Effect of different training systems on growth and vigour in passion fruit (Passiflora edulis) under prayagraj agro-climatic region

Introduction

Passion fruit (Passiflora edulis Sims.), often viewed as a minor fruit in India, produces delicious fruit available in two varieties: Purple (Passiflora edulis f. edulis) and Yellow (Passiflora edulis f. flavicarpa) (Joy 2010) [9] . Native to Brazil, passion fruit belongs to the Passifloraceae family and primarily grows in tropical and subtropical regions, including South America, Australia, Asia, and Africa. In India, passion fruit is cultivated in Himachal Pradesh, Kerala, Tamil Nadu (Nilgiris Hills and Kodaikanal), Karnataka (Coorg), and the northeastern states (Mizoram, Nagaland, Manipur, and Sikkim), covering an area of 9.11 thousand hectares and yielding 25.82 thousand tons (Chonyaphai et. al 2022). Passion fruit is a perennial, vigorous, climbing woody vine producing round, oval-shaped fruit. The fruit contains orange-colored pulpy juice with numerous small, hard, dark brown to black pitted seeds. Popular for its rich flavor and blending quality, it contains sugars, acids, and vitamins, including Vitamin A (1300-2500 IU per 100 g pulp) and Vitamin C (30-50 mg per 100g pulp). Medicinally, passion fruit is used as a mild diuretic, digestive aid, and heart tonic, as well as to treat asthma. Passion fruit vines are trained to grow from a single shoot starting at the plant's base and extending upward to a trellis. At the top, two strong primary branches are guided to grow in opposite directions along the trellis. From these main branches, smaller lateral branches grow downward, serving as the primary sites for fruit production. Tendrils and excess growth are regularly pruned to maintain structure and optimize fruit yield. Training passion fruit vines involves various systems designed to guide vine growth, maximize space utilization, and enhance fruit production (Sulladmath et al. 2012) [14] . This study attempts to evaluate the effect of different training systems on the growth and vigour of passion fruit under Prayagraj agro climatic conditions.

Materials and Methods

The experiment was conducted during the 2024-2025 season in the Department of Horticulture at Naini Agricultural Institute, Sam Higginbottom University of Agriculture Technology and Sciences in Prayagraj. Located in the southeastern part of Uttar Pradesh, Prayagraj falls within a subtropical climate zone characterized by extremely hot summers and relatively cool winters. Summer temperatures can reach as high as 46-48 °C, whereas winter temperatures may drop to around 4-5 °C. Relative humidity in the region ranges from 20% to 94%, and it receives an average annual rainfall of approximately 1013.4 mm. A Randomized Block Design (RBD) with three replications was employed to evaluate the performance of four distinct training systems: The Kniffin system (with 2-arm and 4-arm configurations), the High trellis system (featuring single and double cordons), the Tatutra system (with 4-arm and 8-arm variations), and the Bower system (comprising 2 cordons and 4 cordons). Old seedlings were initially transplanted into the main field, followed by the transplantation of passion fruit seedlings at a spacing of 1.5 m × 1.5 m. Vegetative growth parameters-including plant height (cm), the number of leaves, chlorophyll content (as measured by SPAD values), and stem diameter (mm)-were recorded and statistically analyzed using the methodology described by Panse and Sukhatme (1967).

Results and Discussion

The study evaluated several vegetative growth parametersplant height (cm), number of leaves per plant, chlorophyll content (SPAD value), and stem diameter (mm). The data, presented as mean values in the accompanying tables, were statistically analyzed to ensure accuracy and reliability.

Number of Leaves:

The T 7 Bower system with 2 cordons recorded the highest number of leaves per plant, an average of 174. This was followed by the T8 Bower system (4 cordons) and the T6 Tatutra system (8 arms). In contrast, the T 2 Kniffin system (4 arms) exhibited the lowest leaf count, an average of 40.6 leaves per plant.

Plant Height: Plant height reached its maximum of 169 cm in the T8 Bower system (4 cordons). The T7 Bower system (2 cordons) and the T 5 Tatura system (4 arms) also produced notably high plant heights. Conversely, the T0 Control consistently recorded the lowest plant height at 115 cm.

Stem Diameter: Regarding stem diameter, the T7 Bower system (2 cordons) yielded the largest girth at 6.38 mm. This was closely followed by the T 8 Bower system (4 cordons) and the T 2 Kniffin system (4 arms). The smallest stem diameter of 4.5 mm was observed in the T1 Kniffin system (2 arms).

Chlorophyll Content: Chlorophyll content, measured by SPAD values, was highest in the T 8 Bower system (4 cordons) with an average value of 52.4. The T7 Bower system (2 cordons) and the T 2 Kniffin system (4 arms) also recorded high chlorophyll levels, whereas the T 3 High Trellis system (single cordon) registered the lowest SPAD value at 45.3. Collectively, these findings indicate that training systems significantly influence vegetative growth parameters. In particular, the Bower system-with both its 2-cordon and 4cordon configurations-consistently resulted in enhanced growth, underscoring its potential for improving plant vigor and productivity.

Discussion

The differences in vegetative growth parameters among the various training systems are strongly linked to how each system alters the plant's microenvironment and internal physiological processes.

Microclimatic Modifications and Stress Mitigation

The architectural design of the training system also influences the local microclimate. Systems like the Bower configurations offer better air circulation and prevent the buildup of heat and humidity around the foliage. Reduced microclimatic stress helps maintain optimal enzymatic and metabolic activity, thus supporting active chlorophyll synthesis and photosynthesis (Kingara and Kaur, 2017). In contrast, more compact systems may create microenvironments that exacerbate thermal or water stress, leading to lower growth performance.

Mechanical Stimuli and Thigmomorphogenesis:

The training systems impart mechanical stimuli to the plants, a phenomenon known as thigmomorphogenesis, where physical forces influence plant form and structure (Braam et al., 2005) Continuous yet moderate mechanical stress can stimulate responses such as lignification and cell wall thickening, resulting in a robust stem structure. This adaptive response is evident in the significantly larger stem diameters seen in treatments like T 7 , where the moderate mechanical stress helps improve resource support for overall growth.

Chlorophyll Content and Photosynthesis: Higher

SPAD values in the T 8 Bower system, as well as in the T 7 and T 2 treatments, indicate a well-developed photosynthetic apparatus. With improved light exposure and reduced stress, plants can synthesize more chlorophyll. This increase in chlorophyll content not only reflects healthier leaves but also confirms that the biochemical pathways associated with photosynthesis are functioning more efficiently, which enhances the overall vigor and productivity of the plant (Li et al., 2018).

Conclusion

Based on the investigation findings, the T 7 Bower system (2 Cordons) demonstrated the best performance, with 174 leaves, a vine length of 162 cm, a stem girth of 6.38 cm, and a chlorophyll content (SPAD value) of 52.1. Additionally, the T 4 High Trellis system (Double Cordon) was identified as the most cost-effective training system, costing Rs. 50,160/ ha.

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