龙眼钙、镁营养元素诊断技术的研究

通过对4个果园中产量高、中、低三个等级龙眼的土壤和植株养分分析，结合龙眼产量测定，探讨龙眼钙、镁营养元素的营养诊断指标。以交换性钙和交换性镁作土壤钙、镁营养元素诊断的诊断形态，以1月份时中上部老熟秋梢（结果母枝）第2位叶的全量钙、镁作为龙眼植株钙、镁营养元素的诊断形态，分别拟定出了土壤、植株钙和镁营养的诊断指标。     

Interelemental relationships in the soil and plant tissue and photosynthesis of field‐cultivated wheat growing in naturally enriched copper soils

Several interelemental relationships have been examined in field‐cultivated wheat (Triticum aestivum L. cv Vergina) growing on naturally enriched copper (Cu) soils. Mean soil Cu concentration per site ranged from 103–394 μg.g^‐1 dry weight (DW). Interrelationships between Cu, iron (Fe), calcium (Ca), potassium (K), zinc (Zn), lead (Pb), and magnesium (Mg) concentrations in the soil and plant tissue (roots, stems, and leaves) were examined using Principle Components Analysis. Soil samples were clustered according to collection site and were primarily differentiated according to their Cu concentrations. Soil Cu concentrations were positively correlated with Zn, Ca, Fe, and K in the soil, with Cu, K, and Ca in the roots, and Cu and Fe in the leaves and negatively correlated with Fe in the roots. The increase in Cu in the roots and leaves was positively correlated with increases in K and Ca in the roots and Fe and Ca in the leaves, but negatively with Fe in the roots. Increases in leaf Ca concentrations were correlated with increases in Mg and decreases in Zn concentrations in the leaf. Plants growing in soil with high Cu concentration exhibited toxicity symptoms with reduced height, decreased total leaf area and lower chlorophyll concentrations. Photosynthesis expressed per unit leaf area was not affected by increasing Cu concentrations in the soil or plant tissue.     

Impact of organic and inorganic nutrition on soil–plant nutrient balance in arecanut (Areca catechu L.) on a laterite soil

The study assessed the impact of continuous application of vermicompost and chemical fertilizers nitrogen, phosphorus and potassium (NPK) on arecanut in India. Key parameters examined were biomass production, nutrient uptake, yield, soil fertility and net benefit. Pooled analysis of 8-year data revealed that nutrient application registered significantly higher yield (2585–3331 kg ha^?1) than no nutrition (1827 kg ha^?1). Yields in organic nutrition were around 85% of the yields obtained in inorganic NPK. The concentrations of leaf N and K were significantly higher with NPK than with vermicompost. Vermicompost significantly increased soil organic carbon and the availability of calcium (Ca), magnesium (Mg), manganese (Mn) and copper (Cu), but reduced exchangeable K in soil. The total uptake of K and Ca together contributed positively to 75% variability in total biomass production. Nutrient removal of iron (Fe), P, K and Cu positively influenced the yield with about 81% variability. Biomass partitioning and nutrient uptake pattern are important for fertilization program of arecanut.     

Integrated Management of Organic Manures and Chemical Fertilizers for Enhancing Paddy Yield and the Nutrient Content of Rice Cultivars

The integrated nutrient management with organic manure and chemical fertilizers can improve rice (Oryza sativa L.) production, soil health, and fertility. Hence, this study aimed to evaluate the combined effects of organic manures and chemical fertilizers on the yield and nutrient content of wetland rice under field conditions. It was conducted in northern Iran in two consecutive years, 2015 and 2016 as a factorial experiment based on a randomized complete blocks design (RCBD) with three replications. Two local rice cultivars, Tarom Hashemi and Tarom Mahalli, were chosen as the first factor; mineral fertilizers in four levels: 100% recommended nitrogen-phosphorus-potassium (NPK), 75% recommended nitrogen with 100% phosphorus-potassium (PK), 75% recommended phosphorus with 100% nitrogen-potassium (NK), and 75% recommended potassium with 100% nitrogen-phosphorus (NP), were selected based on soil analysis and were arranged as the second factor; and three levels of organic manures, namely zero and eight tons of vermicompost per hectare, and 10 tons of rotted manure per hectare was the third factor. Results revealed that the highest paddy yield occurs with vermicompost and manure consumption for both cultivars. Moreover, the highest paddy yield (3962 kg ha^?1) occurs with 100% recommended NPK and vermicompost consumption. For both cultivars, the most chlorophyll a and chlorophyll ab content was produced with application of 100% recommended NPK. The most grain nitrogen content, grain nitrogen uptake, protein content, and protein yield were observed with 100% recommended NPK applied with 10 tons of rotted manure and eight tons of vermicompost usage per hectare. Therefore, in view of the ever-increasing use of chemical fertilizers and irreversible damage thereby, the additional use of these compounds can benefit the environment and human health. The global attention to sustainable agricultural concepts and organic manure can, in addition to producing reasonable yields, be considered as an appropriate alternative to chemical fertilizers.     

