Effect of soil moisture and the phenyl mercuric acetate on the physiology of lupine and safflower

Transpiration rate, leaf area, the content of nitrogen and saccharides decreased with the decrease in soil moisture content from 90 % to 30 % of full field capacity. Stomatal frequency, fresh and dry matter and the chlorophyll and carotenoid contents of lupine or safflower remained more or less unaffected. After spraying with the antitranspirant (PMA) the saccharide contents were raised. As concern the lipids content and the contents of Ca, Mg and P, treated plants exhibited variable response to both drought stress and spraying with various PMA concentrations.     

The effect of soil moisture tension and nitrogen supply on nitrate reduction and accumulation in wheat seedlings

Summary The effect of soil moisture tension on nitrate reductase and on nitrate accumulation in wheat plants was studied. Nitrate reductase activity was inhibited when soil moisture tension was increased to about 3.0 bars associated with a drop in leaf relative water content to about 90 per cent. The decrease in nitrate reductase activity did not result in nitrate accumulation in short-term experiments (10 days) when plants were exposed to only 1–2 cycles of elevated soil moisture tensions. However, when the period of different moisture regimes was extended up to the flag-leaf stage, nitrate accumulated in stressed plants.Significant increase in plant nitrate concentration as a result of increased moisture tensions was only found at the high levels of added nitrogen. On the other hand, moisture tensions had no effect on the content of total nitrogen in wheat shoots, implying that nitrate reduction was rather limiting under stress conditions.An effect of soil moisture tension and nitrogen nutrition on dry matter production by wheat seedlings was also found in the long-term experiment. At the highest dose of soil nitrogen an increase in maximal soil moisture tension from 0.1 to 0.33 bars reduced plant growth; at intermediate nitrogen doses only tension higher than 2 bars reduced growth. Under complete nitrogen deficiency, plant dry matter production was very low and was not affected by soil moisture tensions.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 1972 Series, No. 2185-E.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 1972 Series, No. 2185-E.     

共生期土壤水分对麦棉套种冬小麦比叶重、WUE和产量的影响

在麦棉套种的条件下,研究了共生期土壤水分对冬小麦旗叶比叶重(LSW)、水分利用效率(WUE)和产量的影响,并对旗叶干物质衰减速率(DM DR)、叶绿素含量和旗叶的籽粒贡献率做了测定.试验结果表明,共生期土壤水分条件明显影响了比叶重的下降速度,土壤水分高时比叶重的下降速度较小.不同土壤水分条件的旗叶水分利用效率(LWUE)在共生期均经历了先上升后下降,接近成熟期又上升3个阶段.在共生后期,土壤含水量高的冬小麦具有较高的比叶重和叶绿素含量,但其产量和产量水平水分利用效率(YWUE)则显著下降(P<0.01).     

土壤水分对返青期断根冬小麦补偿效应的影响

通过盆栽试验研究了不同土壤水分条件下返青期断根冬小麦的补偿效应.结果表明,断根小麦的早期生长受到抑制,叶面积在返青 拔节期间显著下降,到开花期能恢复至对照水平.高水分条件下断根小麦拔节期的叶绿素荧光参数包括表观光合电子传递速率、实际光化量子产量、光化学淬灭系数、非光化学淬灭值均显著大于对照,开花后单茎干物质积累为0.81 g,显著大于对照（0.56 g）,花后干物质积累系数比对照提高了38.79%,断根小麦根量虽有所下降但差异不显著;低水分条件下断根小麦的叶绿素荧光参数和花后干物质积累与对照之间没有显著差异,但断根小麦的根系生物量（7.83 g·pot^-1）显著小于对照（9.77 g·pot^-1）.土壤水分对断根小麦的地上生物量和籽粒产量的补偿效应没有显著影响.断根处理的冬小麦在两种土壤水分条件下均显著降低了耗水量,在整个生育期,高水分条件下冬小麦断根处理可节水2 000 ml左右,水分利用效率为1.97 g·kg ^-1,显著大于对照的1.70 g·kg ^-1;低水分条件下也可节水1 500 ml左右,水分利用效率虽有所提高,但未达到显著性差异.     

