梨果生刺盘孢子囊孢子单孢菌系的生物学特性及致病性研究

 梨果生刺盘孢的2种致病型菌株FJ-85(产生黑点症状)和菌株FJ-11-2(产生坏死斑症状)的子囊孢子单孢培养均可产生正、负2种类型的单孢菌系。正型单孢菌系菌落浅白色,其上形成的子囊孢子再培养,可形成正、负2种类型的单孢菌系;负型单孢菌系菌落深灰色,其上形成的子囊孢子再培养,只形成负型一种单孢菌系。2个菌株的单孢菌系中,负型的比例明显多于正型。2种类型的单孢菌系对峙培养,在菌落内及菌落交界处均可形成子囊壳,而同种类型的单孢菌系对峙培养仅在菌落内产生子囊壳。结果表明同种类型的单孢菌系可同宗配合,而正、负2种类型的单孢菌系还可异宗配合。正型单孢菌系的致病力与原始菌株相近,而负型单孢菌系较原始菌株弱。2个菌株的单孢菌系在翠冠梨上引起的症状差异与其原始菌株相同。研究结果为解析梨果生刺盘孢的有性生殖与致病的关系提供了新的有用信息。     

Effect of Defoliants Application on Physiological Characters of Cotton Leaf without Defoliants

[Objective]The aim of this study is to elucidate the physiological mechanism of cotton leaf without defoliant response to thidiazuron (TDZ). [Method] A pot experiment was conducted to study the effect of defoliants on the photosynthesis, chlorophyll fluorescence, antioxidant enzyme activity, and endogenous hormone contents of cotton leaf without defoliant at 1 d, 3 d, 6 d and 10 d after the application of TDZ. Cultivar CCRI-50 was used for this experiment. [Result] TDZ rapidly induced cotton leaf abscission, however, no abscission was detected to the cotton leaf without defoliants. The net photosynthetic rate (P_n) of cotton leaf without defoliants was reduced by 1 d, 3 d and 6 d after TDZ applied, but rise to the control treated with water level by 10 d. TDZ also caused a significant decline in the maximum photochemical efficiency of photosystem II (F_v/F_m), the quantum yield of electron transport (Φ_PSII), the electron transport rate (R_et) and the photochemical quenching coefficient (q_P), but an increase in the non-photochemical quenching coefficient (qNP). However, with the same changes as P_n, the chlorophyll fluorescence characters got to the control by 10 d. TDZ application significantly increased the superoxide dismutase activity, did not affect the peroxidase activity, decease the malondialdehyde content. Abscisic acid contents in the cotton leaf without defoliant were lower than control by 3 d and 6 d after the applied of TDZ, but have the same level with control at 10 d, and the auxin had a little changes compared with control during the whole period of experimental time. [Conclusion] TDZ application significantly affect the photosynthesis, chlorophyll fluorescence, antioxidant enzyme activity, and endogenous hormone contents of cotton leaf without defoliant. When the leaf with defoliant drop off, the physiological characters of cotton leaf without of defoliants recovered to control level, and no abscission were detected.     

中国南方主要梨产区果生炭疽菌对苯醚甲环唑的敏感性

为明确苯醚甲环唑对果生炭疽菌Colletotrichum fructicola不同发育阶段的毒力,并建立中国南方主要梨产区(湖北、安徽、江西、江苏、浙江和福建)果生炭疽菌对苯醚甲环唑的敏感基线,采用孢子萌发法测定了苯醚甲环唑对6个代表性菌株孢子萌发和芽管伸长的影响,采用离体叶片接种法评价了苯醚甲环唑对该病菌的防治效果,采用菌丝生长速率法测定了120株果生炭疽菌对苯醚甲环唑的敏感性。结果表明:苯醚甲环唑对果生炭疽菌菌丝生长和芽管伸长的抑制效果较强,而对分生孢子萌发的抑制效果较弱,其平均EC50值分别为(0.33±0.03)、(2.61±0.26)和(29.87±1.31)μg/mL。160μg/mL的苯醚甲环唑对梨果生炭疽病的保护作用和治疗作用防效分别为92%和79%,而1000μg/mL的多菌灵则分别为51%和23%。来源于中国南方主要梨产区的120株果生炭疽菌对苯醚甲环唑均表现为敏感,EC50值范围0.27~1.12μg/mL,敏感性频率分布呈连续单峰曲线,符合正偏态分布,其平均EC50值(0.59±0.02)μg/mL可以作为我国南方主要梨产区果生炭疽菌对苯醚甲环唑的敏感基线。本研究结果为监测梨果生炭疽菌对苯醚甲环唑的田间抗药性发展奠定了基础,并为梨产区应用该药剂防治炭疽病提供了依据。     

