根际ACC脱氨酶活性细菌的分离及其促生作用研究

从不同来源的植物根际土壤中分离出能以1-氨基环丙烷-1-羧酸(ACC)为唯一氮源生长的细菌4株,经测定均具有较高的ACC脱氨酶活性,并进一步研究了菌株对植物的促生长作用。首先进行了种子根长试验,利用菌株菌悬液处理玉米和番茄种子,结果表明,经过细菌1101、2101、4201和GXGD002处理,种子的生根长度较对照组均有明显增长,玉米种子根长相对伸长率依次为78.73%、61.72%、47.37%、47.08%;番茄种子根长相对伸长率依次为61.19%、55.84%、54.34%、51.19%。其次进行了番茄穴盘栽培试验,分别在播种后40 d和55 d收苗,测定植株的株高、茎粗、根长等生长指标,结果表明,菌株4201和GXGD002具有显著促进生长作用,其处理组植株在株高、根长、根系活力等方面较对照组均有明显增强。     

Phosphate solubilization by Chryseobacterium sp. and their combined effect with N and P fertilizers on plant growth promotion

The capabilities of soil microorganisms to solubilize phosphate have been known for many years, but their isolation and use as crop inoculants have met with little success. Thirty-five bacterial isolates were screened for their phosphate-solubilizing ability, and two of them, PSR10 and RGR13, identified through 16S rDNA sequencing as Chryseobacterium sp. PSR10 and Escherichia coli RGR13, respectively, screened for plant growth promotion in the greenhouse. Seed inoculation of Macrotyloma uniflorum (horsegram) by Chryseobacterium sp. PSR10 showed better plant growth promotion in sterilized and unsterilized soil under greenhouse conditions and was selected for a field experiment with 100, 50 and 30% of recommended doses of nitrogen and phosphorus fertilizer. Seed inoculation with 50% of the recommended dose of nitrogen and phosphorus increased plant growth (agronomical parameters, chlorophyll content, nitrate reductase activity, phosphorus content and crop yield). We conclude that effective plant growth-promoting bacterium Chryseobacterium sp. PSR10 broadens the spectrum of phosphate solubilizers available for field applications and might be used together with 50% dose of nitrogen and phosphate.     

Nitrogen acquisition by pea and barley and the effect of their crop residues on available nitrogen for subsequent crops

Nitrogen acquisition by field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) grown on a sandy loam soil and availability of N in three subsequent sequences of a cropping system were studied in an outdoor pot experiment. The effect of crop residues on the N availability was evaluated using ¹⁵N-labelled residues. Field pea fixed 75% of its N requirement and the N₂ fixation almost balanced the N removed with the seeds. The barley crop recovered 80% of the ¹⁵N-labelled fertilizer N supplied and the N in the barley grain corresponded to 80% of the fertilizer N taken up by the crop. The uptake of soil-derived N by a test crop (N catch crop) of white mustard (Sinapis alba L.) grown in the autumn was higher after pea than after barley. The N uptake in the test crop was reduced by 27% and 34% after pea and barley residue incorporation, respectively, probably due to N immobilization. The dry matter production and total N uptake of a spring barley crop following pea or barley, with a period of unplanted soil in the autumn/winter, were significantly higher after pea than after barley. The barley crop following pea and barley recovered 11% of the pea and 8% of the barley residue N. The pea and barley residue N recovered constituted only 2.5% and <1%, respectively, of total N in the N-fertilized barley. The total N uptake in a test crop of mustard grown in the second autumn following pea and barley cultivation was not significantly influenced by pre-precrop and residue treatment. In the short term, the incorporation of crop residues was not important in terms of contributing N to the subsequent crop compared to soil and fertilizer N sources, but residues improved the conservation of soil N in the autumn. In the long-term, crop residues are an important factor in maintaining soil fertility and supplying plant-available N via mineralization.     

