Effect of plant growth regulators on growth parameters of papaya (Carica papaya L.) cv. Red Lady

Introduction

Papaya (Carica papaya L.) is an important tropical fruit crop valued for its early bearing habit, year-round fruiting potential, nutritive pulp and wide adaptability under irrigated horticultural systems. The hybrid Red Lady has gained commercial preference because of its uniform plant stand, attractive fruit shape and acceptable eating quality. For profitable papaya cultivation, early vegetative vigour is important because plant height, stem girth, leaf number and canopy expansion directly influence photosynthetic capacity, flowering behaviour and subsequent fruit development. Plant growth regulators are commonly used in fruit crops to regulate growth, flowering and fruiting. Gibberellic acid promotes cell division and cell elongation, while NAA helps in hormonal balance, assimilate movement and reduction of fruit drop. Earlier studies in papaya have shown that plant growth regulators can significantly influence plant height, girth, canopy spread, fruiting and quality attributes (Hazarika et al., 2016; Maurya et al., 2025) [7,10] . Similar responses have also been reported in other fruit crops where GA₃ and NAA improved fruit retention, yield and quality (Nkansah et al., 2012) [12] . The response of papaya to growth regulators may vary with cultivar, stage of application, concentration and growing environment. Therefore, the present study was undertaken to assess the effect of different concentrations of GA₃ and NAA, applied alone and in combination, on the growth parameters of papaya cv. Red Lady under the Gird agro-climatic zone of Madhya Pradesh. Materials and Methods: Experimental site and crop, The field experiment was carried out during 2024-25 at Agriculture Research and Development Centre, Sakatpura, School of Agriculture Science, Vikrant University, Gwalior, Madhya Pradesh. The experimental area falls under a semi-arid to subtropical climate with hot summers, moderate monsoon rainfall and comparatively cool winters. The soil of the experimental field was sandy loam to clay loam in texture, well drained and slightly alkaline in reaction. Experimental design, treatments and crop management. The experiment was arranged in randomized block design with seven treatments and three replications. Papaya cv. Red Lady seedlings were transplanted at a spacing of 1.8 m × 1.8 m. Each plot measured 3.6 m × 3.6 m and contained four plants. GA₃ and NAA solutions were prepared at the required concentrations and applied as foliar spray at preflowering and fruit set stages. Uniform cultural practices including irrigation, weeding, earthing up and plant protection measures were followed in all plots. Observations and statistical analysis: Observations on plant height, stem girth and number of leaves per plant were recorded at 30, 60, 90, 120 DAT and at first flowering. Canopy spread was recorded at 60, 90, 120 DAT and at first flowering. The recorded data were statistically analyzed according to the procedure of randomized block design. Treatment means were compared using critical difference at 5% level of significance wherever the F-test was significant (Gomez and Gomez, 1984) [6] . Results and Discussion: Effect on plant height Plant height increased progressively with crop age and was significantly influenced by growth regulator treatments from 60 DAT onwards. At 30 DAT, the treatment effect was non-significant, although T₇ recorded the numerically highest value (48.9 cm). At first flowering, T₇ recorded the maximum plant height (177.8 cm), which remained statistically at par with T₆ (168.4 cm) and was superior to the remaining treatments. The lowest plant height was observed under T₁-control: water spray (126.4 cm). The improved plant height under combined GA₃ and NAA may be attributed to enhanced cell division and elongation, better nutrient movement and improved vegetative activity. Effect on stem girth: Stem girth followed a trend similar to plant height. At 30 DAT, the differences were nonsignificant, whereas significant variation was observed at 60, 90, 120 DAT and at first flowering. The maximum stem girth at first flowering was recorded in T₇ (18.72 cm), which was statistically at par with T₆ (17.64 cm). The minimum value was recorded in the control (11.84 cm). The thicker stem under combined growth regulator treatments indicates better structural growth and greater assimilate accumulation. [7] also reported higher vegetative growth in papaya cv. Red Lady under growth regulator application.

Conclusion

The results clearly indicated that combined foliar application of GA₃ and NAA improved growth performance of papaya cv. Red Lady. Among the treatments, T₇ (GA₃ @ 150 ppm + NAA @ 100 ppm) produced the highest plant height, stem girth, number of leaves and canopy spread, followed by T₆ (GA₃ @ 75 ppm + NAA @ 50 ppm). The superiority of combined treatments may be due to favorable hormonal balance and enhanced vegetative growth. On the basis of one-season results, T₇ may be considered the most effective treatment for improving vegetative growth of papaya under the Gwalior region, subject to further multiseason validation.

Acknowledgement

AcknowledgementThe authors acknowledge the School of Agriculture Science, Vikrant University, Gwalior, for providing field and laboratory facilities to conduct the experiment.

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