Influence of Nitrogen and Potassium Fertilization on Yield and Quality of Rosemary in Relation to Harvest Number

Rosemary is an important aromatic and spice plant. Its cultivation for production of its essential oil has gained importance in recent years. An experiment was conducted in a red sandy loam (Kandiustalf) soil to study the impact of cultivation of this multiharvest crop at different nitrogen (N) and potassium (K) application regimes on soil fertility and crop yield at the farm of the Central Institute of Medicinal and Aromatic Plants, Resource Center, Bangalore, during 2003–2005. The treatments consisted of all combinations of N levels (0, 150, and 300 kg per hectare per year) and K levels (0, 50, and 100 kg per hectare per year). Five harvests were taken at about 5‐month intervals. The results showed that initially the soil alone was able to meet the crop requirements for K, but with the progress of time, addition of K to the soil in the form of fertilizer became necessary for obtaining optimum yields. At the end of five harvests, exchangeable K in soil was significantly lower as application of K decreased from 100 to 50 and 0 kg per hectare per year. Soil fertility could be maintained and oil yields of rosemary from four harvests could be increased from 146.6 L to 344.7 L per hectare by application of 150 kg N and 100 kg K.     

Response of Pepper Plants to Different Rates of Mineral Fertilizers After Soil Biofumigation and Solarization

ABSTRACT

A greenhouse experiment was conducted to examine the effect of using three different rates (zero, low-input, and high-input) of a mineral fertilizer (nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)) on growth and yield of pepper cultivated in a soil after biofumigation (with horse manure at the rate of 4 kg· m^{? 2}) and solarization. Several physiological traits related with pepper plant development (leaf mineral concentration, net photosynthesis rate, transpiration, leaf sugar, and chlorophyll concentration) and fruit yield were determined. In T-1, chlorophyll was significantly lower and sugar concentration was significantly higher than in those where mineral fertilizers had been added (T-2 and T-3). There were no significant differences in photosynthetic rate among treatments. Increasing mineral fertilizer rates increased vegetative growth at the expense of fruit yield. Leaf nutrient concentrations most affected by the treatments were the N-fractions, and changes in the other parameters measured are discussed on the basis of these differences.     

Macro element status of Mandarin orchards in Southern Turkey

Abstract

Citrus nutrition and fertility of the orchards are not intensively studied in Turkey compared to the size of orchards and amount of production. A survey study was conducted in Eastern Mediterranean Coast of Turkey to evaluate the macro element status of Mandarin orchards and to define potential correlations between the soil parameters and leaf element contents. Twenty five mandarin orchards were selected for the survey study. Soil and leaf samples were collected from each orchard based on the size and uniformity. The amounts of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were measured in soil and leaf samples. The results indicated that there were not apparent nutrient deficiencies in the soils, however, the macro element deficiencies in the leaves were detected. Only a few number of correlations existed between the soil and leaf parameters. Previous fertilizer applications by growers should be considered in the current fertilizer programs.     

