ABSTRACT                               

Micronutrients applications are effective for better crop production in calcareous soils because these soils are usually deficit in iron (Fe), zinc (Zn) and boron (B). In Pakistan, most of soils are calcareous in nature. When tuberose is grown in such soils as a cut flower, its production is negatively affected. Therefore, a study was aimed to evaluate the effects of micronutrients as foliar sprays on cut tuberose production in calcareous soil. Micronutrients (Fe, Zn and B) alone and in combinations were sprayed on the plants after 60, 90 and 120 days of planting. The mixture of all these three micronutrients increased the plant height (95.77 cm), chlorophyll content (38.13 SPAD), number of leaves (79.63), leaf length (44.73 cm), fresh (111.64 g) and dry (16.16 g) plant weights, root length (15.13 cm), number of stalks (3.73), stalk length (79.03 cm), spike length (22 cm), number of florets (51.67), floret fresh weight (11.85 g), leaf Zn concentration (53.6 mg/g) and vase life (8.4 days). Fe + Zn enhanced the number of leaves (76.60), leaf length (45.83 cm), root length (15.05 cm), spike length (22.33 cm), and leaf Fe (128.18 mg/g) and Zn concentrations (55.02 mg/g). The Fe spray increased the leaf length (44.10 cm), days to flower initiation (142.47 days) and leaf Fe concentration (130.75 mg/g) in tuberose plants. Application of Zn improved the leaf length (45.87 cm) and diameter (1.32 cm), root (15.03 cm), spike (21.77 cm) and floret lengths (4.74 cm), floret dry weight (1.49 g) and leaf Zn concentration (57.5 mg/g). Foliar spray of B increased the B concentration (21.1 mg/g) in tuberose leaves. It is concluded that foliar application of micronutrients alone and in combinations improved the plant growth, flowering, leaf minerals concentrations and vase life of tuberose spikes. However, mixture of Fe, Zn and B was more effective as compared to other treatments. Moreover, current study encourages the foliar application of micronutrients in tuberose when grown in calcareous soils.

INTRODUCTION

Tuberose (Polianthes tuberosa L.) is a famous bulbous perennial grown throughout the world as bedding plant and cut flower. The temperature requirement for optimum plant growth is 30 °C and plant does not require any shade and support (Muriithi et al., 2011). Sandy loam and loamy soils with pH ranging from 6.5 to 7.5 are needed for its optimal growth. It is grown commercially in USA, China, Taiwan, New Zealand, Netherlands, Rwanda, Japan, South Africa, Mexico, France, Egypt, Italy, and India (Barba-Gonzalez et al., 2012). It is used as cut flower and when production is in excess then essential oil can be extracted for export (Muriithi et al., 2011). In Pakistan, it is mostly grown around the big cities. Peri-urban areas of Multan, Lahore, Pattoki, Sheikhupura, Faisalabad, Quetta, Islamabad, Rawalpindi, Hyderabad, and Karachi are famous sites for tuberose cultivation in Pakistan (Usman and Ashfaq, 2013; Shahzad et al., 2021). Tuberose flower yield and spike quality are still low in Pakistan because of poor soils and inappropriate fertilization of micronutrients.

Most of the soils in developing countries are deficit in Zn and B (Sharma and Khare, 2014). Flowering crops are much responsive to micronutrients (Jatav et al., 2020), therefore their application is necessary for proper plant growth and flowering when roots are not going to uptake these nutrients. The appropriate amounts of suitable micronutrients, their time and method of application are vital for enhanced growth and quality flowering of tuberose plants. Foliar spray by direct application on aerial plant parts is effective method than root fertilization to rectify deficiency symptoms, maintain nutritional status and improve growth and produce quality in marginal soils (Otálora et al., 2018). The trend of foliar application is increasing to overcome the nutritional deficiency more quickly than root application (Niu et al., 2020). Soil pH may affect the availability and uptake of micronutrients. Higher soil pH increases the deficiency of micronutrients in crop plants and causes different physiological problems, i.e., chlorosis, scorching and rosetting in plants which limit plant growth and flowering (Singh et al., 2012). In calcareous soils, application of micronutrients, viz. B, Zn, Fe, Cu and Mn is more effective through spray on leaves as compared to root application (Kaya et al., 2005) because liquid fertilizers spray rapidly recovers the deficiency of these micronutrients. Moreover, nutrients penetrate leaf cuticle and then transported into plant parts by plasmodesmata (Kannan, 2010) as in strawberry (Pestana et al., 2012) .

