Influence of sowing windows and foliar application of plant growth regulators on growth and seed yield of green gram (Vigna Radiata (L.) Wilczek)

Introduction

Pulses occupy a vital position in ensuring global food and nutritional security, being rich sources of protein, vitamins and minerals besides improving soil health through biological nitrogen fixation. Green gram is a short-duration, warm-season pulse crop belonging to the family Fabaceae, widely grown across the rainy, winter and summer seasons in India, which contributes nearly seventy per cent of world production. India produced about 4.24 million tonnes of green gram from 5.9 million hectares during 2024-25, while Karnataka contributed 2.42 lakh tonnes from 5.67 lakh hectares at a modest productivity of 659 kilograms per hectare [1] . Sowing window is among the most critical agronomic factors governing crop establishment, growth, phenology and yield, since timely sowing ensures optimum utilization of soil moisture, temperature and photoperiod for vigorous vegetative growth and efficient reproductive development. In Karnataka, green gram is generally sown from the second fortnight of June to the second fortnight of July depending on the onset of monsoon; however, increasingly erratic rainfall has frequently delayed sowing, exposing the crop to unfavourable conditions and considerable yield variation [2] . Foliar application of plant growth regulators has emerged as a complementary strategy to mitigate the adverse effects of delayed sowing and climatic stress. Salicylic acid enhances chlorophyll content, photosynthetic efficiency and reproductive efficiency under stress [3] ; naphthalene acetic acid promotes cell elongation and reduces flower abscission; and thiourea improves nitrogen metabolism and early vigour under moisture stress. Despite the individual International Journal of Advanced Biochemistry Research 2026; SP-10(9): 1227-1231 benefits reported for sowing time and growth regulators, information on their combined influence on the growth and seed yield of green gram under the agro-climatic conditions of northern Karnataka remains limited. In view of this, the present investigation was undertaken to assess the influence of different sowing windows and foliar application of plant growth regulators on the growth and seed yield of green gram.

Materials and Methods

A field experiment was conducted during kharif 2025 at the Agricultural Research Station, Hanumanamatti, University of Agricultural Sciences, Dharwad (14°47' N, 75°37' E; 650 m above mean sea level), situated in the Northern Transitional Zone (Zone 8) of Karnataka, India. The experiment comprised two factors: three sowing windows, namely D1-second fortnight of June, D2-first fortnight of July and D3-second fortnight of July; and four foliar sprays of plant growth regulators, namely S1-control (water spray), S2-salicylic acid at 150 ppm, S3-naphthalene acetic acid at 75 ppm and S4-thiourea at 250 ppm, applied twice at the pre-flowering and pod formation stages. The experiment was laid out in a factorial randomized block design with twelve treatment combinations replicated thrice, with a net plot size of 3.0 × 2.8 m. Green gram cultivar DGGV 2 was sown at a spacing of 30 × 10 cm, with a fertilizer dose of 25:30:0 kilograms N:P:K per hectare. Plant height and relative chlorophyll content were recorded on five randomly tagged plants using a chlorophyll meter at 30 and 60 days after sowing, with plant height recorded additionally at harvest and the number of branches per plant was recorded at harvest. The number of pods per plant and seed yield per plant were recorded on the same tagged plants and seed yield per hectare was computed from the net plot yield. The data generated were statistically analysed following the method described by Panse and Sukhatme [4] .

