1 Introduction

Agriculture in Nepal is the largest economic sector that solely contributes around 24.1% of National GDP, providing employment to 60.4% of the population. 28.0% of total land is cultivated. The data shows productivity of vegetable is 14.48 mt/ha with production of 3,993,167 mt (MoALD, 2022/23). Higher level of diversification in terms of climatic and geographic variations is a key characteristic of Nepalese agriculture. Agriculture in Nepal has peculiar characteristics due to the high range of altitudes and temperature throughout the country. Within almost 200 Km in north-south, we find all kinds of temperature and crop types as well. This provides both opportunities and challenges for agriculture development in Nepal.

Cauliflower (Brassica oleracea var. botrytis) is an annual plant of Brassicaceae family that reproduces through seeds and it develops a white compact inflorescence meristem known as a "curd", which is the edible portion (Singh et al., 2021). It has high nutritional value and it is known as one of the healthiest plants on the planet and is gaining popularity worldwide as a low-calorie, gluten-free substitute for rice and flour, leading to an increase in both cultivation and consumption. The global production of cauliflower reached over 25.5 million tons in 2020, with a market value of $14.1 billion (Chen et al., 2024). The top producers of cauliflower in the world include China, India, America, Mexico, Spain, etc., where China is the leading country with 26.5 million tons production. In Nepal as per MoALD (2022/23), the total area coverage of cauliflower is 39 214 ha producing 611 015 mt with average productivity of 14.81mt/ha. One of the major constraints for the cauliflower production is unmanaged fertilization and unavailability of nutrients in soils. Nepalese soils, particularly in mid-hill and inner Terai regions like Marin, Sindhuli, are often characterized by micronutrient deficiencies, among which boron deficiency is especially widespread and under-addressed. The growth, reproductive development, and marketable yield of cauliflower (a crop that is highly sensitive to boron levels) are significantly hampered by this shortfall.

Boron is an essential micronutrient required for normal plant growth, including crucial functions in cauliflower which plays an important role in cell wall formation, reproductive development, nutrient translocation, and the prevention of physiological disorders. Although required in trace amounts, boron deficiency can cause significant damage to cauliflower’s yield and quality (Wimmer and Eichert, 2013). One of the most notable impacts of boron deficiency in cauliflower is the occurrence of hollow stems or hollowness in curds. This condition, characterized by cavities inside the stem or curd, reduces the commercial value of the crop (Islam et al., 2015).

Boron’s role in cell division and the maintenance of xylem differentiation is critical for preventing this disorder. It ensures proper nutrient and water transport, reducing the incidence of hollow stem formation (Troeh et al., 2005). Boron plays a major role in the maintenance of structural integrity of the plant membranes, cell division and elongation, metabolism of biomolecules like carbohydrates and nucleic acids, protein synthesis, sugar translocation, as well as uptake of essential plant nutrients from the soil, all of which are critical for curd development. Therefore, the deficiency of boron affects all these processes (Pilbeam and Kirkby, 1983; Ahmad et al., 2009; Shaaban, 2010; Funakawa and Miwa, 2015; Shireen et al., 2018).

Under certain soil pH conditions, conventional soil-based boron fertilization has shown inconsistent results due to leaching losses and low availability. In this context, foliar application of boron presents a potentially more efficient and targeted approach, yet it remains underexplored in Nepalese agro-ecological zones. Moreover, no research work has been reported on the effects of boron in cauliflower production in the Sindhuli district. The present study uniquely aims to evaluate the effectiveness of different foliar boron concentrations on cauliflower growth and productivity under the specific soil-climatic conditions of Marin, Sindhuli. By addressing a localized nutrient management gap through a practical and scalable method, this research contributes novel insights for optimizing micronutrient strategies in vegetable production systems across similar regions of Nepal.

2 Materials and Methods

2.1 Selection of site

The experiment was conducted at College of Natural Resource Management, Sindhuli, Nepal. This region is situated at the latitude of 27° 15' 24.1" N and the longitude of 85° 46' 39.5" E. The altitude of this region is 299 meter above sea level. The duration of the experiment was from 2^nd January 2024 to 30^th March 2024. The average daytime temperature of cultivation period ranged between 14 °C (January) to 24 °C (March) and rainfall during cultivation period ranged from 7.4 mm (January) to 13 mm (March). While testing the boron availability in an experimental field, low availability of boron (0.28 ppm) was found.