氮素形态对解磷细菌发酵液解磷效果及小白菜生长和品质的影响

采用盆栽试验,研究了施用硝态氮、铵态氮对解磷细菌发酵液不同组分解磷活性及其对小白菜产量、品质的影响。结果表明,施用相同氮肥时,浇灌解磷细菌原发酵液处理 T3的作用效果明显优于菌体悬浮液T2及菌液上清T1;以硝态氮为底肥时,施用发酵原液的土壤有效态磷含量较高,小白菜产量最高,品质明显优化,即硝态氮含量下降, Vc、可溶性糖、可溶性蛋白、纤维素以及植株磷含量显著增加,且增加变幅均高于以铵态氮为底肥的效果。由此可知,硝态氮与解磷细菌发酵原液配施时, W1菌株解磷效果更好,可能是解磷菌株W1最适的氮源。因此,种植小白菜时直接向其根际施用解磷细菌发酵液并配施硝态氮肥,更有利于提高小白菜的品质及产量。     

一株人参根区解磷细菌的筛选、鉴定及对人参生长的影响

人参是我国传统名贵中药材,也是吉林省对外交往中的代名词。吉林参畦土壤有效磷含量低,但大量施用磷肥又会导致人参品质的下降,因此,本研究从人参根区土壤中筛选高效解磷细菌,接种到人参根部,研究其对人参生长、品质、土壤速效养分、土壤酶活性的影响,以期为人参解磷微生物肥料提供优良菌株,从而促进人参产业绿色发展。采用PKO平板初筛及摇瓶复筛从野山参根区土壤筛选高效解磷细菌。盆栽试验以3年生人参种苗为材料,每盆种植6棵单株重相同的人参种苗,设对照(CK)和处理组,待完全展叶后间苗,留取4棵长势一致的人参苗,采用滴灌的方式将菌液接种在人参苗根部附近,生长至红果期(90 d)取样,测定植物生长量和叶绿素含量、土壤速效养分、参根和参叶中NPK的含量、土壤酶活性、参根中微量元素和8种皂苷的含量。结果表明,1)平板初筛和摇瓶复筛得到P1、P7菌株,摇瓶培养中,P1可溶性磷为472.85μg/m L,P7可溶性磷为437.33μg/m L。2)P1处理的人参参根鲜重、干重显著高于P7、BM、CK处理,株高显著高于对照,叶绿素含量显著高于P7、BM、CK(P0.05)。3)P1处理促进人参对土壤钾元素的吸收,提高磷素在参根中的积累量。4)接种菌剂可以不同程度的提高土壤酶活性,以P1处理的效果最显著,P1处理人参根际土壤脲酶、酸性磷酸酶、过氧化物酶活性均为最高。5)P1处理显著提高了人参根中Fe、Mn、Cu的含量,分别较对照增加了52.74%、127.03%、28.96%,P1处理Zn与对照相比增加19.96%;人参根中8种单体皂苷P1处理均显著高于P7、BM、CK。6)经16S rRNA分析结合P1形态初步鉴定为假单胞菌。     

接种固氮菌Klebsiella sp.120对甘蔗光合特性和主要矿质营养元素含量的影响

【目的】甘蔗是最重要的糖料和能源作物,生物量大,产量高,但大量氮肥的使用不仅增加了甘蔗的种植成本,而且对农田环境造成了污染。发挥与甘蔗联合固氮的生物固氮菌的作用,是降低甘蔗氮肥施用量的方法之一。Klebsiella sp.120是从广西种植的甘蔗体内分离到的具有固氮能力的菌株。为了探讨该菌对甘蔗的促生效应及其在甘蔗上的应用潜能,本文研究了接种该固氮菌对甘蔗光合特性及矿质元素含量的影响。【方法】采用桶栽方法,在甘蔗的分蘖期用接种菌株淋浇4个不同甘蔗品种的根际,在处理后的30 d和60 d取样分析该菌对甘蔗的光合生理和矿质营养元素含量的影响。【结果】接种菌株对4个甘蔗品种的叶绿素含量和净光合速率有一定的促进作用,但不同品种之间存在差异。处理30 d后,淋浇固氮菌处理的甘蔗品种ROC22的叶绿素含量明显提高,比对照增加23%。另外3个甘蔗品种(B8、GT21和GT28)处理组的叶绿素含量均有一定的提高,但与对照相比差异不显著。处理30 d后,只有ROC22和B8品种的净光合速率高于对照,且ROC22品种处理与对照间的差异达到了显著水平。处理60 d后,4个甘蔗品种的净光合速率均高于处理30 d,而且各品种接种处理均高于对照,其中以对ROC22和GT21的促进效果最为明显,达到了显著水平。接种处理对不同甘蔗品种的营养元素含量影响不同,接种处理对4个甘蔗品种叶片中的氮元素含量有促进作用,其中对ROC22的促进效果最为明显,接种处理比对照增加59.8%。接种固氮菌对甘蔗叶片磷和钾元素含量的影响不明显。接种固氮菌对4个甘蔗品种叶片的铁、锰元素含量的影响不明显;ROC22叶片中的锌含量及ROC22和B8叶片中的铜含量接种处理与对照相比显著提高。【结论】接种Klebsiella sp.120固氮菌对甘蔗光合特性及矿质元素含量的影响与甘蔗品种有关,其中对ROC22品种的促生效果最为明显。研究结果可为固氮菌株Klebsiella sp.120在甘蔗上的进一步应用提供参考依据。     

