刈割对羊草叶面积指数的影响

对经过17年不同刈割处理的内蒙古羊草草原羊草种群的叶面积指数进行了比较研究,结果表明:连年刈割使羊草叶面积指数迅速下降,轮休则能减弱下降趋势;隔几年刈割一次会促进羊草种群的生长,增加其叶面积指数;结实期和结实后期刈割,叶面积指数下降最大,开花期刈割次之,果后营养期刈割下降最小;羊草叶面积指数的变化主要由刈割后种群密度的变化引起,平均单叶面积对其影响较小;分株叶片数的变化对叶面积指数无显著影响;羊草叶面积指数的变化与羊草营养枝高度、干重、密度和种群相对生物量之间呈显著相关关系,与生殖枝高度和群落总生物量相关不显著.     

含油污水对牧草生产性能影响的研究

研究了１１种主要栽培牧草不同矿物油投配量下的生育特性和生产性能。结果表明，适量的矿物油可使多数草种植株高度和叶面积增大，分蘖分枝数增多，产草量提高，叶片中叶绿素含量增加，其幅度因种而异。     

不同退化程度下嵩草草甸矮嵩草无性系构件的研究

对不同退化程度下嵩草草甸矮嵩草无性系构件进行了研究。结果表明，矮嵩草无性系的面积大小与矮嵩草构件总数量和生物量显著相关（P〈0．05），与其各构件平均值基本不相关。随着退化程度的加重，在一定限度内单位面积上各分株和各分蘖数量和生物量有所增加，随后呈下降趋势；平均分株数量与生物量、分蘖数量与生物量均呈下降趋势；每分株分蘖（营养、生殖）、每分蘖（营养、生殖）、生殖（叶、秆）的数量和生物量也呈下降趋势；平均分蘖节直径有增加的趋势，平均分蘖节距地面的高度除极度退化外均呈上升趋势。     

N、P对裸燕麦生产性状的影响

以裸燕麦青引3号(Avena nuda L.ev.Qingyin No.3)为材料,研究了施氮和施磷对株高、生殖枝数、营养蘖数和总分蘖数、叶面积的影响.结果表明,施氮和施磷对生产性状各指标具有影响.在N135P90处理下,裸燕麦株高最高;N135P0处理下营养蘖最多,在N90P90处理下,生殖枝数和总分蘖数最多;N135P90处理下叶面积最大.     

刈割对干热河谷坚尼草生产性能的影响

通过研究干热河谷坚尼草不同刈割周期及留茬高度对其生产性能的影响,结果表明：随着刈割周期延长,坚尼草产草量、株高和分蘖数逐渐增加,以20～30d刈割产草量相对较高,分蘖强,差异不显著,但生长高度与10～15d刈割差异显著;不同刈割高度对坚尼草产草量没有显著影响,随着刈割高度增加,产草量和分蘖数逐渐降低,而生长量增加,刈割高度为10～20cm时,其产草量、分蘖数和生长性较好。为促进其分蘖、生长和提高产草量,其刈割周期与刈割高度分别25～30d和10～20cm为宜。     

小黑麦+光叶紫花苕混播草地叶面积指数及产草量动态研究

根据云南省晋宁县特有的生态和经济发展特点，在冬闲田上用小黑麦 WOH939、WOH830、NTH237三个品种与光叶紫花苕分别以6：4和7：3的比例混播，共6种组合为研究对象，测定分析了各混播处理中植株高度、叶面积指数、产草量的变化规律。结果表明，不同处理在同一生态环境下表现出相似的叶面积指数及产草量变化规律：小黑麦的叶面积指数从孕穗期之后逐渐下降，而光叶紫花苕的叶面积指数始终保持上升趋势，混播草地叶面积变化规律与小黑麦相似。各混播草地产草量快速增长阶段出现在小黑麦的分蘖期到孕穗期；在开花期，干草产量可以达到9．7～12．4 t/hm~2。     

松嫩平原野大麦种群可塑性生长及密度调节

松嫩平原野大麦种群数量特征的野外调查和统计分析结果表明:在籽实乳熟～成熟期,野大麦种群尚未达到环境最大容纳量,其生物量随种群密度增加呈极显著增长;营养蘖可塑性大于生殖蘖,生殖蘖生产力约是营养蘖的1.3倍;种群抽穗率有较大的变异度;分蘖株的生长已经受到种群密度的调节,分蘖株单蘖重与种群密度和营养蘖密度,以及营养蘖、生殖蘖单蘖重与种群密度间均为幂函数关系.     

