Nitrogen and Potassium Fertilization Affect Apple Fruit Quality in Southern Brazil

Abstract

Nitrogen (N) and potassium (K) are usually found in higher concentrations than other macronutrients in apple (Malus x domestica Borkh) fruits and are most frequently associated with changes in fruit quality. The aim of this article was to evaluate the effects of N and K fertilization on some fruit quality attributes of Fuji apple. The experiment was conducted at São Joaquim, State of Santa Catarina, Brazil, during 2004 and 2005. A factorial design was used with N and K annual fertilizer rates (0, 50, 100, and 200 kg ha^?1 of N and K₂O) replicated in three orchards. Fifteen days prior to harvest, three fruit samples were collected from each treatment and site. One sample was used for total soluble solid content (TSS), titratable acidity, pulp firmness, and fruit color parameter analyses, and the other samples were refrigerated in a conventional atmosphere for 3 and 6 months for subsequent determination of fruit quality. Nitrogen fertilization negatively affected fruit color, flesh firmness, and TSS content. These same variables were positively affected by K fertilization, except for flesh firmness.     

Soil and plant calibration for cucumbers grown in the mid‐Atlantic coastal plain

Abstract

Few soil test and plant tissue calibration data exist for cucumbers (Cucumis sativus L.). Two years of a singly‐replicated cucumber fertility study were conducted to develop soil and plant data for calibration purposes employing the Boundary Line Approach. Fertility treatments consisting of 4 K levels (as KC1), 3 Mg levels (as MgCl₂), 3 pH levels (as Calcitic limestone), and 4 N rates (as urea ammonium nitrate) were factorilly arranged and completely randomized to give 108 treatments in both 1987 and 1988. Analyses were performed upon leaf samples for N, P, K, Ca and Mg at early bloom and soil samples for Mehlich (M) 1‐ and 3‐ P, K, Ca and Mg, and pH. Cucumber yields were determined on early (two fruit pickings) and total (four fruit pickings) sampling periods. High‐yielding cucumbers were attained at soil K (Ml = 64 mg/kg) and Mg (Ml = 29 mg/kg) levels lower than currently recommended. No significant differences in correlation coefficients between either Mehlich (Ml, M3) extractant and cucumber leaf P, K, Ca and Mg concentrations were found. Co‐efficients of determination (R²) values for the relationships (in 1987, 1988) between Ml‐ and M3‐extractable P (0.53, 0.40), K (0.77, 0.64), Ca (0.81, 0.71) and Mg (0.89, 0.74) were all highly significant (P ≤ 0.01). No significant differences were noted between early and total high‐yielding cucumber leaf concentrations and ratios developed for use as preliminary sufficiency ranges and DRIS norms, respectively. A reevaluation of cucumber coastal plain soil test calibrations, especially with regard to K, appears necessary. This study provides further support for the conversion of Ml to M3 soil extraction methodology.     

Season-Dependent Fruit Loading: Effect on Nutrient Homeostasis of Tomato Plants

ABSTRACT

Greenhouse tomato plants were grown hydroponically during the period of lower temperatures of winter (LT) versus the period of higher temperatures of summer (HT). In these plants, the effect of season on fruit load was dramatic. In order to study the alterations season introduces to the developmental allocation of nutrients within the various organs, concentrations of total nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined during each season at weekly intervals in the dry mass of leaves and roots and in the extract of upper, middle, and lower parts of the stem. The level of N/P ratio was always higher in the leaves than in the roots, and these differences were more intense during HT. The short-term changes of ratio in the leaves during HT and LT were positively related with the changes in temperature (r = 0.59 and 0.51 for HT and LT, respectively). In contrast, such correlations in the root were negative (r = ?0.54 and r = ?0.33 for HT and LT, respectively). The increase of temperature increased P uptake but not its translocation to upper plant parts. HT affected the translocation of N, K, Mg, and Ca more and their uptake less. Fruit load differentially affected the concentration of nutrients. In contrast to total N and K, Ca concentration in plant parts presented a positive relation with the increase of fruit load. Calcium and total N concentration (as opposed to P and micronutrient concentrations) were always higher in the leaves than in the roots. Under HT conditions, P was accumulated in roots in combination with high concentrations of Fe, Zn, and Mn. On the other hand, K and N were accumulated in the roots during the period of low temperature in winter. Calcium and K compared with other nutrients presented a pronounced tendency to be transported toward the top of the stem during HT, and their extractable concentration in the upper part of stem presented a significant increase during summer. Extractable K concentration was two to nine times higher than that of the other macronutrients. Our data suggest that the extractable concentration of nutrients of the stem is a good index for the diagnosis of the mineral nutritional status of the plant.     

