Ecology of an Indian grassland millipede Streptogonopus phipsoni (Diplopoda: Polydesmoidea)

Each of stadia II-VII and adults (stadia VIII) of Streptogonopus phipsoni (Pocock) can be distinguished by segment numbers, length, breadth and paired legs. Sexes are separate from stadium IV and sex ratios in immature stages were more or less 50% throughout the year, but high proportions of adult females are noted from June to September. High ratios of immature to adult were related to the breeding periods, from May to October, and in other months adults increased in proportion as a result of heavy mortality of immatures.
Adults were aggregated in distribution from April to October while solitary individuals were common in other months of the year.
Population density of S. phipsoni varied from 0.25 to 98 m^-2 on the soil surface and 1 to 11.75 m^-2 in the lower layer (0–7 cm deep). Biomass ranged from 12.25 to 2253 mg^-2 on the surface and 50.75 to 424.75 mg^-2 in the lower layer (0–7 cm deep).
A positive and significant correlation was found between mean monthly population density and mean monthly rainfall.
Streptogonopus phipsoni appears to complete its life cycle in one or two years     

高寒地区不同海拔梯度西北小檗生境土壤微生物群落结构及多样性分析

以青海高原2 300～4 000 m海拔范围的6处西北小檗(Berberis vernae)生境土壤为试材,采用高通量测序方法,分析不同海拔梯度西北小檗生境土壤微生物群落结构及多样性。研究结果表明:(1)在西北小檗生境土壤中,细菌群落组成主要包括10个细菌门21个细菌属,真菌群落由子囊菌门、担子菌门等8个真菌门59个真菌属组成。(2)低海拔位置的海东乐都1号样点(hdld1) 0～20 cm土层的细菌群落丰富性及多样性均最高,黄南泽库样点(hnzk) 0～20 cm土层的真菌群落丰富度最高,西宁大通样点(xndt) 0～20 cm土层的真菌群落多样性最高;随着海拔的升高,0～20 cm、40～60 cm土层的细菌群落丰富度及多样性呈现出先降低再升高再降低的趋势,20～40 cm土层的细菌群落丰富度及多样性则呈现出先升高后降低的趋势,0～20 cm、20～40 cm土层土壤微生物真菌群落丰富度呈现出先升高再降低再升高的趋势,0～20 cm、40～60 cm土层真菌群落多样性呈现先升高再降低的趋势,40～60 cm土层的真菌丰富度及20～40 cm土层的真菌多样性的变化趋势不明显。(3)硝态氮、速效磷和速效钾对土壤微生物群落的影响较明显。综上可知,高寒地区不同海拔梯度西北小檗生境土壤微生物群落结构多样性呈现出一定的海拔差异趋势,其海拔差异主要受到环境条件、土壤理化性质和植被分布的影响。     

Soil Biological and Chemical Properties in Restored Perennial Grassland in California

Restoration of California native perennial grassland is often initiated with cultivation to reduce the density and cover of non‐native annual grasses before seeding with native perennials. Tillage is known to adversely impact agriculturally cultivated land; thus changes in soil biological functions, as indicated by carbon (C) turnover and C retention, may also be negatively affected by these restoration techniques. We investigated a restored perennial grassland in the fourth year after planting Nassella pulchra, Elymus glaucus, and Hordeum brachyantherum ssp. californicum for total soil C and nitrogen (N), microbial biomass C, microbial respiration, CO₂ concentrations in the soil atmosphere, surface efflux of CO₂, and root distribution (0‐ to 15‐, 15‐ to 30‐, 30‐ to 60‐, and 60‐ to 80‐cm depths). A comparison was made between untreated annual grassland and plots without plant cover still maintained by tillage and herbicide. In the uppermost layer (0‐ to 15‐cm depth), total C, microbial biomass C, and respiration were lower in the tilled, bare soil than in the grassland soils, as was CO₂ efflux from the soil surface. Root length near perennial bunchgrasses was lower at the surface and greater at lower depths than in the annual grass–dominated areas; a similar but less pronounced trend was observed for root biomass. Few differences in soil biological or chemical properties occurred below 15‐cm depth, except that at lower depths, the CO₂ concentration in the soil atmosphere was lower in the plots without vegetation, possibly from reduced production of CO₂ due to the lack of root respiration. Similar microbiological properties in soil layers below 15‐cm depth suggest that deeper microbiota rely on more recalcitrant C sources and are less affected by plant removal than in the surface layer, even after 6 years. Without primary production, restoration procedures with extended periods of tillage and herbicide applications led to net losses of C during the plant‐free periods. However, at 4 years after planting native grasses, soil microbial biomass and activity were nearly the same as the former conditions represented by annual grassland, suggesting high resilience to the temporary disturbance caused by tillage.     

