Effect of foliar application of micronutrients on the growth and yield of cotton (Gossypium hirsutum)

Introduction

Cotton (Gossypium hirsutum L.) is one of the most important commercial fibre crops and is popularly known as "White Gold" due to its economic importance. It provides natural fibre for the textile industry, while cottonseed serves as a valuable source of edible oil and protein-rich meal. India has the largest area under cotton cultivation in the world; however, productivity remains comparatively low because a major proportion of the crop is grown under rainfed conditions. Cotton requires a balanced supply of nutrients throughout its growth period. Continuous cultivation, inadequate use of organic manures and imbalanced fertilizer application have resulted in widespread deficiencies of micronutrients such as zinc, iron and boron. These nutrients play an important role in plant growth, flowering, boll development and yield. Under rainfed conditions, nutrient uptake from the soil is often restricted because of limited moisture availability during critical growth stages. Foliar application of micronutrients is an effective method of supplying nutrients directly to plants, improving nutrient use efficiency and reducing micronutrient deficiencies. Maharashtra is one of the major cotton-growing states of India, where declining soil fertility and micronutrient deficiencies often limit crop productivity. Therefore, foliar application of micronutrients can serve as an effective nutrient management practice to improve crop growth and yield under field conditions. Keeping these facts in view, the present investigation was undertaken to evaluate the effect of foliar application of micronutrients on the growth and yield of cotton under the agro-climatic conditions of Akola, Maharashtra. The experiment was laid out in a Randomized Block Design (RBD) with different foliar micronutrient treatments and replications under recommended agronomic practices. Foliar application of micronutrients was carried out at the prescribed crop growth stages. Observations were recorded on growth parameters, namely plant height, number of monopodial branches plant -1 and number of sympodial branches plant -1 . Yield parameters such as number of bolls plant -1 , boll weight and seed cotton yield were also recorded. The experimental data were subjected to statistical analysis following the standard procedure for Randomized Block Design, and treatment means were compared at the 5 per cent level of significance.

Materials and methods

A

Results and discussion

Growth parameter 1.1 Plant height

Plant height was significantly influenced by foliar application of micronutrients at 60, 90, 120 DAS and at harvest, whereas no significant differences were observed at 30 DAS. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1

) recorded the highest plant height at 60 DAS (64.98 cm), 90 DAS (123.98 cm), 120 DAS (136.65 cm) and at harvest (146.02 cm), which was statistically at par with T 6 (12.5 ml L -1

) and T 5 (10 ml L -1 ). The lowest plant height was recorded under T 1 (RDF), with values of 28.04, 45.23, 86.75, 95.23 and 102.32 cm at 30, 60, 90, 120 DAS and harvest, respectively. The increased plant height under T 7 may be attributed to the combined effect of recommended fertilization and foliar application of micronutrients, which enhanced chlorophyll synthesis, auxin production, cell elongation and overall plant growth. Similar findings were reported by Hallikeri et al. (2011) [1] , Katkar et al. (2012) [2] , Giri et al. (2014) [3] and Kulvir Singh et al. (2015).

Number of monopodial branches plant-1

The number of monopodial branches plant -1 was significantly influenced by foliar application of micronutrients at all growth stages. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1

) recorded the highest number of monopodial branches at 60 DAS (2.10), 90 DAS (2.24), 120 DAS (2.24) and at harvest (2.24). At 90 DAS, 120 DAS and harvest, T 7 remained statistically at par with T 6 (RDF + foliar spray of MNS @ 12.5 ml L -1 ). The lowest number of monopodial branches was recorded under T 1 (RDF), with values of 1.26, 1.40, 1.40 and 1.40 at 60, 90, 120 DAS and harvest, respectively. The increase in monopodial branches under T 7 may be attributed to the role of micronutrients in enhancing auxin synthesis, chlorophyll formation and cell division, resulting in vigorous vegetative growth and branch development. Similar findings were reported by More et al. (2018) [4] , Raj et al. (2019) [5] and Karademir (2020).

Number of sympodial branches plant-1

The number of sympodial branches plant -1 was significantly influenced by foliar application of micronutrients at all growth stages. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1

) recorded the highest number of sympodial branches at 60 DAS (7.86), 90 DAS (17.20), 120 DAS (24.34) and at harvest (24.34). At 90 DAS, T 7 was statistically at par with T 6 (16.64) and T 5 (15.39), while at 120 DAS and harvest it remained at par with T 6 (22.04). The lowest number of sympodial branches was recorded under T 1 (RDF), with values of 4.40, 13.32, 17.34 and 17.34 at 60, 90, 120 DAS and harvest, respectively. The increased number of sympodial branches under T 7 may be attributed to improved photosynthetic efficiency, enhanced carbohydrate translocation and better reproductive growth due to foliar application of micronutrients. Similar findings were reported by Nehra et al. (2006) [6] , Bhalerao et al. (2012) [7] , Gangaiah et al.

