Influence of varied concentrations of salicylic acid and ethrel treated at different stages on morphological, phenological and economic traits of cucumber (Cucumis sativus L.)

Introduction

Cucumber (Cucumis sativus L.) is one of the most important and popular vegetable crops belonging to the family Cucurbitaceae, which comprises approximately 118 genera and 825 species. It is characterized by a chromosome number of 2n = 2X = 14 and is native to India, where large diversity has been observed. It is a popular salad and pickle ingredient, known for its crisp texture and juicy flavour. It contains potassium, fibre, magnesium, manganese and vitamins A, C and K (Chakraborty and Rayalu, 2021) [4] . The fruits are highly nutritious, comprise 95% water and have very few calories (approximately 15 calories per cup), as described by Mukherjee et al. (2013) [16] . Application of plant growth regulators (PGRs) in cucurbits is very common. Plant growth regulators (PGRs), called bio-stimulants or bio-inhibitors, act inside plant cells to stimulate or inhibit specific enzymes or enzyme systems and thus regulate plant metabolism. Among the plant hormones, Salicylic acid and Ethylene have been found to be effective on various attributes, which affect the yield of cucumber. The application of ethylene (a gaseous plant hormone) enhances the female flowers and reduces the male flower production, which enhances the yield potential of the crop (Zhang et al., 2017) [25] . It also helps to manage the plant architecture by having a positive effect on morphological parameters like internode length, number of branches and leaf area etc. (Thappa et al., 2011) [22] . Similarly, the application of Salicylic acid provides tolerance to temperature and moisture stresses. Also found effective for root growth, photosynthesis, transport and uptake of solutes (Sultan et al., 2016) [21] .

Methods and Materials

The experimental trials "Effect of Salicylic Acid and Ethrel on Growth, Yield, and Quality of Cucumber (Cucumis sativus L.)" was conducted at the experimental field, Department of Horticulture, College of Agriculture Indore (M.P.) during kharif season 2023. This experiment was carried out to see the effect of foliar application of different growth regulators on growth, yield and quality parameters in cucumber. The experiment was laid out in Randomized Block Design (RBD) with thirteen treatments along with the control (water spray) treatment and three replication. The treatment of PGRs with varied concentration namely salicylic acid (0.5 and 1.0 mM) and ethrel (250 and 500 ppm) was sprayed once at particular growth stage namely 2-4 leaf stage, vine initiation stage and flowering stage.

Treatments Treatment Symbol

Detail of treatments 1. T0 Control 2.

T1 Salicylic acid @ 0.5 mM at 2-4 leaf stage 3.

T2 Salicylic acid @ 0.5 mM at vine initiation 4.

T3 Salicylic acid @ 0.5 mM at flowering stage 5.

T4 Salicylic acid @ 1.0 mM at 2-4 leaf stage 6.

T5 Salicylic acid @ 1.0 mM at vine initiation 7.

T6 Salicylic acid @ 1.0 mM at flowering stage 8. T7 Ethrel @ 250 ppm at 2-4 leaf stage 9.

T8 Ethrel @ 250 ppm at vine initiation 10.

T9 Ethrel @ 250 ppm at flowering stage 11. T10 Ethrel @ 500 ppm at 2-4 leaf stage 12.

T11 Ethrel @ 500 ppm at vine initiation 13.

T12 Ethrel @ 500 ppm at flowering stage A well rotten Farm Yard Manure was applied @ 20 tons/ha before preparing of the bed. Nitrogen, Phosphorus and potash were applied @ 100:50:50 kg/ha in the form of urea, single super phosphate and murate of potash, respectively. First hoeing and weeding was done after twenty days of sowing. Regular watering and plant protection measures were carried out as and when required. Ridge and furrow method was applied for planting of seedling. Seedling was prepared in pro tray in the month of August. The plants were trained upward so that the main stem was allowed to climb to the overhead wire along a rope. Wires were fixed 8-9 feet above the ground. The twine of each plant was alternatively tied to the horizontal overhead wires running along with the length of rows. The base of the twine (string) was anchored loosely to the base of the stem with a non-slip vine. As the stem developed, it was trellised on the twine up to the height of horizontal wires (8-9 feet height) and then the vines were again turned downward direction. The observations were recorded on various characters. The experimental data were subjected to analysis of variances (ANOVA) (Fisher and Yates 1963).