The Influence of Moisture Stress on Liriodendron tulipifera L. Seedlings

A comparison of yellow poplar seedlings subjected to availablemoisture ranging from 100 per cent to 20 per cent of field capacityin two separate experiments (a soil study and a solution study)indicated that total dry matter production, stem height, totalleaf area and area of individual leaves, decreased with increasedmoisture stress. Differences in unit leaf rate (ULR) were primarilyresponsible for final plant size. Leaf area: weight ratio wasaffected by the method of induced stress. As stress increasedthe ratio increased in the soil study but decreased in the solutionstudy. The number of leaves produced was unaffected by stress,except at the most severe stresses. The number of senescentleaves increased as moisture stress increased. The allocationof new growth was unaffected by either moisture stress or timeand decreased in order of root, foliage, stem for the soil grownplants and foliage, root, stem for the solution grown plants.ULR and relative growth rate (RGR) were reduced by both moisturestress and time. A growth simulation of the soil-grown plantsbased on results from the solution moisture stress experimentpredicted the final plant dry weight within 12 per cent andleaf area within 7 per cent of the actual values.     

Effect of sodium fertiliser on water status and yield of sugar beet

Effects of sodium fertiliser on growth, water status and yield of sugar beet crops were measured in 1974 and 1975. Sodium increased leaf area index early in the growing period, the water content of the leaves and the final yields of root dry matter and sugar in both years. In 1974, it increased leaf relative water content and diffusive conductance under conditions of moderate soil moisture deficit in August but had no effect in June or September when soil moisture deficits were low. There was also no effect in June 1975 but later, when there was a severe drought, sodium decreased leaf water potential. Further evidence of an interaction between sodium and soil moisture on leaf water status was obtained from a reappraisal of results of field experiments made between 1965 and 1976. Sodium increased sugar yield through at least two different physiological mechanisms; it improved interception of radiation by the crop by increasing leaf area early in the season and it improved the efficiency of leaves under conditions of moderate water stress.     

The effect of level of CaCO3, inoculation and lime pelleting on the nodulation and growth of beans in five acid soils

Summary The effect of level of CaCO₃, inoculation and lime pelleting on the nodulation, dry matter yield and % N content of common bean plants (Phaseolus vulgaris) grown in five acid soils was investigated in a greenhouse study. The soils represented a range in pH from 3.9 to 5.1, in exchangeable Al from 0.0 to 4 meq/100 gm, in exchangeable Mn from 0.35 to 2.32 me/100 gm, and in %C from 0.69 to 5.60.Nodule weight decreased with increasing %C and for the soil with highest %C (5.60) no nodules were observed. In soils with low organic matter and low exchangeable Al and Mn, inoculation increased nodule weight, dry matter yield and %N especially at the lowest pH level. Where the seeds were not inoculated, nodule weight and dry matter yield increased with soil pH. No such increases were observed where the seeds were inoculated. There was no apparent advantage in lime pelleting in such soils.In soils with low organic matter content and with substantial amounts of Al and/or Mn, liming increased nodule weight and dry matter yield, and decreased exchangeable Al and/or Mn. Lime pelleting was superior to mere inoculation in increasing nodule weight particularly at low lime rates.In soils with relatively high organic matter content, nodulation was very low or none at all. Low lime rates had little effect on exchangeable Al and Ca and dry matter yield. Higher lime rates, however, decreased exchangeable Al and dry matter yield but increased exchangeable Ca.     

Dry matter response of ryegrass to ammonium and nitrate sources of nitrogen as a function of soil texture and moisture

Summary InLolium perenne cv. S23 grown in pots of soil to which nitrogen was applied at rates of 0, 60, 120 and 180 mg N/kg, ammonium significantly increased root mass compared with nitrate, whereas both nitrogen sources produced similar yields of herbage. Total dry matter production in the herbage and roots increased within the textural sequence: loamy sand, coarse sandy loam and loam. The increases in the latter two soils over the loamy sand were 35% and 50%, respectively. Depletions of available water of 50% and 80% reduced yields at the first harvest by 19% and 50% compared with the field capacity. The corresponding reductions in the second harvest were only 16% and 10%, because residual effects were then limiting. The amount of dry matter produced per unit of nitrogen absorbed indicated that textural class was less restrictive than moisture supply to efficient use of nitrogen within the plant. Furthermore, its efficient physiological use was limited at the 50% depletion, although its absorption from the soil was not affected. The results illustrated the inefficiency of the substitution of nitrogen for soil moisture: even at low yield levels three times more nitrogen was absorbed per unit increase in dry matter at 80% depletion of available water compared with the field capacity. The significant first-order interactions that affected yield were moisture by soils, and moisture by nitrogen rate.     

