不同果桑品种对低温胁迫的反应及抗寒性评价

在休眠初期,果桑极易受到秋季低温冻害。以14个果桑品种为材料,在低温胁迫下,测定与抗寒性相关的6个生理生化指标,结合相关性检验,采用隶属函数法进行抗寒性综合评价,以期筛选抗寒性强的优良品种。结果表明:14个果桑品种可划分为3级,其中I级高抗寒型3个品种,II级抗寒型7个品种,III级低抗寒型4个品种。     

Silicon,biological seed treatment and cutting reduce the intensity of leaf spot diseases affecting Lolium multiflorum

Italian ryegrass is a major pasture crop cultivated mainly for feeding cattle in southern Brazil. The choice of crop is based on nutritional quality and the shortage of pastures that occur during the winter in the southernmost part of Brazil. In this region, the production of biomass and seeds are threatened by diseases, in particular fungal diseases that affect the foliage. In this study we identified and monitored the natural occurrence of a complex of leaf spotting diseases and evaluated the effects of combined management practices to reduce the intensity of foliar diseases: seed treatment with Trichoderma atroviride, soil amendment with silicon and cutting frequency (none, one or two cuts). Three diseases were present in a two-season experiment: grey leaf spot (Pyricularia oryzae), brown leaf spot (Bipolaris sorokiniana) and parrot's eye leaf spot (Cercospora sp.). Grey leaf spot had the highest severity, regardless of treatment, during the first season, and was the only disease present in the following season. Grey leaf spot dominated, and plants receiving only one cut were more prone to P. oryzae infection. The treatments with silicon or T. atroviride reduced the relative disease by 40% to 80%, in relation to untreated and uncut regimes. This study showed the main leaf spot diseases associated with L. multiflorum. Moreover, it demonstrates for the first time in the region the effectiveness of reducing leaf spot via the application of silicon in the soil, inoculation of seeds with T. atroviride and managing the cutting regime.     

减氮配施有机肥对夏玉米——冬小麦土壤硝态氮及氮肥利用的影响

为实现华北平原夏玉米-冬小麦的高产及氮肥的高效利用,采用田间小区试验方法,研究了氮肥减量及其与有机肥配施对夏玉米-冬小麦轮作体系内土壤硝态氮分布及氮肥利用的影响。结果表明:与不施氮处理(CK)相比,施用氮肥增加了冬小麦和夏玉米的生物量和产量,而在农民习惯施氮基础上减量1/3不会显著影响到生物量和产量。其中减氮配施有机肥(ONM)处理的周年总产最高,相比习惯施氮(CN)和减氮处理(ON)分别提高了1.85%和3.78%。处理CN的0~180 cm土壤硝态氮累积量的周年变化均值达502.7 kg hm^-2,分别是处理CK、ONM、ON的2.95、2.17、1.56倍。与处理CN相比,处理ONM显著降低了剖面(0~180 cm)土壤中的硝态氮含量,其中在夏玉米季和冬小麦季的降低幅度分别为18.1%~66.7%和37.3%~87.2%。处理ON和ONM相比处理CN,植株周年总吸氮量无显著性差异,氮肥利用率却得到了显著提高。其中处理ONM的周年氮肥利用最高,比处理CN提高了36.9%。综合分析,减氮与有机肥配施不仅显著降低了0~180 cm土壤硝态氮含量,大幅度提高了氮肥利用率,且有助于增加冬小麦和夏玉米的生物量及产量。     

1957-2017年京津冀主要作物水分利用效率及节水潜力分析

水资源短缺以及农业用水效率不高制约着京津冀一体化国家战略的实施。【目的】提高主要作物水分利用效率,缓解京津冀地区农业水资源矛盾。【方法】基于FAO推荐的Penman-Monteith公式及有效降水计算公式估算了1957-2017年京津冀地区冬小麦、夏玉米的耗水量及水分利用效率以及冬小麦、夏玉米的节水潜力。【结果】冬小麦、夏玉米水分利用效率呈逐年线性增长趋势。冬小麦、夏玉米水分利用效率仍有20%~30%的提升空间,在产量不变的前提下,京津冀地区可节约水量43.6亿~60.4亿m^3。冬小麦节水潜力高于夏玉米。【结论】可通过改善土壤条件,优化灌溉管理以及秸秆覆盖等措施提高冬小麦及夏玉米的水分利用效率。     

不同生育时期低温胁迫对水稻保护酶的影响

通过吉林省内外优质水稻品种为材料,分别在苗期、分蘖期、减数分裂期、灌浆成熟期进行低 温胁迫处理,并进行其生理特性研究。结果表明,低温胁迫下水稻的CAT、POD、SOD 酶活性均有所 增高,其中部分品种的SOD 酶活性整体较强,在各个时期均有所增幅,而CAT 和POD 酶活性在不同 时期存在品种差异,且分蘖期大部分品种的三种保护酶均有明显提升。本试验材料中,不同时期低温 胁迫下,通系935、龙稻18、吉粳816、绥粳14、延粳22、通35 的整体酶活性在各个时期表现优异,优于 其余品种。     

硫酸二乙酯诱变苜蓿愈伤组织抗寒生理的研究

对诱导的苜蓿Medicago sativa愈伤组织进行不同浓度的硫酸二乙酯(DES)诱变处理,确定其半致死浓度,在-7℃低温下进行筛选,以获得抗寒性突变体;进行了相对电导率、游离脯氨酸含量、过氧化物酶的活性等抗寒性生理指标的测定.结果表明,苜蓿愈伤组织经DES处理,DES的半致死浓度为0.3%,愈伤组织的抗寒性增强.     

