Research Article

Effect of Calcium, Boron and Zinc Foliar Application on Growth and Fruit Production of Tomato

Bibi Haleema1*, Abdur Rab1 and Syed Asghar Hussain2

1Department of Horticulture, The University of Agriculture Peshawar-3125 Pakistan; 2Agriculture Research Station (ARS), Baffa, Mansehra-21300 Pakistan.

Received | September 28, 2017; Accepted | November 18, 2017; Published | December 21, 2017

*Correspondence | Bibi Haleema, Department of Horticulture, The University of Agriculture Peshawar-3125 Pakistan; Email: [email protected]

Citation | Haleema, B., A. Rab, S.A. Hussain. 2018. Effect of calcium, boron and zinc foliar application on growth and fruit production of tomato. Sarhad Journal of Agriculture, 34(1): 19-30.

DOI | http://dx.doi.org/10.17582/journal.sja/2018/34.1.19.30

Keywords | Boron levels, Calcium concentration, Fruit production, Growth attributes, Tomato, Zinc concentration

Introduction

Tomato (Lycopersicom esculentum Mill.) is a key vegetable crop grown throughout the world (Srividya et al., 2014) and a good source of vitamin A, vitamin C, Ca, Fe, protein, Na, K, Mg (USDA, 2016) antioxidant and carotenoids (Di Masico et al., 1989) that helps in retarding cancer and degenerative diseases (Giovannucci, 1999). Tomato yield in Pakistan is 10.12 t ha-1, which is much less than global yield of 36 t ha-1 (MINFA, 2009). Besides, cultivars and cultural practices, many biotic and abiotic factors also limit the yield of tomato crop. (Ali, 2014). Abiotic stresses like changes in environmental conditions and nutrition results in physiological disorders ultimately decrease crop yield (Khavari-Nejad et al., 2009).

Nutrients management is essential to maximize crop yield (Menzel and Simpson, 1987), enhance fruit quality and increase profitability (Ganeshamurthy et al., 2011). Tomato plant requires macro and micro nutrients for growth and development as well as to complete its life cycle (Fageria, 1992; Brady and Weil, 2002). Essential nutrients are needed for optimum plant growth and development (Fageria, 2005; 2007; Fageria and Baligar, 2005). Soil characterized by high pH limits micronutrients availability to the plant (Ibrahim et al., 2008). Thus, application of essential nutrients enhances the uptake and utilization of nutrients (Phillips et al., 2004) and decrease nutrients deficiency related disorders.

The nutrients required in large quantity are supplied through soil application (Fageria et al., 2009) but nutrients needed in lower quantity can be better absorbed through foliar spray (Fageria et al., 2009; Girma et al., 2007). Calcium is an important secondary macro nutrient (Kadir, 2005), which may be deficient in plants either due to low calcium in soil, low calcium availability due to high soil pH, and low mobility in the plants especially to the fruits (Kadir, 2005; Peter, 2005). Therefore, a continuous supply of calcium is required for leaf development, plant canopy, and vigorous root growth (Del-Amor and Marcelis, 2006). Foliar fertilization can supplement soil fertilization to maximize crop yield (Fageria et al., 2009).

Boron is another important micro nutrient required for good quality and high yield of crops (Dale and Krystyna, 1998). It is involved in the synthesis and integrity of cell wall, cell wall lignification, metabolism of RNA, carbohydrate, phenol and Indole Accetic Acid (IAA), respiration and cell membrane integrity (Parr and Loughman, 1983). Boron increases the fruit set percentage by promoting pollen germination and elongation of pollen tube (Abdalla, 2006). Boron content also influences calcium metabolism and its deficiency declines the calcium associated with pectin constituents (Yamaguchi et al., 1986). Boron deficiency results in wilting and leaf drop (Zekri and Obreza, 2003) and adversely affect the quality and yield of many vegetables especially tomato (Imtiaz et al., 2010). Its requirements of plants can be satisfied by both foliar and soil application during growing season, especially during reproductive growth stage (Sajid, 2009).