濒危物种胡杨和灰叶胡杨的克隆生长特征

研究不同生态环境条件下胡杨和灰叶胡杨横走侧根的空间分布及其形态特征、不定芽及克隆分株的数量格局特征及其与土壤水分的关系。研究结果表明:(1)16团3个生境中灰叶胡杨克隆分株所在横走侧根均分布在10—20cm的土层;阿瓦提混交林内灰叶胡杨和胡杨克隆分株所在横走侧根分布在20—40cm的土层;轮台县河道边胡杨克隆分株所在横走侧根分布在10—20cm的土层,林内胡杨克隆分株所在横走侧根分布在20—40cm的土层。不定芽、克隆分株所在部位横走侧根最粗,向两端逐渐变细,且远端根始终比近端根要粗;(2)不定芽具有以前期克隆分株为中心向两端延伸发生分布的空间格局特征,横走侧根上不定芽数与出土克隆分株数呈极显著正相关,未出土克隆分株数与出土克隆分株数呈显著正相关,说明不定芽、未出土克隆分株的数量都直接影响出土克隆分株的数量。(3)不定芽、未出土克隆分株和出土克隆分株出现频率、空间分布范围在同一生境同一根段均表现为不定芽未出土克隆分株出土克隆分株,在不同研究区表现为16团(地下水位1.08m)轮台县(地下水位2.56m)阿瓦提县(地下水位3.34m);相关分析显示土壤水分含量与不定芽和出土克隆分株数量均呈极显著正相关。综合分析认为,地下水位和土壤含水量均对不定芽发生以及不定芽向克隆分株转化有显著的影响。     

Interaction Between “Safe Sites” and “Safe Sides” for Germination of Neurada procumbens (Neuradaceae) in the Middle East

The seed bank of Neurada procumbens, a prostrate annual common in sandy desert habitats, is vulnerable to surface disturbances. Moreover, its seeds are highly heteromorphic, having both spinose and non-spinose sides, which affects both the vertical distribution of seeds and diaspores, and the precise position in which they lie in the soil. Here we explore the ecological implications of two factors, “safe sites” within habitats and seed orientation or “safe sides”, on seedling establishment and the seed bank. In three natural populations, the vertical distribution of buried, germinable diaspores decreased with soil depth. Most diaspores occurred at the surface (0–1 cm below the surface), while none were observed below 10 cm. Seedling emergence decreased with depth and reached zero in diaspores below 5 cm. Seedling emergence also proved highly sensitive to the orientation of diaspores in soil. Diaspores lying on their smooth side with the spinose upper side directed upwards reached the highest seedling emergence of 61 %. Root length ranged from 10 to 16 cm, and the root to shoot ratio varied between 22.8 and 30.3 cm, depending on diaspore size. Diaspores near the surface may constitute a more transient component of the seed bank, as few of these remained viable for more than a year. Persistence of Neurada seed banks seems to depend not only on vertical movement of diaspores among habitat “safe sites” but also on different seed position alternatives.     