Micronutrients usually improve chlorophyll pigments, synthesis of protein and nucleic acid, which further improves growth and flowering in floral crops i.e., gladiolus (Sharma and Khare, 2014), chrysanthemum (Vanlalruati et al., 2019) and marigold (Yadegari, 2013). Fe is necessary for protein, chlorophyll and thylakoid synthesis, respiratory enzymes, energy transportation and cofactor to activate the enzymes(Marschner, 1995; George and Manuel, 2013). Fe deficiency reduces photosynthetic pigments and leaves show yellow colour. However, young leaves and new flushes are firstly affected than older leaves (Havlin, 2014). Zn is important for proper functioning of photosynthetic processes, nitrogen metabolism and uptake, carbon anhydrase activity, metabolism and synthesis of carbohydrate, tryptophan synthesis, protein quality, precursor of IAA and increase tolerance against oxidative stress, and enhances vase life of flowers (Sofy et al., 2020; Toor et al., 2020). Leaf size is reduced, and internodes are shortened due to deficiency of Zn. Moreover, susceptibility to light and temperature, and chances of fungal diseases increase in harvested produce (Cakmak, 2000). B is required for photosynthesis, enzymes activation, carbohydrate chemistry, cell wall strengthening, hormones production, respiration, stomatal regulation, IAA and RNA metabolism, sugars translocation, cell division and membranes integrity in plants (Yermiyahu et al., 2008). So, foliar application of Fe, Zn and B results in increased growth and yield of floral crops.

Nutritional deficiency is major problem for farmers having calcareous soils. In Pakistan, most of the soils are calcareous in nature, especially in arid and semi-areas of South Punjab. These soils have higher pH level range of 7.5 to 8.5, rich in calcium carbonate and low in organic matter (Anjum et al., 2019). Higher pH and calcium carbonate depress the availability and absorption of different nutrients, viz. P, K, Zn, Fe and B. Therefore, foliar application is effective strategy to improve the nutritional status of plants grown in such soils. Huge work has been conducted on application of macronutrients to tuberose plants; however, application of micronutrients still is neglected. A balanced fertilization is necessary for excellent growth and good quality spikes of tuberose. Hence, current work was conducted to evaluate the effects of foliar applications of micronutrients, i.e., Fe, Zn and B alone and in various combinations on growth, flowering, leaf minerals and vase life of tuberose plants grown in calcareous soil.

MATERIALS AND METHODS

Experimental site

Current experiment was performed at the Horticultural Research Area, Bahauddin Zakariya University, Multan, Pakistan during 2018 and 2019. Monthly temperature and rainfall data collected from sowing to harvesting of tuberose crop during 2018 and 2019 is listed in Fig. 1.

Figure 1: Monthly temperature and rainfall data collected from sowing to harvesting during 2018 and 2019.

Soil analysis

For soil analysis of experimental area, soil samples were taken from different field locations to a depth of 0-25 cm during both years of study. These samples were air dried to determine the soil physico-chemical properties as listed in Table 1.

Table 1: Soil analysis before planting of tuberose.

Treatment applications

The detailed description of different micronutrients sprayed on tuberose plants are presented in Table 2. Experimental field was prepared with thorough ploughing followed by planking to obtain better soil tilth. Tuberose cv. Pearl Double was propagated through bulbs, obtained from a nursery (Sadabahar Nursery) at Pattoki, Kasur, Pakistan. The bulbs of 3-5 cm diameter were planted on ridges at 30 cm apart with 20 cm interplant distance on March 10, 2018. Sixty bulbs were planted in each treatment. First irrigation was applied immediately after planting and then at weekly intervals. The bulbs’ sprouting was observed after 20-25 days of planting. During the second year (2019), the bulbs were planted on the same date (March 10). All the agronomic practices followed were same during both years.

Table 2: The detail of micronutrients treatments.