Results and Discussion

Plant height, relative chlorophyll content and number of branches per plant were significantly influenced by sowing windows and foliar application of plant growth regulators, while their interaction remained non-significant for all three parameters (Table 1, Fig. 1). Among sowing windows, significantly higher plant height was recorded with the second fortnight of June (D1) (32.27, 56.00 and 63.22 cm at 30 days after sowing, 60 days after sowing and at harvest, respectively), which was on par with the first fortnight of July (D2) (27.58, 53.93 and 60.45 cm, respectively), while lower plant height was recorded with the second fortnight of July (D3) (26.86, 51.08 and 58.06 cm, respectively). Similarly, higher chlorophyll content was recorded with D1 (35.59 and 55.83 at 30 and 60 days after sowing, respectively), on par with D2 (33.29 and 52.57, respectively), while lower chlorophyll content was recorded with D3 (32.38 and 51.75, respectively). The number of branches per plant was also higher with D1 (5.47), against the lowest with D3 (4.17). Timely sowing ensures favourable soil moisture, temperature and photoperiod for vigorous vegetative growth, whereas delayed sowing exposes the crop to declining moisture and rising temperature, restricting cell division, chlorophyll synthesis and branching. These findings were consistent with Rao et al. [5] in greengram and Singh et al. [6] in mungbean. Plant height at 30 days after sowing was not significantly influenced by growth regulators, but at 60 days after sowing and at harvest, significantly higher plant height was recorded with salicylic acid at 150 ppm (S2) (56.83 and 63.59 cm, respectively), on par with thiourea at 250 ppm (S4) (53.64 and 61.53 cm, respectively), while lower plant height was recorded with the control (S1) (51.33 and 57.91 cm, respectively). Chlorophyll content at 60 days after sowing was higher with S2 (56.39), on par with S4 (54.08), against the lowest with S1 (50.96). The number of branches per plant was highest with S2 (5.06), on par with S4 (4.79), against the lowest with S1 (4.39). Salicylic acid, being an important signalling molecule, enhances chlorophyll content, photosynthetic efficiency and cell elongation, corroborating Singh and Jambukiya [7] and Reddy and Singh [8] in greengram. Among the twelve treatment combinations, the interaction of the second fortnight of June sowing with salicylic acid spray (D1S2) recorded the numerically highest plant height (65.93 cm), chlorophyll content (59.35 at 60 days after sowing) and branches per plant (5.87), while the combination of delayed sowing with the untreated control (D3S1) recorded the lowest values for these parameters (Table 1, Fig. 1). Number of pods per plant, seed yield per plant and seed yield per hectare differed significantly due to sowing windows and growth regulators, while their interaction was non-significant for all three parameters (Table 2, Fig. 2). Significantly higher number of pods per plant was recorded with the second fortnight of June (D1) (24.91), followed by the first fortnight of July (D2) (21.90), while lower pods per plant was recorded with the second fortnight of July (D3) (21.20). Similarly, higher seed yield per plant and per hectare was recorded with D1 (7.91 g and 908.26 kg per hectare, respectively), followed by D2 (7.02 g and 763.10 kg per hectare, respectively), while lower values were recorded with D3 (6.52 g and 664.63 kg per hectare, respectively). Early sowing, coinciding with better vegetative growth and photosynthetic efficiency, favoured translocation of photosynthates towards reproductive sinks, resulting in higher pod set and seed yield, corroborating Rao et al. [5] and Bobade et al. [9] in greengram. Among growth regulators, significantly higher number of pods per plant was recorded with salicylic acid at 150 ppm (S2) (23.93), on par with thiourea at 250 ppm (S4) (22.90), while lower pods per plant was recorded with the control (S1) (21.63). Similarly, higher seed yield per plant was recorded with S2 (7.63 g), on par with S4 (7.39 g), while lower seed yield per plant was recorded with S1 (6.62 g), and seed yield per hectare was also higher with S2 (815.14 kg per hectare), on par with S4 (782.69 kg per hectare) and naphthalene acetic acid at 75 ppm (S3) (777.59 kg per hectare), against the lowest value with S1 (739.22 kg per hectare). Improved reproductive efficiency, reduced flower and pod drop, and better partitioning of photosynthates under salicylic acid application account for this response, corroborating Bhadru et al. [10] in greengram and Yadav et al. [11] in mungbean. Among the twelve treatment combinations, the highest number of pods per plant (25.81), seed yield per plant (8.46 g) and seed yield per hectare (953.59 kg) were recorded with the combination of the second fortnight of June sowing and salicylic acid spray (D1S2), while the lowest values (20.12 pods, 6.10 g and 625.96 kg per hectare) were recorded with the combination of delayed sowing and the untreated control (D3S1) (Table 2, Fig. 2).

Conclusion

Sowing of green gram cultivar DGGV 2 during the second fortnight of June, coupled with foliar spray of salicylic acid at 150 ppm at the pre-flowering and pod formation stages, was the most effective combination for realizing higher growth and seed yield. Hence, timely sowing during the second fortnight of June along with salicylic acid spray can be recommended to green gram growers of northern Karnataka for improving productivity.

Acknowledgement

AcknowledgmentsThe authors are grateful to the University of Agricultural Sciences, Dharwad and the Agricultural Research Station, Hanumanamatti for providing the necessary facilities to carry out this research and to the members of the advisory committee for their guidance throughout the study.

References

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