播量、行距对裸燕麦生产性状的影响

以裸燕麦青引3号(Avena nuda L.cv.Qingyin No.3)为材料,研究了播量和行距对株高、生殖枝数、营养蘖数、总分蘖数、叶面积、穗长的影响.结果表明,播量和行距对裸燕麦生产性状均有的影响.在播量60kg/hm2和行距20cm处理下,裸燕麦株高和叶面积达最高值;在播量120kg/hm2和行距20cm时的生殖枝数和总分蘖数最多,穗最长;在播量150kg/hm2和行距30cm时营养蘖数最多.     

不同退化程度下嵩草草甸矮嵩草无性系构件的研究

对不同退化程度下嵩草草甸矮嵩草无性系构件进行了研究。结果表明,矮嵩草无性系的面积大小与矮嵩草构件总数量和生物量显著相关(P<0.05),与其各构件平均值基本不相关。随着退化程度的加重,在一定限度内单位面积上各分株和各分蘖数量和生物量有所增加,随后呈下降趋势;平均分株数量与生物量、分蘖数量与生物量均呈下降趋势;每分株分蘖(营养、生殖)、每分蘖(营养、生殖)、生殖(叶、秆)的数量和生物量也呈下降趋势;平均分蘖节直径有增加的趋势,平均分蘖节距地面的高度除极度退化外均呈上升趋势。     

景泰绿洲3种小谷物的产草量与牧草营养成分预测

为了预测景泰绿洲春小麦(Triticum aestivum)、燕麦(Avena sativa)、黑麦(Secale cereale)的产草量和营养品质,通过田间试验,测得牧产草量、株高和分蘖,室内测定粗蛋白、粗脂肪、中性洗涤纤维、酸性洗涤纤维、粗灰分和可溶性碳水化合物,分析各指标之间的相关性。结果表明,收获干草的3种小谷物分蘖和株高均与可溶性碳水化合物之外其它5个营养指标存在显著相关性(P0.05),模拟轮牧的春小麦和黑麦株高与营养指标均无相关性(P0.05),燕麦和黑麦的分蘖与6个营养指标均呈显著相关(P0.05)。建立了根据株高预测产草量和营养品质的模型、用分蘖预测牧草营养品质的模型、用产草量预测牧草营养品质的模型、用分蘖和产草量两个因子综合预测营养品质的模型。经过与实测值对比,各预测模型的准确性均较高。     

Factors affecting recovery of Dictyocaulus viviparus third stage larvae from herbage and growth of Pilobolus on dung pats

Significantly greater Dictyocaulus viviparus stage three larval recoveries from herbage samples adjoining first stage larval infected dung pats with Pilobolus, and the effects of biotic and mechanical factors on dung pat integrity supported previous findings. Several meteorological factors including sunshine hours, relative humidity, rain total and wind speed showed significant correlations with growth of Pilobolus on dung surfaces. The influence of monitored variables on the recovery of third stage larvae from herbage and the growth of Pilobolus was modified by height of the sward surrounding the dung pat. Multiple regression analysis showed that 60 per cent of variation in D viviparus third stage larvae recovery from herbage was accounted for by known variables.     

The relationship between sward structure,ingestive behaviour and dietary quality in cattle grazing a Chloris gayana pasture

The relationship between sward structure, ingestive behaviour (bite size, biting rate and intake rate) and dietary crude protein (CP) content was studied on a Chloris gayana pasture at different growth stages using oesopha‐geally‐fistulated steers. As the pasture matured, leaf table height, plant height, disc height, stemminess and standing herbage increased while leaf density and leaf percentage (%) declined. In conjunction with these changes, biting rate and dietary CP declined sharply, while bite size increased. Intake rate remained relatively constant for all sward structures. Animals adjusted biting rates to compensate for changes in bite size and thus maintained rates of intake. Bite size and dietary CP were negatively correlated. It was argued that, in the present study, leaf table height, stemminess, leaf density and leaf % were the main determinants of dietary CP and ingestive behaviour.     

