Response to Tomato To Irrigation, Foliar Application of Calcium, Boron, Zinc and Post Harvest Calcium Treatments

Abstract

Three experiments were conducted at Agriculture Research Institute (ARI) Tarnab, Peshawar, Pakistan during the year 2012-14 to study the “Response of tomato to irrigation, foliar application of calcium (Ca), boron (B), zinc (Zn) and post harvest calcium treatments”. In the first experiment, tomato plants were irrigated at 3, 6 and 9 days intervals. The nutrients (Calcium, Boron, and Zinc) content of tomato crop were investigated in relation to irrigation intervals and sampling time (0, 20, 40, 60 and 80 days after transplantation). The yield and quality attributes were evaluated in relation to irrigation intervals only. The highest leaf Ca content (1.19%), leaf Zn content (3.28 mg 100g-1 DW ), number of leaves (129.00 ), leaf area (56.88 cm2), number of flowers (6.33) and fruit cluster-1 (4.33), yield (21.66 t ha-1), fruit firmness (3.33 kg cm-2), lowest blossom end rot (4.80%) and fruit cracking (4.17%) were recorded in plants irrigated after 6 days, while the highest leaf boron content (4.07 mg 100g-1 DW), lowest TSS (1.72 °brix) and non reducing sugars (0.56%) were measured in plants with irrigation after every 3rd days. Root weight (164 g), reducing sugars (3.80%), and ascorbic acid content (13.67mg 100g-1) were recorded as maximum in plants with 9 days irrigation interval. The highest leaf Ca content (1.12%) was recorded in plants, when leaf samples were taken after 60 days, while leaf B and Zn content were recorded the highest i.e. 3.92 and 4.71 mg 100g-1 DW, respectively in tomato leaves, sampled after 80 days. In the second experiment, the effects of calcium, boron, and zinc foliar application on yield and fruit quality of tomato were studied. Calcium (0, 0.3, 0.6 and 0.9%), Boron (0, 0.25, 0.5%) and Zinc (0, 0.25, 0.5%) were applied as foliar spray, three times, 1st before flowering, 2nd at the time of fruit set and 3rd application was repeated 15 days after 2nd application. Calcium application at 0.6% increased plant height (88.04 cm), number of primary (2.63) and secondary (7.15) branches, number of leaves plant-1 (182), leaf area (65.52 cm2), number of flowers cluster-1 (6.33), fruit cluster-1 (4.82), fruit plant-1 (66.15), yield (28.11 t ha-1 ) and decreased the flower drop (18.85%). Moreover, The highest number of flower cluster plant-1 (16.78), fruit weight (99.94 g), fruit firmness (2.99 kg cm-2), fruit Ca content (10.21 mg/100 DW), least TSS (3.38 °brix), blossom end rot (6.70%), fruit cracking (3.63%) and Zn content (2.08 mg/100 DW) were recorded at 0.9% Ca foliar application. In case of B levels, more plant height (88.14 cm), number of primary (2.61) and secondary (7.44) branches, number of leaves plant-1 (177), number of flowers cluster-1 (6.06), fruit cluster-1 (4.97), fruits plant-1 (67.78), yield (28.30 t ha-1) and reduced flower drop (17.86%), fruit cracking (4.44%) were recorded with foliar spray of B at 0.25%. Similarly, 0.5% B application significantly increased leaf area (62.33 cm2), number of flower cluster plant-1 (17.42), fruit weight (96.41 g), fruit firmness (2.86 kg cm-2), fruit Ca content (9.97 mg/100DW) and fruit B content (3.24 mg/100DW), lowest blossom end rot (11.44.0%), TSS (3.56 ° brix) and fruit Zn content (2.18 mg/100 DW). Comparing the means for Zn concentrations, maximum plant height (86.53 cm), number of primary (2.53) and secondary (6.42) branches, number of leaves plant-1 (167), leaf area (63.33 cm2), number of flowers cluster-1 (6.06), fruit cluster-1 (4.64), number of cluster plant-1 (16.64), fruit plant-1 (63.78), fruit weight (94.98 g), yield (28.80 t ha-1), ascorbic acid content (14.52 mg/ml), reducing sugar (3.07%), fruit B (3.27 mg/100 DW) and Zn (2.59 mg/100 DW) contents were higher while the incidence of blossom end rot (11.00%), fruit cracking (4.83%), non-reducing sugar content (1.11%) and fruit Ca content (8.88 mg/100DW) were lower with 0.5% foliar Zn application while the effect of Zn on flower drop was found non significant. By contrast, firmer fruit (2.82 kg cm-2) with lowest TSS (3.36 °brix) were recorded in plot, where Zn was not applied. In the 3rd experiment, the fruits of tomato were dipped in different calcium sources (calcium chloride, calcium gluconate, calcium lactate and calcium sulphate) at various concentration (0, 0.25, 0.50 and 0.75) and stored at low temperature (10± 2°C) and ambient temperature (32±2°C) and at relative humidity (60±5%) for 21 days. Higher fruit firmness (2.25 kg cm-2), percent acidity (0.34%), ascorbic acid content (9.90 mg 100g-1), non reducing sugars (1.58%), minimum physiological weight loss (20.18), TSS (4.99 °brix), reducing sugars (3.53%), sugar acid ratio (16.07), soft rot (18.49%) and black mold (16.63%) were recorded in fruits stored at low temperature, while minimum cell membrane and cell wall ion leakage (41.58 and 22.64%, respectively) and green mold (20.58%) was recorded in fruits stored at ambient temperature. For calcium concentration, Ca at 0.75% significantly increased fruit calcium content (12.89 mg 100g-1), fruit firmness (2.60 kg cm-2), percent acidity (0.38%), ascorbic acid content (9.68 mg 100g-1), non reducing sugars (1.74%) and reduced physiological weight loss (14.33%), cell membrane and cell wall ion leakage (40.25 and 21,38%, respectively), TSS (5.03 °brix), sugar acid ratio (14.03), soft rot (11.02%) and green mold (13.73%) while reducing sugars (3.26%) and black mold (16.0%) were recorded minimum in tomatoes supplied with 0.5% calcium concentration. Regarding the means for calcium sources, more fruit firmness (2.82 kg cm-2), percent acidity (0.44%), ascorbic acid content (13.52 mg 100g-1), non reducing sugars (2.34%), minimum physiological weight loss (12.72%), cell membrane and cell wall ion leakage (37.50 and 19.06%, respectively), TSS (4.96 °brix), reducing sugars (3.10%), sugar acid ratio (11.49), soft rot (6.11%) and black mold (13.17%) and green mold (10.04%) were recorded in fruits treated with CaCl2. Therefore, it is concluded that 6 days irrigation interval resulted in better growth, more nutrient uptake, fruit quality and minimum physiological disorders (blossom end rot and fruit cracking). Calcium decline started after 60 days of growth, so foliar calcium should be applied before flowering and after fruit set to correct the calcium deficiency and control the Ca related physiological disorders like blossom end rot and fruit cracking. Foliar application on Ca, B, and Zn should be used alone or in combination to improve the fruit yield, minimize the physiological disorders and (blossom end rot and fruit cracking) and enhance fruit quality of tomato. Furthermore, CaCl2 at high concentration and low temperature should be used for maintaining quality of tomato fruits by reducing the post harvet diseases, increasing the fruit firmness, delaying ripening process, and prolonging the shelf life.