土层厚度对刺槐旱季水分状况和生长的影响

该研究测定了旱季和雨季刺槐(Robinia pseudoacacia)林不同土层厚度的土壤含水量, 刺槐的树高、胸径、小枝凌晨水势、叶片碳稳定同位素组成(δ¹³C)、叶面积、比叶重和气体交换指标; 分析了刺槐旱季和雨季的水分状况和土层厚度之间的关系; 通过刺槐对季节性干旱胁迫的反应, 估计华北石质山区不同土层厚度土壤水分对刺槐的承载能力; 并求证近年来该地区刺槐衰败和水分因素的关系。结果显示: 随着土层厚度减小, 旱季土壤含水量下降、凌晨小枝水势降低; 气孔导度和最大光合速率都减小, 而瞬时水分利用效率增加, 雨季上述指标无显著性差异, 旱季土壤含水量只有雨季的60%左右。随着土层变薄, 刺槐叶片δ¹³C增高, 叶面积减小, 比叶重增加; 刺槐树高和胸径减小。以上结果表明: 刺槐在不同季节下的水分状况综合反映土壤的供水能力, 土层浅薄导致土壤水分承载力不足, 致使刺槐在旱季受到较严重的水分胁迫, 这可能是刺槐出现衰败的重要原因。     

Effect of soil moisture on the response of subterranean clover to lime

Summary A pot experiment was carried out using a soil high in aluminium to investigate the relationship between the dry matter responses of subterranean clover to lime at two soil moisture levels. Subterranean clover, which is reputed to be tolerant to high aluminium levels in the soil, showed an increase in the dry weight of plant tops of 50% when lime was added on the low moisture treatments. By contrast the response on the high moisture treatment was only 5.6%.     

不同耕作方式对旱作冬小麦旗叶衰老和籽粒产量的影响

在旱作条件下研究了一次深翻、免耕、深松和传统耕作4种耕作方式对冬小麦花后旗叶衰老、小麦籽粒产量及土壤水分和养分状况的影响.结果表明：免耕和深松提高了小麦旗叶SOD和POD活性及可溶性蛋白和叶绿素含量,降低了MDA和O₂^-·含量,延缓了小麦叶片的衰老进程;同时,免耕、深松在开花期和灌浆期0～40 cm土层土壤水分含量分别比传统耕作提高了4.13％、6.23％和5.50％、9.27％,土壤碱解氮、速效磷和速效钾含量均显著高于传统耕作.一次深翻0～40 cm土层土壤水分含量低于传统耕作,土壤养分含量高于传统耕作,但两处理间差异不显著.与传统耕作相比,免耕和深松花后干物质生产量分别提高4.34％和4.76％,花后干物质转运率分别提高15.56％和13.51％,产量分别提高10.22％和9.26%.免耕和深松为冬小麦花后生长发育提供了良好的环境,延缓了小麦叶片衰老,促进了花后干物质积累及干物质向籽粒的转运,从而使籽粒产量显著提高,是旱作麦区适宜的耕作方式.     

Influence of mulching on the pattern of growth and water use by spring wheat and moisture storage on a fine textured soil

