Non-structural carbohydrate: Analysis by near infrared reflectance spectroscopy and its importance as an indicator of plant growth

Plant shoot samples are frequently analysed to assess if crops require additional nitrogen or mineral elements to maintain satisfactory growth. If plant growth is limited by temperature, water stress, disease, lodging or a mineral deficiency, non-structural carbohydrates (NSC) may be accumulated in, or depleted from, tissues especially those in the lower stems. Plant testing laboratories do not routinely analyse NSC to assist in the identification of plant stress probably because skilled technicians and time are required for the wet chemical determination. In this paper we report that routine determination of NSC is possible using near-infrared reflectance spectroscopy; the errors of determination are comparable with traditional chemical methods.The concentration of NSC in the shoots of rice grown in south eastern Australia ranges from 1.6 to 22.8%, as starch. In the shoots of wheat grown in eastern Australia the range is from 2.4 to 35.2%, as fructans. In both crops the NSC content is highly inversely correlated with the shoot nitrogen content. Based on data from commercial wheat and rice crops we suggest that the ratio between nitrogen and NSC can be used to identify crops in which growth has been limited by a stress other than nitrogen and so are unlikely to show the predicted response to an application of nitrogen fertilizer.     

氮肥运筹对免耕水稻根系生长、根际土壤特性及产量的影响

为探索氮肥运筹对免耕条件下水稻根系生长以及对根际土壤特性、产量的影响,以金优253为材料进行试验。结果表明：平衡施肥显著提高单株根系干重、根长、单株生物量、根半径、单株根表面积、根长密度及根系活力,实收单产高于重穗肥和重基肥处理,且与重基肥差异达95％的显著水平,主要是有效穗数、结实率的增加。平衡施肥显著提高0~10 cm土层的0~2 mm根际土壤有机质、碱解氮含量及脲酶、蔗糖酶活性。因此平衡施肥能明显促进免耕水稻根系生长和有效穗数的增加,对提高水稻产量具有促进作用。     

Seedling vigour and the early growth of transplanted rice (Oryza sativa)

Previous studies suggest that the positive response of transplanted rice (Oryza sativa L.) to nursery fertiliser application was due to increased seedling vigour or possibly to increased nutrient content. This paper presents results of two glasshouse experiments designed to test the hypothesis that seedling vigour was responsible for the response of transplanted seedlings to nursery treatments. The aim of the present study was to explore the concept of seedling vigour of transplanted rice and to determine what plant attributes conferred vigour on the seedlings. Seedling vigour treatments were established by subjecting seedlings to short-term submergence (0, 1 and 2 days/week) in one experiment and to leaf clipping or root pruning and water stress in another to determine their effect on plant growth after transplanting. Submerging seedlings increased plant height but depressed shoot and root dry matter and root:shoot ratio of the seedling at 28 days after sowing. After transplanting these seedlings, prior submergence depressed shoot dry matter at 40 days. Nursery nutrient application increased plant height, increased root and shoot dry matter, but generally decreased root:shoot ratio. Pruning up to 60% of the roots at transplanting decreased shoot and root dry matter, P concentration in leaves at panicle initiation (PI) and straw dry matter and grain yield at maturity. By contrast, pruning 30% of leaves depressed shoot and root dry matter by 30% at PI, and root dry matter and straw and grain yield by 20% at maturity. The combined effects of leaf clipping and root pruning on shoot, root and straw dry matter were largely additive. It is concluded that the response of rice yield to nursery treatments is largely due to increased seedling vigour and can be effected by a range of nutritional as well as non-nutritional treatments of seedlings that increase seedling dry matter, nutrient content, and nutrient concentration. Impairment of leaf growth and to a lesser extent root growth in the nursery depressed seedling vigour after transplanting. However, rather than increasing stress tolerance, seedling vigour was more beneficial when post transplant growth was not limited by nutrient or water stresses.     