Relationship of Leaf Macronutrient Concentrations in New Tomato Varieties to Fruit Yield

Abstract

This study was performed to evaluate the response of different newly established tomato (Lycopersicon esculentum Mill.) cultivars (Búfalo [control, a widely cultivated variety], Corindon, Dombelo, GC‐773, GC‐775, Nancy, Noa, Sarky, Yunque, Volcani, 617/83, and 2084/81), all cultivated under identical greenhouse conditions, in relation to the efficiency in macronutrient utilization to ascertain whether the genotype and the plant developmental stages affect the concentrations of nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), and sulfur (S) in leaves. The cultivar with greater foliar‐biomass production (Volcani) or greater concentration of nutrients as organic N (Noa, Yunque, 617/83) showed less marketable and more non‐commercial fruit production. The phenological phases of developing and ripening fruits significantly increased the concentration of P and reduced the concentration of all N forms and total K, as well as Na, Ca, Mg, and S forms in the leaves.     

Eggplant dry matter composition fruit yield and quality as affected by phosphate and total salinity caused by potassium fertilizers in the irrigation solution

Eggplant (Solanum melongena L.) grown under winter conditions in unheated polyethylene covered greenhouse displays unmarketable red color fruit skin. The purpose of this work was to study the effect of potassium (K), phosphate and total salinity levels in the irrigation solution on the quality of eggplant fruit grown at winter and spring seasons. Eggplant was grown in containers filled with basalt erupted tuff scoria. The fertigation solutions were composed of three levels of P: 18, 36, and 54 g P m^‐3, using mono K phosphate (MKP). Each level of P was applied on two levels of total K concentrations, 475 and 920 g K m^‐3 composed of K nitrate, MKP, and K chloride (KCl). The KNO₃ fertilizer was used in all treatments at 150 g N m^‐3. Increasing the KCl concentration increased the average electrical conductivity (EC) in the irrigation solution from 2.3 to 3.9 dS m^‐1, reduced class A fruit number and weight, but had no effect on the skin color. During the cold winter period the intensity of the skin color was weaker than in the normal hot growing period. Increasing the average phosphorus (P) concentration in the irrigation solution throughout the growing season from 36 to 54 g m^‐3 increased the number of fruit per plant, the number of class A fruits but has no significant effect on total fruit yield. Increasing the total electrical conductivity of the nutrient solutions by K fertilizers above 3.8 dS m^‐1 decreased fruit yield and total dry matter in the spring growth period.     

Fruit quality and partitioning of mineral elements in processing tomato in response to saline nutrients

A sand culture experiment was conducted to study the effect of saline water on the growth and fruit quality of processing tomato (Lycopersicon esculentum Mill.) Seedlings of five tomato cultivars were transplanted in quartz‐sand pots in a greenhouse at the Agricultural Experiment Station of Sultan Qaboos University. There were four saline nutrient solutions and a control consisting of half‐strength Hoagland solution. Salinity treatments were: 50 raM NaCl + 3 mM K₂SO₄ (EC 6.75), 50 mM NaCl + 1.5 mM orthophosphoric acid (EC = 7.18), 50 mM NaCl + 1.5 mM orthophosphoric acid + 3 mM R₂SO₄ (EC 7.29), and 50 mM NaCL (EC = 5.6). Treatments were applied daily commencing two weeks after transplanting. Data were collected on growth, and fruit yield and quality. Partitioning of mineral elements was determined in the vegetative tissue. The results obtained clearly show that concentrations of total soluble solids were increased in fruits treated with saline nutrients. Dry matter content of fruits exposed to salinity were higher than those from the control plants. Fruit acidity was increased with salinity, possibly due to a lower water content and increased organic acid accumulation. In the saline treatments, sodium (Na) content was decreased when potassium (K) was applied with NaCl but Na was higher in stems followed by root and leaf tissues. The partitioning of K followed a trend opposite to that for Na but with higher content in leaves. A similar situation was observed for calcium (Ca) and magnesium (Mg). Accumulation of phosphorus (P) was the lowest among all the ions. These results indicated that survival under saline conditions was accompanied by high ion accumulation. The study confirmed that saline nutrients are important for improving fruit quality of processing tomatoes.     