Experimental Layout

Micronutrients (Fe, Zn and B) alone and in combinations were sprayed on the plants after 60, 90 and 120 days of planting. Per plant, 20 mL of solution was sprayed. The experiment was arranged in a randomized complete block design (RCBD) with three replications. Ten plants were randomly selected in each treatment from each replication for data collection.

Growth traits

Chlorophyll content was recorded by SPAD meter (MINOLTA-502). Plant height, leaf and root lengths were measured through a measuring scale. Leaf diameter was estimated through a Vernier calliper (IKKEGOL). Number of leaves was counted from each randomly selected plant. Fresh and dry weights of plant were recorded by using a digital weighing balance (HB-600). Fresh samples were dried in hotbox oven at 70 °C till constant dry weight.

Flowering traits

Flower- emergence, number of stalks and number of florets per spike were counted. Lengths of stalk, spike and floret were measured by using a measuring scale. Fresh and dry weights of stalk and floret were estimated through a digital weighing balance (HB-600). Vase life of flowers was recorded in days till the wilting of 50% florets as described by Shahzad et al. (2021). Half opened flowers were harvested and put in distilled water for estimation of vase life at room temperature.

Micronutrient estimation in leaves

Micronutrients i.e., Fe and Zn in tuberose leaves were measured by a digestion procedure described by Rashid (1986). Dry-ashing method was adopted for determination of B in leaves as described by Chapman and Pratt (1961) and Bingham (1982).

Statistical analysis

A software, Statistix 8.1 (Tallahassee Florida, USA), was employed for evaluation of collected data using analysis of variance (ANOVA) technique. Two year’s data were pooled, and averages were computed. Treatment means were separated through least significant difference (LSD) test at 5% probability level (Steel et al., 1997).

RESULTS

Growth traits

Tuberose plants had greatest plant height under application of Fe + Zn + B (95.77 cm), while lowest plant height was recorded in plants where micronutrients were not sprayed (control) (60 cm) (Table 3). Chlorophyll content were found to be highest when plants were supplied with foliar application of Fe + Zn + B (38.13 SPAD), followed by Zn, while lowest chlorophyll content was recorded in plants without any foliar spray (23.79 SPAD) and Fe only (26.27 SPAD) (Table 3). The maximum number of leaves per plant was counted under application of Fe + Zn + B (79.63) and Fe + Zn (76.6) than control (45.1) (Table 3). Larger leaf length was measured in Fe + Zn + B, Fe + Zn (44.73 cm), Zn (45.83 cm) and Fe (44.1 cm), followed by Fe + B (43.13 cm), while smaller leaf length was measured in control (35.27 cm), followed by B (37.53 cm) (Table 3). Leaf diameter was found to be larger under spray of Zn (1.32 cm), Fe + B (1.32 cm), followed by Fe + Zn + B (1.27 cm), Zn + B (1.21 cm) and Fe + Zn (1.19 cm) (Table 3). The maximum fresh weight per plant was recorded in Fe + Zn + B (111.64 g), while the minimum fresh weight per plant was obtained in control (43.77 g) (Table 3). Dry weight per plant was found to be greater in Fe + Zn + B (16.16 g), followed by Fe + Zn (14. 87 g) and Zn (14.38 g), while lower dry weight per plant was recorded in control (7.71 g) (Table 3). Root length was longer in Fe + Zn + B (15.13 cm), Fe + Zn (15.05 cm) and Zn (15.03 cm), followed by Fe + B (13.68 cm), Zn + B (14.03 cm) and Fe (14.05 cm), while shorter root length was measured in control (11.67 cm) and B (12.11 cm) (Table 3).

Table 3: Effect of foliar application of micronutrients on growth traits of tuberose plants.

Means with different letter(s) in a column are statistically significant at p = 0.05 (LSD) test.