Zinc (Zn) is another important essential micronutrient which helps in the formation of tryptophan, a precursor of IAA responsible for growth stimulation (Mallick and Muthukrishnan, 1979) and plays a vital role in synthesis of carbonic anhydrase enzyme which helps in transport of CO2 in photosynthesis (Alloway, 2008). Zinc deficiency causes shorter and thinner internodes, stunted growth, appearance of chlorotic flecks on the older leaves and twisting of leaf borders in upward direction and plant with abnormal features (Passam et al., 2007). The zinc deficiency may be due to soil deficient in Zn, competition with Ca, Mn, Fe, P, to some degree K, and soil properties that influence Zn availability (Srivastava and Singh, 2003). Soil application of Zn is less effective due to roots limitations and low Zn mobility in soil and it is partially immobile in the phloem. By contrast, foliar uptake is rapid, thus, repeated sprays of Zn are needed to overcome the Zn deficiency (Swietlik, 2002).

Keeping in view the importance of Ca, B and Zn in improving tomato growth and yield of tomato, the current study was conducted to evaluate the effect of foliar applied Ca, B and Zn for improved growth of tomato, to enhance the growth of tomato through Ca, B and Zn management and to elucidate the interactive effect of Ca, B, and Zn for the maximum vegetative and reproductive growth of tomato fruit.

Materials and Methods

Effect of calcium, boron, and zinc foliar application on growth and fruit production of tomato was investigated during the year 2013, from January-July at Agricultural Research Institute (ARI), Tarnab Peshawar, Pakistan.

The experiment was conducted in RCB Design with 3 replications. Different concentrations of Calcium (0, 0.3, 0.6 and 0.9%), Boron (0, 0.25 and 0.5%), and Zinc (0, 0.25 and 0.5%) were applied as foliar spray three times during the season. First foliar application was made before start of flowering. 2nd at the time of fruit set and 3rd application was repeated at 15 days after fruit set.

The sources of Ca, B, and Zn were CaCl2.2H2O, boric acid, and zinc sulphate, respectively. AnalaR Grade chemicals were used to prepare the nutrient solution. The percent calcium was calculated in molecular formula of the respective source and then found the quantity of calcium, boron and zinc source used for the mentioned percent solutions. Hand sprayer was used to spray the nutrients uniformly on each plant. Tween-Twenty, a surfactant, was added to the solution at the rate of 0.5 cc / 100 ml of water for better retention of the chemicals. The plants of control group were sprayed with plain water. All foliar applications were made early in morning for better absorption and long lasting effect.

The seeds of tomato cultivar Riogrande were obtained from National Agriculture Research Council (NARC) Islamabad and nursery was raised at ARI Tarnab during third week of January. Seedlings were hardened-off and transplanted in the first week of March on one side of raised bed keeping row-to-row distance 70 cm and plant to plant distance 30 cm. Plot size was 6.1 m2.

Experimental area was thoroughly prepared and all routine cultural practices like weeding and hoeing during crop growth and development were kept constant and uniform. The nursery plants were sown on raised bed with 3 m length and 1 m width.

Physico-chemical analysis of the soil of the experimental site

The soil of the experimental site was slightly alkaline in reaction with pH of 8.13, electrical conductivity of 0.475 dSm-1, deficient in some nutrients like P, Zn, B and Ca (4.06, 1.38, <0.5 mg kg-1and 7.4%, respectively). The potassium content was adequate in the experimental site i.e. 337.2 mg kg-1.

Data were recorded on vegetative and reproductive parameters as per following procedure:

Plant height (cm): The plant height of five plants, taken at random was measured from soil level to the tip of the longest stem. The mean plant height was recorded after final harvest.

Number of primary branches plant-1: The number of primary branches of five randomly taken plants was counted and average to represent the corresponding treatments.

Number of secondary branches plant-1: The secondary branches developed on primary branches of each 5 randomly taken plants were counted and averaged to represent the corresponding treatments.