Eight tonnes ha^–1 of stubble were used to mulch spring wheat (Triticum aestivum) on a fine textured soil with the aim of controlling both transpiration and soil evaporation during the wet pre-anthesis phase to increase moisture supply during grain filling in the eastern wheatbelt of Western Australia. Mulching reduced leaf area per plant by reducing the culm number; consequently the green area index was reduced. Reduced culm number was associated with low soil temperature which at 50 mm depth averaged 7°C lower under the mulched crop relative to the control crop in mid-season. The smaller canopies of the mulched crop used 15 mm less water than those of the control before anthesis; this difference in water-use was due equally to reduced transpiration and soil evaporation. However, the mulched crop was unable to increase ET during grain filling, a response associated with the persistence of low soil temperature for most of the growth period. Hence, total ET for the season was significantly lower (18 mm) under the mulched crop than the control crop. At harvest, mulching did not have significant effects on total above-ground dry matter and grain yields, but it increased water use efficiency for grain yield by 18%, grain weight by almost 17% and available moisture in both uncropped and cropped plots by an average of 43 mm.To determine whether there was any residual effects of soil treatment on moisture storage during the summer fallow period, soil moisture was monitored both in cropped plots and uncropped plots, that were either mulched or unmulched during the growing season, from harvest in October 1988 until next planting in June 1989. Available moisture at next planting was correlated with moisture storage at harvest despite the differences in run-off, soil evaporation and fallowing efficiency (increase in moisture storage as a percentage of rainfall) between treatments during fallowing. Therefore, the mulched treatments had more moisture available (30 mm), mostly as a result of less water use during cropping in the previous growing season, than the unmulched treatment.The study shows that mulching may be used to restrain both transpiration and soil evaporation early in the season to increase availability of soil moisture during grain filling. Secondly, mulching during the previous growing season had little effect on soil moisture during the summer fallow period, however, the moisture saved by mulching during cropping was conserved for the following season. These results indicate the importance of evaluating mulching of winter crops in terms of crop yield in the subsequent growing season as well as in the current season in which the soil was treated.Abbreviations D through drainage - DAS days after sowing of the crop on 31 May 1988 - DM dry matter produced in the above-ground portion of the crop (kg ha^–1) - E₀ evaporation from Class A pan (mm) - E_s evaporation from uncropped soil (mm) - E_sc evaporation from soil beneath the wheat canopy (mm) - ET evapotranspiration (mm) - FE fallowing efficiency (gain in soil moisture storage/rainfall) - GAI green area index (area of green vegetation per unit land area) - GWUE water-use efficiency for grain production (grain yield/total ET, kg ha^–1mm^–1) - K extinction coefficient (see equation 1) - RO run-off of moisture from soil surface during/following rainfall (mm) - SM available soil moisture (mm) at harvest (SMh) or at planting (SMp) - WUE water-use efficiency for total above-ground dry matter yield (see GWUE)     

不同土壤水分条件下无机营养对小麦物质生产和水分利用的影响

本文通过讨论不同土壤水分条件下,无机营养对春小麦净光合率、叶片导度、干物质生产、水分消耗等的影响,表明施肥使营养缺乏的春小麦的光合物质生产,水分消耗及水分利用效率(WUE)都明显增大,无机营养对春小麦物质同化和生长的促进要远大于其因增加水分散失而带来的不利影响;在土壤干旱时,施肥春小麦的光合物质生产、水分消耗下降幅度都大于不施肥春小麦,干旱削弱了无机营养在提高春小麦光合物质生产和产量方面的作用。据此,对旱地的合理施肥技术提出了建议。     

土壤深层供水对冬小麦干物质生产的影响

采用根系研究装置研究了土壤深层供水对冬小麦干物质生产的影响 .结果表明 ,上层低湿度下层高湿度的处理在小麦灌浆期仍然保持了较高的土壤和叶片含水量 ,具有发达的根系 ,特别是 1m以下的根量在 4个处理中为最高 ,旗叶和穗的干重也最大 ,具有最大的产量潜力 .本研究表明 ,上层土壤较干下层土壤湿润有利于发挥小麦根信号的积极作用 ,平衡水分利用 ,同时通过对土壤水分的合理调节可以促进深层根的发育 ,有利于提高产量和水分利用效率 .     

Changes in dry matter and nutrient yields during the restoration of species-rich grasslands

Abstract. In two moderately productive grasslands that had been withdrawn from agricultural use, one on humic sandy soil and one on heavy clay, the decrease in dry matter, N-, P- and K-yields were measured for 14 and 11 years respectively, after fertilization had been stopped. The grasslands were mown twice a year. The yields and concentrations of nutrients were compared with those of already unproductive grasslands under the same growing conditions. On sandy soil, the annual dry matter yield decreased from 10.2 to 6.5 ton / ha in four years. After nine years, the dry matter (4.1 ton / ha) and K (20.5 kg / ha) yields were as low as those of the unproductive grassland. At that time yields and concentrations of N and P were still greater. The low K- concentration of 0.50 % and the lack of response upon N fertilizing indicate that the supply of K limits biomass production. On clay, during the first three years, the dry matter yield decreased from 10.2 to 5.0 ton / ha, after 6 yr the production increased again. The low N-concentration of 1.52 % after 10 yr indicates that N is likely to limit biomass production, but the low P-concentration of 0.14% indicates that P shortage can also be expected. In the lower productive grassland on sand the number of species that invaded was higher.     

