低温胁迫对暖季型草坪草细胞膜系统的影响

暖季型草坪草细胞膜是感受低温胁迫最敏感的部位，也是植物低温伤害的根本所在。针对低温胁迫下暖季型草坪草细胞膜系统变化情况，如膜组成结构的变化、膜透性、酶活性的变化等进行综述，为植物低温伤害基础理论研究和实际生产提供一定的参考。     

暖季型草坪草的抗寒性研究概况

由于暖季型草坪草抗寒性较弱,冬季存在枯黄现象而影响草坪观赏性和草坪质量,从而限制了暖季型草坪草的利用与发展。本文综述了低温胁迫对暖季型草坪草光合作用、生理结构的影响以及如何提高暖季型草坪草抗寒性的措施,同时提出了对于暖季型草坪草抗寒性今后的研究趋势。     

用电导率法测定六种暖季型草坪草的抗寒性

本试验用电导率法测定在短时间低温胁迫下，６种暖季型草坪草细胞质膜透性的变化，得出抗寒性切尼狗牙根＞沙哈拉狗牙根＞假俭草＞太阳神狗牙根＞雀稗＞地毯草的结果。     

温度胁迫对亚热带常用草坪草活性氧代谢相关酶的影响

研究了在高温和低温胁迫下,亚热带建坪常用草坪草叶片的活性氧代谢相关酶与细胞膜透性的变化,并依据"自由基"假说,探讨了温度胁迫条件下自由基对草坪草细胞(主要是细胞膜体系)的伤害机理,初步揭示了不同温度胁迫下草坪草受害的致成原因以及不同品种间的差异.研究结果表明,以活性氧代谢指标与细胞膜透性为评判抗性大小的依据,各类品种的抗寒性大小顺序是匍匐剪股颖Agrostis stolonifere>草地早熟禾Poa pratensis>多年生黑麦草Lolium perenne>高羊茅Festuca arundinacea>狗牙根Cynodon dactylon,抗热性大小顺序是狗牙根 > 高羊茅 > 草地早熟禾 > 多年生黑麦草 > 匍匐剪股颖.研究运用了亚热型草坪草活性氧代谢相关酶测定的方法进行了草坪草品种鉴定和抗性比较,为亚热带地区草坪草品种选择、建植和维护提供了科学的理论依据.     

低温对假俭草生理生化特性的影响

低温是影响植物生长、发育的重要环境因素之一,以假俭草为实验材料,测定了假俭草叶片中细胞膜相对电导率、可溶性糖、脯氨酸及丙二醛等生理、生化指标的变化,初步探讨假俭草低温胁迫的伤害与适应。结果发现,假俭草具有较强的抗寒能力,能通过一系列保护性的生理、生化反应来适应低温胁迫,以减轻低温伤害。     

H_2O_2对沟叶结缕草抗氧化系统及其耐寒性的影响

采用盆栽试验,对暖季型草坪草沟叶结缕草进行叶面喷施10mmol/L H2O2的处理,研究外源低浓度H2O2对沟叶结缕草抗寒性的影响。结果表明,H2O2可能充当了信号分子的作用,在胁迫发生前即显著增加了叶片中CAT、APX、GPX和GST的活性,从而减轻了随后的低温胁迫对草坪草造成的氧化伤害;在低温胁迫过程中H2O2预处理降低了叶片中MDA和H2O2水平,CAT、POD、APX、GR和GPX活性增加,提高了其抗寒性;胁迫过程中叶片中总谷胱甘肽含量不变,但GSSG/GSH比值在胁迫前被H2O2预处理降低并随着胁迫的进行逐渐降低,这一比值变化可能也参与了胁迫信号的传导。     

生长调节剂在暖季型草坪中的研究应用

近年来,植物生长调节剂在草业中的研究应用已经成为草业工作者研究的一大热点.植物生长调节剂被广泛地研究应用于调节暖季型草坪草的营养生长、改善草坪质量、增强暖季型草坪草的抗逆性以及提高其种子的产量等方面,并且取得了一定成果.     

