Leaf Calcium Content Research Articles

Nano-Biochar Suspension Mediated Alterations in Growth, Physio-Biochemical Activities and Nutrient Content in Wheat (Triticum aestivum L.) at the Vegetative Stage.

Nano-biochar is a source of blackish carbonaceous material, a prerequisite for sustainable crop productivity. By using a variety of feedstock materials, nanobiochar synthesis can be employed via pyrolysis. Therefore, a project was initiated to explore the morpho-physio-biochemical alteration at the vegetative stage of wheat crops after the foliar application of nanobiochar suspension (NBS). This investigation was conducted at the Botanical Research Area of the University of Lahore in a randomized complete block design (RCBD) arrangement, with four treatments (0, 1, 3, and 5% NBS) by maintaining three replications for each treatment using the wheat variety "Zincol". Nano biochar suspension in above mentioned concentrations were foliarly applied at the end of tillering/beginning of leaf sheath elongation of wheat seedlings to assess the morphological changes (root length, shoot length, number of leaves, fresh biomass/plant, dry biomass/plant), physio-biochemical alterations (total free amino acids, total sugars, chlorophyll content, protein, phenols, flavonoids), and nutrient uptake (Na, K, Ca, Mg, N, P contents. Our findings indicate that the foliar application of 3% NBS yielded the most favorable results across all measured attributes. Furthermore, Treatment-4 (5% NBS) specifically improved certain traits, including leaf area, total soluble proteins, and leaf calcium content. Finally, all NBS resulted in a decrease in carotenoid and sodium content in wheat seedlings.

Elucidation of Shoot and Root Growth, Physiological Responses, and Quality Traits of Tomato (Solanum lycopersicon L.) Exposed to Elevated Calcium Carbonate Concentrations

The excess presence of calcium carbonate (CaCO3) in soil poses challenges for production of horticultural crops, including tomatoes. This condition is prevalent in arid and semi-arid regions of Afghanistan. The objective of this study was to evaluate the effects of elevated concentrations of CaCO3 on growth, physiology, and quality attributes of tomato. Seedlings were exposed to different concentrations of CaCO3 (0%, 2.5%, 5%, 10%, and 20% w/w) in soil. The results showed that elevated concentrations of CaCO3 (10% and 20%) significantly increased soil electrical conductivity (EC) and pH, and subsequently affected growth, physiology, and quality of tomato. CaCO3 effects resulted in an increase in leaf electrolyte leakage, leaf calcium content, root respiration rate, root ethylene production, fruit firmness, total soluble solids, ascorbic acid, and organic acids, as well as a decrease in plant height, leaf length, leaf magnesium content, leaf SPAD value, number of leaves per plant, root weight and length, and root activity. At higher concentrations, CaCO3 decreased number of flowers and fruit per plant, as well as fruit weight and diameter, consequently affecting yield production. Although elevated concentrations of CaCO3 is characteristic of soils in Afghanistan, limited information is available about this topic. These findings enhance our understanding of soil conditions in the country and provide valuable insights for farmers.

Leaf stoichiometry of potassium, calcium, and magnesium in tropical plants: Responses to climatic and geographical variations—A case study from Hainan Island

AbstractGrasping how climate change will affect the tropical region's leaf potassium, calcium, and magnesium content is pivotal for enhancing our comprehension of plant stoichiometry. Currently, there is limited research on leaf potassium, calcium, and magnesium in tropical plants, which is particularly evident with the increasing importance of tropical rainforest biodiversity studies. This study investigated the impact of geographical and climatic factors on the leaf potassium, calcium, and magnesium content in 346 plants (including woody plants, herbs, and vines) on Hainan Island. The findings demonstrated that the average leaf potassium, calcium, and magnesium contents were 5.77, 11.86, and 2.92 mg·g−1, respectively, which were less than that in the Chinese flora. Mean annual precipitation (MAP) has a promoting effect on leaf potassium content (p < 0.05), suggesting that artificial potassium fertilization is needed due to the increasing MAP. Leaf potassium and magnesium content were positively correlated with latitude (p < 0.05) and longitude (p < 0.01); and there was a negative correlation between leaf calcium content and latitude (p < 0.05), showing that geographical factors have a significant impact on the potassium, calcium, and magnesium content of plant leaves. Additionally, the variables regulating leaf potassium, calcium, and magnesium varied across woody plants, herbs, and vines. Therefore, it is necessary to make corresponding adjustments according to local conditions and the plant functional types during nutrient management. In conclusion, this study sheds light on their potential responses to global changes and is instrumental in informing the management of these nutrients in tropical rainforest plants.