Concomitant biocontrol of pepper Phytophthora blight by soil indigenous arbuscular mycorrhizal fungi via upfront film-mulching with reductive fertilizer and tobacco waste

Purpose

Both reductive disinfestation and germicide can suppress Phytophthora blight, while soil arbuscular mycorrhizal (AM) fungi also have biocontrol effects on soilborne diseases. However, the combined effects of reductive disinfestation and botanical germicide [e.g., tobacco (Nicotiana tabacum L.) waste] on pepper (Capsicum annuum L.) Phytophthora blight and soil AM fungi are at present unclear. The purposes of this work were to develop application strategy for dealing with pepper Phytophthora blight, and to explore the concomitant contribution from soil indigenous AM fungi.

Materials and methods

A field experiment with four treatments was carried out in a pepper continuous planting field, including normal film-mulching with common fertilizer (control), normal film-mulching with reductive fertilizer (RF), upfront film-mulching with reductive fertilizer (UM+RF), and upfront film-mulching with reductive fertilizer and tobacco waste (UM+RF+TW). Phytophthora blight severity index, root mycorrhizal colonization rate, and the biomass and nutrient (N, P, and K) concentrations of shoots, roots, and fruits of pepper were measured. Soil pH, organic C, mineral N, available P, available K, acid phosphatase activity, and AM fungal abundance were also tested. The Pearson correlation analysis was carried out among plant and soil parameters.

Results and discussion

RF tended to increase pepper fruit yield compared with control, and UM+RF tended to decrease Phytophthora blight severity in relative to RF, while UM+RF+TW tended to decrease blight severity and increase fruit yield compared with UM+RF, and had a significantly (P?<?0.05) lower blight severity and a significantly higher fruit yield in comparison with control. UM+RF+TW also significantly decreased soil pH, and significantly increased AM fungal population and colonization, as well as soil acid phosphatase activity and available P concentration. In addition, UM+RF+TW had a significantly higher fruit K accumulation ratio, which negatively correlated with blight severity and positively correlated with fruit yield. However, fruit K accumulation ratio positively correlated with fruit P accumulation ratio, which was greatly elevated by the enhanced mycorrhizal colonization.

Conclusions

The coalition of reductive disinfestation (upfront film-mulching with reductive fertilizer) and tobacco waste had the greatest suppression of pepper Phytophthora blight, and the highest fruit yield and AM fungal population. It suggests that combined application of reductive disinfestation and botanical germicide has superposition in inhibiting Phytophthora blight and increasing fruit yield, and there seems to be a concomitant biocontrol by soil indigenous AM fungi which could enhance P and K transfer from plant to fruit.

     

Influence of mid‐summer boron sprays on boron content and quality indices of ‘delicious’ Apple 1

Boron (B) is required for optimal yield and quality of apple fruit (Malus domestica Borkh.) but may impair fruit quality if present in excessive amounts. A field experiment was conducted to examine the effects of a single mid‐July foliar B spray (0, 11.3, 22.6 g B/tree) on the B content and postharvest quality indices of 220‐gram ‘Starking Delicious’ apples. Fruit B concentration was positively related to B application rate and ranged from 9 to 55 mg/kg dry mass (1.3 to 7.7 mg/kg fresh mass). The relative B increases were greater in the core and inner cortex than in the outer cortex and skin, suggesting that some of the applied B entered the fruit through the tree vascular system. Increasing fruit B concentrations caused minor changes in fruit external color indices L and b and internal color index b but had no effect on firmness, soluble solids concentration, titratable acidity, starch index, external color index a, or internal color indices L and a. None of the effects were of horticultural significance. Most fruit quality indices were influenced by postharvest sampling time and reflected typical postharvest ripening patterns. The results suggest that ‘Delicious’ apple quality is relatively insensitive to high fruit B concentrations.     

