Effect of eggplant (Solanum melongena) rootstocks on growth and yield performance of grafted tomato (Solanum lycopersicum L.) (cv. Pusa Ruby) under Bastar agro-climatic conditions

Introduction

The tomato (Solanum lycopersicum L.), one of the most significant crops in the Solanaceae (Night Shade) family, is native to the Andes region of South America, specifically Peru, Equador and Bolivia (Rick, 1969) [13] . The term "tomato" comes from the Spanish word "tomate". After China, India is the world's second-largest producer of horticulture crops. India, tomato was grown over an area of 0.873 MH in 2023-24 with an annual production of 21.238 MT (Anonymous 23-2024) [2] . It is mainly grown in Madhya Pradesh, Andhra Pradesh, Karnataka, Tamil Nadu, Orissa, Gujrat and West Bengal. Whereas, the area and production of tomato in Bastar was 0.001MH and 0.017 MT (Anonymous 2022-23) [1] . In Chhattisgarh tomato are mainly grown in Durg, Jashpur, Kondagaon, Raigarh and Bastar. The main goal of agriculture over the past few decades has been to boost crop productivity and yield in order to meet the growing global population's demand for food. Because of this, intensive cropping systems with few crop rotations which are particularly used for vegetable crops grown in open fields and under protection have led to the accumulation of harmful elements (biotic or abiotic) that can have a severe impact on yield and quality. Concerns about the environment and human health have resulted from the increased usage of input variables (water, chemical fertilizer, pesticides etc.) brought on by these unfavourable circumstances. A number of biotic and abiotic variables impact tomato cultivation, resulting in subpar development and decreased output (Pugalendhi et al., 2019) [11] . Developing a new hybrid with all the desirable traits can be done to overcome the problems, but the time taken to develop such a hybrid is also considerable. Hence, grafting can be a better alternative to overcome those hindrances. Grafting has proven to mitigate some soil-borne diseases and abiotic stresses as well as improve plant growth, yield (Shipepe, B. T. and T. J. Msogoya, 2018) [15] .

Rootstock and scion parameters 2.2.1 Germination percentage

The germination percentage of scion seeds as well as rootstocks seeds were calculated by dividing the number of seeds germinating to the total number of seeds sown multiplied by hundred.

Number of seeds germinated

Total number of seed sown × 100

Observation of grafted plant 2.3.1 Survival percentage

The total numbers of grafted seedlings survived in each treatment after transplanting were recorded and survival percentages of grafted seedlings were calculated.

Survival percentage of grafted seedlings =

Number of grafted seedling survived

Total number of grafted seedling × 100

The plant height of five randomly selected plants from each plot were measured from the ground level to the apical bud of the plant with the help of measuring tape.

Days to first flowering

In each treatment, the date of the first flower bud initiation was recorded, and the number of days counted from the date of transplanting was recorded as the days to first flowering.

Days to first fruiting

In each treatment, the date of first fruit initiation was recorded, and the number of days counted from the date of sowing was recorded.

The weight of fruits was measured at marketable stage from randomly selected plants from each plot at the time of peak harvest and average value was computed.

In each treatment, the length of five randomly selected fruits at marketable stage from each plot was measured longitudinally by vernier callipers from head end to blossom scar and the mean value was recorded in centimetres.

Total weight of marketable fruits of each plant was recorded under full range of picking and was summed and averaged by dividing with the number of plants to get total yield plant -1 .

Result and Discussion

The germination percentage of wild relatives of S. melongena (Rootstocks) and commercial tomato cultivar (Scion) is presented in table no. 1 it revealed significantly highest germination was recorded under the treatment T15: 30 days old pusa ruby + Solmel obtained the highest (83.07%) but it was statically at par with T1: 20 days old pusa ruby + Solanum torvum (78.14), T7: 25 days old pusa ruby + Solanum xanthocarpum (78.69%), T9: 25 days old pusa ruby + Solanum indicum (78.83%), T6: 25 days old pusa ruby + Solanum torvum (79.68%), T12: 20 days old pusa ruby + Solanum xanthocarpum (80.46%), T5: 20 days old pusa ruby + Solmel (80.73%), T14: 30 days old pusa ruby + Solanum indicum (80.76%), T11: 25 days old pusa ruby + Solanum torvum (81.19%), T10: 25 days old pusa ruby + Solmel (82.17%) whereas, the lowest germination was noted under the treatment T3: 20 days old pusa ruby + Solanum viarum (74.16%). In the present investigation rootstocks seed sowed and observed that temperature was a critical factor which affected the germination. It was reported that germination was 85-98 per cent in all the rootstocks. The above result is in agreement with (Ibrahim et al. 2001) [7] .

The data pertaining to the graft success percentage is presented in table no.1. Among the different graft combinations, the maximum survival percent was recorded in the treatment combination T15: 30 days old pusa ruby + Solmel (76.67%) but it was statically at par with T11: 30 days old pusa ruby + Solanum torvum (73.33%). Under these combinations the minimum survival percentage (48.33%) was observed under the treatment combination T4 (20 days old pusa ruby + Solanum indicum). Soltan et al. (2017) [17] reported that grafting success and the survival of the grafted plant depends on the cohesion between rootstock and scion (i.e., callus formation, vascular bundle differentiation and connectivity at the graft interface) that insure the balanced development of both scion and rootstock necessary for optimum horticultural performance.

The data pertaining to the plant height percentage is presented in table no. 1. Maximum plant height was recorded in treatment T15: 30 days old pusa ruby + Solmel rootstock (73.91 cm). Plant heights of treatment T5: 20 days old pusa ruby + Solmel (64.49 cm) and T10: 30 days old pusa ruby + Solmel (65.82 cm) rootstocks were also on par with each other. Minimum plant height was recorded in treatment T4: 20 days old pusa ruby + Solanum indicum (49.12 cm). Lee, (1994) [8] found that grafted plants were taller and more vigorous than self-rooted ones. Similarly, Rathod, (2017) [12] also recorded minimum plant height in self-rooted brinjal and maximum plant height was recorded in grafted brinjal (Mahyco-9 on Solanum torvum).