黄土丘陵沟壑区不同降水年型下土壤水分动态

采用定位监测法,对黄土丘陵沟壑区不同降水年型下旱农坡地、刺槐林、沙棘灌丛和白羊草地土壤水分的时空变化规律进行了分析.结果表明,降水年型对研究区不同植被类型土壤水分的季节变化和剖面垂直变化均有一定影响.旱农坡地平水年土壤水分的季节变化平缓;枯水年雨季前土壤水分缓慢减小,雨季后显著增加;丰水年则整体增加,且雨季后增加明显.刺槐林、沙棘灌丛和白羊草地平水年土壤水分的季节变化表现为整体降低;枯水年沙棘灌丛土壤水分先减后增,刺槐林与白羊草地呈“W”型曲线变化,两个最低值均出现在6月和8月;丰水年沙棘灌丛和刺槐林土壤水分的季节变化呈“V”型,白羊草地的波动较大,最低值出现在8月.旱农坡地枯水年的土壤水分活跃层和次活跃层深度较平水年下移,丰水年次活跃层消失;丰水年和枯水年,刺槐林和白羊草地土壤水分活跃层深度均较平水年下移,沙棘灌丛则上移.     

冻融条件和土壤湿度对森林土壤渗漏液溶解性有机质含量与光谱结构特征的影响

土壤溶解性有机质(DOM)含量及其稳定性影响土壤碳氮循环关键过程,目前气候变化下森林土壤DOM含量及其光谱结构特征仍不明确.本研究利用长白山阔叶红松混交林和次生白桦林表层土壤进行室内冻融模拟试验,结合三维荧光光谱-平行因子分析方法,研究冻融强度和冻融循环次数及其交互作用对不同湿度温带森林土壤渗漏液DOM含量、组分和光谱结构特征的影响.结果表明: 森林土壤渗漏液DOM含量及其组分因林分类型、土壤湿度、冻融强度、冻融循环次数不同而存在差异.2种林分土壤渗漏液DOM含量均在中湿度下最低,并受高强度冻融影响显著,且随冻融循环次数增加呈现先增加后降低的趋势.可鉴别DOM的3个荧光组分:胡敏酸类DOM、富里酸类DOM和蛋白类DOM;阔叶红松混交林土壤渗漏液DOM组分以富里酸类物质为主,腐殖化程度较高;而次生白桦林土壤渗漏液DOM组分以胡敏酸类物质为主,3组分受冻融强度显著影响,稳定性较低.经冗余分析(RDA)发现,林分在很大程度上决定森林土壤DOM属性变化,次生白桦林土壤渗漏液DOM含量及其3组分荧光强度大于阔叶红松混交林;土壤湿度显著影响DOM芳香性,2种林分土壤渗漏液DOM芳香性均呈中湿度>高湿度>低湿度的趋势;随冻融强度增加,阔叶红松混交林土壤渗漏液DOM芳香性显著降低;多次冻融循环显著提高2种林分土壤渗漏液DOM腐殖化程度.因此,不同冻融作用下,低湿度温带森林土壤渗漏液DOM含量及其生物有效性呈现增加的趋势,尤其是次生白桦林土壤,可能会增加春季冻融期温带森林土壤溶解性有机质淋溶损失.这些结果可为深入研究野外冻融期温带森林土壤溶解性有机质周转机制提供参考.     