Habitat choice and seed–seedling conflict of Spartina alterniflora on the coast of China

To elucidate the seed–seedling conflict and the process of habitat choices during the expansion of S. alterniflora, densities of seeds and seedlings in three different habitats, foreland, Spartina meadow, and canopy gap patch, were measured. Statistical analyses of these measurements were performed to investigate the interaction between seeds or seedlings and environmental factors. Also, the process of habitat choice during the expansion of S. alterniflora was explored. The results show that, in the upper soil seed bank (0–5 cm), both the ratio of germinated seeds and the ratio of survival seedlings to total seeds do not differ significantly among the three habitats. However, in the lower soil seed bank (5–10 cm), these ratios differ significantly, suggesting the seed–seedling conflict of S. alterniflora generally occurs in the lower soil seed bank. The remarkable conflict occurs in the meadow habitat. Greenhouse experiments indicate that the germination rate decreases significantly and the mortality of pre-emerged seedlings increases significantly with increasing burial depth. The maximal burial depth of emerged seedlings varies with sediment types. Comparisons of burial depth effects on seedling height, mesocotyl length, coleoptile length, and root length show that the major responses of S. alterniflora pre-emerged seedlings to the burial treatments are the elongation of coleoptiles and mesocotyls, which favor seedling survival by enhancing aeration and accelerating emergence. These results suggest that burial treatment is a key selection factor, which leads to the seed–seedling conflict in recruitment of S. alterniflora population, and directly affects the expansion rate and the area infected by S. alterniflora. Handling editor: S. M. Thomaz Ziwang Deng: co-first author.     

黄土丘陵区坡面整地和植被耦合下的土壤水分特征

水分是干旱半干旱地区植被恢复的主要环境制约因子。在黄土高原小流域,合理整地能够有效截留降雨补给土壤水,进而促进植被恢复。选择地处甘肃定西的半干旱黄土小流域为研究区,基于野外实测数据,分析不同植被和整地方式(柠条水平阶、山杏水平沟、侧柏反坡台,油松反坡台)综合影响下的土壤水分特征。采用最优分割法将不同整地方式土壤水分垂直层次划分为活跃层,次活跃层和相对稳定层。结果表明:生长季不同整地方式土壤水分的变化与降水量的变化密切相关,不同月份以及不同深度各整地方式土壤水分之间差异显著(P0.05)。根据土壤水分垂直变化特征,山杏水平沟水分活跃层与次活跃层为0—80cm,其深度范围均大于其他3种整地方式,而柠条水平阶土壤水分均在30 cm以下较为稳定,其深度范围均小于其他3种整地方式。不同整地方式土壤水分含量具体表现为:山杏水平沟侧柏反坡台柠条水平阶油松反坡台。     

Acari and Collembola in the litter and soil of three north Queensland rainforests

The population changes, distribution and composition of litter and soil Acari and Collembola from three north Queensland rainforests are described based on samples collected on six occasions at approximately 3-monthly intervals. Numbers of Acari and Collembola collected from litter were lower in the north Queensland rainforests than those reported from rainforests outside Australia: however, numbers of Acari and Collembola in the soil were similar to numbers in rainforest soils elsewhere. Cryptostigmata were the most abundant group of Acari in the litter and 0–4 cm soil layer, comprising 41–55% and 42–55% of the total Acari in the litter and 0–4 cm soil layers respectively. Most of the Acari and Collembola are located in the 0–4 cm soil layer at each site (53–75%), with the litter layer containing the smallest proportion (3–20%). Most of the groups of Acari and Collembola examined show little evidence of seasonal vertical migration between the litter and soil to 8 cm. Minimum numbers of Acari and Collembola in the litter occurred in the dry season and maximum numbers occurred in the wet season. Seasonal fluctuations in numbers of Cryptostigmata appear to be influenced by the periodic saturation of the soil during the wet season.     

