm could be good sources of energy.     

玉米‖花生茬口对冬小麦旗叶光化学活性的影响

为探明玉米‖花生茬口显著提高冬小麦旗叶的光合速率和产量的光反应机理,研究了玉米‖花生茬口(间作茬口,ICR)、玉米茬口(MCR)和花生茬口(PCR)及不同施磷水平对冬小麦播前土壤含水量、冬小麦花后旗叶的气体交换参数、光系统Ⅱ(PSⅡ)、光系统I(PSⅠ)及二者间的性能协调性的影响。结果表明,间作茬口较玉米茬口显著提高了冬小麦播前土壤含水量及旗叶的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和PSⅡ反应中心供(Wk)/受体侧(Vj)的活性,增强了单位面积吸收的光能(ABS/CSo)、捕获的能量(TRo/CSo)和进入电子传递的光能(ETo/CSo)。间作茬口较玉米茬口显著提高了冬小麦扬花期旗叶PSⅡ初级光化学最大量子产额(φpo)、转化效率(Ψo)、电子传递效率(δRo)及乳熟期的PSⅠ的性能(ΔI/Io)、PSⅡ与PSⅠ协调性(ΦPSⅠ/PSⅡ)和籽粒产量,较花生茬口显著提高了乳熟期的φpo和δRo值。施磷提高了Pn、ABS/CSo、TRo/CSo、ETo/CSo、φpo、Ψo、δRo、ΔI/Io和ΦPSⅠ/PSⅡ值。这说明间作茬口较玉米茬口提高了冬小麦旗叶光反应中心活性,从而提高净光合速率,重要原因可能是间作茬口能保持耕层较高的土壤含水量。     

小麦新品种鄂恩5号性状表现及栽培要点

小麦新品种鄂恩5号集高产、稳产、多抗、广适于一体,分蘖力较强,成穗率高,穗层整齐,子粒饱满度好,农艺性状稳定,适宜长江中下游平原麦区单作或套作种植,在保证适时播种,密度合适,合理施肥,田间管理到位的条件下可获得高产。     

藜麦种质资源对霜霉病的抗性鉴定与评价

为探究藜麦(Chenopodium quinoa)种质资源在本土环境条件下对霜霉病的抗性,采用田间自然感病和室内离体叶片接菌鉴定方法对50份国内外藜麦种质资源进行了霜霉病抗性鉴定和评价。结果表明：霜霉菌Preonos variabilis对藜麦的侵染程度存在较大变异(发病率变化13.30%～100.00%;病情指数1.00～100.00),藜麦种质对霜霉病的抗性存在明显差异;筛选到1份高抗材料‘台湾红藜’,占参试材料的2.00%1份抗病材料‘QA064’,占比2.00%,2份中抗材料‘陇藜2号’和‘HL-Q5’,占比4.00%,3份感病材料‘QA045’‘QA050-2’和‘青海-02’,占比6.00%;其余43份材料均表现高感,占比86.00%。本研究首次发现‘台湾红藜’能够被P.variabilis侵染,表现为高抗,还进一步证实田间藜麦霜霉病抗性鉴定采用“三叶法”在藜麦盛花期进行效果较好,相比而言,室内离体叶片接菌鉴定技术更具优势,应作为抗性鉴定的首选。     

Effects of formulating growing pig diet with increasing levels of wheat‐corn distillers dried grains with solubles on digestible nutrient basis on growth performance and nutrient digestibility

Formulating swine diets containing fibrous coproducts based on net energy (NE) and standardized ileal digestible amino acid (SID AA) values is recommended for optimizing pig performance. However, the effects of applying this approach to diets with increasing dietary levels of wheat‐corn‐derived distillers dried grains with soluble (wcDDGS) on pig performance have not been evaluated. Thus, 48 pigs with an average body weight [BW] of 25.5 kg were used to determine the effects of increasing wcDDGS (1:1 wheat to corn ratio) content in grower diets on performance and apparent total tract digestibility (ATTD) of energy and nutrients. Pigs were housed in pens of either 2 barrows or gilts balanced for BW and fed 4 diets within sex for 42 days. Diets were a nutrient adequate corn–barley–soybean meal‐based diet with 0%, 10%, 20% and 30% wcDDGS, and were similar in calculated NE and SID AA values. Acid insoluble ash was used as the indigestible marker. Final BW and overall average daily gain (ADG) linearly decreased (p < 0.05) and feed efficiency tended to decrease (p = 0.07) with increased dietary wcDDGS. Overall average daily feed intake was not affected (p > 0.10) by dietary treatment. The ATTD of dry matter and energy linearly decreased (p < 0.01), whereas the ATTD of neutral detergent fibre linearly increased (p < 0.01) with increasing dietary level of wcDDGS. Increasing dietary wcDDGS content did not affect (p > 0.10) ATTD of Ca and P. In conclusion, increasing dietary wcDDGS content reduced growth performance and ATTD of energy in growing pigs. Thus, the risks of high dietary wcDGGS content may not be completely alleviated by formulating growing pig diets on the basis of NE and SID AA systems.     