Nutritional Status,Yield, and Fruit Quality of “Encore” Mandarin Trees Grown in Two Sites of an Orchard with Different Soil Properties

Abstract

The nutrient status [annual fluctuation of leaf nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn)], yield and fruit quality [soluble solids concentration (SSC), titratable acids (TA), SSS/TA and juice content] of “Encore” mandarin trees cultivated in two sites of the same orchard were studied. The trees were grafted on Carrizo citrange rootstock and grown under identical conditions, apart from some soil properties. Soil B (site B of orchard) contained more K, Ca, Mg, and organic matter than soil A (site A of orchard). The patterns of annual variation of leaf nutrient concentrations were similar in both soils, although leaf concentrations of Ca, Mg, Mn, and Fe in soil A were significantly higher than those of soil boron (B), while leaf K concentrations were significantly lower. The mineral analyses of the leaves revealed some interesting antagonisms between K–Mg, K–Ca, and K–Mn. Manganese deficiency was especially limited in the trees grown in soil B. The average fruit yield per tree in soil A, on two-year basis, was significantly higher than this in soil B. The significantly higher water infiltration rate in soil B, in contrast to soil A, seemed to be the dominant factor responsible for the differences among the two sites in yielding and leaf mineral composition.     

Response of Forage Chicory Seedlings to Available Soil Phosphorus in Two Soils in a Controlled Environment

Poor phosphorus (P) fertility is a problem limiting productivity on unimproved Appalachian soils and has been implicated in poor palatability of forage chicory (Cichorium intybus L.). Three cultivars were grown in a greenhouse at varying soil P levels in Gilpin and Hagerstown silt loam soils and harvested 48 and 77 days after planting. In Gilpin soil, available soil P (ASP) was positively associated with dry shoot mass, leaf mass, leaf area, and leaves per plant and negatively associated with specific leaf area. In Hagerstown soil, ASP was positively associated only with only dry shoot and leaf mass. At equivalent ASP levels, dry shoot and leaf mass, leaf area, and shoot concentrations of P, potassium, calcium, and magnesium were always greater in Hagerstown than Gilpin soil, whereas specific leaf area was less. Equalization of ASP concentration and environmental conditions did not eliminate growth-limiting differences between Gilpin and Hagerstown soils for chicory.     

Relationship between Oil Palm Yield and Soil Fertility as Affected by Topography in an Indonesian Plantation

Abstract

Typically, Indonesian oil palm plantations rest on rolling topography. There is limited information on how topography affects soil fertility and oil palm yields. A study was conducted to evaluate these relationships in a commercial oil palm plantation located in South Sumatra, Indonesia. Two sites with differing past management history and fertility regimes were each partitioned into three topographic positions. At each topographic position, yields were recorded at 10‐day intervals over a period of 2 years. Leaf and soil samples were collected from corresponding points spaced at 36.4 m (x direction) and 8.7 m (y direction) using a systematic scheme. Leaf analysis was performed to quantify nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and calcium (Ca), and soil analysis was carried out to determine pH, organic carbon (C), extractable P, exchangeable K, Mg, and Ca, effective cation exchange capacity (ECEC), and texture. The collected data were subjected to exploratory, univariate, and bivariate analyses, as well as analysis of variance. Empirical production functions based on measured variables were defined for each topographic position. Results showed that average yields at both study sites varied with topographic position. At site 1 (Sungai Pelepah Estate), the sideslope and the summit consistently gave higher yields than the toeslope. At site 2 (Sri Gunung Estate), a yield gradient was observed with the highest yield occurring at the toeslope and the lowest yield from the summit. Soil fertility varied across topographic positions at both sites. The measured leaf/soil variables showed varying levels of optimality/sufficiency across topographic positions. In most cases, leaf and soil variables showed comparable performance as yield predictors. Validation of the calibrated models showed reasonable accuracy for the toeslope of site 1 and all three positions at site 2.     

SOIL LIMING AND MINERAL FERTILIZATION FOR ROOT NODULATION AND GROWTH OF FABA BEANS IN AN ACID SOIL IN TUNISIA

Faba beans (Vicia faba L) are grown in northern Tunisia where annual rainfall approaches 1200 mm and where the soil acidity is the most limiting factor for plant growth. Aluminum (Al) and manganese (Mn) toxicities provide a hostile environment to root growth. To alleviate such a problem, farmers use selected acid-tolerant species. However, crop yields remain far below their optimal levels. Liming, a practice to eliminate acidity, has never been tried in this area before. This research aimed to evaluate the impact of lime and mineral fertilizers on root nodulation, plant uptake and yield of faba beans using a pot experiment. Treatments were combinations of two rates of calcium carbonate with three rates of superphosphate and three rates of potassium sulfate. Liming produced significantly higher number and weight of nodules on roots as well as higher nitrogen, phosphorus, and potassium contents in plant tissue. Liming also increased shoot growth and bean yield.     