2.2 Experimental materials and treatment applications

The used variety in the experiment was Snow Mystique (A late variety) and seeds of cauliflower were brought from nearby Agrovet of Marin rural municipality, Sindhuli. The used fertilizers were also brought from nearby fertilizer distributor of Marin rural municipality. One and a half tons of compost plus 120:80:80 kg per ha of N: P₂O₅: K₂O was applied in all the plots. Half Nitrogen was applied as a basal application and the other half as top dressing after 45 days.

Borax was used as boron source with purity of 10 % and was brought from nearby agrovet of Marin rural municipality, Sindhuli. Three different foliar sprays were done at 30 DAT, and 45 DAT and 60 DAT. Boron was sprayed by using a small hand sprayer in the leaf portion of cauliflower. The experiment involved ten treatments where Treatment 1 (T1) served as the control, where no borax was added in spraying solution i.e. water. Treatments 2 to 4 (T2, T3, and T4) involved a low concentration of borax at 2.5 grams per liter of water, applied once, twice, and thrice, respectively, during the crop growth period. Treatments 5 to 7 (T5, T6, and T7) were given a moderate concentration of 5 grams of borax per liter of water, also sprayed at increasing frequencies—once, twice, and thrice, respectively. Similarly, treatments 8 to 10 (T8, T9, and T10) involved a higher concentration of 7.5 grams of borax per liter, applied once, twice, and thrice, respectively.

2.3 Soil characteristics

Prior to field preparation, a soil test was conducted to assess the baseline fertility status. The soil was found to have low organic matter (1.26%), low nitrogen content (0.06%), high phosphorus levels (78 kg/ha), medium potassium levels (34 kg/ha), and low available boron (0.28 ppm). The soil pH was recorded at 5.2, indicating acidic conditions. These initial soil properties provided a baseline for understanding the impact of boron supplementation on cauliflower performance.

2.4 Experimental design and data collection

The experiment was conducted in a Randomized Complete Block Design (RCBD) with 10 treatments and each treatment was replicated 3- times. Ten treatments are Control (No Boron spray), 0.025% Boron (1- time spray), 0.025% Boron (2- times spray), 0.025% Boron (3-times spray), 0.05% Boron (1- time spray) ,0.05% Boron (2- times spray), 0.05% Boron (3- times spray), 0.075% Boron (1- time spray), 0.075% Boron (2-times spray), 0.075% Boron (3-times spray). The crop was harvested in March. With six sample plants, there were twenty-five total population of cauliflower in one plot (i.e. 30 * 25= 750 plants in the experimental field). The length of the experimental field was 39 m and width was 14.25 m. The length of the plot was 3.75 m with a width of 3 m. The plant spacing was 75 * 60 cm² and the spacing between two plots was 1 m while spacing at the outer line of the field was 0.5 m.

2.5 Data record and analysis

Six inner plants per plot, excluding border rows, were taken as sample plants for study. Plant growth and yield characters were recorded. All the recorded data were arranged systematically in Microsoft Excel version 16.89.1. To determine the significance difference between treatments, analysis of variance was carried out using R studio version 4.4.1. Duncan’s Multiple Range Test (DMRT) was used for mean separation at 5% level of significance. recorded and analyzed statistically by least significant difference test.

3 Results and Analysis

The statistical analysis showed that plant height was not significantly affected by different concentrations of boron on different days of observation. At 45 DAT, 0.025% Boron (1-time spray) was found with a maximum height of 35.21 cm, and 0.025% Boron (2-times spray) was found with minimum height of 29.62 cm. At 60 DAT, 0.075% Boron (2-times spray) was found to have a maximum height of 51.63 cm, and control was found with a minimum height of 46.47 cm. At 75 DAT, 0.025% Boron (1-time spray) was found to have a maximum height of 58.15 cm, and control was found with a minimum height of 52.45 cm. At 80 DAT, a maximum height of 59.88 cm was found in 0.05% (1-time spray), and minimum height of 53.32 cm was found in control (Table 1).

Similarly, it was found that the leaf number was not statistically significantly affected by different concentrations of boron on different days of observation except at 60 DAT. At 45 DAT, 0.025% Boron (1-time spray) was found with a maximum number of leaves i.e. 9.22 and 0.025% Boron (2- times spray was found with a minimum number of leaves with 8.50. At 60 DAT, the maximum number of leaves with 12.50 was found at 0.025% Boron (2- times spray) and the least number of leaves was found at control with 10.72. At 75 DAT, 0.05% Boron (3- times spray) was found to have the highest number of leaves with 14.16, and 0.05% Boron (1-time spray) was found with the lowest number of leaves with 11.80. At 80 DAT, a maximum number of leaves i.e. 18 was found in 0.05% (1-time spray), and the lowest number of leaves i.e. 15.72 was found in 0.025% Boron (3- times spray) (Table 2).