Effect of Recent Genetic Improvement on Some Analytical Parameters of Tomato Fruit Quality

Abstract

Poor flavor in tomato fruit is a serious consumer concern. It could be said that tomato flavor has declined as variety selection and tomato production has placed emphasis on yield, fruit size, firmness, disease resistance, and processing performance and not on aspects of organoleptic fruit quality. Consumers frequently associate recent varieties with a lack of flavor, although such an association has not been proven. We have reviewed the scarce available literature on the influence of recent genetic improvement on quality attributes of tomato. As a case study, we have analyzed several parameters related to fruit quality in some traditional Spanish cultivars and commercial F1 hybrids of tomato. Organic acids and sugars were determined by high performance liquid chromatography (HPLC). Sodium (Na), potassium (P), and phosphorus (K) were analyzed by atomic absorption spectroscopy. Levels of respiration and ethylene production were measured, and fruit firmness was determined using a texture analyzer. All determinations were performed at two maturity stages, representing two frequent consumption stages. Differences between traditional cultivars and hybrids were found for respiration rates, ethylene production, P and K fruit contents. We also found important differences between “old” and “modern” cultivars for their organic acids profile. All cultivars showed similar levels of malic and succinic acids, but the modern hybrids showed a ～75% higher content of citric acid. This could be due to the F1 hybrids carrying chromosomal segments recently introgressed from wild Lycopersicon species. The influence of recent genetic improvement on quality attributes of tomato fruit is discussed.     

Response of apple and pear trees to nitrogen,phosphorus, and potassium fertilizers

Apple (Malus domestica, Borkh) and pear (Pyrus communis, L.) trees responded to nitrogen (N), phosphorus (P), and potassium (K) fertilizers. In low P soils, leaf, and fruit P concentrations were increased and yield was improved with moderate rates of mono‐ammonium phosphate (MAP) fertilizers. Improved fruit quality including fruit firmness, red fruit color of ‘Delicious’ apples, and a lower incidence of fruit disorders of apples (bitter pit) and pears (alfalfa greening and cork spot) was frequently associated with trees that were fertilized with calcium nitrate [Ca(NO₃)₂] (CN). Although yield was often improved in experiments containing N‐P‐K or MAP fertilizers, long‐term use of N‐P‐K or MAP could be associated with a higher incidence of fruit disorders and a lower soil pH than with CN fertilizer at equivalent rates of N.     

Effects of Arbuscular Mycorrhizal Fungi on Growth and Yield of Cucumber Plants

Abstract

In two pot experiments, cucumber (Cucumis sativus L. cv. Jinlu No. 3) seedlings were each inoculated with one of three arbuscular mycorrhizal fungi (AMF), Glomus mosseae, Glomus intraradices, or Glomus versiforme, or uninoculated. Seedling growth and weight of single fruit were investigated. The results indicated that growth of seedlings was significantly enhanced by G. mosseae, inhibited by G. versiforme, and not significantly influenced by G. intraradices. The dry weight of seedlings inoculated with G. mosseae was 1.2 times its counterparts. The concentrations of nitrogen (N) and phosphorus (P) in roots and magnesium (Mg), copper (Cu), and zinc (Zn) concentration in shoots were increased by inoculating the three AMF, and potassium (K) and iron (Fe) concentrations in shoots decreased significantly. The weights of single fruit of plants preinoculated with G. mosseae and G. versiforme were about 1.4 and 1.3 times higher than those from the uninoculated treatment, respectively.     