Effect of crop type and crop growth on atmospheric nitrogen deposition

Varying atmospheric nitrogen (N) depositions for different crops were observed at Bad Lauchstädt (Saxony‐Anhalt, Germany) when using the ITNI system (ITNI = Integrated Total Nitrogen Input), which is based on the ¹⁵N isotope dilution method. These differences were only partly explained by climatic influences. The effects of crops on the atmospheric N deposition measured by the ITNI system are discussed. For this purpose, data of six different plant species recorded in 1998 were re‐analyzed. It was found that the airborne N input is closely correlated with the morphology and metabolism of crops. Daily atmospheric N depositions of 129.0–360.8 g per hectare were measured for the plant species used. The nutritional supply of plants, especially with N, is another factor of influence on the N input from the atmosphere which should be considered. To investigate this aspect, a pot experiment was conducted with the grass Lolium perenne at three different N levels. An increase in the airborne N uptake (corresponding to N fertilization) was observed as biomass production rose.     

Balance and concentration of nitrogen and potassium affect growth and nutrient status in soilless cultivated lisianthus

Purpose: Nitrogen (N) / potassium (K) nutrient balance has been studied for some ornamental plants, however, available information is limited. Here we investigate the optimum N and K balance and concentration for lisianthus production in soilless medium.

Materials and methods: The effect of three N / K balances: 1.43, 2.14 and 4.29, prepared by varying the concentration of N and K, were evaluated in lisianthus grown in soilless medium (volcanic rock).

Results: Plants fertigated with a N / K balance of 2.14 exhibited enhanced height and stem dry weight when compared to plants fertigated with a balance of 4.29, and a higher flower buds count and total dry weight than those fertigated with a balance of 1.43 or 4.29. Plants fertigated with a balance of 2.14 exhibited increased dry weight when N was reduced from 15 to 9?meq?L^?1 and K from 7 to 4.2?meq?L^?1, suggesting that lisianthus does not require high levels of these nutrients. Although shoot N concentration was not correlated with N concentration in the nutrient solution or balance, increasing N in the shoot was associated with higher P and Mg in the plant tissues. In general, P, Ca, and Mg in plant tissues were unaffected by the external N / K balance, however, the internal P and Mg concentrations were positively correlated with shoot dry weight. Shoot K concentration significantly increased when the N / K balance decreased, which is related to the higher concentrations of external K when the balance decreased.

Conclusions: The optimum N / K balance for lisianthus was 2.14. However, there was a concentration effect, as fertigation with solutions containing a N / K balance of 2.14 and an N and K concentration of 9 and 4.2?meq?L^?1 respectively, resulted in plants with the greatest dry weight.     

Influence of pH on growth and nutrient uptake by crop species in an Oxisol

Abstract

Crop growth in Oxisols is known to be limited by high soil acidity and low levels of basic cations. Five greenhouse experiments were conducted to evaluate the effects of soil pH on the growth and nutrient uptake of upland rice (Oryza sativa L.), wheat (Triticum aestivum L.), corn (Zea mays L.), common bean (Phaseolus vulgaris L.), and cowpea (Vigna unguiculata L. Walp.). Six levels of soil pH (4.1, 4.7, 5.3, 5.9, 6.6, and 7.0) were achieved by addition of various levels of CaCO₃. Crop species responded differently to pH, reflecting the genetic diversity among species. Higher dry matter accumulation in roots and tops of rice, corn, and cowpea was observed at acidic pH ranges indicating that these species are tolerant to soil acidity. However, increasing soil pH enhanced dry matter accumulation in roots and tops of wheat and common bean, reflecting their intolerance to soil acidity. In all of the crop species, uptake of calcium (Ca) and magnesium (Mg) decreased with a decrease in soil pH. Overall uptake of zinc (Zn), manganese (Mn), and iron (Fe) in all species increase with a decrease in soil pH. Higher pH in an Oxisol might induce micronutrient deficiencies; therefore, one has to avoid overliming. In general, increasing soil pH decreased the uptake of nitrogen (N), phosphorus (P), and potassium (K) in rice, but uptake of these elements increased in wheat, corn, and common bean. In order to achieve the full genetic potential of any given species on an Oxisol, one needs to consider the species tolerance to soil acidity and its nutrient demand.     