Furthermore, the statistical analysis showed that leaf length was not statistically significantly affected by different concentrations of boron on different days of observations. At 45 DAT, 0.075% Boron (2- times spray) was found with maximum leaf length of 23.57 cm, and 0.05% Boron (2- times spray) was found with minimum leaf length of 19.62 cm. At 60 DAT, maximum leaf length with 35.18 cm was found at 0.025% Boron (3- times spray), and the least leaf length with 32.05 cm was found at control. At 75 DAT, 0.025% Boron (1-time spray) was found to have the maximum length of leaf with 45.34 cm, and 0.025% Boron (2- times spray) was found with least length of leaf with 38.51 cm. At 80 DAT, the highest leaf length was found in 0.05% (1-time spray) with 47.35, and the lowest leaf length was found in 0.05% Boron (3- times spray) with 38.37 cm (Table 3).

Likewise, it was found that leaf breadth was not statistically significantly affected by different concentrations of boron on different days of observations. At 45 DAT, 0.075% Boron (2- times sprays) was found with maximum leaf breadth of 16.78 cm, and 0.025% Boron (2- times sprays) was found with minimum leaf breadth of 13.05 cm. At 60 DAT, maximum leaf breadth was found at 0.025% Boron (3- times sprays) with 33.57 cm and least leaf breadth was found at 0.05% Boron (2- times sprays) with 20.56 cm. At 75 DAT, 0.025% Boron (1-time spray) was found to have a maximum breadth of leaf i.e. 21.05 cm, and Control was found with the least breadth of leaf of 18.08 cm. At 80 DAT, the highest leaf breadth was found in 0.05% (1-time spray) i.e. 22.33 cm, and the lowest leaf breadth was found in 0.025% Boron (2- times sprays) i.e. 18.30 cm. The mean value was found to be 20.68 cm (Table 4).

Upon further analyzing the results, the statistical analysis showed that total biomass, curd weight, curd size and curd diameter were statistically significantly affected by different concentrations of boron (Table 5). During the harvesting, the highest biomass of 3.02 kg was found at treatment 0.05% Boron (3- times spray), and the lowest biomass was found at Control with 1.46 kg. The mean value was found to be 2.30 kg. Similarly, the highest curd weight of 1.997 was found at treatment 0.05% Boron (3- times spray) and the lowest curd weight was found at control i.e. 0.71 kg (Table 5). Also, the highest curd size i.e. 66.76 cm was found at treatment 0.075% Boron (2- times spray), and the smallest curd size i.e. 44.55 cm was found at control. The mean value was found to be 61.66 cm (Table 5). Also, the highest curd diameter of 23.03 cm was found at treatment 0.075% Boron (2- times spray), and the lowest curd diameter of 14.25 cm was found at control. The mean value was found to be 21.33 cm (Table 5). This shows the effect of different concentrations of Boron on the yield of cauliflower. 

Similarly, ANOVA showed that the length and diameter of hollowness were significantly affected by different concentrations of boron during the harvesting period (Table 6). The highest length of hollowness i.e. 8.57 cm was found at Control and the lowest length of hollowness i.e. 0.16 cm was found at 0.075% Boron (3- times spray). The mean value was found to be 2.67 cm. The highest diameter of hollowness i.e. 1.83 cm was found in control and the lowest diameter of hollowness i.e. 0.16 cm was found at 0.025% Boron (3- times spray). The mean value was found to be 0.83 cm  (Table 6).

While analyzing the data recorded it was found that yield per hac was significantly affected by different concentrations of boron during the harvesting period. The highest yield per hac i.e. 25.66 t/ha was found at 0.075% Boron (2- times spray) and the lowest yield per hac i.e. 9.6 t/ha was found at control. The mean value was found to be 20.96 t/ha  (Table 7).

4 Discussion

The application of varying concentrations of boron had different effects on cauliflower growth, yield, and other yield-related characteristics. While some traits showed a significant response to boron, others were less influenced. This section analyses boron's impact on key plant parameters and compares the findings with previous studies.

Boron application had no significant effect on plant height. Although certain boron treatments resulted in slight increases, the variations were not statistically significant. Similar findings were reported by Bakhtiar et al. (2018), who found that applying micronutrients, including boron, had minimal impact on vegetative growth when soil conditions were optimal. This lack of significant impact may be attributed to low nitrogen and boron availability in the soil, as well as environmental factors that may have masked boron's effects.