黄土塬区旱作农田长期定位施肥对冬小麦水分利用的影响

对长期定位施肥试验第22年度的测定数据进行了分析,探讨了旱地施肥对冬小麦水分利用的影响。试验结果表明,测定年份冬小麦的耗水深度受播种前雨季降雨入渗深度的影响位于地下200 cm左右。长期施肥单施磷肥处理,播种期土壤有效贮水量与不施肥的对照接近,而单施氮肥,氮磷配施和氮磷钾配施均显著低于对照;在施P2O5 90 kg/hm2配施氮肥或施N 90 kg/hm2配施磷肥,随着施氮量或施磷量从0增加到180 kg/hm2,播种期土壤有效贮水量均逐渐降低,但前者作物的土壤水分消耗表现出降低趋势,而后者表现出增加趋势。与对照相比,各施肥处理均提高了土壤有效底墒的利用率。氮磷配施比单施磷肥降低了土壤供水占作物耗水的比例,使得作物生长和产量的形成对当季降水的依赖性增加。与对照相比,氮磷配施及氮磷钾配施显著提高了冬小麦收获指数、产量和水分利用效率,而单施磷肥和氮肥使收获指数、产量和水分利用效率显著降低。施P2O5 90 kg/hm2的条件下,不同施氮量之间收获指数差异较小,而产量和水分利用效率均高于单施磷肥;施N 90 kg/hm2的条件下,不同施磷量作物的收获指数、产量和水分利用效率均得到提高。     

冷季补饲对白牦牛生产性能及草地生产力的影响

【目的】研究冷季补饲对白牦牛生产性能及草地生产力的影响,旨在为缓解冷季白牦牛掉膘现象以及减少白牦牛冬春季草场放牧压力提供参考。【方法】选取24头8月龄牦牛犊牛,分为4组,3组为补饲试验组,燕麦籽粒补饲量分别为0.1,0.2,0.3kg/(d·头),另1组为对照;同时选取72头5~7岁成年牦牛,分为4组,其中3组为试验组,青贮玉米秸秆补饲量分别为1,2,3kg/(d·头),另1组为对照,所有试验组采用白天放牧+早晨补饲,对照组只进行放牧;在补饲同时,随机选取补饲组成年牛18头,对照组成年牛18头进行放牧试验,研究冷季补饲放牧对草地植被群落及开花、结实的影响。【结果】成年牦牛青贮玉米秸秆饲喂量为2kg/(d·头)时,冬季掉膘与对照有显著差异(P0.05);犊牛燕麦籽粒饲喂量为0.3kg/(d·头)时,冷季增加体质量与对照差异达到显著水平(P0.05);补饲与放牧结合区草地的植被盖度、高度、植物种数以及地上生物量总体优于纯放牧区,植被开花、结实株数总体高于纯放牧区;白牦牛成年牛在青贮玉米秸秆补饲饲喂量为2kg/(d·头)时,经济效益最高,可达99.6元/头。【结论】牦牛成年牛青贮玉米秸秆最佳补饲量为2kg/(d·头),不建议犊牛使用燕麦籽粒进行冷季补饲;补饲与放牧结合可以改善高寒牧区草地状况。     

四川冬春季参考作物蒸散量时空变化及其成因

为深入认识四川冬春季参考作物蒸散量(ET₀)的变化特征,利用1980—2016年四川35个气象站的逐日气象观测资料,采用泰森多边形、气候倾向率和克里金空间插值等方法对其冬春季ET₀的时空变化特征进行分析,并通过敏感性和贡献率分析了ET₀的变化成因。结果表明:ET₀的年代际变化呈先降后增的趋势,空间上呈明显的西南高东部低的分布特征,且高值区范围持续扩大,低值区范围波动缩小。ET₀的年际变化呈上升趋势,春季ET₀气候倾向率和空间差异明显大于冬季,且ET₀高值区与低值区空间分布受海拔高度影响明显。ET₀的同一日多年平均值自初冬至初春逐渐上升,1月22日—5月2日仅有8 d的ET₀值低于多年日平均值,具有明显连续的高值时段。ET₀对日照时数的变化最敏感,其次是对相对湿度与平均气温,对三者均呈高敏感性。平均气温的正贡献率是引起ET₀变化的主导因子,其次是相对...     

Cold tolerance of Acacia karroo and A. nilotica, two tree species from South Africa, in Beijing

Fynbos plant communities developed under geographic and climatic conditions unique to South Africa. Acacia karroo is the most widespread tree species, well known for its drought tolerance. A. nilotica exudes a good quality gum which is edible and suitable for confectionery. The two species have been introduced to China but little is known about their adaptability under the new environmental conditions. For our present study, the growth potential and physiological and biochemical parameters of the two species in response to cold stress were investigated. The results, measured as seed qualities (purity, thousand seed weights, germination, etc.) show differences between A. karroo and A. nilotica. The seed germination rate was between 10% and 60%. Seedlings were established in fields, pots and plugs. Those in the field grew well during the growing season but completely died in the winter. Those in pots or plugs were moved to and managed in the greenhouse. The plants were green in winter. The electrical conductivity of cells, the contents of water soluble sugars, proteins, malondialdehyde (MDA) increased during eight hours of low temperature treatment at 4℃. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) decreased markedly during the eight hours of 4℃treatment. We conclude that A. karroo and A. nilotica have little adaptability to the cold winter weather and cannot survive in the outdoors in the Beijing area, but could grow well indoors as ornamentals.