Flowering traits

Fe application delayed flowering in tuberose with the maximum days to flower emergence (142.47 days), followed by control (140.87 days) and Fe + B application (141.07 days), while the minimum days to flower emergence was observed in Zn + B (135.70 days), B (135.03 days) and Fe + Zn (136.70 days), followed by Zn (138.47 days) and Fe + Zn + B (137.17 days) (Table 4). Number of stalks was greater in Fe + Zn + B (3.73), followed by Fe + Zn (3.33), while least number of stalks was obtained in control (1.87) (Table 4). Stalk length was greater in Fe + Zn + B (79.03 cm), while shorter stalk length was obtained in B (36.17 cm) and control (38.50 cm) (Table 4).Spike length was larger in Fe + Zn (22.33 cm), Zn (21.77 cm) and Fe + Zn + B (22 cm), while smaller spike length was found in B (11.60 cm) and control (12.67 cm) (Table 4). Greater floret length was observed in Zn (4.74 cm), followed by Fe + Zn + B (4.33 cm), Fe (3.70 cm), Fe + Zn (4 cm), Fe + B (3.75 cm) and Zn + B (3.71 cm), while smaller floret length was measured in control (2.45 cm), followed by B (3.52 cm) (Table 4). The maximum number of florets was counted in Fe + Zn + B (21.57), followed by Fe + Zn (19.93), while the minimum number of florets was counted in control (8.20) (Table 4). Fresh weight of florets per spike was found to be greater in Fe + Zn + B (11.85 g), while lesser fresh weight of florets per spike was observed in control (3.25 g), followed by B (4.43 g) (Table 4). The maximum dry weight of florets per spike was obtained in Zn (1.49 g), while the minimum dry weight of florets per spike was fund in control plants (0.34 g) of tuberose (Table 4).

Table 4: Effect of foliar application of micronutrients on flowering of tuberose plants.

Means with different letter(s) in a column are statistically significant at p = 0.05 (LSD) test.

Leaf Fe, Zn and B contents

The presence of Fe content in tuberose leaves was found to be higher in Fe + Zn (128.18 mg/g) and Fe (130.75 mg/g) treatments, while lower Fe content was present in plants sprayed with B (11.71 mg/g) and Zn + B (11.97 mg/g) (Fig. 2A).Zn content in leaves was greater in Zn (57.5 mg/g), Fe + Zn (55.02 mg/g) and Fe + Zn + B (53.6 mg/g) sprayed plants, while lesser Zn content was estimated in control (8.79 mg/g) (Fig. 2B).The maximum B content was found in leaves of B treated plants (21.1 mg/g), while the minimum B content were present in leaves of control (6.53 mg/g), Fe + Zn (7.07 mg/g), Zn (6.53 mg/g) and Fe (7.27 mg/g) sprayed plants (Fig. 2C).

Figure 2: Effect of foliar application of micronutrients on minerals in leaves of tuberose plants. Vertical bars indicate SE of the means and data are mean of three biological replicates. Different letters indicate significant differences among the means according to LSD test p ≤ 0.05. T₀ = control, T₁ = Fe, T₂ = Zn, T₃ = B, T₄ = Fe + Zn, T₅ = Fe + B, T₆ = Zn + B, T₇ = Fe + Zn + B.

Vase life of spikes

Under application of different micronutrients, vase life of spikes was found to higher in Fe + Zn + B (8.4 days), while the lower vase life of spike was recorded in control (5.4 days) and B (5.7 days) treated plants of tuberose as compared to other micronutrients treatments (Fig. 3).

Figure 3: Effect of foliar application of micronutrients on vase life of tuberose flowers. Vertical bars indicate SE of the means and data are mean of three biological replicates. Different letters indicate significant differences among the means according to LSD test p ≤ 0.05. T₀ = control, T₁ = Fe, T₂ = Zn, T₃ = B, T₄ = Fe + Zn, T₅ = Fe + B, T₆ = Zn + B, T₇ = Fe + Zn + B.