Subsequent nitrogen utilisation and soil water distribution as affected by forage radish cover crop and nitrogen fertiliser in a corn silage production system

Forage radish is a unique winter cover crop that is relatively new but becoming rapidly adopted in temperate, humid North America. Little is known about how the use of this cover crop may influence subsequent nitrogen availability, soil water accumulation in the soil profile in corn silage production system. In this present work, the average nitrogen uptake by silage corn increased significantly by 11.6% in cover plots compared with the no-cover control plots. The recovery efficiency and agronomic efficiency of applied nitrogen in silage corn declined in cover plots compared to no-cover plots. The average soil water storage in cover plots was significantly higher than in the control after corn sowing and at the harvest stage. With increasing nitrogen application level, the average corn grain yield increased significantly at 56 and 112 kg N ha^?1 by 13.1% and 39.8%, respectively. Planting a forage radish cover crop can facilitate growth of silage corn and markedly improve total nitrogen uptake of corn. Consideration should be given to nitrogen application rate and also to avoiding excessive nitrogen input in the subsequent crop following a cover crop, thereby truly improving subsequent fertiliser use efficiency.     

养分缺乏对紫云英苗期生长及氮磷钾吸收的影响

溶液培养条件下研究氮、磷、钾、钙、镁、硫缺乏对苗期紫云英外部形态、生长发育、养分吸收的影响。结果表明,养分供应不足均不同程度地抑制了苗期紫云英生长,表现出特定的缺素症状。氮、磷、钙、镁缺乏显著降低紫云英株高16.4%～54.0%,而钾和硫缺乏无显著影响。氮和钙缺乏使根长分别减少31.9%和22.5%,其他养分缺乏对根长无显著影响。大量矿质元素(硫除外)缺乏使紫云英地上部干重显著降低22.0%～60.7%。根部干重受不同养分缺乏影响不同,氮、钙和镁缺乏后显著降低23.4%～51.6%,磷和硫缺乏后分别增加40.6%和18.8%,而缺钾对根干重无显著影响。单株干重随养分缺乏的变化趋势与地上部类似,除镁外其他元素缺乏均显著增加根冠比。紫云英苗期叶绿素含量在氮、钙、镁和硫缺乏时显著降低,缺钾和磷时无显著变化。受养分缺乏胁迫时,紫云英苗期地上部氮、钾含量(除了钾、硫缺乏时的氮含量及磷、镁缺乏时的钾含量)通常显著降低,紫云英磷含量仅在缺磷时显著降低。6种大量矿质养分缺乏一般导致紫云英氮、磷、钾累积量显著降低。聚类分析表明,溶液培养条件下钙和氮缺乏对苗期紫云英伤害程度最大,其次为磷,再次为钾,镁和硫缺乏的影响程度相对较轻。综上所述,矿质养分缺乏均不同程度地抑制紫云英生长和养分积累,生产中应结合实际开展养分管理,以提高绿肥生产利用效益。     

一株具有ACC脱氨酶活性固氮菌的筛选与鉴定

ACC（1-aminocyclopropane-1-carboxylate, 1-氨基环丙烷-1-羧酸）脱氨酶是近年来发现的许多植物促生细菌（Plant growth promoting bacteria, PGPB）共有的一个特征性酶,很多具有ACC脱氨酶活性的细菌能够增强植物抗逆性,缓解干旱、淹水、盐碱、高温、病虫害等对植物的危害。因此,ACC脱氨酶阳性细菌的筛选和研究对促进农业生产具有重要意义。本文从大量样品中分离、筛选到1株ACC脱氨酶阳性固氮菌,编号为7037,该菌株ACC脱氨酶活性为-丁酮酸2.530 mol /(hmg),protein,固氮酶活性为C2H410.068 nmol /(hmg), protein;具有较为广泛的碳源利用能力和很强的环境适应能力,被鉴定为节杆菌属（Arthrobacter sp.）的一个种。盆栽试验显示,小白菜接种7037菌株比对照组鲜重增加了139%,差异极显著。该菌株可望进一步研究开发成为微生物肥料的生产菌种。     

Evidence that fresh weight measurement is imprecise for reporting the effect of plant growth-promoting (rhizo)bacteria on growth promotion of crop plants

