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1.
Abstract

Differences in elemental content of pecan [Carya illinoensis (Wang.) K. Koch] leaves among cultivars were found for N, P, K, Ca, Mg, Mn and Zn. Of the 7 elements studied, only leaf K indicated a date by cultivar interaction. Differences in leaf K among cultivars became greater as the season progressed. Increasing rate of application of N‐P‐K fertilizer increased leaf N, Ca, Mn, and Al, but had very little or erratic effect on leaf P, K, Fe, B, Cu, Zn, and Sr. There were very few consistent significant fertilizer rate by date interactions for the 13 elements tested. Seasonal trends for element leaf contents from mid‐May through October were generally downward for N, upward for Ca, Mn, Fe, B, Cu, Al, and Ba and changed very little for Mg, Zn, and Sr. Leaf P and K responses to sampling date varied with year. Large year to year variations in leaf trends over dates suggests difficulty in selecting a period for leaf sampling where little change in leaf levels consistently occurs.  相似文献   

2.
Nutrient concentrations in leaves of self‐rooted apple trees propagated by tissue culture (TC) were compared to the same cultivars budded on seedling, MM 106, and M.26 rootstock planted at two sites, Beltsville, MD and Kearneysville, WV. Leaf samples were monitored annually for 3 years after planting for N, P, K, Ca, Mg, Mn, Fe, Cu, B, Zn and Al from ‘Ozark Gold’ and ‘Stayman’ apples at both sites and ‘Northern Spy’ at Beltsville only. Leaf K and Mn concentrations tended to be higher in trees on M.26 and MM 106, while Ca was higher in TC or seedling trees. Foliar Mg was lower in trees budded on MM 106. Variation in P concentrations was greatest over years, while leaf N and Fe displayed only slight variation among rootstocks. Leaf B and Zn did not exhibit any consistent trends and Cu and Al were not affected by year, rootstock, cultivar or site.  相似文献   

3.
Plants of Norland potatoes (Solanum tuberosum L.) were maintained for 42 days at Mg concentrations of 0.05, 0.125, 0.25, 1, 2, and 4 mM in a nonrecirculating nutrient film system under controlled environment. With the increased Mg supply from 0.05 to 4 mM, Mg concentrations in the leaves of the 42-day old plants increased significantly from 1.1 to 11.2 mg g-1 dry weight. Plant leaf area and plant and tuber dry weights increased with increased Mg concentrations up to 1 mM in solution or 6.7 mg g-1 in leaves, and then decreased with further increases in Mg concentrations. Rates of CO2 assimilation measured on leaflets in situ at ambient and various intercellular CO2 concentrations were consistently lower at 0.05 and 4 mM Mg than at other Mg treatments, which may indicate decreased photosynthetic activity in mesophyll tissues at the lowest and highest Mg concentrations. Dark respiration rates in leaves were highest at 0.05 and 4 mM Mg, lowest at 0.25 and 1 mM Mg, and intermediate at 0.125 and 2 mM Mg. The different Mg treatments also influenced accumulation of other minerals in leaves. Leaf concentrations of Ca and Mn decreased with increased Mg supply except that Ca and Mn were lower at 0.05 mM than at 0.125 mM Mg. Leaf K concentrations were lower at 1, 2 and 4 mM Mg than at other Mg treatments. Foliar concentrations of P, Fe, Zn, and Cu had small but inconsistent variation with different Mg concentrations. Leaf concentrations of N, S, and B were similar at different Mg concentrations. This study demonstrates that various Mg nutrition, along with altered accumulation of other nutrients, could regulate dry matter production in potatoes by affecting not only leaf area but also leaf carbon dioxide assimilation and respiration.  相似文献   

4.
Leaves of olive (Olea europaea var. minor rotunda) were collected from mature non-irrigated trees in an “off” year, at monthly intervals, from May 2015 to April 2016. Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and boron (B) were determined. Seasonal fluctuation curves were developed for each nutrient, in order to use them for interpretation of leaf analysis. Concentrations of N, P, K, Ca and Mg showed significant fluctuation throughout the year, while B, Fe, Mn and Zn showed less intense changes. Nutrient accumulation varied according to tree vegetative growth and weather conditions.  相似文献   

