Salinity tolerance in tomato: Implications of potassium,calcium, and phosphorus

Abstract

The effect of salinity on the growth and yield of tomato plants and mineral composition of tomato leaves was studied. Five tomato (Lycopersicon esculentum Mill) cultivars, Pearson, Strain B, Montecarlo, Tropic, and Marikit, were grown in sand nutrient culture. The nutrient solutions applied consisted of a modified half‐strength Hoagland solution with 50 mM sodium chloride (NaCl), 3 mM potassium sulphate (K₂SO₄), 1.5 mM orthophosphoric acid (H₃PO₄), and 10 mM calcium sulphate (CaSO₄). Stem height and number of leaves of tomato plants were not found to be significantly different but leaf and stem dry weight were reduced significantly in plants irrigated with saline nutrient solution in contrast with control plants. The total yield was reduced in plants that received saline treatments, but there was no significant difference in fruit number and fruit set percentage. The fruit electrical conductivity and total soluble solids were increased in plants irrigated with saline nutrient solution. Fruit pH was not found to be significantly different among salinity treatments. Mineral composition of tomato leaves were increased by addition of potassium (K), phosphorus (P), and calcium (Ca) to the saline nutrient solution. The addition of K to the solution resulted in an increase in sodium (Na) leaf content. The amounts of K and magnesium (Mg) were not significantly different among salinity treatments. Calcium content was increased when CaSO₄ was added. Application of H₃PO₄ resulted in the highest amount of P in tomato leaves under saline conditions. The present study revealed that application of K, P, and Ca under saline conditions improved fruit electrical conductivity and total soluble solids. Sufficiency levels of the mineral nutrients K and P were obtained in tomato leaves when the appropriate nutrient was used in the saline solution.     

Effects of saline nutrient solutions on the growth and accumulation of mineral elements in some tomato cultivars

Abstract

Tomato cultivars were grown in a saline nutrient culture system to investigate growth and fruiting responses in relation to the application of 3 mM potassium (K), 1.5 mM phosphorus (P), and 10 mM calcium (Ca). The deleterious effects of salinity on tomato stem growth and fruit yield were ameliorated following the addition of K, P, and Ca to the nutrient solution. Potassium levels in tomato leaves were increased 4‐fold compared to control plants in the presence of applied K. The use of K resulted in an increase in Na content, however, a comparatively low level of sodium (Na) was obtained in treatments receiving K, Ca, and P. Calcium content was greater than sufficiency levels in all treatments, whereas magnesium (Mg) declined with the increase in salinity. The amount of P in tomato leaves was increased 4–5 fold when the nutrient solution was supplemented with 1.5 mM P. Correlation of vegetative parameters, such as stem height and leaf growth to salinity, revealed no significant responses, however commercial parameters such as total soluble solids and fruit weight correlated significantly with the saline nutrient treatments.     

The effects of silicon on nutrient levels and yields of tomatoes under saline stress in artificial medium culture

The purpose of this study was to determine the effects of silicon on the stem + leaf dry weight, fruit yield, quality and nutrient levels of tomatoes, cultured under saline stress on an artificial medium. Silicon doses (0, 0.5, 1.0, 2.0 mM) were combined in nutrient solution with 0, 44.4 and 70.4 mM NaCl in a factorial experiment with three replications. All silicon concentrations without NaCl increased stem + leaf dry weight and 1.0 mM Si increased fruit yield. Silicon increased fruit yield at 44.4 mM NaCl and steam + leaf dry weight at high NaCl concentrations. NaCl significantly increased the level of soluble solids in fruit and decreased the pH of fruit juice. Silicon significantly increased the pH of the tomato juice and decreased the number of fruits at high concentrations of NaCl. The effects of NaCl, Si and their interaction on nutrient contents and Si levels in leaves were statistically significant at different concentrations.     