Microbial community response to soil solarization in Nepal's rice-wheat cropping system

The Indo-Gangetic Plains of South Asia support 13.5 million hectares of rice-wheat cropping systems, which currently feed over one billion people. Intensified agriculture has resulted in a more than two-fold increase in rice and wheat yields since the 1970s; however, this continuous cropping has also exacerbated weed, pest and disease problems. Soil solarization is an accessible, low-risk management practice for small-holder farmers that has ameliorated these problems in some settings and has the potential to dramatically improve yields. Field trials were conducted at two sites in Nepal to test whether soil solarization: (i) had a lasting effect on soil bacterial, fungal and nematode communities; (ii) altered the rhizosphere communities of rice nursery seedlings and (iii) improved crop growth and yield in the rice-wheat cropping system. Rice seedlings were grown in nursery plots that were solarized for 28 days or left untreated and were transplanted to field plots that were also either solarized for 28 days or not in a randomized complete block design with four replications. Rice was grown to maturity and harvested, followed by a complete wheat cropping cycle. Solarization of main field plots increased counts of fungal propagules and decreased root galling and nematode counts and decreased weed biomass. Terminal restriction fragment length polymorphism (T-RFLP) analyses of extracted soil DNA revealed significant shifts in fungal community composition following soil solarization, which was sustained throughout the entire rice cropping cycle at both field sites. The bacterial community composition was similarly affected, but at only one of the two sites. Despite the observed changes in soil microbial community composition over more than one cropping period, solarization had no impact on crop productivity at either site. Nevertheless, such changes in soil microbial communities in response to solarization may be responsible for increased yields observed at other sites with greater pathogen pressure. This practice has shown promising results in many farmers’ fields in South Asia, but further elucidation of the mechanisms by which solarization increases productivity is needed.     

Surface Application of Lime and Cover Black Oat and Corn Residues for No‐Till Soybean Production

Abstract: Crop residues that are left on the soil surface to serve as mulch can diminish the soybean response to surface application of lime under no‐till management by ameliorating soil chemical and physical attributes and the plant nutrition. A field experiment was performed in the period from 2000 through 2003 in Paraná State, Brazil, on a clayey‐sandy Rhodic Hapludox. Soil chemical attributes and soybean [Glycine max (L.) Merrill] nutrition, grain yield, and quality were evaluated after surface application of lime and covering with crop residues of black oat (Avena strigosa Schreb) and corn (Zea mays L.) under a no‐till system. Dolomitic lime was surface applied at the rates of 0, 2.5, 5.0, and 7.5 t ha^?1 on the main plots, and three treatments with vegetable covering were applied on the subplots: (i) without covering, (ii) with covering of corn straw, and (iii) with covering of corn straw and black oat residue (oat–corn–oat). After 30 months, surface‐applied lime increased soil pH and the exchangeable calcium (Ca²⁺) and magnesium (Mg²⁺) levels down to a 10‐cm depth, independent of the vegetable covering treatments. The black oat and corn residues on the soil surface increased the soil exchangeable K⁺ level at the 5‐ to 10‐cm depth. Liming increased leaf potassium (K) content and phosphorus (P) content in the soybean grain and reduced leaf zinc (Zn) content and manganese (Mn) content in the soybean leaf and grain. There was no effect of liming on soybean grain, oil, or protein yields, independent of the vegetable residues kept on the soil surface. The treatment with black oat covering and corn straw increased leaf N content, P content in the leaf and grain, and the contents of K, Mg, copper (Cu), and Zn in the soybean grain. It also increased soybean grain and protein yields. The corn straw left at the surface after harvesting was very important to the performance of the no‐till soybean.     