Number of leaves plant-1: The parameter was recorded by counting leaves of five plants at random and then averaged.

Leaf area (cm2): The leaf area of 5 randomly selected plants was recorded by taking five leaves for each plant in each experimental unit. The leaf area was estimated with a leaf area machine (C1-2O2-Area Meter USA) calculated in cm2.

Number of fruit plant-1: The number of fruits plant-1 was counted from tagged plant at each picking till final harvest from last week of May to July. The number of fruits at each harvest was added and average was calculated for each treatment.

Statistical analysis

The data were analyzed statistically using procedure appropriate for Randomized Complete Block Design (RCBD) with three factors using statistical software Statistix 8 (Statistix® 8 Analytical Software, 2003). Means were compared using LSD when F test was found significant (Jan et al., 2009).

Results and Discussion

Plant height (cm)

The foliar application of Ca, B, and Zn significantly affected plant height of tomato. The interactions of Ca x B and B x Zn were also significant, but the interactions of Ca x Zn and Ca x B x Zn had no significant effect on plant height of tomato (Table 1). An increase from 78.82 cm to 88.14 cm in plant height of tomato was recorded with increasing the Ca concentration of foliar spray from control to 0.6% but 0.9% Ca spray significantly decreased plant height to 83.37 cm (Table 1). The plant height of tomato also increased from 77.22 cm to 88.14 cm with increasing B from 0 to 0.25%, but adding more B up to 0.5% decreased the plant height (84.78 cm) of tomato (Table 1). Moreover, the plant height increased consistently with increasing concentration of Zn as foliar spray. The Plant height was 80.61 and 83.61 cm with 0 and 0.25% Zn application that significantly increased to 86.53 cm with increasing the Zn concentration to 0.5% (Table 1). Regarding the interaction of Ca and B, the minimum plant height (75.33 cm) was recorded with 0.3% Ca + 0% B while plant treated with 0.6% Ca +0.25% B had the maximum plant height (95.33 cm) (Figure 1). The interaction of Ca and Zn was also found significant. The minimum plant height (72.00 cm) was recorded in control plants that increased to 91.00 cm in plants treated with 0.25% B + 0.25% Zn (Figure 2).

Number of primary branches per plant

Foliar application of Ca, B and Zn significantly affected primary branches plant-1. The interactions of

Table 1: Effect of calcium, boron, and zinc foliar application on plant height, number of primary branches and number of secondary branches of tomato.

Calcium Levels (%)	Plant height (cm)	No. of primary branches plant-1	No. of secondary branches plant-1
0	78.82 c	1.85 c	4.74 c
0.3	83.29 b	1.93 c	5.30 c
0.6	88.04 a	2.63 a	7.15 a
0.9	83.37 b	2.26 b	5.96 b
LSD at α 0.05	3.23	0.29	0.56
Boron (%)
0	77.22 c	1.83 b	4.47 c
0.25	88.14 a	2.61 a	7.44 a
0.5	84.78 b	2.06 b	5.44 b
LSD at α 0.05	2.80	0.25	0.49
Zinc (%)
0	80.61 c	1.92 b	5.08 c
0.25	83.61 b	2.06 b	5.86 b
0.5	86.53 a	2.53 a	6.42 a
LSD at α 0.05	2.80	0.25	0.49
Interactions
Ca x B	Fig 1	Fig 3	Fig 5
Level of Significance	**	**	**
Ca x Zn	---	---	---
Level of Significance	NS	NS	NS
B x Zn	Fig 2	Fig 4	Fig 6
Level of Significance	**	**	**
Ca x B x Zn	---	---	---
Level of Significance	NS	NS	NS

Means followed by similar letter(s) in column do not differ significantly from one another. NS: Non-significant; *, **: Significant at 5 and 1% level of probability, respectively.

