氮素和刈割对桂牧1号杂交象草光合作用、产量和品质的影响

采用L16(45)正交试验设计,研究了喀斯特地区桂牧1号杂交象草光合生理特性、产量和品质对不同施氮水平、刈割次数、刈割强度的响应。结果表明,施用氮肥显著增加了桂牧1号杂交象草的叶绿素a、b和叶绿素总含量、净光合速率、产量及营养成分含量,肥效最佳水平是1000kg·hm-2·a-1。刈割次数显著影响桂牧1号杂交象草的净光合速率、叶绿素含量和牧草营养成分含量,刈割过2～3次,桂牧1号光合作用能力显著提高,而每年刈割3～4次,牧草的营养品质最优。刈割强度对粗蛋白含量影响显著,对其他营养成分含量和产量均无显著影响,以5或20cm刈割强度为最优。综合各指标结果,提出了喀斯特地区栽培桂牧1号杂交象草获得高产优质的最优方案,即施氮1000kg·hm-2·a-1,刈割牧草3次,刈割强度为5或20cm。     

刈割制度对呼伦贝尔草原群落特征及牧草质量的影响

为确定呼伦贝尔草原高效生产和可持续利用的最佳刈割制度,于2019—2021年在呼伦贝尔草原开展刈割时间(7月31日、8月10日、8月20日、8月30日、9月9日)、留茬高度(3、9、15 cm)及两者交互作用对草原群落特征、牧草产量和品质影响的研究。结果表明: 较晚时间刈割和低留茬刈割会降低翌年群落高度和盖度;低留茬刈割降低翌年地上部分生物量,但刈割时间对其影响不显著。禾草、莎草相对生物量随刈割时间的延迟表现出先增加后减少的趋势,杂类草则与之相反,而豆科植物无明显变化。低留茬刈割在当年能够获得高的干草产量,但翌年的干草产量显著下降;8月30日,留茬3 cm刈割时干草产量达到最高值(469 g·m^-2),高于最低值361.5%。牧草品质中粗蛋白含量在8月30日刈割时亦达到峰值,高于最低值约6.5%,且在高留茬刈割下含量更高;酸、中性洗涤纤维含量随刈割时间延迟逐渐升高,9月9日刈割高于7月31日8.0%、5.9%,并且随留茬高度增加而降低。呼伦贝尔草原刈割制度设置为留茬高度9 cm左右、8月20—30日刈割为最佳,但需更长期的刈割试验观测才能得到更可靠、更客观的结论。     

刈割与施肥对高寒草甸土壤和植物N、P化学计量学特征的影响

通过6年的控制实验,研究刈割(留茬1cm、3cm、不刈割)和施肥(12.75g·m~(-2)尿素+3.06g·m~(-2)磷酸二铵、不施肥)对高寒草甸土壤和植物中N、P化学计量学特征的影响,探讨植物养分限制类型,为天然草原的管理利用、保护和恢复研究提供资料。结果显示:(1)刈割、施肥后土壤全N、全P含量及其N∶P比值无显著变化,但速效P含量显著增加;因速效养分被植物吸收,施肥与不施肥群落的土壤速效N、P含量无显著差异。(2)刈割和施肥引起群落叶层N、P含量增加,施肥导致叶层N∶P比降低。(3)刈割、施肥对豆科植物N、P含量及其N∶P比无显著影响,单独刈割增加了禾草的P含量和莎草的N含量,并降低了禾草的N∶P比值;单独施肥处理增加了禾草的P含量和莎草的N、P含量;豆科植物的N含量最高,莎草的P含量最低,禾草的N∶P比最低。(4)群落叶层、禾草及莎草的N含量与P含量呈显著正相关关系,N∶P比与N含量无显著相关性,而与P含量呈显著负相关关系;豆科植物的N、P含量呈显著负相关关系,N∶P比与N含量呈正相关关系,而与P含量呈显著负相关关系;说明群落和植物功能群营养状况主要受P限制。(5)群落地上生物量的相对生长率与群落叶层的N、P含量呈显著正相关关系,而与N∶P比呈显著负相关关系,符合生长速率假说,说明生长速率假说不仅适用于物种水平,在群落水平也成立。     