7个暖季型草坪草品种对低温胁迫的抗性差异研究

本研究以假俭草（Eremochloa ophiuroides ）、海滨雀稗（Paspalum vaginatum）、结缕草（Zoysia japonica）、‘天堂草419’（Cynodon dactylon ‘Tiffgreen 419’）和普通狗牙根（Cynodon dactylon）等5种暖季型草坪草种的7个品种为供试材料,研究了在25℃（CK）和15℃,10℃,5℃3个低温胁迫下的生理生化特征。结果表明：7个品种在低温胁迫下坪用性状指标不同程度下降,随胁迫温度的降低,草坪草叶片中丙二醛、游离脯氨酸、可溶性糖含量和相对电导率上升,叶绿素含量快速减少;海滨雀稗在5℃低温胁迫3 d枯黄,沟叶结缕草在5 d枯黄。综合7种暖季型草坪草品种的生长表现与生理指标,其抗寒性由强到弱依次为普通狗牙根 > ‘天堂草419’ > 中国假俭草 >‘兰引三号’结缕草 > 中华结缕草 > 沟叶结缕草 > 海滨雀稗。     

暖季型草坪草冬季枯黄原因及对策探讨

从暖季型草坪草自然分布及生理生化两个角度较为深入地探讨了造成暖季型草坪草冬季枯黄的原因,并且还比较详细的介绍了当前国内外的草坪专家,通过冬季补播,覆盖,施肥,植物生长调节剂等方法来推迟草坪的冬季枯黄期,提早草坪的春季返青期,从而改变暖季型草坪草冬季枯黄的方法和试验。     

低温胁迫对野牛草幼苗渗透调节物与根系活力的影响

以暖季型草坪草"中坪一号"野牛草为材料,研究低温胁迫对其幼苗渗透调节物与根系活力的影响。结果表明,渗透调节物与野牛草幼苗低温调节机制密切相关。在低温胁迫下,可溶性糖、可溶性蛋白质、游离脯氨酸含量呈上升的趋势。随着低温处理时间的延长,可溶性糖含量的增加趋于平缓;可溶性蛋白质含量受低温影响较大,随低温胁迫强度的增大,叶片中可溶性蛋白质含量明显增加;游离脯氨酸含量的变化较敏感,低温处理初期,脯氨酸含量急剧上升,随着处理时间延长脯氨酸含量又缓慢降低,但整个过程中脯氨酸含量保持在较高水平;低温胁迫对野牛草幼苗根系活力的影响较显著,随着低温胁迫时间的延长,根系活力急剧降低,说明根系对维持植物正常生长发育的重要性,或可作为植物抗寒性鉴定的一项重要指标。     

Estimation of direct and correlated responses to selection using univariate animal models.

Analytic results obtained using simple models show that estimates of selection response of univariate experiments using animal models are completely dependent on the heritability used as prior when fixed effects are nested within generations, and both on the prior and on the true heritability parameter when fixed effects overlap across generations. Univariate animal model estimators of correlated changes of a trait not selected directly are usually biased. The absolute value of the estimate of the correlated response is smaller than the true value when the traits are only genetically correlated and larger than the expected value of zero when they are only environmentally correlated. The validity of the results derived from the analysis of simple models is confirmed using computer simulations, which illustrate the magnitude of the bias. It is emphasized that use of univariate animal models to estimate response in breeding programs whose breeding objectives include several correlated traits may lead to erroneous conclusions.     

汉代苜蓿传入我国的时间考述

苜蓿不仅是世界性优良牧草,而且也是中西科技文化交流的象征,更是丝绸之路上的一颗耀眼的明珠。虽然苜蓿在我国已有2000多年的栽培史,但是苜蓿是什么时间传入我国的,不论是草学界还是农史界乃至史学界对其看法不一。本文以前人的研究为基础,试图从张骞两次出使西域的时间或使者往来于汉的活动背景,对苜蓿传入我国的时间进行梳理归纳和考释,以期对其有个清晰的认识,为我国苜蓿起源和苜蓿史研究提供依据。研究表明,目前对苜蓿传入我国的时间有4类看法:1)围绕张骞两次出使西域所确定的苜蓿输入我国的时间,主要包括公元前139年/138年、公元前129年、公元前126年、公元前119-115年和张骞两次出使西域带回; 2)围绕汗血马引入我国的时间,即公元前102/101年;3)时间不确定;4)张骞死后或其他时间。经考证,张骞公元前139年/138年、公元前129年带入苜蓿的观点明显不妥,公元前126年带归苜蓿的观点还需做进一步的研究;从实际需求出发考证,苜蓿与汗血马同时输入我国的可能性是存在的;其他两类看法还需要挖掘史料做进一步的证实。     

