遮阴和干旱对荩草光合特性影响的协同作用

为明确遮阴和干旱协同处理对荩草光合作用的影响,揭示荩草对遮阴和干旱胁迫的抗逆潜力和生态学特点。以具有边坡草坪开发价值的野生荩草为材料,设置5个遮阴梯度和4个干旱梯度交互形成的20个协同处理,对其进行叶生物量分配比、光合色素含量、光响应能力及光合参数的测定。结果表明,荩草叶面积、叶数、叶生物量和叶分配比均显著受遮阴、干旱、遮阴和干旱协同作用的影响(P<0.05),遮阴和干旱对叶面积、生物量和分配比有极显著协同作用(P<0.01),作用大小为分配比>叶数>叶面积>叶生物量;荩草的Chla、Chlb和Chla+b含量及Chla/b显著受遮阴、干旱、遮阴和干旱协同作用影响(P<0.05),Chlb比Chla易受生境影响,遮阴是影响叶绿素含量和比例的主要因子,干旱次之,遮阴和干旱对Chlb和Chla+b含量及Chla/b有显著协同作用(P<0.05);荩草光响应能力极显著的受遮阴、干旱、遮阴和干旱协同作用的影响(P<0.01),遮阴和干旱对光饱和点(LSP)、光补偿点(LCP)和最大净光合速率(P_nmax)有显著的协同作用(P<0.05),作用大小为P_nmax>LSP>LCP;荩草的光合速率(P_n)、蒸腾速率(T_r)、胞间CO₂浓度(C_i)、气孔导度(G_s)均显著受遮阴、干旱、遮阴和干旱协同作用影响(P<0.05),遮阴和干旱对光合参数有极显著协同作用(P<0.01),遮阴主要影响P_n,干旱主要影响G_s、C_i 和T_r,协同作用对T_r的影响最大,≤30%遮阴可缓解干旱引起的P_n、T_r、C_i、G_s下降程度,>30%遮阴则加重了下降趋势。遮阴和干旱协同作用比遮阴或干旱单一胁迫,提高了荩草光合叶面积和叶绿素含量,改变了光响应能力和光合参数,可提升荩草的抗逆潜力和生态适应范围。     

川西北高原老芒麦的遗传多样性研究

以老芒麦品种川草1号和川草2号为对照,采用酸性聚丙烯酰胺凝胶电泳(A-PAGE)方法对采自川西北高原的36份野生老芒麦(Elymus sibiricw L.)种质和5份老芒麦新品系进行了遗传多样性分析.从供试材料中共分离出了42条醇溶蛋白条带,4个电泳分区(α、β、γ、ω)的多态性带数分别为9、10、8和12条,多态率达92.86%;材料间的Nei-Li遗传相似系数(GS)的变异范围为0.333 3～0.956 5,平均值为0.6196.说明供试老芒麦材料具有较为丰富的醇溶蛋白遗传多样性.对所有材料的聚类分析和主成分分析发现.在GS值为0.636的水平上供试材料可聚成5个大类,来自同一地区的老芒麦基本聚在同一类.呈现出一定的地域性分布规律.几个老芒麦新品系间的遗传多样性水平较低,醇溶蛋白条带多态率为48.00%.相似系数变异范围为0.648 6～0.956 5,且在聚类分析和主成分分析中单独聚为一类,说明老芒麦新品系和野生种质间存在较大的遗传差异.     

K肥对假俭草草坪绿度和品质的影响

施K对改善假俭草草坪的颜色、延长青绿期、提高品质有一定的作用。适时适量地给假俭草施以K肥，可增加其叶绿素含量，但是施肥量不得超过7．5g／m’K：O，否则将影响到对其他阳离子尤其是Ca^2 、Mg^2 的吸收。K肥可延长青绿期2～4d，尤其是4．5g／m^2 K2O分3次施用会使枯黄期推迟4d，而返青提前6d，结果使青绿期达313d。施K肥可以增加草坪的密度，减弱草坪在不良条件下颜色变红泛发等现象，增强草坪抗性，在不同时期都使草坪的品质有所提高。等量肥料分次施用的效果好于一次施用，每次施肥量不得高于2．25g／m^2K2O，年总施肥量不得高于7．5g／m^2K2O。假俭草在不同的生长时期都需要K肥，但在高温和低温条件下，施用的效果较好，这与K可以提高抗逆性有关。     