5.
Abstract

Leaf analysis is a tool for effective fertilizer recommendations in fruit trees. To achieve this goal, a suitable leaf sampling method is a very important step. This study aimed to investigate suitable leaf position and leaf age to establish standardized leaf sampling method, which can collect representative leaf sample for leaf nutrient analysis in rose apple cultivar Tubtimjan. The experiment consisted of 3 leaf positions (1st, 2nd, and 3rd leaf position) from the growing tip and 1-8?months leaf age. The results indicated that the suitable leaf position to be the index leaves were 2nd and 3rd leaf position with 6–7?months old leaf age due to minimum variation of the leaf nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations. Moreover, the concentrations of N, P, and K tended to decrease, whereas, Ca, Mg, Fe, Cu, Mn, and Zn concentrations tended to increase as leaf age increased.  相似文献   

6.
The seasonal variation of mineral elements and the relationships among them were studied in natural populations of foxglove (Digitalis obscura). Young and mature leaves were collected in 10 different populations and on four sample dates (May, July, October, and February). Leaf mineral elements [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu)] were determined. The highest concentrations of N, P, and K in young leaf were recorded in May, followed by a decrease in the other months, while in contrast Ca and Fe showed the lowest concentration in May. Mature leaves showed differential seasonal behavior. Besides seasonal variations, significant fluctuations of N/P and Ca/Mg ratios were observed in young leaves. Strong positive correlations existed among N, P and K, while negative correlations were found between Ca and N, P, or K.  相似文献   

7.
Abstract

A nutritional survey of 23 commercial peach orchards was carried out in the Murrumbidgee Irrigation Areas (M.I.A.) of New South Wales during three growing seasons (1961–62, 1962–63 and 1963–64). Sampling sites were chosen to provide the widest possible coverage of peach orchards of above average productivity. Leaf and soil samples were taken from each site for chemical analysis.

The lighter textured (loamy sand) soils were found to have low reserves of N, P, Ca, Mg and K which could limit growth and yield. The heavier textured colluvial (sandy loam) and alluvial (clay loam) soils contained adequate reserves of most nutrients except N and P. Colluvial soils were particularly low in P. On all soils organic matter contents were very low, generally being below 1.0%.

Leaf N, P, K and B contents decreased during the growing season from October to April. In contrast, leaf Ca, Mg, Na and Cl contents increased over the same period. Since there was a tendency for the leaf N and P contents to decrease slightly during January, this month is suggested as being the most suitable for the collection of leaf samples for diagnostic purposes. Despite the low reserves of some nutrients as indicated by soil analysis, generally satisfactory levels of leaf N, P, K, Ca, Mg, Na, Cl, B, Fe, Mn, Cu and Zn were found.  相似文献   

8.
巨桉人工林叶片养分交互效应   总被引：1，自引：0，他引：1  
在四川巨桉栽培区设立了60个标准地,采用相关分析和矢量诊断法进行分析,以了解巨桉人工林养分的相互作用关系。结果表明,巨桉人工林叶片的养分交互作用较为复杂。N可促进P、K、Ca、Mn等的吸收,但易受到Fe、Zn、高Ca、高Mg的拮抗,而且高N抑制了Mn的吸收;P可促进K、Mg、Mn等的吸收,但易受Zn、Fe、高Mn、高K、高Ca、高Mg的拮抗,而高浓度的P将抑制K、Zn、Fe等的吸收;K对其他养分元素均没有明显的促进作用,但高浓度K限制P的吸收;Ca、Mg之间可相互促进吸收。同时,低浓度的Ca和Mg有利于Fe、Zn的吸收,高浓度的Ca和Mg将对N、P、Fe、Mn、S、B等养分产生拮抗,限制吸收;S可促进Zn的吸收,但易受高Ca、高Mg拮抗;Cu、Zn、Fe、Mn之间主要以拮抗为主。B相互作用较少,对其他养分几乎没有明显的促进作用。  相似文献   