外源5-氨基乙酰丙酸对番茄成熟过程中果实品质和矿质元素含量的影响

5-氨基乙酰丙酸(ALA)为高等植物中叶绿素等卟啉类化合物的生物合成前体,在促进作物生长、增强抗逆性及提高产量方面发挥着重要作用。为探究ALA对番茄果实成熟过程中品质和矿质元素含量的影响,本研究以原味1号品种为试验材料,向绿熟期番茄果实表面涂抹不同浓度(0、50、100、200、300 mg·L^-1)ALA溶液,筛选出促进设施栽培番茄成熟及品质形成的最佳ALA施用浓度,并进一步研究其对设施番茄果实成熟过程中硬度、可溶性固形物以及矿质元素含量的影响。结果表明,外源ALA通过降低果实硬度促进了果实的成熟,并通过提高番茄果实中可溶性固形物含量提升了果实品质。另外,在坐果后40 d,200 mg·L^-1ALA处理的K、Ca和Fe元素含量分别比对照提高了21.82%、56.25%和12.86%,但P、Mg和Cu元素含量分别比对照降低了9.92%、21.74%和25.00%。相关性分析结果表明,可溶性固形物含量与K含量呈正相关关系,与Cu含量呈负相关关系;果实硬度与K含量呈负相关关系。成熟期番茄果实中P含量与Cu含量呈正相关,与Mn、K和Ca含量呈负相关...     

不同营养液浓度对温室盆栽黄瓜产量与品质的影响

营养液浓度与供液方式会影响温室黄瓜的产量与品质。本文通过盆栽试验,以山崎黄瓜专用营养液配方标准浓度1S为基准,研究了负水头供水控水盆栽装置供液条件下 1/2S、3/4S、1S、1S 4种营养液浓度以及常规浇灌1S（CK）营养液浓度对温室盆栽基质栽培黄瓜产量与品质的影响。结果表明, 地上部干重和产量与营养液浓度成显著正相关关系; 1S处理产量与地上部干重显著大于1S (CK)处理,但营养液生产效率差异不显著; 黄瓜整体品质随生育进程而提高,采收初期果实品质整体指标各处理差异较大,1S处理的较高; 采收中期1S与1S处理的较高,而采收末期各处理整体品质差异较小,1/2S与1S（CK）处理的相对较高; 其中1S（CK）处理各采收时期果实硝酸盐含量明显高于1S处理,而其它各指标两者无显著差异。负水头供水控水盆栽装置供液方式与1S营养液浓度处理是一种较好的供液方式与供液浓度。同时,适当提高黄瓜生育前期与降低生育末期营养液浓度能提高黄瓜的整体品质。     

Controlled-release fertilizer of zinc encapsulated by a manganese hollow core shell

Abstract

The distribution of azolla, its growth, and P-deficiency were studied in the Philippines by collecting 232 azolla samples from ponds (33%) and rice fields (67%: 40% with rice and 27% without rice) in 11 regions. The dominant species, coverage, color, healthiness, fertilizer treatment, and use by farmers were recorded. The N and P concentrations in azolla were expressed on an ash-free dry matter basis. The average N concentration was 4.5% and the median 4.5%. The average P concentration was 0.385% and the median 0.332%. Region, species, color, and visual judgment of healthiness were correlated with P concentration. Red Azolla pinnata var. imbricata samples had a lower average P content (n = 42, P = 0.245%) than green samples (n = 41, P = 0.46%). A. microphylla was always green and had significantly higher N and P concentrations than A. pinnata var. imbricata. Nitrogen and P contents were highly correlated (simple correlation coefficient = 0.64, ranking correlation coefficient = 0.73). As the content of P increased, the content of N was likely to approach a plateau. The N concentration at the plateau and the P concentration required to reach this plateau were higher in the A. microphylla-dominated samples than in A. pinnata var. imbricata-dominated samples. When the P concentration corresponding to 90% of the N% plateau was set as the critical concentration for P deficiency, 53% of azolla plants was considered to be P deficient. Soil samples were taken from 66 out of the total number of azolla sampling sites, and their chemical properties were analyzed. Average available soil P content of the soils, where the azolla samples were taken, was higher than the average for the Philippine soils. There was a distinct difference in the content of available soil P (Olsen P) between the soils where A. pinnata var. imbricata was dominant (n = 51) and those where A. microphylla was dominant (n = 8). The average content of available soil P of the former was 28 ppm and the median 12.5 ppm, whereas the average of the latter was 54 ppm and the median 47 ppm. No statistically significant differences were observed in other chemical properties. In soils where A. pinnata var. imbricata was dominant, the simple correlation coefficient between plant P concentration and soil available P content was 0.31 and the ranking correlation coefficient 0.34. The ranking correlation coefficient excluding samples from ponds was 0.54 (n = 42).     