DISCUSSION

Calcareous soils are deficit in Fe, Zn and B, which result in poor quality of spikes in tuberose plants. Therefore, spray of Fe, Zn and B on leaves is very effective and rapid way of nutrients absorption in plants to protect from nutritional deficit conditions (Niu et al., 2020). In the present results, the enhanced chlorophyll content was due to foliar application of Fe + Zn + B in tuberose plants which indicated the improved level of chlorophyll content in leaves by fulfilling the plant nutrition. The increase of leaf chlorophyll content was possibly due to increased availability of nutrients in appropriate quantity and at right time (Balakrishnan et al., 2007; Rabnawaz et al., 2020). In the current study, the enhanced growth and biomass of tuberose plants grown in calcareous soils were observed under application of mixture of Fe + Zn + B. Recently, similar increase in growth of a flowering crop “Ascocenda orchid” was observed under foliar application of micronutrients (Kumar and Singh, 2020). Fe sprays on leaves regulate the development of chloroplast, formation of chlorophyll, photosynthesis, and respiration activities of plants (Miller et al., 1995). Moreover, physiological, and biochemical mechanism of plants were also improved by Fe application. Zn acts as a catalyst in activation of enzymes and chlorophyll development (Patil et al., 2010). Foliar application of B, Zn and Fe alone and in mixture increased the plant growth possibly by improving auxin synthesis and chlorophyll content as obtained in present and earlier work (Ahmad et al., 2010). Plant height and biomass were found to be increased in numerous crops i.e., tomato (Bhatt et al., 2004), brinjal (Kiran et al., 2010) and marigold by the foliar application of micronutrients.

Application of micronutrients and their optimum concentrations greatly increased flowering traits and improve vase life of spikes (Ahmad et al., 2010). In the present study, enhanced flowering traits of tuberose were observed under foliar application of mixture of Fe, Zn and B. Current results are in line with earlier work because combination of different micronutrients may improve the flowering traits i.e., weight, size, and vase life of floral crops e.g., gladiolus (Sharma and Khare, 2014), chrysanthemum (Vanlalruati et al., 2019) and marigold (Yadegari, 2013). B application improves cell elongation, IAA synthesis, cell maturation, sugar translocation and protein synthesis. All these compounds are necessary for increase of crop production (Kiran et al., 2010). Recently, Genaidy et al. (2020) also observed increase in pollen germination and improved elongation of pollen tube by application of B and its mixture with other micronutrients. Similarly, Fahad et al. (2014) applied mixture of Fe, Zn and B and obtained enhanced weight and size of stalks in gladiolus. Jat et al. (2007) and Chopde et al. (2015) observed the stimulation of RNA metabolism, DNA formation and carbohydrates synthesis which are necessary for increase of flowering traits in floral crops.

In the present study, foliar application of micronutrients like Fe, Zn and B increased their concentrations in tuberose leaves. Fe alone and in combination with Zn are found to be effective sprays for increase of Fe concentration in tuberose leaves. Absorption of minerals increases by application of different macro and micronutrient as confirmed by earlier work of (Kolekar and Bhagyaresha (2018). However, enhanced concentration of Fe in tuberose leaves was due to foliar application of Fe. Applications of Zn alone and in combination with Fe and B are found to be effective for increase of Zn absorption in tuberose plants. B application also increased B concentration in tuberose leaves. So, current study is in agreement to earlier work of Ahmad et al. (2010) who found that the application of Zn and B increased the concentrations of Zn and B in leaves of roses. In another study, Khosa et al. (2011) also observed improved B concentration in Gerbera leaves under B fertilization.

Tuberose flower spikes are found to be highly perishable at higher temperature (Kumari et al., 2018). Flower quality is mainly based on vase life of flower spikes (Patel et al., 2017). After harvesting, flower spikes lose their turgidity and internal carbohydrates deterioration is enhanced, therefore tuberose flowers have poor vase life (Vidhya and Bhattacharjee, 2002). Foliar applications of different chemicals are necessary to reduce the post-harvest losses of tuberose flower spikes. In the present study, pre-harvest application of mixture of Fe, Zn and B resulted in enhanced vase life of tuberose flowers. The current study is in line with earlier work as pre-harvest foliar application of mixture of Fe, Zn and B increased the vase life of gladiolus (Fahad et al., 2014).

CONCLUSION

From the present work, it is concluded that foliar application of mixture of Fe, Zn and B is effective for increased growth and flowering of tuberose plants, vase life of their spikes and leaf mineral composition when grown in calcareous soil. Thus, micronutrients foliar spray is effective for increased production of floral crops with better quality of flowers and longer vase life. In the light of current results, Fe, Zn and B mixture was more effective than other studied treatments.

Funding statement

The project was funded by a Research Grant of Bahauddin Zakariya University, Multan (Pakistan).