Phosphorus uptake rates of cotton roots at different growth stages from different soil layers

A greenhouse experiment was conducted to determine P uptake at different growth stages by cotton plants from upper and lower 30 cm layers of 60 cm deep uniform soil columns. A radioisotope tracer technique was used to separate uptake from the two soil layers. Root lengths were measured in both layers at each growth stage. P fluxes were calculated for each layer. Root length increased significantly with time from square formation through peak flowering. At all growth stages, total P uptake from the upper soil layer was greater than that from the lower soil layer. P flux from either layer was greater during early growth stages than during later stages. A significant decrease in P flux occurred when plants reached the flowering stage. The flux from the upper layer was about twice that from the lower layer at square forming stage but the difference decreased as the plants matured. Both layers showed similar P fluxes at the first open boll stage. Our data indicate that roots located 30 to 60 cm below the surface are less effective per unit root length than those located at 0 to 30 cm depth when all roots are in the same soil environmental conditions. However, the effectiveness of P absorption from different soil depths under field conditions may depend on the environmental conditions that exist in each soil depth.     

新疆玛纳斯河流域土壤螨类群落多样性

为探究玛纳斯河流域不同生境土壤螨类群落多样性及其时空特征,采用野外采样和改进的Tullgren法采集土壤螨类进行分类鉴定及比较分析。结果,共采集土壤螨类33208只,隶属4亚目86科140属。其中Ceratozetes和Oribatula为优势类群。不同垂直带生境土壤螨类个体数量和类群数量之间差异显著(P0.05),个体数依次为ⅥⅪⅧⅨⅠⅩⅦⅣⅤⅡⅢⅫ。垂直分布表明不同土层间的个体数差异极显著(P0.01),土壤螨类主要集中分布于表层土壤。不同生境土壤螨类在不同季节均有显著差异(P0.05),个体数依次为9月4月7月11月。在12种不同生境之间土壤螨类群落多样性指标均有显著差异(P0.05),Shannon-Wiener多样性指数(H)依次为ⅠⅤⅣⅥⅢⅩⅡⅨⅧⅦⅪⅫ,而Margalef(M)丰富度指数依次为ⅠⅥⅢⅩⅪⅧⅤⅣⅦⅡⅨⅫ。不同生境土壤螨类群落间的相似性处于中等不相似。结果表明研究流域不同垂直带生境土壤螨类群落多样性具有明显的生境和季节变化特征。     

不同耕作方式对陇中旱农区春小麦和豌豆根系空间分布及产量的影响

依托陇中旱农区长期的保护性耕作定位试验,对不同耕作方式下春小麦和豌豆根系空间分布特征及作物产量进行研究,以探索耕作措施影响作物产量的机制.结果表明: 随着生育期的推进,春小麦和豌豆的总根长、根表面积呈先增后减的趋势,开花期达到最大;春小麦根系苗期以0～10 cm最多,花期、成熟期10～30 cm最多;而豌豆根系苗期和成熟期均以0～10 cm最多,花期10～30 cm最多.免耕秸秆覆盖和免耕覆膜增加了根长和根表面积,春小麦和豌豆各生育时期的根长较传统耕作增加了35.9%～92.6%,根表面积增加了43.2%～162.4%.免耕秸秆覆盖和免耕覆膜优化了春小麦和豌豆根系分布,与传统耕作相比,增加了春小麦和豌豆苗期0～10 cm土层根长和根表面积分布比例,花期和成熟期深层次根系分布也显著增加,免耕秸秆覆盖在开花期30～80 cm土层根长和根表面积的分布比例分别比传统耕作提高了3.3%和9.7%.春小麦各生育期的总根长、根表面积与产量呈显著正相关,豌豆各生育期的总根长与豌豆产量呈极显著正相关.免耕秸秆覆盖和免耕覆膜较传统耕作春小麦和豌豆产量增加23.4%～38.7%,水分利用效率提高了13.7%～28.5%.在陇中旱农区,免耕秸秆覆盖和免耕覆膜可以增加作物根长和根表面积,优化了根系在土壤中的空间分布,增强作物根层吸收能力,从而提高作物产量和水分高效利用.     