Nitrogen Application Rate and the Concentration of Other Macronutrients in the Fruit and Leaves of Gold Kiwifruit

ABSTRACT

Gold kiwifruit (Actinidia chinensis Planch. var. chinensis ‘HORT16A’, marketed as ZESPRI?' ‘HORT16A’) is an important export crop for New Zealand. Nutrient management, including the application of nitrogen (N), for ‘HORT16A’ kiwifruit has mimicked strategies for the green (A. deliciosa ‘Hayward’) cultivar, however, physiological differences between Actinidia species necessitate the development of specific nutrient regimes for ‘HORT16A’ vines. In this trial, all nutrients, except N, were applied at levels comparable to commercial practice. The Control treatment received approximately 145 kg N ha/y, and was based on estimates of total N removed each year in the harvested fruit. The Zero-N treatment vines received all nutrients except N, and the High-N treatment received double the Control, approximately 295 kg N ha/y, for two consecutive seasons. The High-N treatment represents the upper limit of N application practices in commercial ‘HORT16A’ kiwifruit production. Zero-N fruit had higher calcium (Ca) and lower N concentration than High-N fruit in both seasons. Fruit potassium (K) and magnesium (Mg) concentrations were equivalent between these treatments in both seasons. Fruit phosphorus (P) concentration throughout the season was increased in the High-N treatment in both years. Fruit sizes were not different between treatments at final harvest in Year 1, being 130.5 ± 4.13 g, 125 ± 1.49 g, and 125 ± 3.29 g for the High, Control, and Zero-N vines, respectively. Larger fruit were harvested from the High-N vines (125 ± 4.69 g) in Year 2, than from either Control (113 ± 2.03 g) or Zero-N (118 ± 1.03 g) vines. Percent fruit dry matter (DM) content was higher in the Zero-N fruit (17.2 ± 0.06, 17.2 ± 0.06, and 16.8 ± 0.14 for Zero, Control, and High-N vines) at final harvest in Year 1. But values of fruit DM for all treatments were similar in Year 2 in spite of fruit size differences between treatments. Fruit DM for all treatments was slightly higher in Year 2 than in Year 1. Differences in fruit mineral concentration and fruit maturity at harvest may have contributed to increased incidence of low temperature breakdown (LTB) in the High-N fruit in Year 1. In Year 2, when fruit DM was higher in all treatments, yellow coloration was more developed. Total fruit N concentration was lower in Year 2 for all treatments than in Year 1, and LTB was minimal and not different between treatments.

Leaves from Zero-N vines had reduced N in both years compared with Control and High-N vines. In contrast, leaf Ca and Mg concentrations were reduced in High N-vines, compared with values recorded in Zero-N vines in both seasons. Leaf K concentrations were comparable between treatments in both seasons. Leaf sulfur (S) concentration was reduced under the High-N treatment, and leaf P levels were increased under the High-N treatment in both years.

These data demonstrate that N application influences the uptake and accumulation of other mineral elements in ‘HORT16A’ kiwifruit. In order to encourage desirable nutrient concentrations in both the fruit and leaves of ‘HORT16A’ kiwifruit, a reduction in N applied is suggested, and this would have little or no detrimental effect on vine performance over two seasons. Reduced N application will also reduce nitrate leaching which is estimated at 39 kg N ha/y under the Control treatment.     