刈牧后休闲期对草地牧草生产的影响

通过不同间隔时期对多年生黑麦草、白三叶混播草地牧草产量的监测与分析,得出随着休闲期的增加,青绿物质和死亡物质均呈现上升趋势,在较低和较高草地牧草现存量下都会降低牧草生长率。     

马蔺不同生长阶段嫩叶POD和EST同工酶分析

利用聚丙烯酰胺凝胶电泳技术,检测了11份不同居群马蔺种质材料叶片过氧化物酶（POD）、酯酶（EST）同工酶的2个酶系统22个同工酶位点,分析马蔺营养生长和生殖生长阶段的同工酶变化。结果表明,11份马蔺种质叶片共有13种POD酶带,9种EST酶带,其中,基本谱带8条,特征谱带4条;与生殖生长阶段相比较,马蔺营养生长阶段E...     

矮壮素对大丽花生长发育和内源激素含量的影响及相关性分析

以大丽花（Dahlia pinnata）高生型品种‘陇上雄鹰’为试材,研究矮壮素不同施用方式及不同浓度对其生长发育和内源激素含量的影响,并对生长发育指标与内源激素含量进行相关性分析。结果表明,喷施和根施矮壮素均可使大丽花株高矮化,节间缩短,茎粗、叶面积、花径和花瓣数增加,花期延长;营养生长期IAA、GA3含量降低,ABA含量升高;生殖生长期IAA和GA3含量升高,ABA含量降低;且随着施用浓度的增加效果增强。各生长发育指标与内源激素间表现一定的相关性。营养生长期株高与IAA、GA3是极显著正相关（P<0.01）,与ABA是极显著负相关;节间长与IAA是极显著正相关;茎粗与GA3是极显著负相关;叶面积与GA3极显著负相关,与ABA是极显著正相关;生殖生长期花期和花径与IAA、GA3是极显著正相关,与ABA是显著负相关（P<0.01）;花瓣数与GA3是极显著正相关。根施3 000 mg·L-1矮壮素对各指标影响效果最显著。     

Patch grazing of Tall Grassveld by cattle after a spring burn

Patterns of herbage removal by rotationally stocked cattle (at a density of 4.85AUE ha^-1) on initially structurally homogenous Tall Grassveld were examined over a single season. Three unreplicated camps were stocked early (29 days), at the recommended '10-15cm' sward height (44 days), and late (80 days) after a spring burn. Temporal change in the spatial distribution of herbage in each treatment was described by intensive measurement of compressed sward height (CSH) with a disc pasture meter and analysed with parametric and spatial statistics. Grazing pressure at the start of the grazing was highest in the early graze, intermediate at the recommended, and least in the late graze treatment because of variation in initial herbage mass related to period of deferment after the burn. The early graze paddock was most spatially uniform and the late graze paddock the most uneven and patchy before grazing. Such initial conditions significantly affected subsequent herbage removal patterns: the greater the amount and spatial variability of herbage accumulated before grazing, the greater the chance for patches to develop through area-selective grazing. The early graze paddock was utilised non-selectively during the first two grazing periods but similar to other treatments, became patchier with time. Spatial pattern, a mosaic of short, intermediate and tall patches, peaked in late summer and was most pronounced in the late graze treatment. Intensive, early stocking after a burn is recommended for minimising intraseasonal development of patches and efficient use of high-quality forage available after a burn.     