叶面施铁对假俭草草坪绿度与品质影响

假俭草对Fe缺乏非常敏感,容易出现缺Fe症状.试验在不同季节对叶面施不同浓度的Fe、N+Fe后,通过测定叶片内Fe与叶绿素含量的变化以及草坪的品质变化情况,结果表明,夏秋季叶施Fe使草坪叶片变短变窄变厚,草坪高度自然降低,叶绿素含量增加,使草坪质地变细、均一性增加、颜色深绿,提高了草坪的品质,也使根系分布范围扩大,增加了假俭草抗旱性,Fe浓度应该低于0.8 L/m2;在秋季叶施Fe可以改善草坪的绿度,延长草坪的绿期,N+Fe效果好于单独施Fe,其最佳浓度为N4g/m2+Fe0.6 L/m2.     

西南区扁穗牛鞭草种质资源生产能力研究

以茎叶比、鲜草产量、干草产量、粗蛋白含量、粗纤维含量等为指标，以“广益”和“重高”品种为对照，对牧草型野生扁穗牛鞭草材料进行连续3年的生产能力分析与评价，结果说明：野生资源中有生产能力表现好于现有品种的材料，第2年H002、H029、H018干草产量分别比“广益”增产3．99％、13．24％、18．63％，分别比“重高”增产9．27％、18．99％、24．66％；第3年H002鲜草产量与干物质产量都高于2个对照，H019、2003—1、2002—5、2003—6等鲜草产量高于“广益”鲜草，干草产量都高于“重高”。     

扁穗牛鞭草水培无性苗构件组成特点的研究

在水培条件下,测定扁穗牛鞭草茎节形成无性苗的构件组成,结果说明:牛鞭草茎节具有无性繁殖能力,自身贮存营养可满足形成构件完整植株的需求;茎节长度与无性苗构件组成和生物量关系不大;无性苗构件间存在着差异,叶片数、叶干重、茎长度和茎干重的变异系数分别为15.08%、28.95%、22.34%、23.37%,根数、根系长、根干重的变异系数分别为45.75%、26.14%、52.86%;无性苗构件间存在着相关性,茎长度与叶片数和叶干重表现为极显著正相关(P<0.01),茎长度与根数和茎干重与根干重表现为显著正相关(P<0.05),叶干重与茎长度、叶片数、根数、根干重都表现为极显著正相关,再生生物量与叶干重为显著正相关,与茎干重、根干重为极显著正相关,根、茎、叶干重之间表现为正相关,说明无性苗地上、地下各构件生长发育是相互协调的,构件间营养分配是均衡的,从而保证了无性苗构件平衡和株型完善。     

Effects of slope on soil properties and post construction desertification of highway embankments in an Alpine Meadow region北大核心CSCD