9.
以山地梨枣(Zizyphus jujuba Mill. cv. Lizao)为试验材料,采用野外试验与室内分析,研究了黄土丘陵区山地滴灌下施用氮磷钾对矮化密植梨枣叶片8种营养元素（N、P、K、Ca、Mg、Fe、Mn、Zn）季节动态变化规律以及施肥对梨枣生长,产量及品质的影响。结果表明:不同生育期梨枣叶片养分含量变化具有一定的规律性。开花坐果期（5月上旬至7月上旬）,叶片N、P、K含量处较高水平,Mg、Fe、Mn、Zn含量处于较低水平。果实膨大期（7月中下旬到8月下旬）,叶片N、P有一个相对稳定的含量,K快速下降,而Fe、Mn、Zn含量上升。果实成熟期（9月初到10月初）,叶片N、P、K含量下降,Mg、Fe、Mn、Zn则是缓慢上升并趋于稳定。叶片N、P、K、Mn含量之间呈正相关,Ca、Mg、Fe、Zn含量之间也呈正相关关系,叶片N、P、K之间达极显著正相关关系,而N、P、K与Ca、Mg、Fe、Zn含量之间呈负相关关系。施氮肥可促进前期枣树新枝生长和枣果膨大;施磷肥可提高产量,达到33210 kg/hm2;施钾肥可明显提高枣果品质。  相似文献   

10.
The dry weight accumulation per leaf as well as the concentration per gram of dry weight and the accumulation of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined in walnut tree leaves (Juglans regia L.) during a complete life cycle. Additionally, the dynamics of plant nutrient concentration in leaf petiole sap and carbohydrate accumulation in leaves were studied in relation to the main life cycle events of the walnut tree. Total N, P, K, Cu, and Zn concentrations decreased, whereas that of Ca, Mg, and Mn increased during the season. Iron concentration fluctuated around a mean value. Total N, P, K, Mg, and Cu concentrations detected in younger mature leaves were at the sufficient level, whereas Ca, Fe, Mn, and Zn concentrations were at higher levels as compared to those previously reported. All the detected nutrient accumulations increased abruptly during leaf ontogeny and leaf maturation until a maximum level was attained in the younger mature leaves. Similarly, sucrose, glucose, and fructose accumulation were observed at the same period. The rates of total N, P, Cu, and Zn accumulation were lower than the rates of the observed dry matter accumulation and nutrient concentration dilution. Potassium and Mn accumulation rates were almost equal, whereas those for Ca and Mg were higher as compared to the dry matter accumulation rate. The fast embryo growing phase resulted in a considerable decrease in dry weight, total N, P, K, Cu, Zn, and carbohydrate accumulation, and to a lesser degree in Ca, Mg, and Mn accumulation. Nutrient accumulation reduction in leaves by the influence of the growing fruits were estimated to be: total N 52%, K 48%, P 29.5%, Mg 16.3%, Ca 15%, Fe 51.2%, Cu 55.2%, Zn 37.3%, and Mn 5.4% of the maximum nutrient value of the younger mature leaves. Old leaves preserved nutrients before leaf fall as follows: total N 25.4%, P 45%, K 31%, Ca 74.8%, Mg 76.5%, Mn 89.2%, Fe and Zn 50%, and Cu 37%. Nutrient remobilization from the senescing old leaves before leaf fall were: total N 22.6%, P 25.5%, K 21%, Ca 10.2%, Mg 7%, Fe 3.2%, Mn 5.4%, Cu 8%, and Zn 13.3% of the maximum value in the younger mature leaves. In early spring, the absorption rates of N, P, and Ca were low while those of Mg, Fe, Mn, Cu, and Zn were high. During the fast growing pollen phase, the N, P, Fe, Mn, Cu, and Zn concentrations were reduced. Calcium concentration is supposed to be more affected by the rate of transpiration rather than during the growing of embryo. Calcium and Mg concentrations in the sap were negatively correlated. The detected K concentration level in the sap was as high as 33 to 50 times that of soluble N, 12 to 21 times to that of P, 5 times to that of Ca, and 10 to 20 times to that of Mg. The first maximum of starch accumulation in mature leaves was observed during the slow growing embryo phase and a second one after fruit ripening. Old senescing leaves showed an extensive carbohydrate depletion before leaf fall.  相似文献   