硝态氮（NO3^—）对水稻侧根生长及其氮吸收的影响

侧根是植物吸收利用土壤养分的重要器官 ,其生长发育受内部遗传因子和外部环境矿质养分的影响。通过琼脂分层培养发现 :局部供应NO-3 可以诱导水稻 (OryzasativaL .)主根或不定根上侧根的生长。为研究旱种条件下NO-3 对水稻侧根发育及其N吸收的影响 ,设置了 3个蛭石培养实验 :分根处理、全株缺N、全株供N处理。分根处理 (一半根系供应 3mmol/LKNO3,另一半根系供应 3mmol/LKCl)结果表明 :局部供应NO-3 能够促进水稻侧根生长。而在全株处理下 ,N饥饿诱导了侧根的伸长。水稻根系对NO-3 的这两种反应都存在着显著的基因型差异。同时对地上部N浓度、可溶性总糖含量及N含量分析表明 ,这些生理指标在分根处理与全株加N处理中的差异均不显著 ,表明分根处理也能基本满足植株正常生长对N的需求。在分根处理中 ,水稻的N含量与分根处理中供N一侧的平均侧根长度存在显著正相关 ,这表明在养分不均一的介质中 ,侧根长度对水稻N素吸收具有十分重要的作用。而在N素充足的条件下 ,两者之间的相关性并不显著 ,这暗示在养分充足的环境下 ,侧根长度可能并不是决定根系吸收N素的主要因素     

Growth direction of nodal roots in rice: its variation and contribution to root system formation

The root system of a rice plant (Oryza sativa L.) consists of numerous nodal roots and their laterals. The growth direction of these nodal roots affects the spatial distribution of the root system in soil, which seems to relate to yield and lodging resistance. The growth angle of a nodal root varies with the type and timing of emergence of the nodal root. The body of a rice plant can be recognized as an integrated set of shoot units, each unit consisting of an internode with a leaf and several roots. Nodal roots formed at the apical part of a shoot unit often elongate horizontally, whereas those formed at the basal part of the shoot unit show various growth directions depending on both the growth stages of the plant and the environmental conditions. Moreover, nodal roots that emerge from the most basal shoot unit of a tiller are usually thick and grow downwards. External factors such as planting density and nitrogen application affect the growth direction of nodal roots, probably partly because of the changing tillering pattern of the shoot. In addition to the growth angle of nodal roots, size of nodal roots may be another important factor determining the spatial distribution of the root system in soil.     

硝态氮(NO-3)对水稻侧根生长及其氮吸收的影响

侧根是植物吸收利用土壤养分的重要器官,其生长发育受内部遗传因子和外部环境矿质养分的影响.通过琼脂分层培养发现:局部供应NO-3可以诱导水稻( Oryza sativa L.)主根或不定根上侧根的生长.为研究旱种条件下NO-3对水稻侧根发育及其N吸收的影响,设置了3个蛭石培养实验:分根处理、全株缺N、全株供N处理.分根处理(一半根系供应3 mmol/L KNO3,另一半根系供应3 mmol/L KCl)结果表明:局部供应NO-3 能够促进水稻侧根生长.而在全株处理下,N饥饿诱导了侧根的伸长.水稻根系对NO-3的这两种反应都存在着显著的基因型差异.同时对地上部N浓度、可溶性总糖含量及N含量分析表明,这些生理指标在分根处理与全株加N处理中的差异均不显著,表明分根处理也能基本满足植株正常生长对N的需求.在分根处理中,水稻的N含量与分根处理中供N一侧的平均侧根长度存在显著正相关,这表明在养分不均一的介质中,侧根长度对水稻N素吸收具有十分重要的作用.而在N素充足的条件下,两者之间的相关性并不显著,这暗示在养分充足的环境下,侧根长度可能并不是决定根系吸收N素的主要因素.     

The urea transporter DUR3 contributes to rice production under nitrogen‐deficient and field conditions

Nitrogen is one of the most important elements for plant growth, and urea is one of the most frequently used nitrogen fertilizers worldwide. Besides the exogenously‐supplied urea to the soil, urea is endogenously synthesized during secondary nitrogen metabolism. Here, we investigated the contribution of a urea transporter, DUR3, to rice production using a reverse genetic approach combined with localization studies. Tos17 insertion lines for DUR3 showed a 50% yield reduction in hydroponic culture, and a 26.2% yield reduction in a paddy field, because of decreased grain filling. Because shoot biomass production and shoot total N was not reduced, insertion lines were disordered not only in nitrogen acquisition but also in nitrogen allocation. During seed development, DUR3 insertion lines accumulated nitrogen in leaves and could not sufficiently develop their panicles, although shoot and root dry weights were not significantly different from the wild‐type. The urea concentration in old leaf harvested from DUR3 insertion lines was lower than that in wild‐type. DUR3 promoter‐dependent β‐glucuronidase (GUS) activity was localized in vascular tissue and the midribs of old leaves. These results indicate that DUR3 contributes to nitrogen translocation and rice yield under nitrogen‐deficient and field conditions.     