P(AA-AM)/SiO2复合保水材料的制备及其在保水缓释肥中应用

开发具有保水缓释双重功能的新型肥料,对于提高水肥利用效率和保障农业可持续发展具有重要意义。该研究探索了纳米二氧化硅(SiO_2)对提升保水材料吸水率及改善保水缓释肥性能的效果,采用丙烯酸(AA)和丙烯酰胺(AM)为原料,首先通过水溶液原位聚合法制备了P(AA-AM)/SiO2复合保水材料,然后采用双层包膜工艺制备了保水缓释肥,在合成保水材料时,丙烯酸和丙烯酰胺的质量比为3.5∶1,引发剂(过硫酸钾和亚硫酸钠)、交联剂(N,N-亚甲基双丙烯酰胺)、增塑剂(丙三醇)和纳米SiO_2分别为单体质量的1%、0.04%、15%和2%。保水缓释肥采用转鼓包膜工艺制备,内包膜层为聚氨酯,占肥料核芯的3%,外包膜层为P(AA-AM)/SiO2复合保水材料,占肥料核芯的24%。保水材料的形貌结构和热稳定性用傅里叶红外光谱(Fourier transform infrared spectroscopy,FTIR)、扫描电镜(Scanning electron microscopy,SEM)和热重(Thermogravimetry,TG)表征,保水材料的吸水率用过滤法测定;采用土壤培养研究保水缓释肥的保水和持水性能,保水缓释肥的缓释性能用水浸泡法研究。结果发现:纳米SiO2能较好地分散于基体P(AA-AM)保水材料中,与P(AA-AM)保水材料相比,添加纳米SiO_2的复合保水材料在去离子水和0.9%Na Cl水溶液中的吸水率分别提高152%和87%,而且热稳定性显著提高;SEM和FTIR结果表明,纳米SiO_2能较好地分散于P(AA-AM)保水材料中,SiO_2表面含有的硅羟基增加了保水材料的交联密度。相比没有保水层的缓释肥,复合保水缓释肥的土壤持水率和保水率(培养25 d后)分别提高了25.5%和47.2%,肥料释放期由60 d增加到72 d。综上所述,纳米SiO_2显著提高了保水材料的吸水率,以此制备的复合保水缓释肥具有优异的保水和缓释能力,该研究为研发高效肥料、提高水肥利用效率提供了新思路。     

三叶草属牧草育种研究进展

进入20世纪80年代后,随着我国南方草地畜牧业的兴起,三叶草在人工草地建设中的作用越来越被重视。选育适宜不同地区种植的三叶草新品种工作开始起步。本文简要总结了国内外三叶草属牧草育种的概况,以期对今后三叶草属牧草的育种改良研究提供借鉴作用。     

不同灌水技术参数对农田水盐运移的影响

【目的】探索滴灌条件下农田高效洗盐适宜灌溉指标。【方法】通过人工控水试验重点研究了不同滴头流量(2.8和5.6L/h)和灌水定额(22.5、37.5和52.5mm)对盐碱地棉花根区盐分淋洗效果的影响。【结果】同一灌水定额条件下,湿润锋半径随着滴头流量的增加而增大;滴头流量增加,土壤水分分布呈宽浅型,表层土壤含水率逐渐升高。同一滴头流量条件下,湿润锋半径随着灌水定额的增加而增大;土壤含水率随着灌水定额的增加而增大。表层土壤盐分随着滴头流量和灌水定额的增大而减小,滴头流量为2.8 L/h时,水平脱盐半径30 cm,垂直脱盐深度60 cm;滴头流量为5.6 L/h时,水平脱盐半径40 cm,垂直脱盐深度40 cm。【结论】灌水定额52.5 mm时,脱盐效果最佳;随着作物的根部伸长,改变滴头流量,扎根40 cm以内用滴头流量5.6 L/h,扎根超过40 cm用滴头流量2.8L/h,可作为适宜的灌水技术参数。     

Understanding the biochar's role in ameliorating soil acidity

Extensive acidic soils, which suffer from accelerated soil acidification, are found in southern China. Soil acidity, aluminum toxicity, and nutrient deficiencies severely limited crop productivity in acidic soils. It has been widely reported that crop residue biochars can ameliorate acidic soils and increase crop productivity. Here, we summarized the positive effects and mechanisms involved in the correction of soil acidity, the alleviation of aluminum toxicity and the increase of soil pH buffering capacity by crop residue biochars. The carbonate, oxygen-containing functional groups and silicates in biochars are the major components responsible for their efficacy in amending acidic soils and resisting soil re-acidification. We conclude that application of crop residue biochars may be a better option than traditional liming to ameliorate acidic soils. Nonetheless, further researches into soil acidification are still required to address some issues that are controversial and poorly understood.     

辣椒炭疽病病原鉴定及其杀菌剂毒力测定

从贵阳市花溪区磊庄村辣椒基地采集疑似炭疽病的典型的自然发病辣椒果实,采用组织分离、培养、形态学观察、致病性测定以及多基因分子系统学,确定病原菌的种类;采用菌丝生长速率法研究了8种杀菌剂对该病菌菌丝生长的抑制作用。结果表明,引起贵阳市花溪区磊庄村辣椒炭疽病的病原菌为尖孢炭疽菌Capsicum acutatum。室内毒力测定发现8种杀菌剂对尖孢炭疽菌均有一定的抑制作用,其中25%咪鲜胺EC和30%吡唑醚菌酯SC抑制效果最好,EC_(50)分别为0.253 5 mg/L和0.720 3 mg/L;其次为22.5%啶氧菌酯SC和22.7%二氰蒽醌SC,EC_(50)分别为7.249 5 mg/L和21.664 5 mg/L。将30%吡唑醚菌酯SC和22.7%二氰蒽醌SC按照9∶1、6∶4、3∶7、4∶6的比例混配,联合毒力测定和评价结果显示两者混配对该病菌具有协同增效作用,且25%咪鲜胺EC和22.5%啶氧菌酯SC以6∶4、4∶6、8∶2的比例进行混配时也表现出明显的增效作用。引起贵阳市花溪区磊庄村辣椒基地辣椒炭疽病的致病菌为尖孢炭疽菌。咪鲜胺、吡唑醚菌酯、啶氧菌酯和二氰蒽醌对该菌具有较好的抑制作用,可为辣椒炭疽病的田间防治提供参考依据。