11.
  【目的】  对比大、中量养分短期缺乏下脐橙新、老叶片中11种必需元素含量及变化,并分析缺素导致的营养元素间的相互影响。  【方法】  以一年生枳砧纽荷尔脐橙幼苗为试材进行了砂培试验。以完全营养液为对照 (CK),设置缺氮 (?N)、缺磷 (?P)、缺钾 (?K)、缺钙 (?Ca)和缺镁 (?Mg)处理,测定不同处理脐橙叶片（老叶和新叶）生长指标及矿质元素含量。  【结果】  所有缺素处理均导致叶片叶绿素含量降低,生物量减少,以缺氮处理最为显著。缺氮降低了叶片N、Ca、Cu、Mo含量;缺磷降低了叶片P、K、Mo含量;缺钾降低了叶片K含量;缺钙降低了叶片N、Cu、Zn、Mo含量但增加了P含量;缺镁降低了叶片Ca、Mg、Zn、Mo含量但增加了K含量。以必需矿质元素为变量分别对各处理老叶和新叶进行主成分分析,老叶中第一主成分 (PC1)明显将缺钾处理与其他处理区分开,与对照相比,缺钾老叶离子组成变化为N (?3%)、P (+1%)、K (?71%)、Ca (+11%)、Mg (+39%)、B (+16%)、Mn (+11%)、Fe (+32%)、Cu (?7%)、Zn (+14%)、Mo (?63%);新叶中PC1明显将缺氮处理与其他处理区分开,缺氮新叶离子组成变化为N (?53%)、P (+8%)、K (+7%)、Ca (?14%)、Mg (+11%)、B (+55%)、Mn (+51%)、Fe (?14%)、Cu (?57%)、Zn (+4%)、Mo (?25%)。老叶和新叶中元素含量呈正相关的元素是N-Cu、N-Ca、Mg-Mn和Cu-Mo,呈负相关的是K-Zn。  【结论】  脐橙幼苗老叶对钾的短期缺乏反应最敏感,缺钾会显著降低老叶中K和Mo含量并增加Mg和Fe含量,而新叶对氮素的短期缺乏最敏感,缺氮显著降低新叶中N、Ca、Cu和Mo含量。短期缺少P、Ca和Mg对脐橙幼苗叶片中的养分含量影响较小。  相似文献   

12.
Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), iron (Fe), and manganese (Mn) in ‘Sterling’ muscadine grapes (Vitis rotundifolia Michaux) grown for two years in sand culture were not influenced by different N‐fertilizer sources. Leaf zinc (Zn) and copper (Cu) were higher with ammonium nitrate (NH4NO3)than ammonium sulfate [(NH4)2SO4]. Shoot growth was greatest with NH4NO3. Leaf Ca, Mg, Mn, and Cu content decreased and leaf N increased as N‐fertilizer rates were raised. Plant growth was positively correlated with leaf N, but was negatively correlated with leaf Ca, Mg, Fe, Cu, and Mn content. Percent Mg in the leaves was reduced when N levels, regardless of N source, were raised from the low (1.8 mM) to the middle (5.4 mM) rate. High leaf‐N levels were correlated with lower Ca and Mg in the leaves, indicating a relationship between N fertilization and the late‐season Mg deficiency often observed in muscadine grapes.  相似文献   

13.
Seasonal changes in nutrient concentrations of leaf and fruit structural parts (rind and pulp) from ‘Newhall’ (Citrus. sinensis Osbeck) and ‘Skagg's Bonanza’ (C. sinensis Osbeck) navel oranges were investigated during fruit development in two successive years. Leaf calcium (Ca), manganese (Mn), and potassium (K) concentrations were relatively constant throughout the whole season with the exception of an increase of K at stage 1, the period of fruitlet growth [before 80 days after full bloom (DAFB)], whereas the magnesium (Mg), boron (B), iron (Fe), and zinc (Zn) concentrations declined distinctly during stage 2 (80–180 DAFB), the period of fruit rapid enlargement. In rind, Ca, B, Fe, and Mn concentrations reached the greatest levels at stage 2, different from K and Mg, which increased at stage 1 and decreased thereafter. In pulp, concentrations of Ca, K, Mg, and Mn declined gradually with time, whereas a small rise in B toward the end of sampling and a clear increase of Fe at stage 2 were observed. It was suggested that ‘Newhall’ required greater B inherently in fruits as the cultivar had greater B concentrations in fruit parts and had greater rind/leaf B concentration ratios than ‘Skagg's Bonanza.’ ‘Newhall’ had relatively greater rind Ca content and exhibited Ca distribution more uniformly within its fruit parts, which probably enhanced the crack resistance.  相似文献   