Carbon allocation to shoots and roots in relation to nitrogen supply is mediated by cytokinins and sucrose: Opinion

In this paper we firstly show some general responses of biomass partitioning upon nitrogen deprivation. Secondly, these responses are explained in terms of allocation of carbon and nitrogen, photosynthesis and respiration, using a simulation model. Thirdly, we present a hypothesis for the regulation of biomass partitioning to shoots and roots.Shortly after nitrogen deprivation, the relative growth rate (RGR) of the roots generally increases and thereafter decreases, whereas that of the shoot decreases immediately. The increased RGR of the root and decreased RGR of the shoot shortly after a reduction in the nitrogen supply, cause the root weight ratio (root weight per unit plant weight) to increase rapidly.We showed previously that allocation of carbon and nitrogen to shoots and roots can satisfactorily be described as a function of the internal organic plant nitrogen concentration. Using these functions in a simulation model, we analyzed why the relative growth rate of the roots increases shortly after a reduction in nitrogen supply. The model predicts that upon nitrogen deprivation, the plant nitrogen concentration and the rate of photosynthesis per unit plant weight rapidly decrease, and the allocation of recently assimilated carbon and nitrogen to roots rapidly increases. Simulations show that the increased relative growth rate of the root upon nitrogen deprivation is explained by decreased use of carbon for root respiration, due to decreased carbon costs for nitrogen uptake. The stimulation of the relative growth rate of the root is further amplified by the increased allocation of carbon and nitrogen to roots. Using the simple relation between the plant nitrogen concentration and allocation, the model describes plant responses quite realistically.Based on information in the literature and on our own experiments we hypothesize that allocation of carbon is mediated by sucrose and cytokinins. We propose that nitrogen deprivation leads to a reduced cytokinin production, a decreased rate of cytokinin export from the roots to the shoot, and decreased cytokinin concentrations. A reduced cytokinin concentration in the shoot represses cell division in leaves, whereas a low cytokinin concentration in roots neutralizes the inhibitory effect of cytokinins on cell division. A reduced rate of cell division in the leaves leads to a reduced unloading of sucrose from the phloem into the expanding cells. Consequently, the sucrose concentration in the phloem nearby the expanding cells increases, leading to an increase in turgor pressure in the phloem nearby the leaf's division zone. In the roots, cell division continues and no accumulation of sugars occurs in dividing cells, leading to only marginal changes in osmotic potential and turgor pressure in the phloem nearby the root's cell division zone. These changes in turgor pressure in the phloem of roots and sink leaves affect the turgor pressure gradients between source leaf-sink leaf and source leaf-root in such a way that relatively more carbohydrates are exported to the roots. As a consequence RWR increases after nitrogen deprivation. This hypothesis also explains the strong relationship between allocation and the plant nitrogen status.     

稻麦叶片氮积累量与冠层反射光谱的定量关系

作物氮素积累动态是评价作物群体长势及估测产量和品质的重要指标,对于作物氮素的实时监测和精确管理具有重要意义。该文以5个小麦(Triticum aestivum)品种和3个水稻(Oryza sativa)品种在不同施氮水平下的3年田间试验为基础,综合研究了稻麦叶片氮积累量与冠层反射光谱的定量关系。结果表明,不同试验中拔节后叶片氮积累量均随施氮水平呈上升趋势;稻麦冠层光谱反射率在不同施氮水平下存在明显差异,可见光区(460~710 nm)反射率一般随施氮水平的增加逐渐降低,近红外波段(760~1 220 nm)反射率却随施氮水平的增加逐渐升高;就单波段而言,810和870 nm处的冠层光谱反射率均与稻麦叶片氮积累量具有相对较高的相关性;在光谱参数中,比值植被指数(Ratio vegetation index, RVI)(870,660)和RVI(810,660)均与稻麦叶片氮积累量具有高度的相关性,且相关系数明显高于单波段反射率,尤其是水稻作物;对于小麦和水稻,均可以利用统一的波段和光谱指数来监测其叶片氮积累量,并可以采用统一的回归方程来描述其叶片氮积累量随单波段反射率和反射光谱参数的变化模式,但若采用单独的回归系数则可以提高稻麦叶片氮积累量估测的准确性。     

Dynamic model of the response of a vegetative grass crop to light, temperature and nitrogen