麦绿素加工专用大麦产量与气象因子的关系

以两个大麦品种为材料,在杭州条件下分7期播种,研究了麦绿素加工专用大麦产量与气象因子的关系．结果表明,第一收获期产量与播种后第1旬平均温度呈显著正相关,与第1、2旬的累积雨量显著负相关;第二收获期产量与第一次刈青后第2旬平均温度、第3旬降雨量显著正相关;三期总产量与播种后第2旬的平均温度呈极显著正相关,与第6旬平均温度呈极显著负相关．分别建立了第一收获期产量、三期总产量与生长天数、积温、降雨量及播种后第1、2、3旬平均温度的一元二次回归模型,寻优获得了在第一收获期高产基础上获较高总产量的适宜气象生态条件．     

不同刈割频度对大针茅草原群落特征及土壤元素含量的影响

在草原生态系统中,土壤是植物生长发育最重要的基质,对植物群落动态有显著的影响。刈割是内蒙古典型草原区除放牧外最重要的利用方式。研究不同刈割频度对典型草原区群落特征和若干土壤性质的影响及土壤因子与群落特征的相关性,旨在得出对群落多样性最有利并最适宜生产利用的刈割频度。研究区设置在内蒙古锡林浩特市东部以大针茅建群的典型草原;在2009—2013年进行不同频度的刈割处理,共设置处理,一年两次刈割、一年一次刈割、两年一次(割一年休一年)刈割、围封,在2013年8月采集测定土壤养分的样品。刈割对群落多样性影响显著,割一年休一年Shannon-Wiener多样性指数、Pielou均匀度指数、丰富度指数均高于其他刈割处理(P0.05);不同频度刈割下,一年两次刈割处理下土壤20—30cm和30—40cm的有机质含量显著高于其他处理(P0.05);不同频度刈割处理下土壤中的速效磷和速效氮的含量没有显著差异;一年两次处理的土壤全氮含量显著高于其他处理(P0.05)。Shannon-Wiener多样性指数与有机质含量、全氮含量呈显著负相关;Pielou均匀度指数与土壤元素间无显著相关关系;Richness指数与有机质含量呈显著负相关,与全氮含量为极显著负相关关系。割一年休一年刈割处理下土壤元素含量呈现更好的状态,结合群落物种多样性及生产利用的角度,割一年休一年为最合理的刈割频度。     

高原鼠兔刈割行为与栖息地植物群落的关系

采用观察法和样条法对不同栖息地高原鼠兔刈割植物的行为、相对频次、生物量百分比以及刈割植物与鼠兔冬季食物组成之间的关系进行了分析,并阐述了高原鼠兔刈割植物的生物学意义。结果表明:高原鼠兔刈割植物始于每年的6 月下旬,早于其它草原小型哺乳动物贮草时间。不同栖息地鼠兔对植物的刈割频次和生物量比例并非完全一致。在矮嵩草草甸,鼠兔刈割频次较高的为垂穗披碱草、二柱头藨草、甘肃棘豆、短穗兔耳草、铺散亚菊和鹅绒萎陵菜;这些植物生物量所占比例亦较高,仅短穗兔耳草比例较低;在垂穗披碱草草甸,鼠兔刈割频次较高的为垂穗披碱草和早熟禾;垂穗披碱草生物量较高;而在杂类草草甸,鼠兔主要刈割植物为铺散亚菊、大籽蒿、黄帚橐吾、长茎藁本和圆齿狗娃花,生物量比例较高的主要为铺散亚菊。相似性分析结果表明,不同栖息地间鼠兔刈割植物频次和生物量比例差异较大,相似性系数最大分别为0. 7862 和0. 6100, 最小仅为0.1422 和0. 1035,而同一栖息地间鼠兔刈割植物频次和生物量差异相对较小,相似性系数最高达0. 9203 和0. 8490,最小亦达到0. 6662 和0. 4440,表明栖息地变化对鼠兔刈割植物频次和比例有明显的影响作用。鼠兔刈割主要植物频次和生物量比例与冬季主要食物组成的相关分析结果表明,生物量比例与主要食物组成呈显著的正相关(r =0.8412,df = 6, P <0. 05),而刈割植物频次与主要食物相关不显著。     