14.
试验于2010~2011年连续2年以济源市4个早实核桃品种香玲、鲁光、中林1号、薄丰为试材进行了对比试验,研究了不同采样时期叶片中N、 P、 K、 Ca、 Mg、 Fe、 Cu、 Mn、 Zn 9种矿质营养元素的含量变化及其与产量的关系。结果表明,早实核桃叶片中9种元素的含量在年周期内呈规律性变化,含量高低依次为 Ca＞N＞Mg＞P＞K,Fe＞Mn＞Zn＞Cu。不同品种各元素的含量变幅最大为127.69~169.53 mg/kg（Mn）,最小为2.1~92.26 g/kg（K）。不同早实核桃品种叶片内矿质元素含量的年变化趋势表现为N、 P、 K总体上呈下降趋势,最高含量为展叶期（4月20日）分别为36.79、 5.54、 2.93 g/kg,最低在落叶前期（9月28日）,分别为17.45、 2.66、 1.86 g/kg;Ca、 Mg、 Fe、 Mn 4元素含量的变化总体上表现为前期低后期高;Cu、Zn含量的变化有差异但差异不明显。总的来看, 5~7月份,即新梢速长期（5月20日）至硬核期（7月20日）是核桃树养分稳定的时期, 叶片中N、 P、 K含量之间呈极显著的正相关, N、 P与Ca、 Mg、 Mn、 Cu间呈极显著的负相关,可以认为N、 P、 K之间存在增效作用,Ca、 Mg、 Mn、 Cu 对N、 P 和 K 均存在一定的拮抗作用。元素含量与产量的相关分析表明,N、 P、 K在新梢速长期均与产量达（极）显著正相关,相关系数分别为0.819、 0.843和0.895。因此, 利用叶片进行营养诊断最佳,采样时间以新梢速长期（5月20日前后）为宜。  相似文献   

15.
’Dormanred’ raspberry (Rubus species) plants grown in sand culture were subjected to varying concentrations of N, Ca, and Mg over a two‐year period. Increasing nitrogen fertilization resulted in linear reductions of leaf Ca, K, Zn, Fe, and Mn but did not affect leaf Mg. Leaf Ca and K increased linearly with Ca fertilization, but applied Ca had an antagonistic influence on leaf Mg. Magnesium fertilization had a positive influence on leaf Mg but negatively affected leaf K, Ca, and Mn. Plant growth was negatively correlated with leaf Ca and leaf K, but had a positive correlation with leaf Mg and Mn. Nitrogen fertilization increased plant growth up to the mid‐level of applied N, but additional N reduced plant growth.  相似文献   

16.
Abstract

Leaf samples were collected from 24 pecan trees on three dates 1 month apart in June, July, and August. Soil samples were collected in June from each site at three depths: 0–6, 6–12, and 12–18 inches. Correlations between leaf analyses and soil test values were significant for Zn, Ca, Mg, and P. Values were not correlated for K. There was a high negative correlation for leaf Mn and soil pH. Means of leaf analysis values for the three sampling dates were not statistically different for any element. The data indicate that soil sampling should be a satisfactory means of determining fertility needs of pecan orchards, except for N.  相似文献   

17.
In separate tests, rabbiteye blueberries (Vaccinium ashei Reade) grown in sand culture were subjected to varying levels of Ca (0–81 mg/liter) and Mg (0–24 mg/liter) applied at rates of 250 ml/plant daily. Other essential nutrients were kept constant. Leaf concentrations of N, P, K, Mg, Ca, Mn, Fe, Cu, B, Zn, Co, and Al were determined. The concentration of Ca in the leaves increased linearly but that of Cu decreased in response to increasing levels of Ca fertilization. Leaf concentrations of other elements were not significantly influenced by Ca fertilization. Leaf Mg and Al concentrations increased linearly in response to increasing levels of Mg fertilization. The P content in leaves followed a quadratic curve with increased Mg fertilization. Percent P increased from the 0 to 12 mg/liter levels and then decreased from the 12 to 24 mg/liter levels of Mg. High levels of Mg fertilization resulted in reduced Cu content of leaves.