Abstract A previously described growth model of the vegetative grass crop is extended to include a simple representation of the root system, uptake of nitrogen from a soil nitrogen pool, and response to fertilizer application. The model simulates the processes of light interception, photosynthesis, partitioning of new growth, leaf area expansion, growth and maintenance respiration, ageing of plant tissues, senescence, recycling of substrates from senescing tissues, nitrogen uptake by the plant, leaching, mineralization, and fertilizer application. A principal component of the model, nitrogen uptake, is assumed to depend positively on plant carbon substrate concentration and soil nitrogen concentration, and to be inhibited by plant nitrogen substrate concentration. The dynamic responses to different levels of soil nitrogen, of shoot and root growth, nitrogen uptake and root activity, carbon and nitrogen plant substrate concentrations, and the fraction of substrate carbon used by the shoots, are examined; realistic behaviour is observed. The model predicts nitrogen fertilizer responses of yield and plant nitrogen content, which are compared directly with experimental data; good agreement is obtained.     

Determination of critical K concentrations in sap from individual leaves or from whole plants using K-interruption experiments

Summary A new method is described for estimating critical K concentrations from K interruption experiments using only 2 treatments. Frequent measurements are made of the growth and K concentration of plants subjected to either continued or interrupted K supply and the data used to define the relation between relative yield and K concentration for the K-deficient plants. Critical concentrations are estimated from the results using a mathematical model of plant growth to interpolate over the critical concentration region of the curve. The method has the advantage that the critical concentrations are determined at the exact time that growth is affected. The method was tested using data from previously published experiments with lettuce in which the concentrations of K were measured in sap from both the total shoot and from individual leaf petioles. The model accurately predicted the form of the relationship between relative yield and K concentration for the total shoot and for young expanding leaves, but consistently deviated from the data for recently matured ones. Average estimates of critical concentration ranged fromca. 18 to 34 mmoll⁻¹ in the young leaves and from 48 to 67 mmoll⁻¹ in the mature ones when Na salts were present or absent respectively. The values for total shoot sap were similar to those for mature leaves. The critical concentrations for young expanding leaves were virtually identical to the minimum believed to be needed for the maintenance of important biochemical processes in individual cells, and suggests that a single critical K concentration for plant sap might apply to a wide range of crops provided an actively growing part of the plant is sampled.     

The effect of rhizoctonia root disease and applied nitrogen on growth,nitrogen uptake and nutrient concentrations in spring wheat

Root disease caused by Rhizoctonia solani is a common problem of spring wheat in South Australia. There are reports that nitrogen applications can reduce the incidence and severity of the disease. A glasshouse trail in pots examined the effects of disease and of applied nitrogen on wheat growth, and evaluated the utility of the basal stem nitrate concentration in diagnosing deficiency in plants with and without root disease. Plants were harvested at the mid-tillering stage. Shoot growth was increased by applied nitrogen until a maximum yield was attained, after which additional N had no effect on shoot yield. Root growth, however, responded positively only to low levels of applied N, after which it declined, and in the highest N treatment root mass was less than in the plants without applied N. Root disease caused severe reductions in plant growth, and both root and shoot mass were affected similarly. Even though growth of diseased plants responded positively to applied nitrogen the response was less than that of disease-free plants. The critical concentration of basal stem nitrate-N did not appear to be affected by root disease, and was estimated at 1200 mg kg^-1, consistent with other glasshouse data. The basal stem nitrate-N concentration, either in fresh or dried tissue, appeared a better diagnostic tool of N stress than did total shoot N concentration or content, because of sharper definition of critical concentrations. Concentrations of other nutrients in shoot tissue were affected differentially by both applied nitrogen and root disease, but generally did not reach critical levels, although phosphorus and magnesium appeared deficient in very disease-stressed plants.     

Physiological and growth responses of Centaurea maculosa (Asteraceae) to root herbivory under varying levels of interspecific plant competition and soil nitrogen availability