Results and Discussion

Morphological parameters

The results revealed that all the morphological parameters such as vine length, inter node length, number of branches and number of leaves were found statistically significant (Table 1). The maximum vine length (87.73, 169.87, 237.27 cm) and internode length (9.27 cm) were recorded in control, while the minimum plant height was recorded in treatments T 10 (Ethrel @ 500 ppm at 2-4 leaf stage) at 15 days after planting valued 67.93 cm and T 11 (Ethrel @ 500 ppm at vine initiation) at 30 and 45 days after planting valued 134.83 and 204.64 cm. Minimum internode length (6.13 cm) was observed in treatment T 11 (Ethrel @ 500 ppm at vine initiation). The maximum number of branches was recorded in treatment T 10 (Ethrel @ 500 ppm at 2-4 leaf stage) at 15 days after planting valued 3.60 and in treatment T 11 (Ethrel @ 500 ppm at vine initiation) at 30 and 45 days after planting valued 5.87 and 7.27. The maximum number of leaves (25.87, 51.17 and 95.89) was recorded in treatments T 10 (Ethrel @ 500 ppm at 2-4 leaf stage), T 11 (Ethrel @ 500 ppm at vine initiation), and T 7 (Ethrel @ 250 ppm at 2-4 leaf stage) at 15, 30, and 45 days after planting, respectively. While, the minimum number of branches and leaves per plant was observed in treatment T 4 (Salicylic acid @ 1.0 mM at 2-4 leaf stage) in all three growth stages, i.e., 30, 45, and 60 days after planting. The reduced plant height and length of internodes is because application of ethrel have its antagonistic effect on auxin level in plants which decreases the dominance of the shoot tip while increasing the sprouting of lateral buds (Leiberman and Knegt, 1977) [11] . Similar results were also reported by Ajay et al. (2018) [2] , Kumar et al. (2016) [9] , Sheoran et al.

(2015) [19] , and Mehdi et al. (2012) [14] . Furthermore, the application of ethrel not only reduced the growth of the main vine but also triggered dwarfism, ultimately leading to a surge in the number of branches. The reason for the increased number of leaves is the increase in the number of branches per plant by ethrel. Similar results were also recorded by Duhan et al. (2022) [6] , Rahman et al. (2020) [18] , and Chaurasiya et al. (2016) [5] .

Phenological parameters

The results revealed that all the phenological parameters such as number of days taken to first flower, number of days to fruit set, the number of days to first picking and sex ratio were found statistically significant (Table 2). The maximum number of days taken to first flower was observed in treatment T 10 (Ethrel @ 500 ppm at 2-4 leaf stage), while it was minimum in treatment T 0 (Control), and the number of days to fruit set and the number of days to first picking were recorded as maximum in treatment T 0 (Control) and minimum in treatment T 10 (Ethrel @ 500 ppm at 2-4 leaf stage). The maximum sex ratio (20.30 and 10.75) was recorded in treatment T 0 (control), while the minimum sex ratio was observed in treatment T 10 (Ethrel @ 500 ppm at 2-4 leaf stage) and T 11 (Ethrel @ 500 ppm at vine initiation) at 30 and 45 days after planting valued 4.20 and 1.86, respectively. It was reported by Achard et al. (2007) [1] that the use of ethylene before flowering might stimulate the development of pistillate flowers, either directly or by diminishing endogenous levels of gibberellic acid, or by fostering the synthesis of abscisic acid. This appears to be a possible reason for the delayed emergence of male and early female flowers, due to which ethrel treatments were taken over a longer period of time for flowering. These findings were very close to the results obtained by Mehdi et al. (2012) [14] , Kumari et al. (2019) [8] , and Shukla et al. (2023) [20] . It was also observed that sexual differentiation is influenced by internal levels of auxins, which are affected by ethrel treatment. Ethrel appears to encourage the development of flowering primordia. The counteraction of ethrel against gibberellins seems to inhibit the formation of male flowers while promoting the production of more female flowers, resulting in a lower ratio of male to female flowers. Similar results were reported by Martín-Mex et al. (2013) [13] , Patel et al. (2015) [17] , and Yadav et al. (2022) [24] .

Economic parameters

The results revealed that all the economic parameters such as gross return, net return, and cost-benefit ratio were found statistically significant (Table ). The maximum gross return, net return, and cost-benefit ratio (₹ 2,80,530.00, 2,04,673.75 and 2.69) were recorded in treatment T 7 (Ethrel @250 ppm at 2-4 leaf stage stage), while these were minimum in treatment T 4 (salicylic acid @ 1.0 mM at 2-4 leaf stage) ₹ 1,43,560.00, 68,114.97 and 0.90, respectively. The income is clearly dependent on total yield, since the highest and lowest yields were obtained by the treatments, respectively. The above results were in consonance with those of Mahala et al. (2014) [12] , Kumar et al. (2019) [10] , Mishra and Singh (2021) [15] , and Baral et al. (2022) [3] .

Conclusion

The results indicate that the application of PGRs like ethrel significantly affected the morphological parameters and reduced the vine length and internode length, while increasing the number of branches and leaves. Phenological parameters like days taken to 1 st flower, fruit set, harvesting, and sex ratio were significantly affected when treated with salicylic acid and ethrel. Ethrel 250 ppm at 2-4 leaf stage was beneficial in terms of economic parameters like CBR, gross return, and net return. Over all, ethrel 250 ppm at 2-4 leaf stage was the best treatment, and salicylic acid 1.0 mM at 2-4 leaf stage was the worst treatment in terms of morphological, phenological and economic parameters. It was observed that low concentrations (ethrel 250 ppm and salicylic acid 0.5 mM) gave significantly positive results for most of the parameters.

Scope for further work

 Further research is needed for the identification of the mode of action and effect of salicylic acid on the growth and development of cucumber.  It is also required to study the interactions between the PGRs and their different concentrations.  It is necessary to investigate the proper concentration and stage of application of salicylic acid as there is limited resources available in previous studies.  To validate the findings, it is advisable to replicate the experiment over a span of 3-4 years at various locations, ensuring greater precision.

References

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