The cultivation of nutritionally and economically important crops like tomato are often threatened by dry spells due to drought as these crops largely depend on an assured water supply. The magnitude and intensity of drought is predicted to intensify under climate change scenarios, particularly in semi-arid regions, where water is already a scarce resource. Hence, it is imperative to devise strategies to mitigate the adverse effects of drought on tomato through improvement in the plant’s efficiency to utilise the moisture in the growth medium. Since the root is the entry point for water, its intrinsic structure and functions play a crucial role in maintaining the soil–water–plant continuum during moisture deficit at the rhizosphere. Grafting offers a great opportunity to replace the root system of the cultivated tomato plants with that of wild species and hence provide a rapid solution to modulate root system architecture in contrast to the time-consuming conventional breeding approach. However, the success in developing the best graft combination of cultivated tomato and rootstock depends on the source of rootstock and selection methods. In this study, we used a high throughput phenomics facility to assess the efficiency of tomato, grafted on the rootstocks of different genetic backgrounds, at different levels of moisture in the soil. Rootstocks included tomato cultivars and the hybrids, derived from the crosses involving wild relatives, as donor parents. Among the rootstocks, an interspecific (Solanum lycopersicum × S. pennellii) derivative RF4A was highly efficient in terms of productive use of water. The RF4A rootstock-grafted plants were more conservative in water use with higher plant water status through relatively better stomatal regulation and hence were more efficient in generating greater biomass under water stress conditions. These plants could maintain a higher level of PSII efficiency, signifying better photosynthetic efficiency even under water stress. The distinct response of interspecific rootstock, RF4A, to water stress can be ascribed to the effective root system acquired from a wild parent (S. pennellii), and hence efficient water uptake. Overall, we demonstrated the efficient use of a phenomics platform and developed a protocol to identify promising rootstock–scion combinations of tomato for optimization of water use.

In soil-based protected cultivation, the prevalence of certain diseases like bacterial wilt and nematodes in the bell pepper plant due to its successive cropping pose a threat for maximizing productivity. Considering the potential of grafting to alleviate various biotic and abiotic stresses, often relying on rootstock’s capability, we explored the potential of diverse local genotypes of Capsicum spp. to utilize as rootstocks. In this research, we assessed the performance of a commercial bell pepper cv. Massilia F₁, grafted onto twenty-five rootstocks along with non-grafted and self-grafted Massilia plants under artificial inoculation conditions of bacterial wilt (Ralstonia solanacearum) and nematodes (Meloidogyne incognita) in a plastic greenhouse. The response of rootstock grafting was determined by assessing disease incidences and their effect on plants growth, yield, and physiology, as well as their efficiency in nutrient accumulation. The grafted plants exhibited varied responses to diseases depending on rootstock genotypes. Notably, Massilia grafted onto the CRS-8 and CRS-1 rootstocks exhibited high bacterial wilt resistance by showing lower percent disease incidence (PDI) (22.22 and 27.78 percent, respectively). Others, like CRS-11, CRS-12, CRS-13, CRS-21, and CRS-24, showed moderate resistance (PDI ranging from 33.33 to 38.89 percent, respectively). The self-grafted and non-grafted plants were highly susceptible and recorded complete mortality by the end of the experiment. All of the grafted plants exhibited promising resistance against nematode infestation compared to non-grafted and self-grafted plants with 26.17 and 8.67 percent root galls, respectively. The susceptible plants had lower shoot and root dry weights, while the resistant graft combinations had comparatively higher biomass. Importantly, grafting induced earliness in flowering and provided higher yields, especially in graft combinations involving the CRS-15, CRS-11, and CRS-8 rootstocks. These graft combinations exhibited significantly higher yields over the non-grafted and self-grafted plants. The plant yield was positively associated with plant height, number of leaves, fresh and dry weight of roots, number of fruits per plant, and average fruit weight, but negatively related to bacterial wilt and root-knot nematode incidences. The increased level of antioxidant enzymes such as polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), and peroxidase (POD) and the higher total chlorophyll content in the resistant grafted plants indicates their better ability to cope with diseases at the cellular level. This study highlights the robust performance of certain rootstocks from Capsicum annuum (CRS-1, CRS-2, CRS-11, CRS-15) and Capsicum frutescens (CRS-8, CRS-13, CRS-22) species across multiple measured parameters. Grafting emerges as a sustainable solution for bell pepper production in bacterial wilt- and nematode-infested soil under plastic greenhouses.