Fertilization rates of Ca or Mg had little effect on shoot dry weight except at the 0 mg/liter levels. As leaf Ca decreased below 0.20% Ca, Ca deficiency symptoms became more prevalent. Magnesium deficiency symptoms increased as leaf Mg decreased below 0.15% Mg.  相似文献   


18.
Diagnosis and Recommendation Integrated System (DRIS) approach was employed to monitor the nutrient status of cotton (Gossipium hirsutum) in southwestern districts of Punjab, North-West India. DRIS norms for macro, secondary and micro nutrients in cotton plant are developed. Considering these DRIS norms, the most limiting nutrient for cotton plant in the region is identified along with the order in which the other nutrients become limiting. The DRIS approach indicated that 11, 3, 8, 5, 2, 4, 2, 3, 6 and 2 percent of the total cotton leaf samples collected were low in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu), respectively. Leaf tissues of cotton plant were also found to contain high to excessive content of N, P, K, Ca, Mg, S, Fe, Mn Zn and Cu in 11, 7, 15, 19, 25, 18, 66, 33, 9 and 25 percent samples, respectively. DRIS derived sufficiency concentration ranges obtained from survey of cotton fields in this region were 2.22 to 5.20% N, 0.20 to 0.47% P, 1.05 to 2.14% K, 1.66 to 2.86% Ca, 0.34 to 0.57% Mg, 0.65 to 1.11% S, 106 to 172 mg kg?1 Fe, 35 to 68 mg kg?1 Mn, 18 to 33 mg kg?1 Zn, and 5 to 8 mg kg?1 Cu. The results elucidate that DRIS technique can be used for macro, secondary and micro nutrients indexing of cotton crop irrespective of its cultivar.  相似文献   

19.
ABSTRACT

To test the influence of avocado rootstocks on the scion leaf ionome, the nutritional status of avocado cultivars Hass and Ettinger grafted onto 15 rootstocks was compared over 3 years. The rootstocks were of different genetic origins (West Indian or Mexican) and were clonally or reproductively propagated. The trees were grown in a high-density orchard, and were continually fertigated as is common in modern avocado orchards. Leaf mineral composition was analysed and found to be correlated with crop load. ‘Hass’ leaves had significantly higher levels of B, Ca, Mg, Na, P and K than ‘Ettinger’ leaves. Rootstocks of Mexican origin produced higher foliar Cl levels, but lower levels of Mg and Mn. Rootstocks grown from seedlings conferred higher foliar K and lower B, Ca and Mg. The results demonstrate that avocado rootstocks affect the nutritional status of the tree, by a differential mineral transport, which is indicated by the scion leaf ionome.  相似文献   

20.
ABSTRACT

Citrus growing in humid, tropical India is concentrated in east to northeast India. The region is well known for large-scale commercial cultivation of Citrus reticulata Blanco, cultivar ‘Khasi,’ mandarin. Extensive surveys were conducted covering as many as 108 orchards from 52 locations representing eight states, namely West Bengal, Sikkim, Assam, Meghalaya, Tripura, Mizoram, Arunachal Pradesh, and Manipur. Expressed in milligrams per kilogram, the optimum values for available nutrients in soil were determined to be as: nitrogen (N) (220.8–240.6), phosphorus (P) (21.2–45.6), potassium (K) (252.2–300.8), calcium (Ca) (278.1–318.6), magnesium (Mg) (67.2–92.5), iron (Fe) (82.2–114.6), manganese (Mn) (21.4–32.8), copper (Cu) (0.82–2.62), and zinc (Zn) (2.18–4.22) using multivariate quadratic regression analysis. The corresponding leaf-nutrient values, expressed in percent, were: N (2.23–2.49), P (0.10–0.11), K (1.86–2.12), Ca (2.12–2.32), and Mg (0.28–0.38), and in ppm were Fe (148.2–179.8), Mn (72.2–84.8), Cu (10.4–18.6), and Zn (24.2–38.8). These reference values of soil and leaf analysis were later observed to be well within the range of values obtained for high-performance orchards (45–62 kg tree?1), confirming the hypothesis that soil fertility and leaf nutrient levels maintained under high yielding orchards could be used provisionally as nutrient diagnostics. Nutrient constraints in the form of N, P, Ca, Mg, Cu, and Zn were identified using these diagnostics, which deserve a place in a fertilizer program of mandarin orchards of the region to obtain sustainable optimum fruit yield.  相似文献   

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