Effect of Foliar Feeding of Plant Growth Regulators and Nutrients on Leaf Nutrient Status of Guava (Psidium guajava L.) cv. Gwalior-27

The investigation entitled “Effect of foliar feeding of plant growth regulators and nutrients on leaf nutrient status of Guava (Psidium guajava L.) cv. Gwalior-27” was carried out in the Fruit Orchard, Department of Horticulture, R.V.S.K.V.V, CoA, Gwalior district of Madhya Pradesh during mrig-bahar of 2021-22. The field experiment was laid under FRBD (Factorial randomized block design) which contain 20 treatments and were replicated thrice. The result indicated that the leaf nitrogen content (%) as well as leaf calcium content (%) was affected significantly. The highest N content (2.74%) and leaf calcium content (0.75%) were found with M3 (Ca(NO3)2 2%). However, the plant growth regulators and nutrient spray individually and their interactions both had non-significant effect on both leaf P as well as K content. Maximum leaf boron content (90.67 ppm) and leaf zinc content (60.58 ppm) was obtained with M1 (Borax 0.4%) and M2 (ZnSO4 0.5%) respectively. Therefore, based on the experimental findings it can be concluded that foliar feeding of PGR’s and nutrients was an effective way for enhancing the leaf nutrient status of guava. The effect of nutrients was found to be effective in maximising the leaf N content, leaf boron content, leaf zinc content and leaf calcium content significantly. Although, foliar feeding of various concentrations of PGR’s and nutrients independently as well as their interaction effect did not impact any change in the leaf P and K content of the leaf.

Effect of Calcium Foliar Spray Technique on Mechanical Properties of Strawberries.

The calcium fertilization of strawberry plants (Fragaria × ananassa Duchesne) was evaluated using two types of nozzles, with two liquid pressure levels and two driving speeds. The calcium content of the leaves and fruit were analyzed via flame photometry. Higher leaf calcium content was found in plots sprayed with standard nozzles, while higher fruit calcium content was observed for those sprayed with air induction nozzles. The fruit quality was assessed by determining the basic physical and mechanical properties, using uniaxial compression tests integrated with surface pressure measurements. Different spraying techniques influenced the mechanical resistance of the fruit. A spraying speed of 5 km/h and an operating pressure of 0.4 MPa significantly increased the firmness of the fruit by ~66%, the critical load level by 36%, and the maximum surface pressure by up to 38%, but did not increase the geometrical parameters of the strawberries. Regular foliar feeding during harvest could improve the mechanical strength of strawberries. An appropriate spraying technique with a calcium agent could effectively improve the mechanical properties of the delicate fruit, which is particularly important for limiting losses during harvesting, transportation, and storage.

Effect of Foliar Sprayof Gibberellins, Kelatex (ca), And Aminoplasmal on Vegetative Grwoth And Leaf Nutrient of Pomegranate Trees (punica Granatum L.) Cv. Mahdawi

