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101.
CECILIA INES ONO MORIKAWA RIE MIYAURA MARIA DE LOURDES TAPIA Y FIGUEROA ELSA LILIANA RENGIFO SALGADO YOSHIHARU FUJII 《Weed Biology and Management》2012,12(1):1-11
Peru is one of the 20 botanically extremely diverse countries in the world, with >17 000 flowering plants, of which 30% are endemic. So far, no systematic research has been conducted on the screening of the allelopathic plants. In this study, the allelopathic activity of 170 species from 61 families of Peruvian plants that were collected from the three main regions of Peru – the Costa (Pacific coastline), the Sierra (Andean mountains), and the Selva (Amazonian rainforest) – was evaluated. The allelopathic activity was determined by the Sandwich Method, which can evaluate the activity of leaf leachates. The species that were found to be highly inhibitory in this screening, under the criterion of >90% inhibition of the radicle of lettuce (Lactuca sativa) seedlings, were Aristeguietia ballii and Diplostephium foliosissimum (Asteraceae) and Spondias mombin (Anacardiaceae). All of these species are native plants from Peru. This study gives a strong clue regarding the potential of isolating potent allelochemicals from these plants in the future. 相似文献
102.
103.
不同施氮量对天然草场牧草产量影响 总被引:7,自引:0,他引:7
采用不同施氮量作用于天然草场,研究了草地施肥与牧草产量的关系,通过测定施肥试验的各项参数,确定了干草原类草场产草量和经济效益最佳的施肥方案,最佳施肥量为450kg/hm^2,同时建立了施肥量与牧草产量间的回归方程。 相似文献
104.
ANELISE REZENDE DE MORAES 《山东饲料》2013,(14):60-61
China has required a large quantity of commodities in order to keep with its economic growth path,driven by large exports,rapid urbanization and investment in fixed assets.Commodities exporter countries have benefited from China ’s immense"hunger"for commodities,especially during the 2000s.Brazil,for instance,has emerged in this scenario as one of the largest iron ore producers and exporters.However,the cooling down of the Chinese economy has brought doubts to the iron ore industry,which may remain strong in near future but one cannot claim for certain whether or not this trend will remain this positive in the long run. 相似文献
105.
研究了4个不同施牦牛粪便的处理对高寒草句植物群落多样性和生产力的短期影响。结果表明,(1)处理S1,S2和s3的植物群落盖度显著高于对照(SO)(P〈0.05),各处理的植物群落高度与对照(SO)相比都呈上升趋势,且S3与S0差异显著(P〈0.05);(2)处理S1、S2和S3的Pielou均匀度指数与sO相比逐渐下降,且S2与sO有显著差异(P〈0.05)。处理S1、s2和S3的Shannon—Wiener物种多样性指数与S0相比逐渐下降,且S2与S0差异极显著(P〈0.01)。而Simpson物种多样性指数的变化则表现为无规律性。(3)施牦牛粪便后植物群落的地上总生物量出现增加趋势,且S2,S3与s0间达到差异显著(P〈0.05)。 相似文献
106.
A number of complaints, regarding the presence of resin-infiltrated splits in seasoned boards produced from Pinus elliottii sawlogs supplied from certain stands in State Forests, led to an investigation to determine the incidence of the defect and to find possible causes. This paper deals mainly with the study of the first aspect. In the investigation two samples of stems were selected by a semi-random method from one mature stand, being clearfelled, in Entabeni State Forest (Northern Transvaal) and from three stands receiving, or due to receive, their fifth thinning. The clearfelling and thinning had produced logs containing heart shakes and this had given rise to the complaints. During log preparation it was attempted to prepare as much as possible of the stem length into the longest sawlogs, working as closely as possible to the maximum limits for sweep and knots allowed by the departmental log specifications. This attempt resulted in the preparation of some logs containing slightly more than the permissible defects. Observations were made on stump surfaces of the orientation of shakes, and on log ends of their occurrence higher up in the stem, in an attempt to find a link between shake orientation and the known direction of strong winds, and to determine the height in the stem to which shakes extended from the stump. The orientation study produced no definite proof that wind was responsible, although there were strong indications. This was followed by sowings up the logs mainly into structural timber, kiln seasoning and grading in two ways, viz A ignoring the resin-infiltrated checks and splits but taking all other defects pertinent to the relevant grades into consideration, and B taking all defects, including the checks and splits into consideration (Table 4). During the grading further measurements were taken on boards containing splits, to determine to what heights in the stem the shakes extended. From the grading results, total and graded yields of sawn timber were computed, the differences in yields between the two grading procedures being a measure of the incidence and seriousness of the shake defect. Within log classes, (see footnote to Table 2) the yields obtained separately for each 2 cm top U.B. diameter class into which the logs had been segregated prior to sawing, were weighted according to the percentage size distributions of the logs yielded by the clearfelling and thinning operations in the relevant compartments, to obtain a weighted average for the log class. The heights to which shakes were present in the stems of the two samples are shown in Table 3(a) while their incidence in logs of the various size classes are shown in Table 3(b). It is seen that shakes were more frequent and serious in the larger logs. The presence of shake in the log samples, taken as a whole, caused only minimal yield losses (Table 4) but had the effect of somewhat reducing average board length (Table 5). However, sawn and graded yields are still excellent and the species should not be discriminated against in afforestation, because of the sporadic occurrence of the defect. The yield figures should be of some value to sawmillers processing both normal and shake-containing logs of this species. 相似文献
107.