Fruit growth,carbon allocation,and related enzymes in tomato under different irrigation and potassium application regimes

Background

The increasing concentration of atmospheric CO₂ not only affects the growing environment of crops but also aggravates the global greenhouse effect and further aggravates the problem of water shortage. The combined effect of water deficit and potassium (K) application has not been widely studied.

Aims

A pot experiment was conducted to investigate the effect of deficit irrigation (DI) and K application at different growth stages on carbon allocation and enzyme activities related to sugar metabolism.

Methods

Tomatoes were transplanted and planted on April 26, 2017 and harvested on August 15, 2017. Four irrigation regimes were implemented with two water levels (full irrigation-W and DI-W/2) in different growth stages, and each water treatment was equally divided into two subgroups: with K (K1) and without K (K0). Fruits from the first to fourth trusses of the tomato plants were sampled. Tomato growth, carbon allocation, and related enzyme activities were measured.

Results

The fresh weight (FW), dry weight, and relative growth rate of dry mass were sensitive to irrigation amount under K fertilization, enhancing the promotion effect of irrigation on fruit. Meanwhile, carbon allocation was sensitive to irrigation amount under K regime. Sucrose synthase (SuSy), acid invertase (AI), and sucrose phosphate synthase (SPS) were also highly sensitive to irrigation amount under K application condition. Starch phosphorylase displayed a quadratic parabola for irrigation amount, and adenosine diphosphate glucose pyrophosphorylase (AGPase) was highly sensitive to irrigation amount without K fertilization. Carbon in the form of other carbohydrates, carbon in the form of soluble sugar (Csol), and fruit water content were the factors that had the greatest influence on the principal components. Classification by K-means algorithm and canonical correlation analysis showed that FW, fructose, sucrose, and starch could be used as significant indicators of the dry matter components of the fruit for the treatment without K. In the case of K regime, SuSy, AGPase, AI, and Csol could be used as a significant indicator of the correlation analysis of carbon metabolism activity.

Conclusions

The factors related to the improvement of fruit quality and carbon allocation by deficient irrigation and K application were explored. Water stress changed the distribution of photosynthetic carbon between starch and soluble sugar. K application further changed the balance between soluble sugars and other compounds. In particular, it significantly increased the carbon content of soluble sugars and decreased that of other compounds. AI and SuSy are key enzymes affecting carbon metabolism under water-deficient conditions.     

Influence of Foliar and Ground Fertilization on Yield,Fruit Quality,and Soil,Leaf, and Fruit Mineral Nutrients in Apple

ABSTRACT

The effectiveness of nitrogen (N)+ zinc (Zn) soil and foliar fertilizer applications on growth, yield, and quality of apple (Malus domestic Borkh ‘Golden Delicious’) fruit was studied in the Zanjan province, Iran. There were eight treatments 1) control (no fertilizer), 2) soil applied N, 3) soil applied Zn, 4) soil applied N+Zn, 5) foliar applied N, 6) foliar applied Zn, 7) foliar applied N+Zn and 8) combined soil and foliar applied N+Zn. The N source was urea [CO(NH₂)₂, 46% N] applied at 276 N tree^{? 1} yr^?1 and the Zn source was zinc sulfate (ZnSO₄,7H₂0, 23% Zn) applied at 110 g Zn tree^{? 1} yr^{? 1}. The soil treatments of N and Zn, were applied every two weeks during June through August (total of 6 times/year) in a 1 m radius around the tree trunk (drip line of trees). The foliar solutions of N (10 g l^{? 1} urea) and Zn [8 g l^{? 1} zinc sulfate (ZnSO₄)] were sprayed at the rate of 10 L tree^{? 1} every two weeks at the same times as described for soil applications. The highest yield (49 kg tree^{? 1}), and the heaviest fruits (202 g) were obtained in the soil and foliar combination of N+Zn treatment. The lowest yield (35 kg tree^{? 1}), and the smallest fruits (175 g) were recorded in the control. Nitrogen, and to a lesser extent Zn, foliar application resulted in decreasing fruit quality (caused russeting, and lower soluble solid), but increasing N leaf and fruit concentrations (2.4% DW and 563 mg kg^{? 1}, respectively). There were significant differences among yield and leaf mineral nutrient concentration in different treatments. But there was no significant difference between fruit mineral nutrient concentration (except N). Ratio of N/calcium (Ca), potassium (K)/Ca, and [magnesium (Mg)+K]/Ca in fruits were found suitable for fruit quality prediction. Combining the zinc sulfate with urea in the foliar applications increased the concentration of Zn from 0.7 to 1.5 mg per kg of apple tissue. Leaf N concentration varied during growth season. Foliar applied nutrient can be more efficient than soil applied, but a combination of soil and foliar applications is recommended for apple tree nutrient management.     