Ca x B and B x Zn had a significant effect on the primary branches plant-1, but the interactions of Ca x Zn and Ca x B x Zn was found non-significant (Table 1). The highest primary branches per plant (2.63) was recorded in tomato plants with foliar application of Ca at 0.6%, while the lowest primary branches per plant (1.83) was recorded in control treatment. (Table 1). Similarly, the foliar application of B increased the primary branches per plant up to 2.61 with increase in B levels up to 0.25%. However, more increase in B to 0.5% declined the primary branches to 2.06 (Table 1).

The primary branches of tomato constantly increased with increasing concentration of Zn. while the primary branches was not significant between 0 and 0.25% Zn concentrations (1.92 and 2.06, respectively), it increased significantly with further increase in Zn concentration up to 0.5% (2.53) (Table 1). The interaction between Ca and B indicated that the maximum branches plant-1 (3.55) was recorded with 0.6% Ca + 0.25% B application as compared to 1.67 branches plant-1 in control treatment (Figure 3). The interaction between B and Zn showed that primary branches of tomato were higher (3.58) at 0.5% B + 0.25% Zn while lower number of primary branches (1.83) was recorded in control treatment (Figure 4).

Secondary branches per plant

Foliar application of Ca, B and Zn and interactive effect of CaxB and BxZn had a significant influence on secondary branches per plant of tomato, whereas the rest of the interactions were found non-significant (Table 1). The secondary branches per plant increased from 4.74 to 7.15 with the application of Ca from 0 to 0.6%, respectively. While incremental increase of Ca up to 0.9% reduced the secondary branches (5.96) (Table 1). Likewise, the secondary branches increased from 4.47 to 7.44 with increased B from 0 to 0.25%. However, more application of B to 0.5% decreased the secondary branches (5.44) (Table 1). The secondary branches linearly increased with increasing Zn concentration. The highest secondary branches 6.42 were recorded with Zn at 0.5%, followed by (5.86) secondary branches plant-1 at 0.25% Zn. The minimum secondary branches (5.08) were recorded in untreated plants (Table 1). The interaction of Ca and B indicated that combined application of Ca and B had even greater influence as compared to alone application of each of it. Plants treated with 0.6% Ca + 0.25% B increased the secondary branches to 10.00 as compared to 4.11 in control plants (Figure 5). The interaction between B and Zn indicated that application of 0.25% B + 0.5% Zn resulted in the maximum number of secondary branches (8.67), while plants sprayed with 0.5% B + 0% Zn had the minimum (3.83) number of secondary branches plant-1 (Figure 6).

Number of leaves per plant

The foliar application of Ca, B, and Zn significantly affected the number of leaves plant-1. The Ca x B, Ca x Zn and B x Zn interactions were also significant, but Ca x B x Zn interaction was not significant (Table 2). Increasing Ca from 0 to 0.6% significantly increased the leaves plant-1 increased from 103 to 182, respectively but declined to 148 with additional Ca application up to 0.9% (Table 2). Foliar application of B from 0 to 0.25% significantly increased the leaves from 112 to 177. However, high B concentration (0.5%) decreased the leaves plant-1 to 132 (Table 2). Increasing Zn concentration increased the number of leaves, which was the highest (167) with the application of 0.5% Zn, followed by 148 leaves plant-1 recorded with 0.25% Zn application. Whereas the least leaves number per plant (106) were noted in control (Table 2). The interaction between Ca and B indicated that leaves plant-1 increased tomato leaves to the maximum (240) at 0.25% B + 0.6% Ca, while the control plants had the minimum leaves plant-1 (69.78) (Figure 7).

The interaction between Ca and Zn revealed that the highest leaves (236) were counted in plants sprayed with combination of 0.25% Zn + 0.6% Ca. The minimum leaf number (78) was recorded in control plants (Figure 8). The interaction between B and Zn resulted in increased leaves plant-1. The maximum leaves plant-1 (213.58) was found in plants treated with 0.25% B + 0.5% Zn, while the minimum number of leaves plant-1 (98.83) was in plants sprayed with 0.5% B and no Zn (Figure 9).

Table 2: Effect of calcium, boron, and zinc foliar application on No. of leaves plant-1, leaf area (cm2) and number of fruit plant-1 of tomato.