春播小麦品质与生育进程和气候条件的关系

1998～2000年,用10个小麦品种在北京进行了3个年度的春播试验,以探讨生育进程和气候条件对品质的影响．结果表明,一些品质性状的品种间差异不显著,而年度间差异显著．播种．成熟天数和籽粒硬度呈极显著负相关．抽穗-成熟天数与籽粒湿面筋含量也呈极显著负相关．抽穗．成熟期间的昼夜温差与籽粒NIR蛋白含量呈显著负相关;总辐射量、昼夜温差与湿面筋含量呈极显著负相关,总日照与湿面筋含量呈极显著正相关;总辐射量、总日照、日均温、昼夜温差与沉降值呈显著负相关．在春播小麦优质栽培中,根据不同需要,既可使用生育期较短的品种,也可使用生育期较长的品种．种植生育期较长的品种时,可与间作、套种结合起来．     

不同光照质量和刈割强度对小糠草无性繁殖特性的影响

本实验于1996年在美国德克萨斯理工大学草原,野生动物和渔类系的温室和实验室中进行,实验材料均为盆栽糠草,实验设计为在自然光照下（R／FR＝1．1）,以不同留茬高度（10,15,20cm和不刈割）作为不同刈割强度,用不同红光／远红光比例（R／FR＝1．3和0．7）处理不同刈割强度的小糠草,观测不同处理对小糠草无性繁殖特性的影响,结果表明,小糠草净增蘖数随刈割强度增加而减少,除不刈割处理外,光照质量变化（R／FR的比例）对分蘖性能影响不大,所有刈割强度下都不存在分蘖的补偿性生长效应,但幼叶伸长速度随刈割强度的增大而加快,可以认为小糠草应适度利用,强度利用或不利均不利于该草生长发育。     

不同刈割程度对油莎豆非结构性碳水化合物代谢及生物量的影响

为探讨不同留茬高度对油莎豆(Cyperus esculentus)非结构性碳水化合物代谢的影响,进一步明确不同留茬高度与油莎豆地上生物量的关系,并寻求最佳刈割高度,该研究以油莎豆为研究对象,测定6个留茬高度(10、20、30、40、50 cm和未刈割)油莎豆叶片生长生理参数、非结构性碳水化合物含量和地上生物量。结果显示:刈割对于油莎豆光合作用有刺激作用,刈割后油莎豆在第1–14天达到再生生长高峰期。留茬30cm油莎豆叶片可溶性糖含量(第7、21和28天)均高于其他处理,分别为9.22%、10.83%、9.07%,其淀粉含量(第14和21天)均高于其他处理,分别为4.88%和4.11%。留茬40 cm (第21、28天)蔗糖含量均高于其他处理,分别为7.88%和11.38%;其果糖含量(第14和21天)均高于其他处理,分别为5.29%和6.40%。刈割促进了留茬30和40cm油莎豆叶片蔗糖磷酸合成酶和蔗糖合成酶活性的提高。留茬10cm抑制了油莎豆叶片蔗糖含量增加和相关酶活性。合计刈割时和收获时的饲草质量之和,留茬30cm油莎豆干草质量最高,为10 605.11kg·hm^-2     

不同刈割频度对绵毛优若藜地上生物量及根系的影响

采用盆栽试验,研究了不同刈割频度对绵毛优若藜地上生物量和根系的影响.结果显示:(1)不同刈割处理下绵毛优若藜地上生物量及其营养成分百分含量差异极显著(P<0.01),地上生物量随刈割频度增大呈先增大后减小,其1次刈割生物量最大,单株均值高达5.63g;随刈割次数增加其地上部分的粗脂肪和粗蛋白百分含量均极显著提高,而粗纤维和粗灰分的百分含量则均极显著降低.(2)与不刈割相比,不同频度的刈割均能使根系生物量、根系体积总量和主根直径减少,并随着刈割频度的增大显著减少.(3)刈割显著抑制植株主根伸长,也限制侧根发生,使整个根系在土壤中的分布因刈割频度增大而逐渐变浅,刈割频度≤1时,植物根系主要分布在0～30cm的土层中;刈割频度≥2时,植物根系基本分布在0～20cm的土层中.试验结果说明,绵毛优若藜在民勤沙区适应低频度刈割管理,即1年刈割1次,其地上生物量最大,而根系受影响最小.     