DRIS NUTRIENT NORMS FOR PINEAPPLE ON ALFISOLS OF INDIA

Sub-optimum production in pineapple fields in India is a common feature in Alfisols. The diagnosis and management of nutrient constraints assume a greater significance in maximizing production sustainability. DRIS norms were computed from the data bank of 324 sub-plots on leaf mineral composition, soil available nutrients, and corresponding mean yield representing three diverse pineapple belts for 3 seasons during 2002 –04. DRIS norms derived primarily from basal portion of ‘D'leaves sampled at 4th to 5th month suggested optimum leaf nutrient concentration viz. 1.21–1.85% nitrogen (N), 0.13–0.18% phosphorus (P), 1.19–1.62% potassium (K), 0.27–0.35% calcium (Ca), 0.43–0.56% magnesium (Mg), and 78.4–102.5 iron (Fe), 41.5–58.3 manganese (Mn), 7.4–10.2 copper (Cu), and 12.2–15.8 zinc (Zn) (ppm) in relation to fruit yield of 55–72 tons ha^?1. Likewise, DRIS norms for soil fertility corresponding to similar level of fruit yield were determined. The norms were further observed validating the leaf/soil test values obtained from productive plots, suggesting the DRIS as a dynamic interpretation tool for diagnosis of nutrient constraints using both, leaf as well as soil analysis.     

古龙酸母液和北虫草废弃培养基混制有机肥对设施蔬菜和土壤肥力的影响

采用温室盆栽试验研究了不同用量古龙酸母液和废弃北虫草培养基制备的有机肥对设施黄瓜的增产效果及对土壤养分和微生物量碳的影响。结果表明,施肥量为15.0和30.0 t·hm-2时,黄瓜产量、株高、全株生物量分别比未施肥处理显著高出了118.79%、91.63%、443.30%和140.83%、196.32%、736.70%。15.0和30.0t·hm-2的有机肥将土壤有机碳、全氮、全磷和全钾含量分别显著提高了17.10%、25.97%、37.14%、30.28%和35.49%、83.37%、42.86%、60.55%。土壤碱解氮、有效磷、速效钾和微生物量碳随着施肥量的增加而增大,其峰值均出现在黄瓜生长的初花期,最低值出现在拉秧期或出苗期。综上所述,15.0和30.0 t·hm-2的混制有机肥施用量能够显著提高设施黄瓜的产量和土壤肥力,土壤肥力的峰值出现在黄瓜生长的初花期。     

土壤消毒措施对土壤物理特性及黄瓜生长发育的影响

采用田间试验方法,研究了垄沟式太阳能消毒、石灰氮麦秸、垄鑫3种土壤消毒方法对日光温室土壤物理特性及黄瓜生长发育的影响。结果表明,垄沟式太阳能消毒处理对土壤物理特性未产生较大影响,处理后粗粉粒含量较对照降低9.5%,砂粒两个粒径(0.1～0.5mm、0.5～1.0mm)含量较对照分别增加39.4%、117.7%,其余组分无明显变化;石灰氮麦秸处理后黏粒含量增加163%,细粉粒两粒径(0.001～0.005mm、0.005～0.01mm)含量较对照分别增加52.1%和116.8%;施用垄鑫处理后土壤黏粒含量较对照降低65.8%,细粉粒两个粒径含量较对照分别降低33.0%、32.2%。不同处理对土壤微团聚体的形成均有一定阻碍作用,其中石灰氮麦秸处理对土壤团聚体的形成影响最大,其次是垄鑫处理,垄沟式太阳能消毒处理影响最小。3个土壤消毒处理都能提高黄瓜平均叶片数、平均株高、叶绿素含量和黄瓜产量,其中垄沟式太阳能消毒处理能显著提高黄瓜生物学指标,有良好的增产效果。     

花后小麦叶面积指数与光合和产量关系的研究

以大穗型品种泰农18（T18）和中穗型品种山农15（S15）为材料,采用裂区设计,主区设置180 kg/hm2和240 kg/hm2 两个氮肥水平（纯氮）,裂区设置75104株/hm2,150104株/hm2和225104株/hm2三个种植密度,研究了叶面积指数与冬小麦光合和产量的关系。结果表明:冬小麦下部叶片叶面积指数（LLAI,倒4叶和倒5叶之和）与群体净光合速率（CAP）和产量呈极显著的正相关关系;从开花到花后14 d 之前,上部叶片叶面积指数（TLAI,旗叶、倒2叶和倒3叶之和）和全部叶面积指数（WLAI,下部叶片和上部叶片之和）与群体净光合速率（CAP）和产量并不呈必然的显著正相关关系（T18 显著正相关,S15相关不显著）,但花后14d 至成熟期,两个品种的 TLAI和 WLAI 均与群体净光合速率（CAP）和产量呈显著的正相关关系。氮肥水平和种植密度对产量存在显著的互作效应,无论是大穗型品种T18还是中穗型品种S15都可以通过适当增加密度（T18以225104//hm2为宜,S15以150104//hm2为宜）,降低氮肥用量（180 kg/hm2）实现高产。     