氮磷添加对草地土壤酸度和化学计量学特征的影响

以内蒙古温带草原为对象,研究了不同比例和水平的氮磷输入对土壤pH和化学计量学特征的影响。结果表明,与不添加氮磷的对照相比,添加氮磷的土壤pH在氮输入大于30g·m~(-2)的情况下显著降低(P0.05),而在不施加磷肥只施加氮肥的情况下,10g·m~(-2)氮输入也显著降低了土壤pH(P0.05),而且显著低于添加磷肥的处理(P0.05)。另外,与高比例和水平的氮磷输入相比,低比例和水平的氮磷输入显著降低土壤大量元素(钾、钙和镁)、微量元素(铁、锰、铜和锌)和毒性元素(铝和锰)(P0.05),而且还降低土壤N∶P。可能是由于该地区土壤磷含量低,低氮高磷输入缓解植物生长受磷限制,促进植物生长的同时,降低土壤养分。由此可见,根据当地土壤养分和氮输入的量,适量添加磷可以缓解外源氮输入对土壤pH和化学计量学特征的影响。     

Effect of season of burning on grass recovery in the false thornveld of the eastern cape

Abstract

Season of burning is one of the most controversial questions concerning the use of fire in veld management. In the summer rainfall areas of South Africa the generally accepted rule of burning only after the first spring rains has proven ineffectual when using fire to control bush encroachment because the fires are too cool when burnt at this time. It was therefore decided to investigate the effect of burning on the regrowth of grass when applied during mid‐winter, spring, late spring and early summer. The results showed that burning when the grass was dormant (mid‐winter) had no deleterious effect on the recovery of grass when compared with burning after the first spring rains (spring). Conversely burning when the grass was actively growing (early summer) seriously retarded its regrowth.     

不同苜蓿品种对豌豆蚜中肠消化酶活性的影响

为了探究取食苜蓿对豌豆蚜中肠消化酶的影响,揭示苜蓿抗蚜的生化机制,本文测定了2种色型豌豆蚜取食8个不同抗性苜蓿品种后中肠主要消化酶的活性。结果表明,红色型豌豆蚜在取食低抗品种渭南后,其中肠蛋白酶活性为（9．71±0．63）U／mL,绿色型豌豆蚜取食感虫品种猎人河后为（9．88±0．56）U／mL,二者取食高抗品种三得利后分别为（0．33±0．10）U／mL 和（0．43±0．02）U／mL;红色型豌豆蚜取食感虫品种猎人河后其中肠脂肪酶活性为（4．12±0．30）U／mL,绿色型豌豆蚜则在取食低抗品种渭南后酶活达（4．00±0．29）U／mL,二者脂肪酶活性在取食高抗品种甘农5号后分别为（1．63±0．10）U／mL 和（1．08±0．13）U／mL;2种色型的豌豆蚜中肠淀粉酶的活性在取食感虫品种猎人河后分别为（2．30±0．40）U／mL、（2．14±0．29）U／mL。此外,豌豆蚜取食8个苜蓿品种后,红、绿色型豌豆蚜的蛋白酶、脂肪酶及绿色型豌豆蚜的淀粉酶活性与苜蓿抗性间均呈高度负线性相关,表明苜蓿品种的抗蚜性越高,蚜虫取食后其中肠3种酶的活性越低,抗性苜蓿品种主要抑制豌豆蚜中肠消化酶的活性。     

奶牛乳头专用消毒剂消毒效力研究

进行了奶牛乳头药浴碘甘油溶液的杀菌作用研究。试验表明,当给药浓度为0．25％（含碘）时,对大肠杆菌、金黄色葡萄球菌和溶血性链球菌的最短作用时间为15s,杀菌率均为100％,对白色念珠菌作用的最短时间为1min,杀菌率为100％。结果说明该消毒剂对上述细菌和真菌均具有良好的杀灭作用,可用于奶牛挤奶前后乳头的药浴消毒,推荐临床药浴使用浓度为0．25％f原液作1：8倍稀释）．     

Guinea pig (Cavia porcellus) drinking preferences: do nipple drinkers compensate for behaviourally deficient diets?