弓杠岭不同海拔云杉细根生物量及形态特征

海拔变化是多环境因子的梯度效应,细根作为植物吸收水分与养分的重要器官,其性状特征在指示植物的生长和分布等方面意义重大.该研究以弓杠岭2500～3300 m海拔地的云杉(Picea asperata)细根为研究对象,采用根序分级法对云杉1～5级根序的生物量及细根形态(平均直径、比根长、根长密度、比表面积)进行测定,以明确...     

中国东北黑土土壤剖面微生物群落碳源代谢特征

利用Biolog Eco微平板培养法,对中国科学院海伦农田生态系统国家野外科学观测研究站农田(CL)、恢复草地(GL)和人工林地(FL)土壤剖面不同深度土壤中微生物群落碳源代谢特征进行研究。理化性质结果显示,有机碳、全氮和碱解氮含量随深度增加逐渐减少,p H则是上层土壤低于底层。可培养微生物数量从表层(0—20 cm)到底层(180—200 cm)逐渐减少,在表层(0—20 cm)3种可培养微生物数量均为草地农田林地。可培养微生物主要生活在近地表0—60 cm土层中,在60—200cm土层中3种利用方式下可培养细菌、真菌和放线菌数量基本相同。Biolog结果显示,在0—40 cm土层中微生物群落活性最大,底层(180—200 cm)土壤微生物群落活性最小。3种利用方式剖面微生物群落Shannon多样性指数和碳源利用数量从表层到底层逐渐减少,并且与SOC和TN呈极显著正相关关系(P0.05)。与农田相比恢复草地和人工林地剖面20—40 cm土层中微生物群落对各类碳源的利用强度都较高,说明没有农业机械作业的植被自然生长条件下根系会打破原来农田中的犁底层,促进表层(0—20 cm)以下微生物群落活性。碳源利用率和主成分分析结果表明长期不同植被覆盖已经改变了剖面微生物群落碳源代谢特征,而且根系已经影响到100 cm的微生物群落,但还没有影响到180—200cm中的微生物群落。     

Population dynamics and vertical distribution of Scaptocoris carvalhoi Becker (Hemiptera: Cydnidae) in pastures

Studies on population dynamics and vertical distribution in the soil of Scaptocoris carvalhoi Becker were carried out in a pasture area in Paraúna, State of Goias, Brazil, from November 2004 to October 2005. One meter-deep holes were excavated in the soil, except on the season of lower precipitation, when 2-meter holes were excavated (June, August and September 2005). On each evaluation, the specimens were collected and grouped according to the depth they were found in the soil profile (0-20, 21-40, 41-60, 61-80 and 81-100 cm). Nymphs occurred during the entire length of the study and were more abundant than adults. Adult population augmented with the increase of rainfall. Nymphs and adults were located in the top layer of the soil during the rainy season and were found deeper in the soil during droughts. However, adults were less tolerant to hydric stress and burrowed deeper into the soil at the beginning of the dry season, while nymphs burrowed deeper only at the end of the season. Results of this study are in accordance to other studies on various species of Scaptocoris, in other regions of Brazil.     

桢楠幼苗适应喀斯特岩溶裂隙生境及降雨时间格局变化的方式

喀斯特生态系统是全球陆地生态系统的重要组成部分,生态环境极为脆弱。由于碳酸盐岩长期强烈的化学溶蚀作用,其基本特征体现为地表土壤和地下岩溶裂隙及洞穴的二元结构。近年来,在全球气候变化下,我国西南地区降雨格局呈现降雨频次减少且单次降雨量增加的趋势。因此,岩溶裂隙和区域降雨时间格局改变将对喀斯特地区的植物生长产生重要影响。通过模拟不同岩溶裂隙生境(S₀:24 cm土壤;S_1/2:12 cm土壤层+12 cm裂隙层;S_3/4:6 cm土壤层+18 cm裂隙层)和不同降雨时间格局(I_2d:2 d降雨间隔;I_19d:19 d降雨间隔),探究二年生桢楠(Phoebe zhennan S. Lee)幼苗是否通过生物量分配及根系分布的调整来适应变化环境。结果显示：(1)短时间降雨格局下,相比全土生境,少量岩溶裂隙存在并不影响桢楠幼苗生物量的积累,然而随着岩溶裂隙层进一步增厚和降雨时间间隔延长,桢楠降低了总生物量,减少了茎且增大了根和叶的生物量分配。(2)桢楠幼苗的根系垂直分布随着深度增加而下降,...     