Enhancement of salinity tolerance in tomato: Implications of potassium and calcium in flowering and yield

Abstract

Five tomato (Lycopersicon esculentum Mill) cultivars were grown in sand nutrient culture experiment in a greenhouse to investigate the effects of salinity on growth and yield. Nutrient solutions were made saline with 50 mM NaCl (EC = 5.5 mS/cm or supplemented with 2 mM KNO₃ (EC = 6.8), 20 mM Ca(NO₃)₂ (EC = 7.5), and combination of potassium (K) and calcium (Ca) (EC = 8.0). Seedlings were irrigated with saline treatments commencing two weeks after transplanting. Determination of sodium (Na) and K in tomato leaves and fruits were by flame photometry. Accumulation of Na in tomato fruits was higher than in leaves under control or saline conditions for all tomato cultivars. The amount of K in the tomato leaves was higher in control than in saline‐grown plants. Addition of K and Ca to the nutrient solution resulted in a 3 to 7 fold increase in K accumulation in all cultivars tested. Stem and leaf growth were significantly reduced with salinity but growth was enhanced following irrigation when K was added to the nutrient solution. Flowering and fruit set were adversely affected by NaCl stress. Reduction of flower number was 44% relative to the control plants. Fresh fruit yield decreased by 78% when plants received 50 mM NaCl. Growth and development of tomatoes under saline conditions was enhanced in this study following the application of K to the saline nutrient solution. Amelioration in growth was also achieved when Ca was used but to a lesser extent. Our results suggest that ion accumulation and regulation of K and Ca contribute to salt tolerance and growth enhancement.     

Effects of Antitranspirant Spray and Potassium: Calcium: Magnesium Ratio on Photosynthesis,Nutrient and Water Uptake,Growth, and Yield of Sweet Pepper

Sweet pepper plants (Capsicum annuum L.) were cultivated hydroponically under different nutrient cation ratios at both high potassium (K)/calcium (Ca) (12:2) or magnesium (Mg)/Ca (4:2) ratios, compared with half strength Hoagland's solution (K:Ca:Mg; 3.5:2:0.5). Additionally, antitranspirant (Pinolene) was sprayed every fortnight to the aerial part of the plant at 1% (v/v). The antitranspirant (AT) did not affect dry weight accumulation in the leaves, stems, roots, total plant leaf area, or leaf dry weight percentage. Net carbon dioxide (CO₂) assimilation was not impaired by the AT but the water uptake was reduced significantly independent of the nutrient solution used. The AT did not affect the cation uptake but high Mg significantly reduced Ca concentration in leaves, stems, and fruits, whilst high K had an effect only in old leaves and fruits. The AT reduced fructose and glucose concentration in the leaves but no effect was found in the fruits. Fruit yield was not affected by AT, but it was increased when plants were grown with high Mg/Ca. The percentage of blossom-end rot was reduced with the AT, whilst it was increased with the solutions having high K/Ca or high Mg/Ca. The AT significantly reduced fruit firmness in high Mg/Ca and control solution but no effect was found for fruit color, shape index, total soluble solids, or pericarp thickness.     

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.     

Fruit nutrient accumulation of four orange varieties during fruit development 1

Evaluation of nutrient accumulation trends in fruit during fruit development and nutrient status in the leaves are important components defining nutrient requirements. Such nutrient demand should be met by nutrient supply in order to develop optimal rate and timing of fertilizer application. In a 3‐year study the citrus (orange) varieties, ‘Valencia’, ‘Parson Brown’, ‘Hamlin’, and ‘Sunburst’ were fertilized with either 168, 224, or 280 kg N ha^‐1 yr^‐1 as a broadcast application of N:P:K dry soluble granular fertilizer. These rates did not significantly affect the fruit nutrient status, juice quality, or nutrients concentrations in the spring flush. The concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the fruit decreased with their enlargement during June through November. However, micronutrient concentrations in the fruits increased from June through August or September and then decreased. Fruit dry weight was greatest in ‘Valencia’ followed by ‘Hamlin’, ‘Parson Brown’, and ‘Sunburst’ varieties. Soluble solids concentration (SSC) were higher in ‘Valencia’ and ‘Sunburst’ fruit than in the other two varieties. Other juice quality parameters were not significantly different among the varieties. This study indicated non‐significant influence of fertilizer rates on concentrations of various mineral elements in 6‐month‐old spring flush with most of those concentrations within the optimal ranges.     