This study was conducted during growing season of 2022 in a private orchard of pomegranate (Punica granatum L.) cv. Mahdawi which is located at Dulib village, Duhok Governorate, Kurdistan region to evaluate the efficacy of foliar spray of, Gibberellins (GA3) Kelatex (Ca) and Aminoplasmal (A). The experiment designed as a factorial experiment in a randomized complete block (RCBD) with three replications, for each treatment and each replicate was represented by one tree. There were three concentrations of Gibberellins (0,50 and 100mg. L-1); three concentration of Ca (0, 200, and 400mg. L-1) and three concentrations of Aminoplasmal (0, 100 and 200ml.L-1) in the study. The results showed that GA3 at 100mg. L-1 had a significant effect on leaf area, leaf dry weight, leaf chlorophyll content, leaf nitrogen content and leaf calcium content when compared to control. On the other hand, that Ca at 400 mg. l-1 had significant effect on leaf dry weight, leaf chlorophyll and leaf calcium content when compared to control, in addition to Aminoplasmal at 200 mg. L-1   had significantly affected leaf area, leaf dry weight, chlorophyll content, nitrogen content, and calcium content. Furthermore, the interaction between (GA3, Ca and A) had significant effect on leaf chlorophyll, leaf calcium content, leaf nitrogen content, and leaf area at concentrations of (100, 400, and 200 mg. L-1) respectively. However, the leaf dry weight was significantly affected at concentrations of (100,200 and 200 mg. L-1) respectively

Effects of Foliar Calcium Applications on Raspberry Fruit Quality and Shelf Life

Abstract— The current study investigates the effect of foliar calcium applications on fruit quality of 'Carmina' raspberry. The first product is a liquid fertilizer (CaO: 12%) applied in three doses: T1 (100 cc/hl), T2 (200 cc/hl) and T3 (400 cc/hl). The second product is Calcium Nitrate (CaO: 26.3%) used in a single dose T4 (230.8 g/hl). Data collected included fruit weight and caliber, rating of fruit colour, firmness, acidity, total soluble solids (TSS), and fruit weight loss during storage. Fruit and leaves were sampled to determine Ca concentration. Results show that foliar treatments had no significant effect on fruits average weight, nor their size. Treatments T2 and T3 significantly increased fruit firmness. Fruit TSS and acidity showed no significant differences from T0. Applications did not affect post-harvest fruit weight losses. Foliar application of calcium caused an increase in leaf calcium content of 46 and 42% respectively for T2 and T3, and an increase in fruit calcium content of 35 and 18% respectively for T2 and T3 compared to T0. There was no difference between the contents of leaves and fruits regarding the other elements (Mg, K, Fe, Mn, Zn and Cu). The right frequency of application is once every 8 days.

Effects of Different Irrigation Waters and Silicon Doses on Leaf SPAD Meter Readings, Chlorophyll and Carotenoid Contents of Tomato Plants

This study was conducted to determine the effects of different irrigation water treatments and silicon doses on leaf SPAD meter readings, chlorophyll content and carotenoid contents of tomato plants. Tybiff Aq tomato seedling were grown in 3-liter pots filled with 1100 g of 1:1 peat-perlite mixture for 70 days. Four different type of irrigation waters were prepared with the use of sea and tap water. Irrigation waters included I) Full sea water, II) ½ sea water + ½ tap water, III) ¼ sea water + ¾ tap water, IV) Full tap water (control). Each irrigation water was supplemented with silica gel (SiO2.xH2O) at 0, 0.5, 1 and 2 mM Si doses. Nutrient solutions were supplied to meet macro and micronutrient requirements of tomato plants. Leaf chlorophyll-a, chlorophyll-b and total chlorophyll contents significantly increased with increasing tap water ratios of the irrigation water. Significant increases were observed in chlorophyll-a, chlorophyll-b and total chlorophyll contents with increasing silicon doses. Such increases achieved with silicon treatments were more remarkable for chlorophyll-a and total chlorophyll contents. Leaf chlorophyll-a, chlorophyll-b and total chlorophyll contents significantly decreased with increasing leaf sodium, chlorine and magnesium contents, but significantly increased with increasing leaf active iron and potassium contents. Leaf chlorophyll-a, chlorophyll-b and total chlorophyll contents increased with increasing leaf calcium contents, but such increases were not significant. Leaf carotenoid contents significantly increased with increasing tap water ratios of the irrigation water. Effects of silicon doses on leaf carotenoid contents varied with the type of irrigation water. The 0.5 mM silicon supplementation into tap water significantly increased carotenoid contents.