Days to first flowering

The data pertaining to days to first flowering showed significant differences among different graft combinations (Table no.-1). The minimum days taken for first flowering was observed in the treatment T15: 30 days old pusa ruby + Solmel (26.43 days) but which was on par with T11: 30 days old pusa ruby + Solanum torvum (27.75 days), T12: 30 days old pusa ruby + Solanum xanthocarpum (28.27 days), T13: 30 days old pusa ruby + Solanum viarum (28.63 days), T14: 30 days old pusa ruby + Solanum indicum (28.83 days), T10: 25 days old pusa ruby + Solmel (30.60 days), T6: 25 days old pusa ruby + Solanum torvum (31.27 days) and T7: 25 days old pusa ruby + Solanum xanthocarpum (31.75 days). The maximum days taken for first flowering was recorded in the treatment T4: 20 days old pusa ruby + Solanum indicum (37.01 days). Madhur et al. (2009) [10] stated that grafted plants need time to acclimatize in field condition where formation of graft union delays the early establishment of plant which may affect the reproductive organs without effecting vegetative growth in the grafted plants at early stages, later, grafted plants significantly influenced the flowering because of wild habit and vigorous root system of rootstock as wild cultivars have gregarious flowering nature. Vigorous plants by grafting extended the growth period and luxurious growth and delayed flowering.

Days to first fruiting

The data regarding the Days to first fruiting is presented in table no.-2. Among the different graft combinations early fruiting (39.17 days) was recorded under the treatment combination T15 in which 30 days old pusa ruby + Solmel which was par T11: 30 days old pusa ruby + Solanum torvum (43.58 days), T12: 30 days old pusa ruby + Solanum xanthocarpum (44.03 days), T8: 25 days old pusa ruby + Solanum viarum (44.90 days), T13: 30 days old pusa ruby + Solanum viarum (44.93 days) and T8: 25 days old pusa ruby + Solanum indicum (45.87 days). whereas, late fruiting (53.67 days) was observed in the combination T4 (20 days old pusa ruby + Solanum indicum) which was par T11: 30 days old pusa ruby + Solanum torvum (43.58 days), T12: 30 days old pusa ruby + Solanum xanthocarpum (44.03 days), T8: 25 days old pusa ruby + Solanum viarum (44.90 days), T13: 30 days old pusa ruby + Solanum viarum (44.93 days) and T8: 25 days old pusa ruby + Solanum indicum (45.87 days).: 20 days old pusa ruby grafted + Solmel (39.86 g) whereas, the lowest average fruit weight (30.03 g) was reported in the 20 days old pusa ruby + Solanum viarum (T3). Tomato grafted onto Solanum torvum rootstock show higher fruit weight than Solanum indicum rootstock since it is a wild species with a vigorous root system, which follows the findings of Fullana-Pericas et al. (2018) [3] .

The observations on the fruit length of fruit are presented in table no. Compared to the non-grafted plants, respective fruit from grafted plants showed higher polar diameters. It is probably due to changes in the concentration of growth regulators or more supply of food nutrients etc., by rootstocks which lead to increased length of the fruit. The results agree with the findings of Hoyos et al. (2010) [6] , Hossain et al. (2019) [5] and Singh et al. (2019) [16] . Rootstocks affected fruit length and it may be due to changes in the concentration of growth regulators induced by the rootstock. Similar findings were reported by Gisbert et al. (2011) [4] .

Fruit yield plant -1

The observations on the Fruit yield per plant are presented in table no.-2. Among all the combinations, maximum fruit yield per plant was recorded (1,745.33 g) in the treatment T15: 30 days old pusa ruby + Solmel which was at par with T5: 20 days old pusa ruby + Solmel (1,520.67 g), T11: 30 days old pusa ruby + Solanum torvum (1,584.67 g), and T10: 25 days old pusa ruby + Solmel (1,660.67 g) whereas, minimum fruit yield plant -1 (724.33 g) was noticed in the treatment T4: 20 days old pusa ruby + Solanum indicum respectively. This could be as a result of increased fruit size, fruit weight and number of fruits in the grafted plants. It is well known that the root system of the plants affects 82 vegetative growth and yield with the increase of water and nutrient uptake due to the vigorous root system of rootstocks (Lee 1994) [8] and thus grafting affects growth and ensures higher yields than in non-grafted plants. Maximum fruit yield obtained from eggplant rootstock in all experiments is likely due to eggplant being more vigorous. Schwarz et al. (2010) [14] also found that the root system of eggplant is more effective in water uptake than tomato root systems.

Conclusion

Significant variation was observed among the graft combinations for growth and yield traits. The treatment T15 (30 days old pusa ruby + Solmel) consistently outperformed others by recording the highest plant height, earliest flowering and fruiting, maximum fruit length and fruit yield plant -1 (1,745.33 g). Other effective combinations included T10, T11 and T5, demonstrating the superiority of Solmel and Solanum torvum as rootstocks. The enhanced performance can be attributed to improved nutrient uptake, graft compatibility and the vigorous root system of the selected rootstocks, indicating their potential for improving tomato productivity through grafting.

Acknowledgement

AcknowledgementWe sincerely thank to Associate Professor and Dean Dr. G. P. Nag, K. D. CHRS, Jagdalpur, Bastar (C.G.), for his valuable guidance and supervision during the research work. I also extend my gratitude to all-faculty members of K. D. CHRS for their support throughout my master research work.

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