High arctic heath soil respiration and biogeochemical dynamics during summer and autumn freeze‐in – effects of long‐term enhanced water and nutrient supply

In High Arctic NE Greenland, temperature and precipitation are predicted to increase during this century, however, relatively little information is available on the role of increased water supply on soil CO ₂ efflux in dry, high arctic ecosystems. We measured soil respiration (R_soil) in summer and autumn of 2009 in combination with microbial biomass and nutrient availability during autumn freeze‐in at a dry, open heath in Zackenberg, NE Greenland. This tundra site has been subject to fully factorial manipulation consisting of increased soil water supply for 14 years, and occasional nitrogen (N) addition in pulses. Summer watering enhanced R_soil during summer, but decreased R_soil in the following autumn. We speculate that this is due to intensified depletion of recently fixed plant carbon by soil organisms. Hence, autumn soil microbial activity seems tightly linked to growing season plant production through plant‐associated carbon pools. Nitrogen addition alone consistently increased R_soil, but when water and nitrogen were added in combination, autumn R_soil declined similarly to when water was added alone. Despite several freeze‐thaw events, the microbial biomass carbon (C) remained constant until finally being reduced by ~60% in late September. In spite of significantly reduced microbial biomass C and phosphorus (P), microbial N did not change. This suggests N released from dead microbes was quickly assimilated by surviving microbes. We observed no change in soil organic matter content after 14 years of environmental manipulations, suggesting high ecosystem resistance to environmental changes.     

降雨量改变对常绿阔叶林干旱和湿润季节土壤呼吸的影响

通过野外原位试验,研究降雨量改变对华西雨屏区常绿阔叶林干旱和湿润季节土壤呼吸速率的影响。采用LI-8100土壤碳通量分析系统(LI-COR Inc.,USA)测定干旱和湿润季节对照(CK)、增雨10%(LA)、增雨5%(TA)、减雨10%(LR)、减雨20%(MR)、减雨50%(HR)6个处理水平的土壤呼吸速率,并通过回归方程分析温度和湿度与土壤呼吸速率间的关系。结果表明:湿润季节土壤呼吸速率高于干旱季节,HR处理对干旱季节土壤呼吸速率影响较大,而LA处理对湿润季节土壤呼吸速率的影响较大。TA和LR处理使土壤呼吸的温度敏感性增加,而HR、LA和MR处理使土壤呼吸的温度敏感性降低,干旱季节Q10值高于湿润季节。各处理湿润季节土壤微生物量碳氮含量显著高于干旱季节,HR、MR和LA处理减少土壤微生物生物量碳、氮的含量,而TA和LR处理增加土壤微生物生物量碳、氮的含量。与湿润季节相比,干旱季节土壤水分对土壤呼吸速率的影响较大;而与土壤温度相比,土壤水分对土壤呼吸速率的影响较小。在降雨量改变的背景下,华西雨屏区常绿阔叶林无论是干旱还是湿润季节,适当增雨和减雨都会促进土壤呼吸速率,而较高量的增雨和减雨会抑制土壤呼吸速率。     

坡向和海拔对高寒草甸山体土壤水热和植物分布格局的定量分解

为明晰坡向和海拔对山体土壤水热和植物分布格局的影响,以青藏高原东北缘山体高寒草甸为研究对象,利用回归分析、典型相关分析(CCA)排序和方差分解等方法,对阶地与同一山体不同坡向和海拔的189个样方内土壤温湿度和植物分布进行分析和定量分解.结果表明: 阴坡物种丰富度最高,阶地最低.随海拔升高,阴坡和山脊物种丰富度先增加后降低,而阳坡物种丰富度呈线性增加.阳坡土壤温度最高,不同坡向0～20 cm土层土壤温度随海拔升高基本不变;阴坡土壤湿度最高,不同坡向0～30 cm土层土壤湿度随海拔升高而增加.方差分解表明,在0～30 cm土层中,坡向和海拔共解释土壤温度变化的100%,土壤湿度变化的51.8%.坡向单独解释土壤温度变化的72.2%,贡献率最高;海拔单独解释土壤湿度变化的51.8%,贡献率最高.大多数植物倾向分布于中等海拔的阴坡与山脊之间.阴坡以莎草科为主,阳坡以禾本科为主,山脊为过渡地带.莎草科、禾本科和豆科主要分布于低海拔区.坡向和海拔共解释了山地植物多度变化的28.6%,坡向单独解释19.9%,贡献率最高.在山地高寒草甸生态系统,综合考虑小尺度地形造成的土壤及植物分布格局差异的基础上,在进行生产与生态恢复的分区管理时,应优先考虑坡向造成的土壤和植物差异.