Plant and sward response to patch grazing in the Highland Sourveld

Abstract

Selective grazing by livestock inevitably results in patch grazing. This study was initiated to determine the effects of patch grazing on (1) the vigour of a single grass species, Themeda triandra, and of the sward, and (2) sward species composition. The generally held idea that a full season's rest followed by an early spring burn would prevent preferential grazing of patch grazed areas which had developed in the seasons before the rest was also tested. The vigour of 71 triandra was estimated from etiolated growth of marked tufts while sward vigour was indexed by above‐ground herbage production (AGHP). Etiolated growth of T. triandra and AGHP of the sward within patches were negatively affected by three seasons of grazing, but a full season's rest appeared sufficient to restore both the etiolated growth of T. triandra and the AGHP of the sward to a level similar to that in the non‐patches. A full season's rest followed by spring burning did not, however, prevent preferential grazing of grazed patches which had developed in the seasons prior to the rest. Species composition within patches (characterised by Increaser II species) differed significantly from the species composition of non‐patches (characterised by Increaser I species). Patch grazing may therefore initiate the rangeland degradation process in Highland Sourveld and patch grazing may be the focus from which rangeland degradation proceeds.     

春施多效唑对高羊茅生长及饲草品质影响

春施不同浓度的多效唑对高羊茅Festuca arundinacea的生长及饲草品质影响的研究结果表明,多效唑对高羊茅的营养生长具有显著的抑制作用,多效唑处理后30 d,处理浓度为250,500,750和1 000 mg/L时,株高分别比对照降低了37.9%,43.5%,62.6%和71.1%.多效唑处理后叶色加深,叶片变小,叶面积指数下降,光合有效面积减小,地上部干物质积累量减少,与此同时单株茎蘖数增加,叶茎比提高,饲草中粗蛋白含量增加,中性洗涤纤维含量下降,饲草品质得到了改善.     

Influence of sward height, daily timing of concentrate supplementation, and restricted time for grazing on forage utilization by lactating beef cows

To establish the effect of sward height, concentrate feeding time, and restricted time for grazing on forage utilization by grazing cattle, 32 crossbred beef (24 Angus and eight Hereford) cows (632 kg BW) and calves (104 kg BW) were grouped by weight and calving date. They were assigned randomly to two sward height treatments (4 to 8 or 8 to 12 cm), replicated four times. The herbage comprised mainly Kentucky bluegrass, orchardgrass, some forbs, and white clover. The cows were restricted to 12 h/d grazing (0700 to 1900) or unrestricted to 24 h/d grazing and fed a concentrate supplement (4.1 kg DM.cow(-1).d(-1), approximately 0.65% of BW or 33% of total DMI) either at 0700 or 1800. The experiment was repeated over three 15-d periods in May, June/July, and August 2000. The herbage on high sward height pasture was higher (P = 0.06) in NDF and ADF and lower (P < 0.01) in CP than low sward height herbage. For cows restricted to 12 h/d grazing, supplementing at 0700 as opposed 1800 resulted in greater (P = 0.04) forage DMI (8.6 vs. 8.1 kg/d), whereas cows that were unrestricted showed little change (8.2 kg/d at 0700 vs. 8.4 kg/d at 1800). Supplementing at 1800 as opposed to 0700 resulted in greater (P = 0.03) herbage DM digestibility (67.7 vs. 64.5%) for cows on high sward height, whereas cows on low sward height exhibited minimal differences (65.4% at 1800 vs. 66.3% at 0700). Cows restricted to 12 h/d grazing and supplemented at 0700 as opposed to 1800 resulted in greater (P = 0.06) digestible DMI (5.0 vs. 4.7 kg/d), whereas unrestricted cows exhibited the opposite response (4.6 kg/d digestible DMI at 0700 vs. 4.9 kg/d at 1800). Supplementing at 1800 as opposed to 0700 increased the time spent grazing to a greater (P = 0.09) extent for restricted than for unrestricted cows. When forage availability or grazing time was limiting (due to a low forage allowance and restricted access to forage, respectively) supplementing concentrates at 0700 resulted in greater forage utilization and intake rate because of increased forage DMI, DM digestibility, and digestible DMI. However, when forage or grazing time was not limiting, supplementing concentrates at 1800 resulted in greater forage utilization because of increased forage DM digestibility.