Changes of Growth,Amino Acids,and Ionic Composition in Strawberry Plants under Salt Stress Conditions

Seedlings of two strawberry cultivars ‘Camarosa’ and ‘Chandler’ were grown using perlite in a greenhouse for 20 days, and then plants were watered with nutrient solution containing 0, 8.5, 17.0, and 34.0 mM sodium chloride (NaCl) for 6 months. Sodium chloride treatments generally reduced the leaf and root dry weight. Relative water content (RWC) of leaves was maintained despite the increased salt concentrations while loss of turgidity was increased by sodium chloride (NaCl) treatments in both cultivars. As the most variable amino acids, aspartic acid, glutamic acid, arginine, proline, serine, and alanine were determined under salt stress in plants. Sodium chloride treatments generally increased sodium (Na) and chloride (Cl) contents in all plant parts. The plants were able to maintain high potassium (K) levels in the aerial parts with the 8.5 mM NaCl treatment. It can be concluded that ‘Camarosa’ has the ability to osmotic regulation. ‘Chandler’ also tolerates the salt injury at low salt concentrations.     

Relationships between leaf and fruit minerals and fruit quality attributes of apples grown under northern conditions

Field experiments were conducted during 1994–1995 in seven apple (Malus spp.) orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Transparente Blanche’, ‘Samo’, ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Åkerö’, ‘Aroma’, and ‘Lobo’. Leaf samples from branches bearing fruits (BF) and not‐bearing fruits (BNF) were collected two times during the growing seasons. Fruit samples were picked about one week before commercial maturity. Macronutrient concentrations in fruits and leaves, fruit diameter and juice pH, titratable acidity (TA) and soluble solids concentrations (SSC) were determined. Leaf nitrogen (N), phosphorus (P), and potassium (K) were higher, but calcium (Ca) and magnesium (Mg) were lower in BNF. Branch types (BF and BNF) were closely related in leaf N, P, and Ca, but not in leaf K and Mg at the first sampling time. Fruit N, P, K, and Mg were closely related to each other but not to fruit Ca. Mean fruit N and Ca and leaf P and Mg were low compared with the recommended levels. Relationships between fruit and leaf nutrient concentrations were found only in P and Mg. Fruit diameter increased and juice SSC decreased with increasing leaf N concentration. Fruit P declined with increasing fruit diameter and juice TA increased and SSC/TA decreased with increasing leaf P and Ca concentrations.     

Effects of chromium on the nutrient element content and morphology of tomato

An hydroponic experiment was conducted to study the effects of chromium (Cr³⁺) on the distribution of nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), and Cr in the plant, and the growth and yield of a tomato plant. Three Cr treatments were established (0, 50, and 100 mg Cr/L in a nutrient solution). In general, the nutrient element concentration in stems and branches was significantly affected by the Cr treatments. Chromium accumulated preferentially in the roots and low transport was detected to the aerial parts. Growth was diminished due to Cr presence in the nutrient solution. Total yield was not affected, however the number of fruits was diminished and the mean fresh weight of fuit increased with each increment of Cr in the nutrient solution. Chromium was not detected in the edible part (fruit) of the plant.     

Barley response to salt stress at varied levels of phosphorus

Increasing plant phosphorus (P) supply can increase or decrease salt tolerance of many plants. Barley (Hordeum vulgare L., cv. ACSAD 176) was grown in nutrient solution under controlled conditions to determine effects of P level on detrimental effects of sodium chloride (NaCl). Increasing level of P improved tolerance of barley to NaCl. At 3, 30, and 60 μM P, the NaCl concentrations to reduce shoot dry matter (DM) by 50% were 158, 193, and 260 mM, respectively. Increased NaCl levels reduced shoot P concentrations. Plants grown with NaCl had higher Internal P requirements. When NaCl in solution was 10, 150, and 300 mM, the corresponding concentrations of P in shoots required to obtain 50% DM were 1.6, 4.2, and 4.7 mg‐g^‐1 dry weight, respectively. Increasing solution P level from 3 to 60 μM P decreased sodium (Na) and increased potassium (K) concentrations in shoots. Accumulation of mineral ions for osmotic adjustment and restriction of Na accumulation in shoots was involved in P enhancement of salt tolerance of barley.     