Eight greenhouse experiments were performed to compare the effect of seven plant growth-promoting (rhizo)bacteria (PGPR/PGPB) on fresh and dry weights of four crop plants. This has been done to validate if fresh weight measurements of plant variables can serve as reliable values when reporting the effect of these bacteria on plant growth. These experiments show that the growth promotion effects by the tested PGPR/PGPB, including Bacillus amyloliquefaciens GB03, Bacillus subtilis IN-937B, Bacillus altitudinis INR7, and Pseudomonas mandelii 89B-27 in corn and cucumber and Azospirillum brasilense Cd, A. brasilense Sp 245, and Azospirillum lipoferum Br 17 in pepper and tomato, varied significantly between fresh and dry weights of shoot, root, and/or whole plant in the repeated greenhouse experiments. These results support our hypothesis that using fresh weight determination for assessing plant growth promotion by beneficial bacteria is inherently faulty. Therefore, it is recommended that dry weight determination rather than fresh weight determination is used for plant growth promotion tests.     

The effect of NPK fertilizer with different nitrogen solubility on growth,nutrient uptake and use by chrysanthemum

The effect of nitrogen, phosphorus and potassium (NPK) fertilizer with different nitrogen forms on N, P, K use, uptake and growth of potted chrysanthemum plants during three vegetation phases was observed in two - years experiment. In the experiment, NPK fertilizer with slow soluble nutrients with different nitrogen forms: ureaform, (IBDU) isobutyledenediurea and melamin, was used. At control treatment the identical fertilizer was applied but the nitrogen was in ammonia and urea forms as usually used in horticulture. The experiment clearly showed the positive effect of NPK fertilizer containing half nitrogen amount in ureaform, on growth and plant nutrient uptake. This effect of nitrogen ureaform was confirmed by both the highest uptake of N, P, K and the highest yield of biomass. The NPK fertilizer with half nitrogen content in ureaform ensured optimal nutrient release according chrysanthemum nutrient requirement.     

钾素营养对饲用玉米养分吸收动态及产量品质形成的影响

在冀西北高原旱滩地条件下,以饲用玉米白马牙为试验材料,研究了钾肥不同施用量对饲用玉米养分吸收动态及产量品质形成的影响。结果表明,施钾使饲用玉米的生物产量增产7.96%～17.60%;显著促进了玉米植株氮素和磷素的吸收。施钾植株的氮素和磷素吸收量分别比不施钾植株提高17.73～40.28.kg/hm2和9.32～28.69kg/hm2;植株粗蛋白、粗脂肪的含量随施钾量增加而增加,且二者产量增幅分别为9.40%～21.5%和8.90%～38.12%。试验结果还看出,随钾肥用量的增加,饲用玉米株高、茎粗、叶面积指数和叶绿素相对含量均有提高,为饲用玉米的高产优质奠定了基础。因此,饲用玉米施用钾肥是提高其产量与营养品质的有效技术手段。     

不同氮源与钾水平对杂交组合及常规稻生长和养分吸收的影响

采用营养液培养法研究了不同氮源和钾水平对杂交稻及其亲本和常规稻生长、叶绿素含量、养分吸收的影响。结果表明 ,水稻生长、叶绿素的含量及养分吸收与氮源供应密切相关。在供钾充足的条件下 ,杂交稻上位叶的干物质产量以硝态氮营养的最高 ,其次为硝态氮与铵态氮混合营养 ;保持系与杂交稻的趋势一致。杂交稻下位叶和根系干物质积累量受 3种氮源的影响与恢复系相一致 ,即 :硝 +铵混合 硝态氮 铵态氮。硝态氮营养比硝 +铵混合及铵态氮更有效地提高杂交稻功能叶片中的叶绿素含量。杂交稻与其亲本植株地上部全氮含量受 3种氮源的影响为 :硝 +铵混合 硝态氮 铵态氮 ;然而杂交稻地上部的吸氮量受氮源的影响为硝态氮硝 +铵混合 铵态氮 ,与保持系的规律一致。杂交稻地上部钾含量及吸收量在 3种氮源处理间有差异 ,表现为硝态氮 硝 +铵混合 铵态氮 ,保持系的趋势一致 ,但与恢复系不同。研究结果还表明 ,杂交稻对硝态氮的营养特性具有明显杂种优势。 3种氮源对水稻生长、营养吸收的影响程度与钾营养状况及水稻品种有关 ;杂交水稻及其亲本较常规稻受影响更大。在高钾供应时 ,各项指标受到氮源影响的程度都明显高于低钾处理 ,其中以硝态氮为氮源更有利于杂交水稻生理及营养优势特性的发挥。     