REFERENCES                                                                                                                                     

Ahmad, I., Khan, M.A., Qasim, M., Ahmad, R. and Randhawa, M.A. 2010. Growth, yield and quality of Rosa hybrida L. as influenced by various micronutrients. Pakistan Journal of Agricultural Sciences, 47: 5-12. [Abstract/FREE full text, Google Scholar]

Anjum, M.A., Muhammad, H.M.D., Balal, R.M. and Ahmad, R. 2019. Performance of two onion (Allium cepa L.) cultivars under two different planting systems in calcareous soil. Journal of Horticultural Science and Technology, 2: 54-59. [Abstract/FREE full text, Google Scholar, CrossRef]

Balakrishnan, V., Jawaharlal, M., Kumar, T.S. and Ganga, M. 2007. Response of micro-nutrients on flowering, yield and xanthophyll content in African marigold (Tagetes erecta Linn.). Journal of Ornamental Horticulture, 10: 153-156. [Abstract/FREE full text, Google Scholar]

Barba-Gonzalez, R., Rodríguez-Domínguez, J.M., Castañeda-Saucedo, M.C., Rodríguez, A., Van Tuyl, J.M. and Tapia-Campos, E. 2012. Mexican geophytes I. the genus Polianthes. Floriculture and Ornamental Biotechnology, 6: 122-128. [Abstract/FREE full text]

Bhatt, L., Srivastava, B.K. and Singh, M.P. 2004. Studies on the effect of foliar application of micronutrients on growth, yield and economics of tomato (Lycopersicon esculentum Mill). Progressive Horticulture, 36: 331-334.

Bingham, F.T. 1982. Boron. Methods of Soil Analysis. Part 2. Soil Science Society of America, Inc. American Society of Agronomy, Inc. Madison, Wisconsin, USA, pp. 431-447. [Google Scholar]

Cakmak, I. 2000. Possible roles of zinc in protecting plant cells from damage by reactive oxygen species. The New Phytologist, 146: 185-205. [Abstract/FREE full text, PubMed, CrossRef]

Chapman, H.D. and Pratt, P.F. 1961. Methods of Analysis for Soils, Plants and Waters. Scientific Research an Academic Publisher, University of California, Los Angeles, pp. 150-179.

Chopde, N., Nehare, N., Maske, S.R., Lokhande, S. and Bhute, P.N. 2015. Effect of foliar application of zinc and iron on growth, yield and quality of gladiolus. Plant Archives, 15: 417-419. [Google Scholar]

Fahad, S., Ahmad, K.M., Anjum, M.A. and Hussain, S. 2014. The effect of micronutrients (B, Zn and Fe) foliar application on the growth, flowering and corm production of gladiolus (Gladiolus grandiflorus L.) in calcareous soils. Journal of Agricultural Science Technololgy, 16: 1671-1682. [Abstract/FREE full text, Google Scholar]

Genaidy, E.A., Abd-Alhamid, N., Hassan, H.S., Hassan, A.M. and Hagagg, L.F. 2020. Effect of foliar application of boron trioxide and zinc oxide nanoparticles on leaves chemical composition, yield and fruit quality of Olea europaea L. cv. Picual. Bulletin of the National Research Centre, 44: 1-12. [Abstract/FREE full text, Google Scholar, CrossRef]

George, P. and Manuel, J. 2013. Low cost tissue culture technology for the regeneration of some economically important plants for developing countries. International Journal of Agriculture, Environment and Biotechnology, 6: 703-711. [Abstract/FREE full text, Google Scholar]

Havlin, J.L. 2014. Soil: Fertility and Nutrient Management. Upper Saddle River, NJ, USA, pp. 460-469.