贝壳堤岛3种植被类型的土壤颗粒分形及水分生态特征

运用土壤粒径质量分布原理与分形学理论,以黄河三角洲贝壳堤岛的3种植被类型为研究对象,以裸地为对照,测定分析土壤颗粒分形维数、粒径组成和水分物理参数,探讨不同植被类型的土壤颗粒分形特征及其影响因素。结果表明：贝壳砂土壤中粗砂粒含量最高;其次是细砂粒,而石砾和粉粘粒含量较低。灌木林地和草地具有降低石砾、粗砂粒,增加细砂粒和粉粘粒含量的作用。不同植被类型土壤颗粒分形维数均值在1.5845－1.9157之间,大小依次为酸枣林、杠柳林和草地,表层高于20－40cm土层。酸枣林、杠柳林及草地0－40cm土壤容重均值分别比裸地低23.87%,14.51%和10.47%;总孔隙度均值分别比裸地增加16.96%,16.71%和1.31%。植被恢复措施对贝壳砂表层的孔隙结构、疏松程度改善较好,草地及灌木林地的蓄水性能均表现为0－20cm高于20－40cm。土壤颗粒分形维数与粉粘粒含量、毛管孔隙度、总孔隙度、饱和蓄水量、吸持蓄水量等呈极显著正相关,与细砂粒含量呈显著正相关,与粗砂粒含量和容重呈极显著负相关,与石砾含量、非毛管孔隙度、滞留蓄水量的相关性不大。从土壤分形维数及其水分生态特征来看,贝壳堤岛3种植被类型的改良土壤物理性质及蓄水保土功能表现为灌木林好于草地,其中酸枣林好于杠柳林,0－20cm好于20－40cm土层。     

DTPA soil extractable and plant heavy metal concentrations with soil-added Cd treatments

Summary The numbers, weights, and ages of root nodules were determined in a homogeneous 6- to 7-year-old stand ofHippophaë rhamnoides in a coastal sand-dune area. Large variations in the number of nodules, which ranges from 30 to 281 per m² were found. Most of the nodules occurred between 10 and 60 cm below the soil surface. In the surface layer and lower than 60 cm only small numbers of nodules were present. It is concluded that relatively large samples have to be investigated to obtain an impression of the nodulation of a given stand and to permit a comparison of the contribution of dinitrogen fixation in different stands.Close correlation was found between nodule numbers and the age of the roots, young roots having the highest numbers. However, the wide variation in the number of nodules per square metre could not be explained solely by the age distribution of the roots. The possible role of some other factors is discussed. No relationship was found between the nodule weight and the age of the nodule. The mean dry weight of living nodule material was 5.3 g per m². Most nodules reached an age of up to 3 years. The significance of nodule decay for the distribution of the endophyte in the soil and in the process of nodule formation is discussed.     