Active modified atmosphere package induced a new physiological disorder of minimally processed romaine lettuce leaves

Abstract Active modified atmosphere (active MAP) is commonly used for browning control of fresh-cut lettuce. However, it induces a disorder which is first reported in this study, described as ‘leaf collapse’. This study attempt to evaluate the possible factors involved in the development of this physiological disorder. Therefore, minimally processed romaine leaves of a sensitive and a resistant cultivar were stored under three different conditions (active MAP, passive MAP, air) for 6 days at 4 °C. The results showed that the development of leaf collapse was correlated with the interaction of cultivar and atmosphere composition. No correlation among leaf calcium content as well as leaf age with collapse index was recorded. On the contrary, results showed increased C2H4 production and membrane permeability of the sensitive lettuce cultivar as well as C2H4 accumulation in packages during storage under active MAP conditions compared to tolerant one.

RESPONSE OF VEGETATIVE GROWTH FOR THE TREATMENT OF ORGANIC NUTRIENT AND CALCIUM CHLORIDE FOR GERBERA PLANT Gerbera jamesonii

This study was conducted in the lath house, Horticultural Department, College of Agriculture – University of Baghdad- Jadriya during the spring and autumn seasons 2015 to investigate the influence of humic acid spray and calcium chloride spray on f “Yanara” gerbera cultivar. This study included two factors; humic acid spray (H) and calcium chloride spray (Ca). The first factor four levels were used, 0, (H0), 5 (H5), 7.5 (H7.5) and 10 (H10) ml.L-1 and four levels of calcium chloride, 0 (Ca0), 50 (Ca50), 100 (Ca100) and 150 (Ca150) mg.L-1. Each treatment replicated three times with a factorial experiment using RCBD. Five plants in experimental unit and the number of plants used was 240 trees. The experimental results showed that humic acid at 10 ml.L-1 and calcium chloride at 150 mg.L-1 (Ca150H0) significantly gave the highest leaves number of 11.20 and 11.47 leaves, the highest leaf area of 195.21 and 210.25 cm2, the highest plant dry weight of 16.92 and 17.95gm, the highest leaf nitrogen content of 2.50 and 2.45 %, highest leaf phosphor content of 0.37 and 0.44% and the highest leaf calcium content of 3.17 and 3.45% for both seasons, respectively. The lowest value of these parameters was found in the control (Ca0H0) treatment. It could be concluded of this experiment that the humic acid at level H10 and calcium chloride at level Ca150 improved vegetative characteristics and leaf mineral content gerbera plant cv. Yanara

Calcium-mediated reduction of soft rot disease in Chinese cabbage

Soft rot of Chinese cabbage is a disease of great economic importance to the State of Pernambuco, Brazil. The present study aimed to evaluate the effect of two calcium sources in different concentrations (calcium nitrate [Ca(NO3)2] at 0, 0.15 and 0.3 g l−1 and calcium chloride (CaCl2) at 0, 1 and 5 g l−1) that were applied through two methods (leaf spraying and soil drenching) on the control of soft rot. Further, it aimed to analyze calcium absorption by the plant and to determine calcium’s role in leaf and cell structure using microscopy. Ca(NO3)2 applied by both methods was effective in controlling soft rot caused by Pectobacterium carotovorum subsp. carotovorum, as it reduced the disease by up to 48.5 % when sprayed onto the leaves (0.15 g l−1). A significant increase in the leaf calcium content was observed only in the plants that were sprayed with higher doses of Ca(NO3)2 and CaCl2. In all of the calcium treatments, light microscopy analyses revealed an increased number of chloroplasts and improved structuring of the palisade parenchyma, while transmission electron microscopy analyses revealed an increased cell wall thickness that was especially evident for the 0.15 g l−1 Ca(NO3)2 treatment applied by leaf spraying and soil drenching.