刈割对外来入侵植物黄顶菊的生长、 气体交换和荧光的影响

为明确不同刈割处理对黄顶菊生长和生理特性的影响,本研究在田间条件下,对黄顶菊在生长季内不同时间进行刈割处理。结果表明,刈割降低了黄顶菊植株各部分的生物量积累,其中以刈割3次效果最为显著,使黄顶菊总生物量、根生物量、茎生物量、叶生物量分别较对照下降82.57%、44.53%、80.04%、91.76%;植株的高度和花序数随刈割次数的增加显著降低,其中刈割3次的花序数为0;刈割1次植株分枝数最大,出现超补偿现象,刈割3次分枝数显著低于其他处理;叶绿素含量除了刈割2次出现增高趋势外,随刈割次数的增加,叶绿素含量逐渐降低;刈割处理使黄顶菊净光合速率(Pn)、气孔导度(Cond)和蒸腾速率(Tr)均显著升高;刈割3次的PSⅡ的最大光化学效率(Fv/Fm)和PSⅡ的潜在活性(Fv/F0)显著低于其它各处理,而初始荧光(F0)则显著增加;生长指标的可塑性指数大于生理指标可塑性指数,表明前者在黄顶菊对刈割处理等物理措施适应方面起到了更为重要的作用。总之,刈割3次处理黄顶菊的各项生长和生理指标所受影响最大,对黄顶菊植株的再生和开花结实抑制效果最为理想。     

不同冷季型牧草品种的产草量及品质比较分析

采用随机区组试验设计,对引进的8个冷季型牧草品种进行产草量和营养成分的比较分析.结果表明:4次刈割的总鲜重和总干重在品种间差异极显著,且以蓝天堂黑麦草(7号)最高.品种间的粗蛋白含量差异显著,其中第1次刈割以奇可利(3号)最高,蓝天堂黑麦草(7号)居第2位;第2次仍以奇可利(3号)最高,特高黑麦草(1号)和蓝天堂黑麦草(7号)居其次;第3次以紫花苜蓿(8号)最高,其次是多年生黑麦草(4号);第4次以奇可利(3号)最高,多年生黑麦草(4号)居第2位;粗纤维、粗脂肪和粗灰分在品种间的差别较小.综合产草量和品质两方面考虑,蓝天堂黑麦草(7号)可作为本地首选推广的冷季型牧草品种,奇可利(3号)和多年生黑麦草(4号)可作为备选推广的牧草品种.     

Effects of Nitrogen on the Growth and Accumulation of Secondary Metabolites of Erigeron breviscapus (Compositae)

Erigeron breviscapus a medicinal plant was planted under different nitrogen levels to investigate effects of nitrogen on the growth and the accumulation of secondary metabolites, address the relationship between them in medicinal plants in the plantation. Results showed that the amount of N fertilizer was significantly positively correlated with the biomass, but negatively to contents of total caffeates and scutellarin of Ebreviscapus Moreover, increasing amount of N fertilizer did not significantly enhance yields of 2 active constituents. The biomass was negatively correlated with contents of total caffeates and scutellarin. Contents of total caffeates and scutellarin were negatively correlated with contents of N in Ebreviscapus, as predicated by the carbon/nutrient balance hypothesis. The result suggested that the nitrogen addition could increase the biomass yield, nevertheless, decrease active constituents ( flavonoids ),there could be a trade off between the growth and accumulation of secondary metabolites in medicinal plants.     

不同小麦品种茎秆特性及其与抗倒性的关系

以黄淮麦区优良品种矮抗58、周麦18、豫麦49、百农418为研究对象,采用田间试验与实验室分析相结合的方法,对不同小麦品种在不同生育时期的抗倒伏性状进行研究.结果表明: 茎秆机械强度在开花期至花后20 d处于较高水平,在花后30 d明显下降;倒伏指数在开花期最小,花后30 d最大,其余两个时期处于中间水平.相关分析表明,开花期机械强度与重心高度呈显著负相关,与纤维素、木质素含量呈显著正相关,倒伏指数与节长、株高、重心高度呈显著正相关,与纤维素、木质素含量呈显著负相关;花后10 d和花后20 d机械强度与节长、株高、重心高度呈显著负相关,与茎粗、纤维素、半纤维素、木质素含量呈显著正相关,倒伏指数这段时期正好与之相反;花后30 d机械强度与株高、重心高度呈显著负相关,倒伏指数与株高、重心高度呈显著正相关,与木质素含量呈显著负相关.因此,明确各个生育时期与抗倒性相关的茎秆特性,可为黄淮麦区高产抗倒性品种的选育提供依据.     