Calcium Levels (%) No. of Leaves plant-1 leaf area (cm2) Number of fruit plant-1 0 103 d 46.33 c 50.11 d 0.3 126 c 58.85 b 55.96 c 0.6 182 a 65.52 a 66.15 a 0.9 148 b 54.37 b 60.89 b LSD at α 0.05 20.67 5.57 2.61 Boron (%)       0 112 c 49.03 c 46.67 c 0.25 177 a 57.44 b 67.78 a 0.5 132 b 62.33 a 60.39 b LSD at α 0.05 17.85 4.82 2.26 Zinc (%)       0 106 c 48.48 c 54.22 c 0.25 148 b 57.06 b 56.83 b 0.5 167 a 63.33 a 63.78 a LSD at α 0.05 17.85 4.82 2.26 Interactions       Ca x B Fig 7 Fig 10 Fig 12 Level of Significance ** * ** Ca x Zn Fig 8 --- --- Level of Significance * NS NS B x Zn Fig 9 Fig 11 Fig 13 Level of Significance ** ** ** Ca x B x Zn --- --- --- Level of Significance NS NS NS

Means followed by similar letter(s) in column do not differ significantly from one another. NS: Non-significant; *, **: Significant at 5 and 1% level of probability, respectively.

Leaf area (cm2)

Foliar application of Ca, B, and Zn significantly affected leaf area of tomato. The Ca x B and B x Zn interactions were also significant, while Ca x Zn and Ca x B x Zn interactions effect was not significant on leaf area (Table 2). The leaf area increased from 46.33 to 65.52 cm2 when Ca concentration of the foliar spray was increased from 0 to 0.6%. However, further increment in the concentration of Ca to 0.9% decreased the leaf area (54.37 cm2), which was statistically at par with leaf area recorded at 0.3% Ca application (58.85 cm2) (Table 2). The average leaf area increased with increase in B concentration from 0 to 0.5%. The leaf area was recorded maximum 62.33 cm2 in plants sprayed with 0.5% B solution was followed by 57.44 cm2 leaf area with 0.25% B application. The least leaf area 49.03 cm2 was recorded in control plants (Table 2). Similarly, leaf area of tomato increased with increasing Zn concentration. The leaf area was the highest (63.33 cm2) at 0.5% Zn followed by leaf area of 57.06 cm2 at 0.25% Zn concentration. Leaf area was the least (48.48 cm2) in control plants (Table 2). The interaction between Ca and B indicated that the leaf area of tomato was the highest at 0.5% concentration of B with increasing concentration of Ca till 0.6%. The plants treated with 0.6% Ca + 0.5% B had the maximum leaf area (79.22 cm2) in contrast to the leaf area (38.22 cm2) of control plants (Figure 10). The interaction between B and Zn illustrated that the leaf area of tomato continuously enhanced with increase in concentration of B at all levels of Zn. The leaf area increased from the minimum of 45.92 cm2 in control plants to the maximum of 78.83 cm2 in plants sprayed with 0.5% of B + 0.5% Zn (Figure 11).

Number of fruits plant-1

Foliar application of Ca, B, and Zn significantly influenced fruits plant-1. The CaxB and BxZn interactions were significant while Ca x Zn and Ca x B x Zn interactions were not significant for fruits plant-1 (Table 2). Fruits plant-1 increased from 50.11 to 66.15 when Ca concentration as foliar spray was increased from 0 to 0.6%. However, additional enhancement in concentration of Ca to 0.9% decreased fruits plant-1 (60.89) (Table 2). Likewise, fruits plant-1 increased from 46.67 to 67.78 with increment in concentration of B as foliar spray from 0 to 0.25%. However, promotion in concentration of B to 0.5% declined fruits plant-1 (60.39) (Table 2). The fruits plant-1 of tomato continuously increased with increasing concentration of Zn. The fruits plant-1 in control plants (0% Zn) was 54.22 that increased to 63.78 when Zn concentration increased to 0.5% followed by 56.83 fruits plant-1 with 0.25% Zn application (Table 2). The interaction between Ca and B indicated that fruits plant-1 improved with increasing concentration of Ca from 0 to 0.6% at 0.25% of B. However, increasing Ca concentration to 0.9% did not increase fruit number plant-1. The increase in number of fruit plant-1 of tomato was higher (78.00) in plants treated with 0.25% B + 0.6% Ca as compared to fruits plant-1 (39.67) in control (Figure 12). The interaction between B and Zn revealed that fruits plant-1 were increased from (38.33) in control to (70.83) in plants treated with 0.5% B + 0.5% Zn (Figure 13).