Adubação nitrogenada via substrato no cultivo de bromélia

One of the reasons for the predatory extraction of bromeliads is the lack of information about the techniques of growing these plants, mainly in relation to fertilization. This work aimed to evaluate the effect of nitrogen on substrate in vegetative growth and nutrient content in leaves of bromeliads Nidularium fulgens. Seedlings were submitted to six levels of nitrogen: 0, 100, 200, 300, 400 and 500 mg/dm3. The experimental design used was the randomized block design with six treatments, five replications and three plants per plot. Plants were evaluated on the number of leaves, height, diameter of base, dry matter and foliar mineral composition. The results showed that there was a linear increase of the height, number of leaves and foliar dry matter with higher nitrogen rates. The increasing levels of nitrogen gave an increase in foliar nitrogen and manganese and reduce leaf content of calcium and copper. Nitrogen rates applied did not influence the contents of P, K, S, B, Zn and Mg. These results suggest that the addition of nitrogen fertilizer at 500 mg/dm3 in Nidularium fulgens provides greater vegetative development, increases the leaf N and Mn content and reduces the content of Ca and Cu.

تأثير معاملات الكالسيوم المختلفة في تطور النقرة المرة على ثمار التفاح صنف غولدن ديليشس = The Effect of Different Calcium Treatments on the Development of Bitter Bit of Golden Delicious Apple Fruits

تفاح | النقرة المرة | كربونات الكالسيوم | نترات الكالسيوم | كلوريد الكالسيوم | محتوى الأوراق من المعادن | Apple | Bitter Pit | Calcium Nitrate | Calcium Carbonate | Calcium Chloride | Leaf Mineral Content

Linking post-fire regenerative strategy and leaf nutrient content in Mediterranean woody plants

Abstract We explored differences in leaf nutrient contents between species from Mediterranean shrublands with the ability to resprout after disturbances such as fire (resprouters) and others without this capacity (non-resprouters). Since it is to be expected that resprouting capacity is related to a more conservative use of nutrients, we hypothesize that resprouter and non-resprouter species will differ in their leaf nutrient concentrations. We measured the following leaf traits: leaf carbon content (LCC), leaf nitrogen content, leaf phosphorous content (LPC), leaf potassium content, leaf calcium content (LCaC), leaf magnesium content and leaf sodium content, in 30 woody species coexisting in a coastal shrubland. We also considered the influence of species’ taxonomic affiliation in our analysis. Non-resprouters had higher LPC and LCaC than resprouter species, and lower LCC, which could be related to their cell and life-history properties. This study also suggests that non-resprouter species have more P in their leaves and are less limited by P than resprouter species. Overall, the differences in leaf nutrient contents suggest that shifts in the proportion of resprouter and non-resprouter species resulting from changes in the fire regime may have effects on the functional properties of the ecosystem.

Adubação orgânica, nutrição e progresso de cercosporiose e ferrugem-do-cafeeiro

O objetivo deste trabalho foi avaliar o efeito de fontes nutricionais orgânicas, no progresso da cercosporiose e da ferrugem-do-cafeeiro, entre novembro/2003 e novembro/2005. Utilizou-se o delineamento de blocos ao acaso, com quatro repetições e seis tratamentos: palha de café + chorume suíno (PC+CS); torta de mamona + crotalária (TM+Cr); palha de café (PC); esterco bovino + crotalária (EB+Cr); palha de café + torta de mamona (PC+TM); e composto orgânico, torta de mamona, chorume suíno e crotalária (testemunha). A maior área abaixo da curva de progresso da incidência da cercosporiose e da ferrugem foi registrada no tratamento PC (respectivamente 62 e 38% superiores à testemunha). O maior progresso das doenças coincidiu com a elevação no teor de K e redução nos teores de Ca foliares no tratamento PC, comparado às demais fontes de adubação, e resultou em maior desfolha e menor produtividade. Os tratamentos PC+TM e PC+CS reduziram a incidência da cercosporiose em 38% e da ferrugem em 31 e 21%, respectivamente, e aumentou o teor de Ca foliar ao final da fase de granação do cafeeiro, em comparação ao tratamento PC. O equilíbrio nutricional desses cafeeiros conferiu-lhes maior resistência e reduziu o efeito da bienalidade nas safras 2003/2004 e 2004/2005.