Nutritional quality and yield of seedling alfalfa established with a barley companion crop and weeds

Alfalfa (Medicago sativa L.) was established with barley (Hordeum vulgare L.) and weeds to determine the effect of weed management treatments on yield and nutritional quality of alfalfa and companion crop and weeds. Alfalfa+barley and alfalfa+wild oat (Avena fatua L.) had much higher yields in August of the first year than alfalfa alone. Total yields for the first three harvests were similar for alfalfa established weed free, with broad leaf weeds, wild oat or green foxtail (Setaria viridis L.). Protein contents in forage from the August harvest were 228, 196, 117 and 181 g/kg dry matter (DM) in weed free alfalfa, alfalfa plus broadleaf weeds, alfalfa plus wild oat, and alfalfa plus green foxtail, respectively. Alfalfa+barley had higher total in vitro gas production than pure alfalfa, which is correlated with the digestibility of the forage. Total in vitro gas production indicated that alfalfa+barley+weeds had slightly lower digestibility than weed free alfalfa+barley. However, alfalfa with a high percentage of redroot pigweed (Amaranthus retroflexus L.), wild oat or green foxtail had similar or higher in vitro gas production than pure alfalfa. The results from this experiment support a previous economic study that indicated herbicide application for weed control in seedling alfalfa was not necessary.     

Green manures and crop sequences influence alfalfa root rot and pathogen inhibitory activity among soil-borne streptomycetes

A two-year trial was conducted to determine the effects of green manures and crop sequences on plant disease, streptomycete and bacterial densities, and inhibitory activity of indigenous streptomycetes against four target pathogens. Green manure treatments, buckwheat (Fagopyrum esculentum L.), canola (Brassica napus L.), sorghum-sudangrass (Sorghum bicolor) (L.) Moench × Sorghum sudanense (Piper) Stapf.), and fallow control were tested in conjunction with three crop sequences in a Phytophthora-infested soil placed in containers. Alfalfa (Medicago sativa L.), potato (Solanum tubersoum L.), or corn (Zea mays L.) was grown in the first year, and alfalfa was grown in all containers in the second year. Compared to fallow controls, alfalfa grown in sorghum-sudangrass- or buckwheat-treated soil had significantly greater stand counts and total biomass, respectively. In addition, alfalfa grown in fallow-treated soils had the greatest Phytophthora root rot as a function of stand count. Crop rotation also had a significant effect on alfalfa root rot and yield. Potato scab disease intensity was greatest on tubers grown in fallow-treated soils, while tubers grown in canola-treated soils had the highest yields (total tuber weight). Green-manure-treated soils tended to have greater streptomycete and bacterial densities than fallow-treated soils. In addition, buckwheat- or sorghum-sudangrass-treated soils had greater proportions of streptomycetes that were antagonistic against the target pathogens than fallow-treated soils. The proportion of antagonists in soil was negatively correlated with alfalfa root rot, and positively correlated with alfalfa stand counts. Inhibitory activity of the streptomycetes was also negatively correlated with potato scab and positively correlated with potato yield. These data suggest that green manures may provide a strategy for increasing pathogen inhibitory activity within the streptomycete community in soil, and, in conjunction with crop rotation, may contribute to the control of a diverse collection of soil-borne plant pathogens on multiple crop species.     

Relationships between membrane lipids and ion transport in red blood cells of Dahl rats