Summary Centaurea maculosa seedlings were grown in pots to study the effects of root herbivory by Agapeta zoegana L. (Lep.: Cochylidae) and Cyphocleonus achates Fahr. (Col.: Curculionidae), grass competition and nitrogen shortage (each present or absent), using a full factorial design. The aims of the study were to analyse the impact of root herbivory on plant growth, resource allocation and physiological processes, and to test if these plant responses to herbivory were influenced by plant competition and nitrogen availability. The two root herbivores differed markedly in their impact on plant growth. While feeding by the moth A. zoegana in the root cortex had no effect on shoot and root mass, feeding by the weevil C. achates in the central vascular tissue greatly reduced shoot mass, but not root mass, leading to a reduced shoot/root ratio. The absence of significant effects of the two herbivores on root biomass, despite considerable consumption, indicates that compensatory root growth occurred. Competition with grass affected plant growth more than herbivory and nutrient status, resulting in reduced shoot and root growth, and number of leaves. Nitrogen shortage did not affect plant growth directly but greatly influenced the compensatory capacity of Centaurea maculosa to root herbivory. Under high nitrogen conditions, shoot biomass of plants infested by the weevil was reduced by 30% compared with uninfested plants. However, under poor nitrogen conditions a 63% reduction was observed compared with corresponding controls. Root herbivory was the most important stress factor affecting plant physiology. Besides a relative increase in biomass allocation to the roots, infested plants also showed a significant increase in nitrogen concentration in the roots and a concomitant reduction in leaf nitrogen concentration, reflecting a redirection of the nitrogen to the stronger sink. The level of fructans was greatly reduced in the roots after herbivore feeding. This is thought to be a consequence of their mobilisation to support compensatory root growth. A preliminary model linking the effects of these root herbivores to the physiological processes of C. maculosa is presented.     

Biofortification of wheat with iron through soil and foliar application of nitrogen and iron fertilizers

Increasing iron (Fe) concentration in food crops is an important global challenge due to high incidence of Fe deficiency in human populations. Evidence is available showing that nitrogen (N) fertilization increases Fe concentration in wheat grain. This positive impact of N on grain Fe was, however, not studied under varied soil and foliar applications of Fe. Greenhouse experiments were conducted to investigate a role of soil- and foliar-applied Fe fertilizers in improving shoot and grain Fe concentration in durum wheat (Triticum durum) grown under increasing N supply as Ca-nitrate. Additionally, an effect of foliar Fe fertilizers on grain Fe was tested with and without urea in the spray solution. Application of various soil or foliar Fe fertilizers had either a little positive effect or remained ineffective on shoot or grain Fe. By contrast, at a given Fe treatment, raising N supply substantially enhanced shoot and grain concentrations of Fe and Zn. Improving N status of plants from low to sufficient resulted in a 3-fold increase in shoot Fe content (e.g., total Fe accumulated), whereas this increase was only 42% for total shoot dry weight. Inclusion of urea in foliar Fe fertilizers had a positive impact on grain Fe concentration. Nitrogen fertilization represents an important agronomic practice in increasing grain Fe. Therefore, the plant N status deserves special attention in biofortification of food crops with Fe.     

植物谷氨酰胺合成酶研究进展及其应用前景

氮素是制约作物产量的主要营养元素之一,谷氨酰胺合成酶(Glutamine synthase,GS;EC 6.3.1.2)是氮素代谢途径中的关键酶。目前,拟南芥、水稻、小麦和玉米等植物中的GS成员均已被分离鉴定。研究表明,超表达GS能够提高植物对氮素的利用效率,从而在植株的生长发育特别是产量形成过程中发挥重要作用,但是其功能在不同植物上并不完全一致,可能与GS基因受到转录和翻译后等水平的调控有关。以下综述了植物GS基因分类、QTL定位、对氮素代谢响应、组织表达特异性、生物学功能及其分子调控机制等方面的研究进展,并展望了植物GS基因的应用前景,以期为利用GS基因来提高植物氮素利用效率提供具有参考价值的信息。     

未来CO2浓度增加和相应增温对水稻产量影响的模拟——以浙江省为例

采用水稻生育生理生态综合模型ORYZA1,模拟分析了未来15种可能气候变化对浙江省水稻产量的影响结果表明,CO2浓度的增加将使水稻增产,温度增加将导致水稻减产虽然CO2增加和相应增温对各季水稻产量在各地区的影响表现不同,但在不考虑温室效应将同时导致旱涝和病虫害变化条件下．GFDL、GISS和UKMO模型预测的气候变化将使浙江省全年水稻产量分别平均增产9．53％、8．92％和0．04％．     