Primary production and nutrient content in two salt marsh species,Atriplex portulacoides L. andLimoniastrum monopetalum L., in Southern Portugal

Seasonal variation patterns of aboveground and belowground biomass, net primary production, and nutrient accumulation were assessed inAtriplex portulacoides L. andLimoniastrum monopetalum (L.) Boiss. in Castro Marim salt marsh, Portugal. Sampling was conducted for five periods during 2001–2002 (autumn, winter, spring, summer, and autumn). This study indicates that both species have a clear seasonal variation pattern for both aboveground and belowground biomass. Mean live biomass was 2516 g m−2 yr−1 forL. monopetalum and 598 g m−2 yr−1 forA. portulacoides. Peak living biomass, in spring for both species, was three times greater in the former, 3502 g m−2 yr−1, than in the latter, 1077 g m−2 yr−1. For both the Smalley (Groenendijk 1984) and Weigert and Evans (1964) methods, productivity ofL. monopetalum (2917 and 3635 g m−2 yr−1, respectively) was greater than that ofA. portulacoides (1002 and 1615 g m−2 yr−1, respectively). Belowground biomass ofL. monopetalum was 1.7 times greater than that ofA. portulacoides. In spite of this, the root:shoot ratio forA. monopetalum to aerial components. Leaf area index was similar for both species, but specific leaf area ofA. portulacoides was twice that ofL. monopetalum. The greatest nutrient contents were found in leaves. Leaf nitrogen content was maximum in summer for both species (14.6 mg g−1 forA. portulacoides and 15.5 mg g−1 forL. monopetalum). Leaf phosphorus concentration was minimum in summer (1.1 mg g−1 inA. portulacoides and 1.2 mg g−1 inL. monopetalum). Leaf potassium contents inA. portulacoides were around three times greater than inL. monopetalum. Leaf calcium contents inL. monopetalum were three times greater than inA. portulacoides. There was a pronounced seasonal variation of calcium content in the former, while in the latter no clear variation was registered. Both species exhibited a decrease in magnesium leaf contents in the summer period. Mangamese content inL. monopetalum leaves was tenfold that inA. portulacoides. Seasonal patterns of nutrient contents inA. portulacoides andL. monopetalum suggest that availability of these elements was not a limiting factor to biomass production.

Liming and quality of guava fruit cultivated in Brazil

An experiment was conducted on guava trees Psidium guajava L. (cv. Paluma) grown in the Experimental Citrus Culture Station of Bebedouro, SP, on dystrophic, acid Typical Hapludox in order to assess the effects of application of increasing lime doses to the soil on the quality of guava fruits on the basis of the physicochemical changes observed in the fruits after harvesting. The treatments consisted of increasing lime doses applied before planting, considering 0, 1.85, 3.79, 5.56 and 7.41 t ha −1, applied in August 1999. Leaf calcium content was assessed at flowering time. After fruit harvesting, calcium content in the pulp, total weight, transverse diameter, length, pulp weight, % pulp, Brix degrees (°Brix), titratable acidity, and fruit ratio were determined. Loss of fruit fresh mass, firmness and color were determined daily during a period of 8 days of storage. Lime application to an acid Red Latosol before guava tree planting did not affect the physical characteristics of the fruits but provided a lower loss of fresh matter and greater fruit firmness when the fruits presented Ca levels close to 0.99 g kg −1. It is important to conduct new studies of the effects of liming on guava fruit quality under different edaphic-climatic conditions and on different guava tree genotypes.

The effect of calcium on the antioxidant enzymes from salt-treated loquat and anger plants.