Nutrient depletion in Ferralsols under hybrid sisal cultivation in Tanzania

Abstract. Sisal production in Tanzania has declined sharply in the past two decades because of a decrease in the area grown and a decrease in yields. As sisal is cultivated without manuring, depletion of soil fertility is considered one of the main causes of the declining yields. This paper presents a balance of the macronutrients N, P, K, Ca and Mg for sisal grown in a plantation in NE Tanzania on deep, red clay soils (Ferralsols). Annual fibre yields declined from 2.5 t/ha in the 1960s to about 1 t/ha in the 1980s. Hybrid sisal is a demanding crop and in ten years, with a total fibre yield of 11 t/ha, about 260 kg of N, 40 kg of P, 385 kg of K, 890 kg of Ca and 330 kg of Mg are removed in the harvested leaves. A comparison of soils after two and three 10-yr cycles of sisal production showed that in the third cycle the pH decreased by 0.5 units and that exchangeable bases were decreased by fifty per cent or more. The amounts of K, Ca and Mg removed from the soil were similar to those in leaves. However, soil analyses could not detect changes in total N and available P, possibly because of the large amount of total N in the soil and the lack of precision in the N and P analyses. In the Ferralsols, potassium is likely to become deficient first, followed by magnesium and calcium. The soil has little available P, and an increase in soil acidity may decrease it further and also create aluminium and manganese toxicities. In order to maintain sisal production, fertilization with P, K, Ca and Mg is necessary, and to improve yields N must also be applied.     

Dynamics and Nutrient Release Pattern of Silica Sources in a Typical Entisol of Tropical Humid Region of Kerala

Silicon is considered as a beneficial element for crop nutrition especially for monocots. In order to study the effect of addition of different silica sources on the nutrient release pattern from an Entisol, a laboratory incubation study was conducted with three silica sources viz., sodium silicate, calcium silicate, and potassium silicate each @ 200 ppm and 400 ppm per kilo gram soil. The positive effect of addition of silicates was obvious on soil reaction, available Si, P, K, Ca, and Mg. Release of plant available silicon was the highest at 60th day after incubation (DAI) with potassium silicate @ 400 ppm per kg soil. Sodium silicate @ 200 ppm resulted in the highest exchangeable magnesium concentration at 45th DAI. The result of the study implies the positive influence of silicates on soil acidity as well as on enhancing the availability of phosphorus, potassium, calcium, and magnesium in an Entisol.     

西瓜钾营养诊断的叶片含量法分析

采用不同土壤钾水平的多点田间试验,研究了施用钾肥对西瓜植株钾含量以及产量、品质的影响,探讨了西瓜植株各叶位钾含量与西瓜产量之间的相关性,分析了叶片钾含量诊断西瓜钾营养的临界指标。结果表明:西瓜新叶钾含量与西瓜产量达极显著相关关系,相关系数为0.600 8(P_(0.01)=0.575)。90%相对产量下新叶钾含量为32.6 g/kg时,西瓜产量可达91.39 t/hm~2。在极低钾含量(50 mg/kg和70 mg/kg)的土壤上,施用钾肥显著提高西瓜产量、开花期西瓜植株新叶和老叶钾含量;显著提高开花期、坐果期和膨大期西瓜植株茎和根中的钾含量。在低钾含量(84 mg/kg和85 mg/kg)的土壤上,施用钾肥显著提高西瓜产量,提高西瓜果实中的可溶性糖和可溶性固形物的含量而降低可滴定酸含量。随着钾肥施用水平的提高,新叶钾含量有提高趋势,老叶和挂果叶中的钾含量逐渐升高;施用钾肥显著提高坐果期和膨大期西瓜植株茎中钾含量。在中钾含量(170 mg/kg)和高钾含量(260 mg/kg)的土壤上,西瓜开花期新叶钾含量的最大值和最高产量相关联。总之,推荐开花期西瓜新叶钾含量32.61 g/kg为营养诊断临界值。