Effect of Explant Size and Season of Explants Excision on Propagation of Wilt Tolerant Interspecific Rootstock of Guava (Psidium molle Bertol x Psidium guajava L.)

Guava (Psidium guajava L.) is an important tropical and subtropical fruit crop valued for its nutritional, economic, and industrial significance. However, morphological characterization and propagation studies of interspecific guava rootstocks remain limited. The present investigation evaluated the effect of season of explants excision and explant size on the propagation of wilt-tolerant interspecific guava rootstock (Psidium molle × Psidium guajava). The study was conducted during 2024–2025 at the Division of Crop Improvement and Biotechnology, ICAR–Central Institute for Subtropical Horticulture (CISH), Rehmankhera, Lucknow, India. The experiment was laid out in a Completely Randomized Design (CRD) with four replications for seasonal treatments and five replications for explant size treatments. Data on season of explants excision revealed that July–September recorded the highest rooting frequency (81.91%), regeneration frequency (83.66%), plant height (32.02 cm), and shoot girth (4.71 mm). Five cm long explants resulted in the earliest root initiation (21.24 days), whereas 10 cm explants showed superior rooting percentage (57.43%), number of primary roots (19.09), number of secondary roots (31.76), primary root length (11.63 cm), and root diameter (0.74 mm). The results demonstrate that both season and explant size significantly influence propagation efficiency in wilt-tolerant interspecific guava rootstock.