Jat, R.N., Khandelwal, S.K. and Gupta, K.N. 2007. Effect of foliar application of urea and zinc sulphate on growth and flowering parameters in African marigold (Tagetes erecta Linn.). Journal of Ornamental Horticulture, 10: 271-273. [Abstract/FREE full text, Google Scholar]

Jatav, H.S., Sharma, L.D., Sadhukhan, R., Singh, S.K., Singh, S., Rajput, V.D., Parihar, M., Jatav, S.S., Jinger, D. and Kumar, S. 2020. An overview of micronutrients: prospects and implication in crop production. In: Aftab T. and Hakeem K.R. (eds.). Plant Micronutrients. Springer, Cham, pp. 1-30. [Abstract/FREE full text, Google Scholar, CrossRef]

Kannan, S. 2010. Foliar fertilization for sustainable crop production. In: Lichtfouse, E. (eds) Genetic Engineering, Biofertilisation, Soil Quality and Organic Farming. Springer, Dordrecht, Switzerland. pp. 371-402. [Google Scholar]

Kaya, M., Atak, M., Mahmood, Khawar, K.M., Ciftci, C.Y. and Ozcan, S. 2005. Effect of pre-sowing seed treatment with zinc and foliar spray of humic acids on yield of common bean (Phaseolus vulgaris L.). International Journal of Agriculture and Biology, 7: 875-878. [Abstract/FREE full text, Google Scholar]

Khosa, S.S., Younis, A., Rayit, A., Yasmeen, S. and Riaz, A. 2011. Effect of foliar application of macro and micronutrients on growth and flowering of Gerbera jamesonii L. American-Eurasian Journal of Agricultural and Environmental Sciences, 11: 736-757. [Abstract/FREE full text, Google Scholar]

Kiran, J., Vyakaranahal, B.S., Raikar, S.D., Ravikumar, G.H. and Deshpande, V.K. 2010. Seed yield and quality of brinjal as influenced by crop nutrition. Indian Journal of Agricultural Research, 44: 1-7. [Abstract/FREE full text, Google Scholar]

Kolekar, P.B. and Bhagyaresha, G. 2018. Studies on macro and micronutrient status in leaf tissue of pomegranate (Punica granatum) orchards of Latur district. International Journal of Current Microbiology and Applied Sciences, 6: 112-119. [Google Scholar]

Kumar, A. and Singh, A.K. 2020. Effect of plant growth regulators and micronutrients on vegetative and flowering characters of gladiolus (Gladiolus grandiflorus L.) cv. Novalux. International Journal of Current Microbiology and Applied Sciences, 9: 1136-1143. [Abstract/FREE full text, Google Scholar, CrossRef]

Kumari, S., Raghupathi, B., Sarika, K. and Deb, P. 2018. Effect of different preservatives on vase-life of cut tuberose (Polianthes tuberosa L.) cv. Calcultta Single. International Journal of Current Microbiology and Applied Sciences, 7: 1651-1657. [Abstract/FREE full text, Google Scholar, CrossRef]

Marschner, H. 1995. Mineral Nutrition of Higher Plants, 2^nd Ed. Academic Press, New York.

Miller, G.W., Huang, I.J., Welkie, G.W. and Pushnik, J.C. 1995. Function of iron in plants with special emphasis on chloroplasts and photosynthetic activity. In: Abadía, J. (ed.). Iron Nutrition in Soils and Plants. Springer, Dordrecht, pp. 19-28. [Abstract/FREE full text, Google Scholar, CrossRef]

Muriithi, A.N., Wamocho, L.S. and Njoroge, J.B.M. 2011. Distribution, production and quality characteristics of tuberose (Polianthes tuberosa L.) cut flower in Kenya. African Journal of Horticultural Science, 5: 26-35. [Abstract/FREE full text, Google Scholar]

Niu, J., Liu, C., Huang, M., Liu, K. and Yan, D. 2020. Effects of foliar fertilization: a review of current status and future perspectives. Journal of Soil Science and Plant Nutrition, 21: 104-118. [Abstract/FREE full text, Google Scholar, CrossRef]

Otálora, G., Piñero, M.C., López-Marín, J., Varó, P. and Amor, D.F.M. 2018. Effects of foliar nitrogen fertilization on the phenolic, mineral, and amino acid composition of escarole (Cichorium endivia L. var. latifolium). Scientia Horticulturae, 239: 87-92. [Abstract/FREE full text, Google Scholar, CrossRef]

Patel, T.D., Viradia, R.R., Tejashwini, C.R., Patel, H.V. and Patel, U.R. 2017. Studied on effect of foliar application of micronutrient (Fe and Zn) on growth, flowering quality and yield of tuberose (Polianthes tuberosa L.) cv. Prajwal. International Journal of Chemical Studies, 5: 93-97. [Abstract/FREE full text, Google Scholar]

Patil, B.C., Hosamani, R.M., Ajjappalavara, P.S., Naik, B.H., Smitha, R.P. and Ukkund, K.C. 2010. Effect of foliar application of micronutrients on growth and yield components of tomato (Lycopersicon esculentum Mill.). Karnataka Journal of Agricultural Sciences, 21: 428-430.