J. Mullins 《New Zealand veterinary journal》2013,61(3)
Extract The time has come, perhaps, to speak of things other than the biological in relation to animal life. 相似文献
108.
[目的]从生理生化角度揭示不同光质处理对枫香家系叶色变化的影响,为探索枫香叶色对光质的响应机理提供参考。[方法]以2个枫香家系的1年生幼苗为试验材料,测定其在不同光质处理下叶片叶绿素、类胡萝卜素、花青素、可溶性糖、类黄酮和苯丙氨酸解氨酶的含量并分析其相关性。[结果]结果表明:试验后2个枫香家系叶色较处理前有一定程度的变化。红光处理组枫香幼苗叶片叶绿素含量显著高于其它处理组,而蓝光处理组叶片叶绿素含量则显著低于其它处理组。蓝光处理后,2个枫香家系叶片花青素含量较对照有显著提高,而红光处理则减少了叶片花青素含量。同时蓝光处理能显著提高枫香幼苗叶片类胡萝卜素、可溶性糖和类黄酮含量以及苯丙氨酸解氨酶活力,红光处理效果较对照无显著差异。方差分析表明,不同光质处理对枫香幼苗叶片叶绿素含量影响显著,而对花青素量和类胡萝卜素含量影响不显著。[结论]2个枫香家系叶色在光质处理下有相同的变化趋势,红光处理可以促进枫香幼苗叶片叶绿素合成;蓝光处理可以促进枫香幼苗叶片积累更多的花青素。 相似文献
109.
植物顶端有限生长相关基因与基因编辑育种研究进展 总被引:1,自引:0,他引:1
随着劳动力成本的增加,农作物的采收将逐步从人工采收过渡到机械采收,因此培育紧凑、矮化、果实成熟集中、耐密植、适宜机械化操作的新品种已成为作物遗传改良的主要目标。本文重点综述了不同物种FT及其同源基因对植物成花的调控功能,植株顶端的无限生长和有限生长的控制基因及其功能研究进展,以及通过基因编辑促进顶端成花进而导致植株顶端由无限营养生长转变为有限生殖生长,进一步介绍了通过多基因同时编辑的方法推动植物株型改变并培育新品种的成功案例。植株顶端成花和有限生长的特性可以促进果实的统一成熟,为适宜机械化采收的株型育种提供理论支持和实践指导。 相似文献
110.
为从氮素平衡的角度研究河套灌区氮素潜在污染风险,本文以河套灌区主要种植作物玉米和向日葵为研究对象,分析了传统种植模式下玉米和向日葵收获期农田土壤无机氮残留现状,并从氮素平衡角度利用氮素盈余、氮素潜在损失对玉米和向日葵种植的环境污染风险进行了分析。结果表明:河套灌区农田土壤残留无机氮随着施氮量的增加而增加,玉米田和向日葵田0~90 cm土壤无机氮(以N计)平均残留量分别为66.11 kg·hm-2和45.53 kg·hm-2。灌区中部的五原县玉米田土壤无机氮残留量最高,可达336.93 kg·hm-2,向日葵田以东部乌拉特前旗最高,残留量达273.66 kg·hm-2。玉米田和向日葵田平均氮素年输入总量分别为514.81 kg·hm-2和314.73 kg·hm-2,以化肥氮为主,占总氮素输入的85%以上。氮素输出主要是作物吸收带走,玉米和向日葵平均氮素年输出总量为362.10 kg·hm-2和209.65 kg·hm-2。过高的氮素输入导致玉米和向日葵年平均氮素盈余分别高达235.71 kg·hm-2和168.08 kg·hm-2,并伴随着每年169.60 kg·hm-2和122.55 kg·hm-2潜在损失的氮素。通过氮素平衡的综合分析得出,内蒙古河套灌区保持现有产量水平的玉米氮肥推荐用量约为280 kg·hm-2,向日葵为150 kg·hm-2,与目前河套灌区玉米和向日葵氮肥投入相比,分别节约198 kg·hm-2和128 kg·hm-2,同时该施用量也可以显著降低潜在损失的氮,降低环境压力。 相似文献