Poinsettia growth,tissue nutrient concentration,and nutrient uptake as influenced by nitrogen form and stage of growth

Growth, development, and uptake of essential nutrients as influenced by nitrogen (N) form and growth stage was evaluated for ‘Freedom’ poinsettias (Euphorbia pulcherrima Willd. Ex Klotz.). Treatments consisted of five nitrate (NH₄ ⁺):ammonium (NO₃ ^‐) ratios (% NH₄ ⁺:% NO₃ ^‐) of 100:0, 75:25, 50:50, 25:75, and 0:100 with a total N concentration of 150 mg L^‐1. Plants were grown in solution culture for ten weeks under greenhouse conditions. Nutrient uptake data was combined into three physiological growth stages. Growth stage I (GSI) included early vegetative growth (long days). Growth stage II (GSII) began at floral induction and leaf and bract expansion (short days). Growth stage III (GSIII) was from visible bud through anthesis and harvest. Dry weights for all plant parts and height increased as the ratio of NO₃ ^‐ increased. Leaf area and bract area were maximized with 25:75 and 50:50 N treatments, respectively. Nitrogen treatments significantly affected foliar nutrient concentrations with calcium (Ca⁺⁺) and magnesium (Mg⁺⁺) being highest when NO₃ ^‐ was the predominant N form. Uptake of each macronutrient was averaged across all treatments and divided into physiological growth stages (GS) to identify peak demand periods during the growth cycle. The greatest uptake of NH₄ ⁺ and NO₃ ^‐ was from the early vegetative stage to floral induction (GSI). Phosphorus (P), potassium (K⁺), and Mg⁺⁺ uptake were greatest from floral induction to visible bud (GSII) and Ca⁺⁺ uptake remained relatively unchanged through GSI and GSII. Uptake was lowest for all nutrients from visible bud to anthesis (GSIII). Results from this study clearly indicate that peak demand periods for macronutrient uptake existed during the growth cycle of poinsettia.     

不同氮肥对油菜生长和养分吸收的影响

利用盆栽试验研究了潮土中不同氮肥对油菜生长和N、P、K、Ca、Mg等养分吸收的影响,结果表明:不同氮肥对油菜生长和养分吸收的影响以生长初期(5周时)差异最显著。生长初期,除硝酸钙外,不同氮肥均显著抑制油菜的生长,氯化铵>硫酸铵、尿素>硝酸铵;对N、K、Ca、Mg的吸收,氯化铵、硫酸铵和尿素表现显著的抑制作用,且氯化铵和尿素有大于硫酸铵的趋势,而硝酸钙表现显著的促进作用,硝酸铵大多情况下作用不明显;对P的吸收,各氮肥均表现显著的抑制作用,且氯化铵>尿素>硫酸铵、硝酸铵和硝酸钙。但随着时间推移,各氮肥最终均显著促进油菜生长和养分吸收,且不同氮肥的差异也逐渐减小。     

钾和湿度对油菜生长及其营养吸收的影响

The Interaction between potassium and moisture during the growth of and nutrient uptake by rapeseed plats grown on K-deficient soils has been investigated in this study.The results show that the dry weight of the above-ground parts of the plant appears to be somewhat reduced when the volume water content of the soil remains 0.15 for 3 successive days.As the shortage in the soil water continues,the weight of the plant root and the permeability of the root plasmalemma are markedly affected;the stem thickness and leaf area are reduced.However,K application can increase the dry matter weight of the above-ground parts,the thickness of the stem,and the area of the leaf.Application of K can also maintain a comparatively low water potential(ψ)and a comparatively high moisture content in the leaves,thus increasing the drought-resisting ability of the plant.When the volume water content of the soil is raised to 0.30,leaf yellowing as a symptom of nutrient deficiency appears on rapeseed plants grown on K-deficient soils.With increase in soil moisture content,the Ca concentration of the aerial parts of the rapeseed plant without K application increases while the K concentration decreases,Both K application and the soil moisture regime have very little effect on the Mg Concentration in the plant.Under soil mosture stress,the nitrogen content and total amount of amino acids in rape leaves increases;and thus more proline and glutamic acid is formed.On the other hand,the impact of soil moisture on pant‘s dry matter is governed by the status of potassium nutrition.On soils with low K.the moisture content has very little effect on yield;when K fertilizer is applied,however,the moisture content shows a very significant effect on yield increase.