The plant height, primary and secondary branches, leaves per plant and average leaf area increased by 12, 42, 51, 77 and 41%, respectively over control treatment when calcium levels were increased from 0 to 0.6% but further increase in Ca (0.9%) reduced these parameters. Likewise, plant height, primary and secondly branches and leaf number per plant significantly increased by 14, 42, 66 and 58, respectively with increased B concentration up to 0.25% whereas further addition of B in foliar spray up to 0.5% decreased these parameters. However, the leaf area increased by 27% at 0.5% level of B. Plant height, primary and secondary branches, leaves plant-1 and leaf area increased by 7, 32, 26, 58 and 31% than control with increasing Zn concentration from 0 to 0.5%. However, the Ca x B and B x Zn interactive effect was found more effective in increasing the growth parameters as compared to the sole application of each nutrient.

The increment in the study attributes by application is due to the fact that calcium is an essential constituent of plant cell wall and plays a significant function in cell division and enlargement (Rashid, 2000; Ilyas et al., 2014). The Ca is directly involved in improving photosynthesis which results in high leaf number (Hussain et al., 2003). The Ca alone improved leaf area by activating enzymes, photosynthesis and carbohydrates metabolism (Bergmann, 1992; Hussain et al., 2003). Therefore, it is likely to observe taller plants, more branches per plant and more leaf area with foliar application of Ca. Increasing Ca+2 concentration enhanced plant length, leaf area and fruits number (Hao and Papadopoulos, 2003; Rubio et al., 2009; Shafeek et al., 2013). The present results are in close conformity with Ayyub et al. (2012) who reported that tomato plant height, generally, respond positively to foliar application of Ca and increases vegetative or shoot growth of tomato plant. Likewise, the boron is also linked with the development of plant cell wall and differentiation of cells and results in improved shoot growth (Basavarajeshwari et al., 2008) and thus increased plant height, branches per plant and leaves per plant (Ilyas et al., 2014; Oyinlola, 2004), which greatly confirmed the present results. It was also observed that further increase in B concentration decrease the plant height, branches, leaves per plant and average leaf area. Plant demand for Boron as micronutrient varies broadly. The ranges of deficiency and excess causing toxicity are also slim. Boron management is tricky as its optimum plant’s application range is restricted and optimal B doses can differ from soil to soil (Gupta, 1993; Marschner, 1995). There is very a slim array in decisive tissue concentrations between boron excess and deficiency for different plant species (Blamey et al., 1997). The toxicity of B exerts different effects on vascular plants such as in decreased photosynthetic rates, decline in the cell division, and decreased suberin and lignin levels (Nable et al., 1997; Reid, 2007). Plant exposed to high B concentration, may have reduced vegetative growth like height, leaves, branches and reproductive growth like flowers and fruits (Nable et al., 1997; Bagheri et al., 1992).