When offered diets with hay ad libitum, rabbits (Oryctolagus cuniculus) clearly prefer open dishes over nipple drinkers, but whether this preference also applies in guinea pigs (Cavia porcellus) is unsure. We tested the drinker preference of 10 guinea pigs when offered open dishes (OD) and nipple drinkers (ND) simultaneously and measured the amount of water consumed by each animal on four different diets (grass hay 100%, or as 10% of intake on diets of fresh parsley, seed mix or pelleted complete feed, respectively) on either of the drinking systems. All animals ingested the hay portion of the combined diets first. The amount of water consumed differed significantly between individual animals. Animals drank less water on parsley than on the other diets. Nine of 10 animals clearly preferred ND when having a choice, and eight of these drank more when on ND only. The difference between the drinking systems was not consistent across all diets: on hay, similar amounts of water were drunk when on OD or ND only. Differences in water intake were reflected in urine production. Because drinking from ND in guinea pigs involves jaw movements similar to those in chewing, the results could suggest that when motivation for oral processing behaviour is not satisfied by a diet, animals may respond in using ND beyond physiological water necessity. Whereas physiological water requirements are probably better investigated with other drinking systems due to a possible overestimation when using ND, offering ND to pet guinea pigs most likely offers a form of behavioural enrichment that at the same time may increase water intake and hence act as prophylaxis against urolithiasis.     

Estimation of effects of single genes on quantitative traits.

Studies involving the effects of single genes on quantitative traits may involve closed populations, selection may be practiced, and the quantitative trait of concern may also be influenced by background genes that are inherited in a polygenic manner. It is shown analytically that analysis of such data by ordinary least squares, the usual method of analysis, can lead to finding an excess of spurious significant effects of single genes, when no effect exists, for both randomly and directionally selected populations and can lead to bias in estimates of single-gene effects when selection has been practiced. The bias depends on heritability of the polygenic effects on the trait, selection intensity, mode of inheritance, magnitude of gene effect, gene frequency, and data structure. It is argued that when genotypes of individuals can be identified for all individuals with observations on the trait, use of mixed-model procedures under an animal model treating single-gene effects as fixed effects can provide unbiased estimates of single-gene effects and exact tests of associated hypotheses for pedigreed populations, even when selection is practiced. Results are illustrated through computer simulation.     

Influence of sarsaponin on growth, feed and nitrogen utilization in growing male rats fed diets with added urea or protein

Two experiments were conducted with growing male rats to determine the effects of 120 ppm of dietary sarsaponin (S) on nitrogen (N) metabolism when urea or protein are added to the diet. Growth, feed efficiency, N digestibility and balance, urinary N and ammonia-N (NH3-N), and cecal urease and NH3-N were measured. Growth and feed utilization were unaffected by dietary S. Adding urea or protein to the diet increased apparent N digestibility and increased urinary-N excretion. Urea did not affect N balance, whereas growth, feed utilization and N balance were maximized with 22% compared with either 16 or 28% dietary protein. Urinary NH3-N excretion was decreased by S when urea was added to the diet but was not affected when fed with increasing dietary protein. Cecal urease was decreased by S when urea was added or when the protein level was increased in the diet; effects on cecal NH3-N varied between the two experiments. Plasma urea-N was decreased by S. It is concluded that S has minor effects on N metabolism in rats and that NH3-N formation or excretion is only marginally affected by dietary S. If S decreases NH3-N level in confinement facilities, it is concluded that the effect is after the waste material is excreted by the animal, perhaps through reduced urease activity.     

克孢灵(ClO2)叶面消毒对桑叶的药害及营养成分的影响

将主要成分为ClO2的蚕用消毒剂克孢灵用作桑树叶面消毒,当药剂质量浓度在200 mg/L以下时,对桑叶叶质没有不良影响;以100 mg/L以下质量浓度药液对桑叶作浸渍消毒时未发现叶片外观出现异常。经50~100mg/L克孢灵处理的桑叶,其水分、糖、蛋白质、脂肪等含量与对照相比没有明显变化,表明50~100 mg/L克孢灵用作桑树叶面消毒剂,对桑叶叶质没有不良影响。