Yield and yield attributes 2.1 Number of picked bolls plant-1

The number of picked bolls plant -1 was significantly influenced by foliar application of micronutrients. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1

) recorded the highest number of picked bolls (48.45), which was statistically at par with T 6 (45.82) and T 5 (44.27), whereas the lowest number of picked bolls (37.24) was recorded under T 1 (RDF). The increased boll production under T 7 may be attributed to improved boll retention, reduced square and boll shedding, and enhanced reproductive development due to foliar application of micronutrients. Similar findings were reported by Giri et al. (2014) [3] , Halemani et al. (2004) and Nehra et al. (2006) [6] .

Lint yield

Foliar application of micronutrients significantly influenced lint yield per plant and per hectare. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1 ) recorded the highest lint yield per plant (76.96 g plant -1 ) and lint yield per hectare (1222.28 kg ha -1 ), which were statistically at par with T 6 (74.84 g plant -1 and 1162.25 kg ha -1 , respectively). The lowest lint yield per plant (60.65 g plant -1 ) was recorded in T 2 , while the minimum lint yield per hectare (915.34 kg ha -1 ) was recorded under T 1 (RDF). The higher lint yield under T 7 may be attributed to improved boll development, enhanced photosynthetic efficiency and better translocation of assimilates due to foliar application of micronutrients. Similar findings were reported by Sawan et al. (2007) [8] , Hallikeri et al. (2010) [9] , Katkar et al. (2013) [10] and Paslawar et al. (2015) [11] .

Seed cotton yield

Foliar application of micronutrients significantly influenced seed cotton yield per plant and per hectare. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1 ) recorded the highest seed cotton yield per plant (219.89 g plant -1 ) and per hectare (3492.22 kg ha -1 ), which were statistically at par with T 6 (213.84 g plant -1 and 3220.71 kg ha -1 , respectively). The lowest seed cotton yield per plant (173.27 g plant -1 ) was recorded in T 2 , while the minimum seed cotton yield per hectare (2615.26 kg ha -1 ) was recorded under T 1 (RDF). The higher seed cotton yield under T 7 may be attributed to increased dry matter accumulation, improved boll retention and enhanced photosynthetic efficiency due to foliar application of micronutrients. Similar findings were reported by Bibi et al. (2008) [12] , Khargkharate et al. [13] .

Table 3. Effect of different treatments on lint yield (g plant -1

), lint yield (kg ha -1 ), seed cotton yield (g plant -1 ) and seed cotton yield (kg ha 1)

Particular

Seed cotton yield (g plant -1 )

Biological yield

Biological yield was significantly influenced by foliar application of micronutrients. Treatment T 7 (RDF + foliar spray of MNS @ 15 ml L -1 ) recorded the highest biological yield (9663.01 kg ha -1 ), which was statistically at par with T 6 (9142.07 kg ha -1 ). The lowest biological yield (7847.10 kg ha -1 ) was recorded under T 1 (RDF). The higher biological yield under T 7 may be attributed to increased dry matter accumulation, enhanced vegetative growth and improved photosynthetic efficiency due to foliar application of micronutrients. Similar findings were reported by Raj et al. (2019) [5] , Hallikeri et al. (2011) [1] , Katkar et al. (2013) [10] and Giri et al. (2014) [3] .

Harvest index

Harvest index was not significantly influenced by the different foliar micronutrient treatments. Although foliar application of micronutrients improved both biological yield and seed cotton yield, the increase in economic yield was proportional to the increase in total biomass, resulting in a non-significant variation in harvest index among the treatments. Similar findings were reported by Sandeep et al. (2014) [14] , Blaise et al. (2016) [15] , Ayyadurai et al. (2019) [16] and Dhamak et al. (2022).

Conclusion

The present investigation demonstrated that foliar application of micronutrients significantly improved the growth and yield of cotton. Among the treatments, T 7 (RDF + foliar spray of PDKV Grade XI micronutrient mixture @ 15 ml L -1 ) recorded superior performance in terms of plant height, number of leaves, monopodial and sympodial branches, number of picked bolls, lint yield, seed cotton yield and biological yield. The treatment remained statistically at par with T 6 (12.5 ml L -1

) and T 5 (10 ml L -1 ) for most of the parameters. Therefore, foliar application of PDKV Grade XI micronutrient mixture @ 15 ml L -1 along with the recommended dose of fertilizers can be recommended for improving growth and productivity of cotton under the agro-climatic conditions of Akola.

References

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