Pestana, M., Correia, P.J., Saavedra, T., Gama, F., Abadía, A. and de Varennes, A. 2012. Development and recovery of iron deficiency by iron resupply to roots or leaves of strawberry plants. Plant Physiology and Biochemistry, 53: 1-5. [Abstract/FREE full text, Google Scholar, CrossRef]

Rabnawaz, A., Ahmad, R. and Anjum, M.A. 2020. Effect of seed priming on growth, flowering and cut flower quality of carnation. Indian Journal of Horticulture, 77: 527-531. [Abstract/FREE full text, Google Scholar, CrossRef]

Rashid, A. 1986. Mapping zinc fertility of soils using indicator plants and soil analyses. Doctoral dissertation, University of Hawaii at Manoa, USA. [Google Scholar]

Shahzad, S., Ali, S., Ahmad, R., Ercisli, S. and Anjum, M.A., 2021. Foliar application of silicon enhances growth, flower yield, quality and postharvest life of tuberose (Polianthes tuberosa l.) under saline conditions by improving antioxidant defense mechanism. Silicon. [Abstract/FREE full text, Google Scholar]

Sharma, U.B. and Khare, R.K. 2014. Effect of bio fertilizers and foliar spray of zinc under different levels of N, P on floral characteristics and economics of Gladiolus grandiflorus. Bhartiya Krishi Anusandhan Patrika, 29: 78-81.

Singh, J.P., Kumar, K. and Katiyar, P.N. 2012. Effect of zinc, iron and copper on yield parameters of gladiolus. HortFlora Research Spectrum, 1: 64-68. [Google Scholar]

Sofy, M.R., Elhindi, K.M., Farouk, S. and Alotaibi, M.A. 2020. Zinc and paclobutrazol mediated regulation of growth, upregulating antioxidant aptitude and plant productivity of pea plants under salinity. Plants, 9: 1197-1212. [Abstract/FREE full text, PubMed, Google Scholar, CrossRef]

Steel, R.G.D., Torrie, J.H., Dickey, D. A. 1997. Principles and procedures of statistics; a biometrical approach. 3. Boston: McGraw-Hill. [Abstract/FREE full text, PubMed, Google Scholar, CrossRef]

Toor, M.D., Adnan, M., Javed, M.S., Habibah, U., Arshad, A., Din, M.M. and Ahmad, R. 2020. Foliar application of Zn: Best way to mitigate drought stress in plants: a review. International Journal of Applied Research, 6: 16-20. [Abstract/FREE full text, Google Scholar]

Usman, M. and Ashfaq, M. 2013. Economic analysis of tuberose production in Punjab, Pakistan. Sarhad Journal of Agriculture, 29: 279-284. [Abstract/FREE full text, Google Scholar]

Vanlalruati, S.S., Anand, P. and Kumar, G. 2019. Effect of micronutrients (Fe and Zn) on flowering and yield attributes of chrysanthemum (Chrysanthemum morifolium) cv. Mayur 5. Indian Journal of Agricultural Sciences, 89: 1282-1286. [Abstract/FREE full text, Google Scholar]

Vidhya, S. and Bhattacharjee, S.K., 2002. Floriculture Research Trend in India. Indian Society of Ornamental Horticulture, New Delhi, pp.83-86.

Yadegari, M. 2013. Foliar application of Fe, Cu, Mn and B on growth, yield, and essential oil yield of marigold (Calendula officinalis). Journal of Applied Science and Agriculture, 8: 559-567. [Google Scholar]

Yermiyahu, U., Ben-Gal, A., Keren, R. and Reid, R.J. 2008. Combined effect of salinity and excess boron on plant growth and yield. Plant and Soil, 304: 73-87. [Abstract/FREE full text, Google Scholar, CrossRef]