陇东旱塬冬小麦复种饲草轮作系统产量和水分利用特征

在陇东黄土高原大田条件下,连续2年研究了冬小麦-饲草复种轮作系统的干物质产量和水分利用,研究采用的处理有:休闲-冬小麦-箭筈豌豆-冬小麦(F-W-V-W),休闲-冬小麦-饲用油菜-冬小麦(F-W-R-W),饲用油菜-冬小麦-箭筈豌豆-冬小麦(R-W-V-W)和饲用油菜-冬小麦-饲用油菜-冬小麦(R-W-R-W)。结果表明:麦茬复种饲草可比麦茬休闲提高系统生产力27%,蛋白质产量增加1100 kg/hm², 同时对后茬冬小麦产量无影响。R-W-R-W模式下干物质产量、粗蛋白产量、干物质水分利用效率和蛋白质水分利用效率均最优,分别为30.68 t/hm²、3.25 t/hm²、7.80 kg/(mm·hm²)和0.92 kg/(mm·hm²)(P<0.05)。复种饲用油菜较箭筈豌豆产量高,有效利用了麦茬后降雨量,但箭筈豌豆粗蛋白含量较饲用油菜高22.4%,因此确定麦茬复种模式则需权衡干物质产量与蛋白质产量的需求。     

Vernalization of immature embryos of winter wheat genotypes

Summary The effect of direct vernalization of immature embryos on flowering was studied in six winter wheat genotypes. Fourteen-, 17-, and 20-day-old embryos were excised and vernalized for 0–6 weeks on synthetic medium during a conditioning period. Percent germination of embryos was high (overall 96.1%), and free from genotypic effects. Genotypes differed for flowering in response to cold treatment of excised embryos. Embryo vernalization was as effective as or more than conventional vernalization (control, seedling vernalization for 6 weeks). Seventeen-day-old embryos were the most responsive to vernalization. With a 5-week vernalization of 17-day-old embryos, the percentage of plants anthesed was higher than those from 14-and 20-day-old embryos. For 17-day-old embryos vernalized for 5 weeks, the mean number of days from culture to anthesis was less than that of 6 week vernalization, less than that of 14- and 20-day-old embryos, and less than controls.Purdue Univ., Agronomy Dept., W. Lafayette, IN 47907, USA.     

小麦白粉病抗病材料的鉴定研究

１９９７－２０００年连续３年,利用陕西小麦白粉病茵模拟病圃混合茵系,对陕西等省新育成的２８０份小麦育种材料进行了苗期与成株期抗病性鉴定,筛选出对小麦白粉病茵高抗－免疫的育种亲本材料１２份,其中高抗材料２份为鉴４４和鉴４７;免疫材料１０份为鉴１９、鉴２０、鉴４０、鉴４６、鉴４９、８８（６０５）－１－５－１－２－２－１、保丰９４－６６、贵农２９和秦８１２０－２３－５－１８。这些材料表现稳定,可供抗白粉     

分层供水施磷对冬小麦磷效率及产量的影响

研究分层供水施磷对冬小麦磷效率及产量的影响,为指导旱地施磷提供一定理论和实践依据。试验设整体湿润(W1)和上干下湿(W2) 2 种水分处理,不施磷(CK)、表施(SP)、深施(DP)3 种施磷处理,供试品种选用水分敏感型（‘小偃22’）和抗旱型（‘长旱58’）。研究结果表明：磷肥施用深度对冬小麦磷根效率比、磷肥利用效率、磷肥偏生产力(PFPP)及产量的影响随土壤水分和品种而异。2 种水分条件下,‘小偃22’DP较SP处理磷肥利用率、PFPp均显著降低(P＜0.05),磷根效率比及产量则差异不显著;W1 处理下,‘长旱58’DP较SP处理除磷根效率比外其他指标均显著降低(P＜0.05),W2 处理下则相反,上述指标均显著增加(P＜0.05)。本试验结果表明,土壤水分供应不足时,磷肥深施有利于提高抗旱性较强冬小麦品种对磷素的吸收利用能力,从而提高磷肥利用率及产量。