Distinct changes of membrane lipid content could contribute to the abnormalities of ion transport that take part in the development of salt hypertension in Dahl rats. The relationships between lipid content and particular ion transport systems were studied in red blood cells (RBC) of Dahl rats kept on low- and high-salt diets for 5 weeks since weaning. Dahl salt-sensitive (SS/Jr) rats on high-salt diet had increased blood pressure, levels of plasma triacylglycerols and total plasma cholesterol compared to salt-resistant (SR/Jr) rats. Furthermore, RBC of SS/Jr rats differed from SR/Jr ones by increased content of total membrane phospholipids, but membrane cholesterol was not changed significantly. SS/Jr rats had higher RBC intracellular Na+ (Na(i)+) content and enhanced bumetanide-sensitive Rb+ uptake. RBC membrane content of cholesterol and phospholipids correlated positively with RBC Na(i)+ content, with the activity of Na+-K+ pump and Na+-K+-2Cl- cotransport and also with Rb+ leak. The content of phosphatidylserines plus phosphatidylinositols was positively associated with RBC Na(i)+ content, with the activity of Na+-K+ pump and Na+-K+-2Cl- cotransport and with Rb+ leak. The content of sphingomyelins was positively related to Na+-K+-2Cl- cotransport activity and negatively to ouabain-sensitive Rb+-K+ exchange. We can conclude that observed relationships between ion transport and the membrane content of cholesterol and/or sphingomyelins, which are known to regulate membrane fluidity, might participate in the pathogenesis of salt hypertension in Dahl rats.     

Analyses of a multi-parent population derived from two diverse alfalfa germplasms: testcross evaluations and phenotype–DNA associations

In a previous study, we showed that the genetic variation present in the Medicago sativa subsp. sativa Peruvian and M. sativa subsp. falcata WISFAL germplasms could be used to improve forage yields when favorable alleles were recombined and used in hybrid combination with cultivated alfalfa. In this paper, we present testcross forage yield and fall growth data for two seasons of a C0 population generated after intermating the Peruvian × WISFAL population for several generations. In addition, we conducted marker-trait association analysis as an attempt to identify Peruvian and WISFAL genomics regions affecting the targeted traits. Five and seven genomic regions were found significantly associated with forage yield and fall growth, respectively. In the case of fall growth, alleles from both accessions were positively associated with plant height. However, more alleles from WISFAL were positively associated with forage yield than from Peruvian. WISFAL is known for its winter hardiness and genomic regions with large effects on winter survival may have masked the effect of forage yield from Peruvian. The fact that most of the genomic regions discovered in this study have been previously associated with traits involved in winter hardiness validates our findings and suggests that associations between DNA fragments and agronomic traits can be detected without the necessity of developing bi-parental mapping populations.     

Effect of growth retardants on growth and essential oil content in Japanese mint

In field experiments with Japanese mint using different growth retardants, chlormequat chloride (2-chloroethyltrimethylammonium chloride) increased the oil content significantly and inhibited growth to some extent only, whilst ethephon (2-chloroethyl phosphonic acid) at 0.06% concentration significantly decreased growth but had no significant effect on oil content. Among the two oil components studied, menthone content only was significantly increased by 0.06% ethephon whereas the other growth retardants were ineffective. Correlation studies indicated a strong negative relationship of leaf/stem ratio with plant height and herb yield while a strong positive relationship was obtained between the latter two characters. The oil content of the plant was negatively correlated with herb yield and plant height but it was related positively with leaf/stem ratio.CIMAP Communication No. 688.     

Correlations among anatomical,morphological, chemical and agronomic characteristics of leaf blades in Panicum maximum genotypes

Tropical forage grasses present high growth rates and biomass yields, partly due to its C₄ photosynthetic pathway. Considering this, the anatomy of the grasses related to morphology and chemical composition of leaf blades may influence consumption and digestibility, thus interfering in the forage quality. Agronomic, morphological, anatomical and chemical characteristics of leaves of nine Panicum maximum genotypes were evaluated in Brazil, to verify if these characteristics and the associations among them may influence the quality of the leaf blades. A randomized complete blocks design was used with nine treatments and three replications. Three evaluation harvests were done in the rainy season and one in the dry season to evaluate forage yields and quality. Quality was determined through NIRS – Near Infrared Spectrometer. One day prior to each harvest, four leaf blades per plot were harvested for morphological and anatomical evaluations. Results were subjected to analysis of variance and mean comparison by Tukey test, and to simple linear and canonical correlations by SAS. Leaf width was positively correlated with mesophyll. The parenchyma bundle sheath was associated with leaf area and specific leaf area. Neutral detergent fibre was positively correlated with the parenchyma bundle sheath area and specific leaf area. The specific leaf area was negatively correlated with in vitro organic matter digestibility. Morphological differences among P. maximum genotypes did not interfere in biomass accumulation. Considering this, leaf width may be a supplementary tool, that may be used in the early phases of the process of genotype selection, for discriminating qualitatively promising high yielding materials.