Effect of top-dressed potassium fertilization on the yield and quality of cucumber

The current study aimed to evaluate the effect of top-dressed potassium (K) application on the production of hybrid cucumber “Sapphire.” The experimental design was a randomized complete block, with five blocks of 0.80 × 0.40 m² each and eight replicate plants per block. The five fertilization rates of K used were 0, 45, 90, 135, and 180 kg K₂O ha^?1. Data collection consisted of the estimation of fruit diameter, fruits length, fruit fresh and dry weights, the number of fruits per plant, and the weight of fruits per plant. The number of fruits per hectare and the fruit fresh weight per hectare were calculated. Fruit tissue was analyzed for determination of macronutrient concentrations, pH, titratable acidity, soluble solids, sugar contents, and protein content. The data were statistically analyzed using regression analysis and analysis of variance (ANOVA). There was a significant effect of the fertilization rate of K on fruit diameter, fruit fresh and dry weights, macronutrients concentrations in fruits, titratable acidity, soluble solids, and reducing sugars. A quadratic equation was adjusted for the number of fruits per plant and per hectare; fruit yield per plant and per hectare, with maximum top-dressing doses, was estimated to be between 60 and 95 kg K₂O ha^?1. A linear increase was obtained in the pH. An increase in the K fertilization rate caused a linear decrease in the fruit length.     

INFLUENCE OF SODIUM CHLORIDE AND CALCIUM FOLIAR SPRAY ON HYDROPONICALLY GROWN PARSLEY IN NUTRIENT FILM TECHNIQUE SYSTEM

The effects of salinity [30 or 90 mM sodium chloride (NaCl)] and calcium (Ca) foliar application on plant growth were investigated in hydroponically-grown parsley (Petroselinum crispum Mill). Increasing salinity reduced fresh weight and leaf number. Calcium alleviated the negative impacts of 30 mM NaCl on plant biomass and leaf fresh weight but not in case of 90 mM. Plant height, leaf and root dry weight and root length did not differ among treatments. Total phenols increased with calcium application, chlorophyll b reduced by salinity, while total carotenoids increased with salinity and/or Ca application. Salinity reduced nutrient uptake [nitrate (NO₃), potassium (K), phosphorus (P) and Ca] and elemental content in leaves and roots. Calcium application reduced P but increased Ca content in plant tissues. Increments of Na uptake in nutrient solution resulted in higher Na content in leaves and roots regardless Ca application. These findings suggest that calcium treatment may alleviate the negative impacts of salinity.     

GENOTYPIC VARIATIONS IN POTASSIUM UPTAKE AND UTILIZATION IN COTTON

Genotypic differences in potassium (K) uptake and utilization were compared for eight cotton cultivars in growth chamber and field experiments. Four of the cultivars (‘SGK3’, ‘SCRC18’, ‘SCRC21’ and ‘SCRC22’) typically produce lower dry mass and the other four (‘Nannong8’, ‘Xiangza2’, ‘Xinluzao12’ and ‘Xiangza3’) produce greater dry mass in K-deficient solution (0.02 mM). The mean dry weight of seedlings (five-leaf stage) of cultivars with greater biomass was 155% higher than that of cultivars with lower biomass yield under K deficiency. However, all the genotypes had similar dry matter yields in K-sufficient solution (2.5 mM). Thus, the four cultivars with superior biomass yield under low K medium may be described as K efficient cultivars while the inferior cultivars may be described as K inefficient. Although seeds of the studied cultivars originated from different research institutes or seed companies, there were little differences in seed K content among them, irrespective of their K efficiency. Consequently, there were no significant differences in K accumulation in seedlings (4 d after germination in a K-free sand medium) just before transferring to nutrient solutions. However, the K efficient genotypes, on average, accumulated twice as much K at 21 d after transferring to K-deficient solution (0.02 mM). A much larger root system as well as a slightly higher uptake rate (K uptake per unit of root dry weight) may have contributed to the higher net K uptake by the K efficient cultivars. In addition, the K efficiency ratio (dry mass produced per unit of K accumulated) and K utilization efficiency (dry mass produced per unit of K concentration) of the K efficient cultivars exceeded those of the K inefficient genotypes by 29% and 234%, respectively, under K deficiency. On average, the K efficient cultivars produced 59% more potential economic yield (dry weight of all reproductive organs) under field conditions even with available soil K at obviously deficient level (60 mg kg^?1). We noted especially that the four K inefficient cultivars studied were all transgenic insect-resistant cotton, suggesting that the introduction of foreign genes (Bt and CpTI) may affect the K use efficiency of cotton.     