Calcium,magnesium, and potassium uptake by crested wheatgrass grown on calcareous soils

Abstract

Forage intake with potassium/(calcium + magnesium) [K/(Mg + Ca)] values in excess of 2.2 are associated with grass tetany and Mg deficiencies in ruminants. This study was conducted to determine the degree to which forage K and Mg concentrations and K/(Ca + Mg) ratios could be predicted from soil bicarbonate (HCO₃) extractable phosphate‐phosphorus (PO₄‐P), and saturation extract Ca, Mg, K, sodium (Na), and nitrate‐nitrogen (NO₃‐N) concentrations. Crested wheatgrass (Agropyron spp) strains and cultivars representing four ploidy levels were grown in the greenhouse on eight calcareous soils with different saturation extract Ca, Mg, K and K/Mg ratios. The plants were harvested three times. Soil solution K/(Ca + Mg) and K/Mg ratios were the only measured soil parameters that showed a consistent correlation with plant K/(Ca + Mg) ratios. Bicarbonate extractable soil P was positively related to plant P and K uptake in the first harvest, but was not related in the second and third harvests nor was soil P related to plant Ca or Mg content. There was a tendency for the higher ploidy level entries to have higher plant K/(Ca + Mg) ratios. It was concluded that soil K/(Ca + Mg) ratios can be used to predict relative forage K/(Ca + Mg) ratios for grasses grown under similar conditions.     

Effects of rootstock and thinning on yield,fruit quality and elemental composition of ‘Redspur Delicious’ apple

Abstract

Influence of two rootstocks and five levels of hand thinning (fruit spacing) on yield, fruit quality at harvest and after storage, and leaf and fruit elemental composition of ‘Redspur Delicious’ apple (Malus domestica Borkh.) were studied. Trees on M.7 rootstock had a higher yield with heavier and firmer fruit at harvest than those on M.26. Trees on M.7 had significantly lower leaf and fruit N which resulted in a darker fruit color than those on M.26 rootstock. Fruit from trees on M.26 had a higher soluble solids concentration (SSC) at harvest than those on M.7. Leaf and fruit potassium (K) increased but fruit calcium (Ca) decreased with an increase in fruit spacing. Thinning fruit to 10 cm or 18 cm spacing, depending on market demand for fruit size, is recommended for improvement of fruit quality. Fruit weight and quality was improved with 18 cm fruit spacing without a significant decrease in yield, while thinning fruit further than 18 cm apart reduced yield without a significant change in the fruit weight or quality.     

Relationship between phosphorus sorption indexes and plant response in a greenhouse experiment

Abstract

Twenty six phosphorus (P) sorption indexes were utilized as complement measurements of P fertility diagnosis on sixteen soils from Sandy Pampa and Ondulating Pampa. Adsorption values behaved as non‐availability indexes and were negatively correlated with P absorption by plants. The best parameters were P‐25–2hrs: adsorbed P with 25 μg P added, equilibrium period: 2 hrs (r = ‐0.89**); BC: buffer capacity (r = 0.86**); P‐1550: adsorbed P with 1550 (μg P added (r = ‐0.80* in Ondulating Pampa). Intensity or desorption related positively with plant P (r = 0.69**).

When applying P fertilization in a greenhouse trial, absorbed P, dry matter, and foliar area showed a positive correlation with adsorption indexes and a negative one with desorption indexes.