Similarly, leaf number, length, and breadth did not show significant variations with different boron concentrations, except for leaf number at 60 DAT. External influences such as temperature, soil fertility, water availability, low organic matter, and insufficient nitrogen levels in the soil may have contributed to these results. These findings are consistent with Chaudhari et al. (2017), who suggested that boron primarily affects reproductive growth rather than vegetative growth in Brassica species, including cauliflower.

A considerable increase in total biomass was observed with higher boron concentrations, particularly with the application of 0.05% boron three times. This aligns with previous research highlighting boron's role in strengthening cell wall formation and overall plant growth (Arunkumar et al., 2018). The increase in biomass at higher boron levels may be due to improved nutrient absorption and efficient carbohydrate translocation to the plant’s growing parts, as reported by Blevins and Lukaszewski (1998). Boron application significantly enhanced both curd weight and size. Higher boron concentrations (0.05% and 0.075%) resulted in larger and heavier curds, which are essential for commercial value. These findings support the research of Alam and Jahan (2007), who reported similar increases in curd size and weight in Brassica crops with boron supplementation.

Curd diameter was also significantly affected by different boron concentrations, with higher doses producing larger curds. This indicates that boron plays a vital role in cauliflower curd development, particularly in promoting size expansion. The application of a 0.025% boron sprayed twice resulted in the largest curd diameter, suggesting that both concentration and frequency of boron application influence curd formation. The increased curd size may be attributed to boron’s involvement in cell wall biosynthesis and its structural role in plant tissues. These findings are consistent with Alam and Jahan (2007), who observed a significant increase in head diameter in cabbage following boron application. Similarly, Md et al. (2018) found that higher boron concentrations improved curd diameter in broccoli. The observed improvements further highlight the importance of micronutrient management in cauliflower cultivation.

Boron also played a crucial role in reducing the occurrence of hollow stems. Boron’s role in cell division and the maintenance of xylem differentiation is critical for reducing this disorder of hollowness. It ensures proper nutrient and water transport, reducing the incidence of hollow stem formation (Troeh et al., 2005). Studies show that boron applications effectively reduce hollowness in cauliflower, enhancing curd quality and marketability (Alam and Jahan, 2007; Chaudhari et al., 2017). A higher boron concentration significantly decreased hollow stem disorder compared to the control treatment. These results closely align with Islam et al. (2015) and Batal et al. (1997). The experimental result of Sartori de Camargo and da Costa Mello (2009) also supports our study where higher hollow stem disorder was found in control plots while comparing to plots treated with higher doses of Boron per hectare.

The highest recorded yield per hectare (25.66 t/ha) was achieved with a 0.075% boron application twice, which was significantly higher than the control yield (9.66 t/ha). Similar results were documented by Kant et al. (2013), who emphasized boron’s role in improving yield by enhancing reproductive growth and nutrient transport. The yield increase can be attributed to boron’s essential role in curd development, as it facilitates the movement of sugars and nutrients to the developing curd (Fouad and Rehab, 2013).

5 Conclusion and Recommendation for Future Research

Overall, the study demonstrated that boron application with higher concentration positively impacts cauliflower yield in comparison to control. The findings are in agreement with the earlier results of Chaudhari et al. (2017). In this research, higher length and width of hollowness in control treatment was observed in comparison with other higher concentrations of boron. The result thus obtained is in close conformity with results obtained by Islam et al. (2015) and also with findings by Batal et al. (1997). This study provides valuable insights for farmers looking to enhance cauliflower production through effective micronutrient management.

Wise application of boron was proved to be fruitful to farmers. Further study on the effect of other micronutrients on plant systems should be focused. Multi-location trails should be done on the same topic. Temperature plays a vital role in both the plant system and the chemical character of various chemicals. Since boron is a chemical substance, temperature parameters should be considered for further research on boron concentration in cauliflower. Consumer preference is a major issue for any commodity to be marketed. Boron-treated fruits were of high curd size. So, the marketing aspect of boron-treated vegetables needs to be studied.

Authors’ contributions

AP carried out the conceptualization of research, designed the experiment and drafted the manuscript. DS and TBB participated in the design of the study and helped in data collection. PS helped in data analysis and helped to draft the manuscript. GL and DK helped to draft the manuscript and supervision of the research. All authors read and approved the final manuscript.

Acknowledgment

The authors thank Agriculture and Forestry University, Nepal and College of Natural Resource Management, Sindhuli for providing this platform. Authors are thankful to Mr. Raja Babu Chaudhary for providing appropriate suggestions and motivations throughout the study.

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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