This research investigated effect of slope on the performance of highway embankment soil properties post construction, as there is a demand for technical data of this nature to underpin the design of highway revetment work in alpine meadow regions of China. A section of national road G248 in Northwest Sichuan Alpine Grassland, built 10 years ago, was identified as a study site and plots were marked out for sampling on five slope classes: gentle slope, 6°-15° (GS); moderate slope, 16°-25° (MS); steep slope, 26°-35° (SS); very steep slope, 36°-45° (VS); extreme slope, >45° (ES). Undisturbed flat natural grassland >10 m distant from the roadbed was used as the control (CK). Measurements conducted included determination of particle size composition, physical and chemical parameters of the soils, vegetation cover and the proportion of the plot area exhibiting degradation or desertification. The relative reduction rate of organic matter and total nitrogen was also determined, and differences in soil water content and fertilizer retention capacity were assessed. It was anticipated these data would provide a basis for the construction of ecologically sound slope protection structures in alpine regions. It was found that: 1) Increased slope significantly decreased the proportion of clay and silt particles and increased the proportion of coarse sand and small stones (P<0.05). The greater the slope, the greater the soil bulk density and pH value, and the lower the soil water content. 2) Slope facilitated leaching of soil carbon fractions with the leaching intensity of the fractions ranking soil organic matter (SOM)>total carbon (TC)>inorganic carbon (IC)>dissolved organic carbon (DOC). For example, SOM levels were, respectively, 115, 92, 72, 30, 9 and 3 mg·kg−1 for CK, GS, MS, SS, VS, and ES slope classes while DOC levels ranged from 35.4 mg·kg−1 in CK to 9.2 mg·kg−1 in ES. 3) The ranking for the effects of slope on various soil fertility measures was: effective N>alkali-hydrolysable N>total N>available K> available P>total K>total P. Thus, available N was more easily lost than total N and alkali-hydrolysable N. Available N levels declined progressively across slope classes from 236 mg·kg−1 in CK to 6.3 mg·kg−1 in ES, while total N and alkali-hydrolysable N showed marked loss between GS and VS slope classes. A slope threshold for sharp increase in loss of total P and available P was observed between GS and MS slope classes. With increase in slope gradient, the total K increased, while the available K content decreased. 4) With respect to the influence of slope on the degree of desertification: for CK and GS >90% of the plot area was classed as non-desertified; for GS 79% of the plot area was moderately or severely desertified; for SS, VS and ES, 79, 86 and 94%, respectively, of the plot area was severely or extremely severely desertified. The proportion of severe desertification increased markedly at > 15° slope (i. e. MS) and the proportion of extremely severe desertification increased markedly at >25° slope (i. e. SS). 5) When the slope effects were expressed in relative terms, the relative increase in desertification was high and changed little at slopes >15°, while the relative decreases in organic matter and total nitrogen were high and changed little once slope exceeded 25°. As slope angle increased, relatively low rate of total coverage percentage and powder particles <0.02 mm and the relative increase rate of sand particles >0.05 mm increase significantly. In summary, as slope of the study plots increased, fine sand, silt and clay particles were progressively lost, soil fertility progressively declined, and the degree of desertification increased markedly. Therefore, the technical plan for ecologically sound slope protection in highway construction should be formulated according to the steepness of the slope. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

川西北高原野生老芒麦居群穗部形态多样性研究

对采集自川西北高原的13个野生老芒麦居群的15项穗部形态指标进行了研究。Shannon-weaver指数分析表明,13个居群在穗部性状上具有丰富的遗传多样性(H′=1.793 7),且居群内遗传变异(69.31%)大于居群间(30.69%);聚类分析将这13个居群分为3组;主成分分析表明单穗长和宽、单穗重、小穗长、内外稃长和每穗轴节小穗数等是造成13个居群老芒麦穗部特征差异的主要因素;相关分析的结果表明海拔、纬度、经度和降水量对川西北高原野生老芒麦居群穗部性状变异贡献较大,而年均温对此影响不大。此外,提出了川西北高原野生老芒麦的保护策略。     

不同青贮玉米品种在四川农区的筛选研究

一直以来,四川省都是西南地区玉米种植大省,也是畜牧大省,为了满足畜牧业对饲草料的需要及推进四川农区的粮改饲工作,试验选取了 10个青贮玉米品种进行了品种比较试验,以期筛选出适宜四川农区种植的青贮玉米品种.本试验比较了先锋公司的8个青贮玉米材料在成都平原的生产情况,对照为青贮玉米品种雅玉8号和地方材料凉山玉米.通过比较筛...     

中国野生老芒麦形态多样性研究与种质利用潜力分析

为揭示野生老芒麦形态变异特征和遗传背景，对我国野生老芒麦主要分布区域不同生态类型的104个居群520份野生老芒麦种质进行了23个形态指标测定和遗传多样性分析。结果表明：不同生境老芒麦材料的形态特征存在显著差异，数量性状变异系数为9.49%～49.56%；聚类分析将104个居群分为具有各自明显特征和开发利用潜力的4类；形态特征与地理环境因子的相关性分析发现，野生老芒麦抽穗早晚及茎秆叶鞘基部小刺等特殊性状与其海拔呈显著相关；主成分分析发现，株高、抽穗、茎节数、单株干鲜重、旗叶长宽等指标代表了老芒麦67.79%形态多样性，是造成老芒麦形态特征变异的主要因素，可作为老芒麦形态分化的重要参考指标。