Salt treatment (50 mM NaCl) reduced plant growth of loquat (Eribotria japonica Lindl.) (by up to 40%) but not that of anger (Cydonia oblonga Mill.). Salt stress induced a strong leaf Na+ accumulation in both species. However, the observed increase in leaf Cl- level was higher in loquat (13-fold) than in anger plants (3.8-fold). Addition of Ca2+ (25 mM) significantly reduced Na+ and Cl- concentrations in both salt-treated species. In anger leaves, calcium addition to the nutrient media did not change the leaf calcium contents in salt-treated or untreated plants, this value being lower in salt-treated plants. However, in loquat plants, an increase in leaf Ca2+ was observed after the calcium addition. Surprisingly, an increase in Ca2+ concentration was also observed in salt-treated loquat plants. In general, anger plants had higher constitutive antioxidant enzyme levels in both control and salt-treated plants. Salt stress did not change antioxidant enzyme levels in loquat plants. A similar effect was observed in anger plants, but in this case a 2-fold induction of monodehydroascorbate reductase (MDHAR) activity was observed.In both species, salinity produced an oxidative stress, indicated by an increase in lipid peroxidation, this value being much higher in loquat (83%) than in anger (40%) plants. In salt-treated plants, Ca2+ addition provided some protection to the membranes, because the increases observed in thiobarbituric-acid-reactive substances (TBARS) were not significant.In contrast, in control plants Ca2+ treatments increased glutathione reductase (GR) and decreased catalase activity in anger, but increased MDHAR, dehydroascorbate reductase (DHAR), GR and superoxide dismutase (SOD) in loquat plants. In salt-treated plants, Ca2+ additions decreased catalase (CAT) and ascorbate peroxidase (APX) for anger and raised DHAR, GR and SOD for loquat. However, the mechanism by which Ca2+ regulates antioxidant enzymes remains to be determined.These results suggest that anger plants have a higher capacity to scavenge AOS, both under saline and non-saline conditions. Accordingly, and related to the smaller Cl- increase observed, anger plants are more salt-tolerant, at least partly owing to the higher antioxidant enzyme levels observed.

541 Effect of Supplemental Calcium on Watermelon Yield, Fruit Weight, Soluble Solids, and Calcium Content of Leaves and Fruit

Inadequate available Ca can cause blossom end rot in watermelons. Many products and materials are marketed to try and help reduce this problem. A 3 X 3 factorial was set up with three soil Ca treatments (none, 1120 kg/ha of dolomite and 1120 kg/ha of qypsum) and three foliar Ca treatments (none, Liqui-Cal at 9.35 L/ha and Foli-Cal at 4.67 L/ha) using both a seeded (2N) and seedless (3N) cultivar. Mehlich-1Ca level prior to planting was 305 ppm. None of the Ca treatments affected leaf or fruit Ca levels. Applied Ca treatments did not affect total yields, fruit weight, or percent soluble solids of the seedless cultivar (Crimson Trio). Yield of `Royal Flush' (2N) was reduced by application of Foli-Cal, but none of the other parameters were affected by the other Ca treatments. Leaf Ca level of `Royal Flush' (3.05%) was almost twice that of `Crimson Trio' (1.59%), while fruit Ca content of `Royal Flush' (0.26%) was lower than that of `Crimson Trio' (0.32%).

Yield and Disease Resistance of Six Tomato Cultivars Grown in Two Media and Three Calcium Concentrations

Calcium has been linked to disease resistance in fruits and vegetables. The effects of calcium nutrition on six hydroponically grown tomato cultivars (`Switch', `Match', `Blitz', `Caruso', `Trust', and `Celebrity') were evaluated in the fall of 1996. Disease resistance and yield were measured for plants grown in either perlite or pine bark mulch. Plants were fertilized with a 5N–11P–26K water-soluble fertilizer solution containing micronutrients and either 60, 120, or 185 mg·L–1 calcium. Disease resistance was determined by measuring disease lesion diameters on mature green harvested fruit 3 to 5 days after inoculating with Botrytis cinerea Pers.: Fr. There was no significant difference in disease when evaluated by medium, cultivar, or calcium treatment. Foliar analysis by Inductively Coupled Argon Plasma Atomic Emission Spectrophotometer (ICAP) indicated that leaf calcium content ranged from 27,000 to 54,000 μg·g–1 dry weight (leaf above fifth flower cluster), but was not significantly different when analyzed by medium, cultivar, or calcium treatment. There was no significant difference in marketable yield due to medium or calcium treatment. Among cultivars, `Trust' had the highest marketable yield at 2.7 kg per plant, which was significantly different from `Celebrity' at 1.6 kg per plant. This experiment suggests that a cheaper medium (pine bark) and lower calcium levels can be utilized in fall tomato production.