The millipedes of a Cheshire wood

The density and surface activity of the millipedes in a quarter of an acre of a sycamore ash wood are described. Seven species were extracted by Tullgren funnels from samples of soil and litter over five years and were also caught in pitfall traps during a further two years; four other species occurred occasionally in the traps. Each square metre of the site supported 100 individuals over the winter, rising to 300 in the summer. Of these, 85 % belonged to three species, Iulus scandinavius, Polydesmus angustus and P. denticulatus .
Male I. scandinavius become adult in either the ninth, tenth or eleventh stadium; females in the tenth and eleventh. Eggs are laid in spring and these take three years to become adults which breed and then die. The majority of Polydesmus spp. in the samples are young belonging to the first six of the eight free-living stadia. The adults fell into the traps in the summer and newly emerged young appear in the samples at this time. They overwinter in their first year mainly as fifth stadia; some might reach maturity (eighth stadia) in the summer following, but it is not certain that they could breed at this time.
The pattern of dispersion of lulus is fairly even and is correlated with the distribution of leaf litter but the Polydesmus spp. are highly aggregated. All stadia of lulus fall into the traps but only the last two of Polydesmus . The aggregation of Polydesmus spp. appears to be correlated with the relative inactivity of the younger stadia. The estimates of density of Polydesmus spp. are unreliable because of their aggregation but those of lulus have determinable limits and it is possible to derive rough though meaningful standing crop, production and life-table data. The overwintering standing crop of lulus consists of the survivors of three generations of 5, 2.2 and 1.4% of the original eggs laid; it has a fresh weight of about 1.25 g and a production in the order of 1.5–2.5 g/m².     

白刺沙包浅层土壤水分动态及其对不同降雨量的响应

以乌兰布和沙漠典型白刺沙包为研究对象,使用EC-5土壤水分传感器对其浅层(0—50 cm)土壤水分进行长期连续监测,分析了白刺沙包不同深度土层对不同降雨量的响应及整个生长季的土壤水分动态特征。结果表明:降雨是乌兰布和沙漠白刺沙包土壤水分的最重要补给源,降雨量大小是影响浅层土壤水分补给深度的决定因素。小于10 mm的降雨完全被表层(0—10 cm)土壤吸收,无法补给10 cm以下土壤水分;10—20 mm的降雨对土壤水分的补给深度达到20 cm;20—30 mm的降雨对土壤水分的补给深度达到40 cm,大于30 mm的降雨补给深度可达到50 cm,甚至更深土层。在研究区降雨量以小于20 mm降雨为主的情况下,20 cm以下土层土壤水分逐步恶化,久之将有利于浅根系草本植物的生长,不利于白刺的生长繁殖。因此,这种降雨格局将对浅层土壤水分及植被演替产生重要影响。     

低温潜沼性逆境下不同耐受能力水稻根系动态变化

水稻根系生长分布与地上部生长及产量形成密切相关,定量研究低温潜沼性逆境下水稻根系分布特征对改进稻田管理方式及耐潜品种的选育等具有重要意义。以4个耐潜等级的8个水稻品种为实验材料,在水稻栽培环境模拟系统中连续栽植3年(2012—2014年),研究水稻根系在低温潜沼性逆境下的动态变化规律和分布规律,明确低温潜沼性逆境下水稻根系变化与产量构成的关系。结果表明:1)低温潜沼性逆境下水稻根系长度和数量的M值(绝对变化率)均大于0,P值(相对变化率)均小于0。表明,低温潜沼性逆境下水稻根系仍有一定增长,但与非低温潜沼性逆境相比,根系长度和数量均显著降低,降低程度因品种耐潜等级的高低而不同,耐潜指数高的品种(泸优5号和C优130)降低程度显著低于耐潜指数低的品种(川谷优204和协优027)。2)低温潜沼性逆境对0—10 cm土层根系的影响在5月底6月初最大;对10—30 cm土层根系的影响在6月底最大;对30—50 cm土层根系的影响在6月30日前后最大。3)低温潜沼性逆境下,水稻孕穗-抽穗期根系长度和数量与穗粒数、实粒数、结实率、产量之间呈显著正相关;与单株有效穗数和千粒重呈显著负相关,根系长度和数量的M值与P值,尤其是白根长度和数量的M值与P值可作为一个水稻耐潜能力评价指标进行考虑。4)低温潜沼性逆境下,不同土层水稻根系与产量构成因素间的相关性不同。0—10 cm土层根系长度和数量与有效分蘖数呈显著负相关;10—20 cm土层白根长度和数量与结实率呈显著正相关;30—50 cm土层根系长度和数量与着粒数呈显著正相关。