Increase in plant height, branches and leaves per plant with foliar application of Zn may be due to Zn role in tryptophan formation, required for auxin synthesis and plant growth (Mallick and Muthukrishnan, 1979). Besides, the increase in the biosynthesis of auxin, Zn also promotes nutrient uptake (Cakmak, 1999) that ultimately increase vegetative growth and so as the leaf number as well. Zinc may also enhance translocation of metabolites as well as cell elongation and thus, increase the leaf area (Hatwar et al., 2003). Since both Ca and B are required for plant growth (Bose and Tripathi, 1996) and B also enhances the metabolism of Ca particularly in the cell wall (Blevins and Lukaszewki, 1998), thus Ca + B combination was proved more effective in producing taller plants, more branches per plant and high leaf number which were in accordance with the results of Asad et al. (2003), Dole and Wilkins (2005), Rab and Haq (2012). Similarly, the combination of Zn and B was more effective in promoting plant height, branches plant-1 and leaves plant-1 probably by increasing photosynthetic and metabolic activity, cell division and cell elongation (Hatwar et al., 2003) Likewise, the combined application of Zn + B was found significantly more effective in increasing number of branches as compared to alone application of each nutrient (Zn and B) (Denre et al., 2014; Harris and Mathuma, 2015) due to enhanced photosynthesis (Rawat and Mathpal, 1984). The Zn + B combination also have significant function in formation of plant meristem (Shnain et al., 2014), so resulted in higher number of branches (Harris and Mathuma, 2015). The Zn + B combined application increased the leaf number per plant of tomato (Ayyub et al., 2012; Singh and Tiwari, 2013). Shnain et al. (2014) recorded an increase in vegetative attributes of tomato with 1.25 g L-1 B and 1.25 g L-1 Zn both alone and in combination.

Fruits per plant increased by 32% when Ca concentration increased from 0 to 0.6% over control. Likewise, fruit per plant increased significantly by 45% when boron was increased from control to 0.25%. Fruits plant-1 consistently increased by 18% when Zn concentration was increased from 0 to 0.5%. The interactions of Ca x B and B x Zn were more effective in increasing the fruit plant-1 than alone application of Ca, B and Zn.

The increase in the number of fruit of tomato with Ca application might be due the higher uptake of phosphorus that resulted in more flower cluster (Dey, 2000; Ilyas et al., 2014) and enhanced fruits plant-1 in tomato plant (Ilyas et al., 2014). Moreover, calcium may also inhibit flower abscission and, thus, results in increased fruits plant-1 (Smit and Combrink, 2005).

The foliar application of B enhances sugars levels of the stigma and helps in fruit set by promoting the pollen tube growth along with pollen germination (Singh et al., 2003). Boron regulates the metabolism of carbohydrates (Haque et al., 2011) and increase carbohydrate supply for formation of flowers and fruit set in tomato (Smit and Combrinke, 2005; Desouky et al., 2009) as well as decrease flower abscission (Smit and Combrink, 2005). Thus, boron application increased fruits plant-1.

The zinc increase the number of fruits plant-1 by increasing IAA synthesis (Shnain et al., 2014) as well as carbohydrates translocation (Singh and Tawari, 2013). The foliar application of Zn also increases the photosynthates translocation to the fruit, and decrease in flowers and fruits abscission (Graham et al., 2000; Ruby et al., 2001; Ali et al., 2008). Thus, Zn foliar application may results in more fruits plant-1. Thus, the combination of Ca+ and B was more effective in increasing fruits plant-1. Similarly, B and Zn promote the translocation of carbohydrate from site of formation to sinks that resulted in increased fruits plant-1 (Singh and Tiwari, 2013).

Conclusions and Reccomendations

Sole application of calcium, boron and zinc and interactive effect of Ca × B and Ca × Zn had a significant effect on the growth as well as on the fruit production of tomato. Therefore, tomato plants could be sprayed with 0.6% Calcium, 0.25% Boron and 0.5% Zn alone and in combination for improving the vegetative and reproductive attributes. However, 0.5% boron enhanced the leaf area of tomato.

Author’s Contributions

Bibi Haleema: is the principal author and this manuscript is part of her Ph.D work.

Abdur Rab: was the main supervisor.

Syed Asghar Hussain: was the co-supervisor of the principal author and helped to make available the resources for completion of research and also helped in reviewing the manuscript.

Acknowledgments

The authors highly appreciate the financial support of Higher Education Commission for the successful completion of this research project.

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