Effect of N rate and split application on bahiagrass production

Abstract

Vegetative and reproductive growth were studied in five tomato (Lycopersicon esculentum Mill) cultivars under saline conditions imposed at the five‐leaf stage by addition of 50 mM NaCl to half strength Hoagland nutrient solution. The plants were raised in pots filled with washed quartz sand kept in a greenhouse. Stem height and number of leaves in tomato plants were significantly reduced when irrigated with saline regimes in contrast with control plants that received only the Hoagland solution. The highest number of flowers were obtained in the cultivar Pearson and the least in cultivar Strain B. Fruit set and yield were little affected by varietal differences and were not related to vegetative growth. Fruit weight was suppressed with NaCl stress, but improvement in weight was achieved when potassium (K) and calcium (Ca) were added to the saline water. The most detrimental effect of NaCl stress was the reduction of biomass yield in tomatoes. However, the relative dry weights of Pearson and Monte Carlo were increased to 60% and 54%, respectively, when NaCl was supplemented with Ca. Large varietal differences in biomass occurred among the NaCl‐treated and control plants. Tomato fruit quality (TSS) was improved by salinization.     

GROWTH,NUTRIENT ACQUISITION,AND PHYSIOLOGICAL RESPONSES OF HYDROPONIC GROWN TOMATO TO SODIUM CHLORIDE SALT INDUCED STRESS

□ Growth and nutrient acquisition of tomato (Lycopersicon esculentum L.) cv ‘Amani’ were studied under induced salt stress in Hoagland's solution. The plants were treated for 37 days with salinity induced by incorporating different concentrations [0.0 (control), 50, 100, 150, or 200 mM] of sodium chloride (NaCl) to the nutrient solution. Slight reduction was obtained in growth represented by (shoot length and number, leaf number, and dry weight) when seedlings were directly exposed to NaCl stress from 0.0 to 100 mM. At higher concentrations (150 or 200 mM), growth parameters were adversely affected and seedlings died thereafter. Elevated salinity significantly reduced crude protein and fiber in shoots and roots. Tomato shoot and root contents of potassium (K), iron (Fe), and ash were reduced significantly in response to increased levels of salinity. Tissue contents of sodium (Na) and chloride (Cl) increased with elevated salinity treatments.     

Salt tolerance evaluation of nine indigenous Greek olive cultivars

The present work was aimed to evaluate nine Greek olive (Olea europaea L.) cultivars for tolerance to sodium chloride (NaCl) salinity, most of which have never been evaluated or considered to be extinct, in order to be used in the future as olive rootstocks in areas with salt toxicity problems.One-year old, self-rooted trees of the cultivars ‘Aetonicholia Kynourias,’ ‘Arvanitolia Serron,’ ‘Ntopia Atsicholou,’ ‘Koroneiki,’ ‘Lefkolia Serron,’ ‘Ntopia Pierias,’ ‘Petrolia Serron,’ ‘Smertolia,’ and ‘Chrysophylli’ were subjected to 0, 50, 100, and 200 mM NaCl, for six months, in nutrient solution pot experiment. The experiment was conducted as a completely randomized factorial design with four replications (of one tree), with the factors being the cultivar (nine levels) and the salt concentration (four levels). According to plant growth parameter results, ‘Arvanitolia Serron’ followed by ‘Lefkolia Serron’ were found to be the most salt tolerant cultivars to growth reduction. The same cultivars accumulated less sodium (Na) and chlorine (Cl) in the leaves by retaining more ions in the roots. Moreover, ‘Arvanitolia Serron’ was able to maintain high potassium (K) levels and K/Na ratio in younger leaves under salinity.     

