Resistance risk and molecular mechanism associated with resistance to picoxystrobin in Colletotrichum truncatum and Colletotrichum gloeosporioides

Anthracnose,caused by Colletotrichum truncatum and C.gloeosporioides,is amongst the most serious diseases of soybean in China.Picoxystrobin,a quinone outside inhibitor fungicide,is commonly used for the control of anthracnose.Its resistance risk and mechanism in C.truncatum and C.gloeosporioides are unclear.In this study,the sensitivities of 128 C.truncatum and 121 C.gloeosporioides isolates to picoxystrobin were investigated,and unimodal distributions were observed with average EC_(50)values of 0.7740 and 1.1561μg mL^(-1),respectively.Eleven picoxystrobin-resistant mutants of C.truncatum and six mutants of C.gloeosporioides were acquired,with EC_(50)values varying from 5.40-152.96 and 13.53-28.30μg mL^(-1),respectively.Compared to the parental isolates,mutants showed similar or higher relative fitness in conidial production and germination,and pathogenicity.Collectively,the resistance risk of C.truncatum and C.gloeosporioides to picoxystrobin is moderate to high.There was positive cross-resistance between picoxystrobin and pyraclostrobin,but not between picoxystrobin and fluazinam,difenoconazole,or propiconazole.The G143S mutation in Cyt b protein was detected in seven high-resistant mutants of C.truncatum(RF>100),and G137R occurred in four moderate-resistant mutants(RF<_(50)).Contrastingly,there were no point mutations in Cyt b of any C.gloeosporioides mutants.Molecular docking confirmed that two mutations conferred different resistance levels to picoxystrobin.Under greenhouse trials,picoxystrobin did not control mutants with the G143S mutation,those bearing G137R or no point mutation were somewhat controlled,but at a lower level compared to wild-type isolates.These results showed that integrated management strategies should be implemented to preserve fungicide effectiveness.

饲草大豆与青贮玉米复合种植对混合饲料产量和品质的影响

试验旨在提高饲草的产量和品质,将不同蔓生型饲草大豆与青贮玉米同行、带状复合种植,测定混合饲草的产量和营养指标,通过聚类和主成分分析筛选出综合性状最优的饲草大豆种质及对应的栽培模式。结果显示:混合种植饲草产量、粗蛋白含量、干物质消化率、干物质采食量和相对饲用价值显著高于单种青贮玉米(P<0.05)。混合饲草通过系统聚类分为3个类群,第Ⅰ类群包括FML10与青贮玉米带状、同行复合种植的混合饲草,FML2与青贮玉米同行复合种植的混合饲草,上述3种饲草为丰产和高相对饲用价值类。主成分综合评价得分第一位的是FML10与青贮玉米带状复合种植的混合饲草。研究表明,FML10青贮玉米带状复合种植为宁夏引黄灌区适宜种植模式。

基于ms1轮回选择的大豆新品系农艺性状综合评价

为了加快大豆育种进程,选育出适合宁夏地区种植的大豆优良品种,对基于ms1轮回选择得到的40份春大豆新品系的11个主要农艺性状进行遗传变异、相关性、主成分和聚类分析,以对其农艺性状做出综合评价。结果表明:各农艺性状存在较为丰富的变异,其中有效分枝的变异系数最大(60.59%),生育天数的变异系数最小(5.2%)。变异系数指标由大到小顺序依次为:有效分枝数>分枝数>单株产量>单株粒数>底荚高>单株有效荚数>单株荚数>株高>主茎节数>百粒重。相关性分析结果显示,各农艺性状之间存在一定的相关性,大豆单株产量与株高、主茎节数、有效分枝数、单株荚数、单株有效荚数、单株粒数呈极显著正相关(r=0.402 6)。聚类分析表明,在遗传距离为45处,40份品系可以分为两大类群。第Ⅰ类群有5个品种,该类群生育天数140~141 d,晚熟品种,产量较高,株高偏高、有效分枝数、单株有效荚数、单株粒数较多,生育日数长,该类群品种适合在宁夏引黄灌区作为晚熟高产品种单作栽培种植。第Ⅱ类群有35个品种,该类群生育天数130~136 d,植株较矮、分枝少、生育日数较短,适合宁夏灌区及南部山区单作密植栽培,也可作为与小麦、玉米、西瓜、果树等作物间作套种种植的品种。主成分分析表明,5个主因子累计贡献率达到93.92%;综合评价得分排序表明,前3位的分别为13LD-222、12LD-89和17LD-46,尤其是产量性状表现突出,与试验应用结果表现出较好的吻合性。最终筛选出适合宁夏引黄灌区以及南北山区单种和宁夏间套作种植的优良品系13LD-222和12LD-89。

宁夏引黄灌区不同蔓生型饲草大豆生产性能及营养品质研究

试验旨在筛选适宜宁夏引黄灌区种植的丰产优质饲草大豆。试验以17个蔓生型大豆种质为研究对象,通过聚类分析和主成分分析,综合评价其产量和品质性状。结果显示:不同饲草大豆的饲草产量、粗蛋白含量、干物质消化率、干物质采食量和相对饲用价值均存在明显差异。主成分综合评价得分前5位的种质为:FML10>HML0164>JD21>F1918-7>FML2,归于系统聚类中的第Ⅰ类,Ⅰ类种质属于相对丰产、高蛋白、高物质采食量和高相对饲用价值类的饲草。研究表明,FML10、HML0164、JD21、F1918-7、FML2大豆种质更适宜于宁夏引黄灌区作牧草大豆利用。

结荚鼓粒期大豆饲草产量和营养品质动态规律研究

研究旨在明确青贮玉米复合种植模式下大豆饲草产量兼顾营养品质的适宜刈割期。试验开展结荚鼓粒阶段不同刈割期大豆饲草产量与营养品质变化规律研究,通过聚类和主成分分析筛选综合性状最优的大豆饲草对应的刈割期。结果显示:结荚鼓粒期大豆饲草产量呈现先升后降的变化规律。粗蛋白含量、粗淀粉含量整体呈先升后缓降的变化规律。酸性洗涤纤维、中性洗涤纤维含量呈现逐步上升的变化规律。干物质消化率、干物质采食量和相对饲用价值呈逐步下降的变化规律。研究表明,宁夏引黄灌区饲草大豆适宜刈割期为8月30日—9月6日,对应大豆发育状态为鼓粒期(R6)至成熟初期(R7)。