开放系统中农作物对空气CO2浓度增加的响应

FACE试验（free-air CO2 enrichment)开展的10多年中,供试农作物主要有：C3禾本科作物小麦（Triticum aestivum L.）、多年生黑麦草（Lolium perenne)和水稻（Oryza sativaL.),C4禾本科类高梁（Sorghum bicolor(L.)Moench),C3豆科植物白三叶草（Trifolium repens ),C3非禾本科块茎状作物马铃薯（Solanum tuberosum L.）,以及多年生C3类木作物棉花（Gossypium hirsutum L.)和葡萄（Vitisvinifera l.)。本文系统整理和分析了以下各项参数的结果;光合作用、气孔导度、冠层温度、水分利用、水势、叶面积指数、根茎生物量累积、作物产量、辐射利用率,比叶面积、N含量、N收益、碳水化合物含量、物候变化、土壤微生物、土壤呼吸、痕量气体交换以及土壤碳固定,CO2浓度升高对农作物的影响作用主要表现在以下方面：（1）促进了植物光合作用,增加了其生物量累积;（2）显著提高C3作物产量,但对C4作物产量的影响很小;（3）降低了C3和C4作物气孔导度,非常显著地提高了所有作物的水分利用率;（4）对植物生长的促进作用在水分不足与水分充中时二者相当或前者大于后者;（6）对根系生长的促进作用要大于地上部分;（7）对多年生植物气孔导度的影响较小,但对其生长的促进作用仍很高;（8）降低了植物体内N含量,但作物体内碳水化合物及某些其他含碳化合物含量增加,且叶部含量要明显高于植物其他器官;（9）对大多数作物的物候略有加速;（10）对某些土壤微生物具显著影响,而对有些则无,但都增加了微生物活性;（11）综合多年、多地点的试验结果表明土壤对大气CO2的固定增加,但单独一个试验无法观测到SOC的显著性变化,对FACE和前期的熏气室试验结果都进行了尽可能的对比研究,除了二例以外,发现在大多数情况下二者的结果基本一致,其中,FACE使气孔导度降低的1.5倍,明显高于前期熏气室试验的结果;其二,相对于熏气室,FACE条件下CO2倍增对根的相对促进作用要高于地上部分,因此,我们对基于这二者的结论的准确性和可靠性是充满信心的,不过,更接近自然环境和具更大小区面积的FACE试验仍是必需的,它可以为我们提供在CO2升高条件下更具代表性的田间试验条件,从而为我们提供更多、更有益的多学科交叉的试验数据和研究结果。     

Influence of time and level of nitrogen application of growth and yield of rice

Summary Results of a greenhouse sand-culture experiment conducted to study the effect of increasing or decreasing nitrogen supply at various stages of growth on the growth, yield, and yield components of rice are reported. Adequate nitrogen during the vegetative phase of growth encouraged tillering which had a bearing on the number of panicles per plant. Excess nitrogen during the reproductive phase of growth produced panicles with unfilled or partly filled grains. Similar effects were observed when the nitrogen status of the growth medium was changed from a low to a high level at the stages of reduction division and anthesis. Decrease in yield was observed when plants growing at a low level of nitrogen were transferred to a high level at the end of the vegetative phase. High levels of nitrogen in the growth medium at time of heading and after increased the concentration of nitrogen in the grain. There was an inverse relationship between yield of filled grain and nitrogen in the grain.     

未来CO2浓度增加和相应增温对水稻产量影响的模拟──以浙江省为例

采用水稻生育生理生态综合模型ORYZA1,模拟分析了未来15种可能气候变化对浙江省水稻产量的影响结果表明,CO₂浓度的增加将使水稻增产,温度增加将导致水稻减产虽然CO₂增加和相应增温对各季水稻产量在各地区的影响表现不同,但在不考虑温室效应将同时导致旱涝和病虫害变化条件下.GFDL、GISS和UKMO模型预测的气候变化将使浙江省全年水稻产量分别平均增产9.53%、8.92%和0.04%.     

冬季作物种植对双季稻根系酶活性及形态指标的影响

基于湖南长沙7a定位试验,以冬闲为对照,研究了冬种马铃薯、紫云英及油菜为前茬作物对早、晚稻根系酶活性、形态指标及产量的影响.结果表明,与冬闲相比,冬种作物后早、晚稻根系丙二醛(MDA)含量增加,但其根系的活性氧清除能力更强(SOD、POD和CAT活性高),能够在一定程度上缓解膜脂过氧化作用带来的伤害;冬种不同作物对早晚稻根系形态的影响表现不一.冬种马铃薯和紫云英处理在早稻生育后期的根系优势明显,并能在一定程度上促进晚稻根系生长,双季稻总产量较对照分别增加6.29％和7.76％,而冬种油菜抑制了晚稻根系生长,导致晚稻产量及双季稻总产分别降低6.31％和1.96％;相关性分析表明,灌浆期较高的根长、根数、根体积和根表面积是冬种作物改善双季稻产量的主要原因.综合来看,冬种马铃薯和紫云英对于促进双季稻根系生长,提高稻谷产量具有重要作用,而冬种油菜则不利于提高双季稻的稻谷生产力.