Effects of Sodium and Potassium Application on Water Content and Yield of Tomato in Southwestern Nigeria

The effects of sodium (Na) and potassium (K) application on tomato (Lycopersicon esculentum (L.) Mill) were studied in soil culture. The study was a 4 × 4 factorial, arranged into a randomized complete block design (RCBD) and replicated four times. Sodium was applied at 0, 5, 10, and 20 mg Na/kg soil as NaCl and K as KCl at 0, 20, 40, and 80 mg K/kg soil. Records of dry matter yields, water content, mineral nutrient, and number of fruits were taken. The application of 10 to 20 mg Na/kg soil and 80 mg K/kg soil depressed the water contents and the fruit yield. The application of 5 mg Na/kg soil and 40 mg K/kg soil produced the highest number of fruits, indicating a Na and K ratio of 1:8. A Na: K ratio of 0.45 up to 0.60 and 1.44 up to 1.80 for shoot and root, respectively, maintained good shoot water balance, resulted in lower floral abortion, and markedly enhanced the fruit yield. A complimentary relationship between Na and K was observed at Na: K ratios between 1:4 and 1:8.     

Different K:Ca ratios affected fruit color and quality of strawberry ‘Selva’ in soilless system

High quality fruit production is the cornerstone of marketability. Optimum plant performance depends on the balanced and timely availability of mineral nutrients. In addition to element concentrations, the ratio of nutrient elements in solution plays a determinative role in growth, productivity, quality, and nutrients uptake. In this experiment, the effects of different Potassium:Calcium (K:Ca) ratios (1.6, 1.4, 1.2, 1, 0.85, and 0.6) in nutrient solution were studied on quality attributes of strawberry ‘Selva’. The highest and lowest leaf number and leaf area were observed in K:Ca 1.4 and 1, respectively. The highest fruit pH, electrical conductivity, total soluble solids/titratable acidity ratio, vitamin C content, ellagic acid, and color were resulted in K:Ca (1.4) ratio. K:Ca (1.6) ratio produced the highest content of protein. Moreover, K:Ca (0.85) ratio was the most effective treatment on fruit firmness. The increased quality attributes were observed in high K:Ca ratios, hence low K:Ca ratio resulted in increased fruit firmness. In conclusion, nutrient solution containing K:Ca ratios between 1 and 1.6 were suitable for producing strawberry ‘Selva’. Taken together, K:Ca (1.4) was an appropriate ratio for producing strawberry ‘Selva’ in soilless culture with coconut fiber: perlite medium.     

Potassium Chloride Enhances Fruit Appearance and Improves Quality of Fertigated Greenhouse Tomato as Compared to Potassium Nitrate

Abstract

The effects of potassium chloride (KCl) as a potassium (K) source in fertigation solution on growth, yield and quality of tomato (cv. Durinta) in a controlled greenhouse were compared with potassium nitrate (KNO₃)—the conventional K source for vegetable fertigation. The treatments consisted of four levels of KCl: (1) 0% KCl (100% KNO₃), (2) 40% KCl (40% KCl and 60% KNO₃), (3) 60% KCl (60% KCl and 40% KNO₃), and (4) 100% KCl (0% KNO₃) in fertigation solution in the season 1999–2000. In 2000–2001, early (12 days after planting) and late (47 days after planting) applications of 100% KCl and 0% KCl were tested. The concentrations of K and other major nutrients were similar in all the treatments. Ammonium nitrate (NH₄NO₃), calcium nitrate [Ca(NO₃)₂] and nitric acid (HNO₃) were used as nitrogen (N) sources in KCl treatments. Electrical conductivity (EC) of all solutions ranged from 1.8 to 2.1 dS m^?1; pH range was from 6.6 to 7.1. Perlite was used as a neutral growing medium. Plant height, time to anthesis, time to harvest, and leaf nutrient content were monitored. Total yield, average fruit weight and number, and fruit size were measured after harvest. The appearance and quality of the fruits were rated following cold storage simulation for export conditions. None of the plants showed chloride (Cl) toxicity symptoms. No significant differences in yield components and plant growth were recorded among the treatments. Fruit dry matter, total soluble solids (TSS), glucose, titrable acidity (TA), pH, and EC of juice after simulation storage were not affected by the K source. Interestingly, fruit firmness, and freshness of calyx were significantly improved, while the number of rotten and blotchy fruits was significantly decreased in KCl treatments. The fruit nitrate (NO₃) content was decreased whereas iron (Fe) content was significantly increased in KCl treatments. The results show that KCl can be used as a substitute for KNO₃ without detrimental effects on plant development and yield, while significantly improving some important quality parameters. It is concluded that KNO₃ can be replaced fully or partially (depending on water quality) by KCl in tomato production while improving the quality of fruits.