Shallot (Allium Cepa Var. Aggregatum) Genotypes and Their Crossbreds Resistance to Fusarium Wilt Disease

Abstract

Shallots are valuable horticultural products consumed worldwide that offer numerous health benefits. Fusarium wilt disease severely limits shallot production, reducing bulb yield by up to 50%; furthermore, wilt disease-resistant shallot cultivars are insufficient. This study confirmed that the 'Batu Ijo' cultivar is resistant to Fusarium wilt, with the lowest percentage of affected bulbs (29.5%). In contrast, the cultivar 'Bima Brebes' showed the highest incidence of Fusarium infection (41.6%). Neither 'Batu Ijo' nor 'Katumi' became resistant parents when crossbred with susceptible plants because both failed to bloom until the end of the plant generative stage. Thus, to generate diverse segregating populations, a cross combination derived from 'Biru Lancor' (resistant parent) and 'Bima Brebes' ensued. The results showed lower values for the number of mature capsules, true seed shallot weight per plant, and seedling vigor were evident in the progenies than in the parental genotypes. These poor crossing results were due to several factors, including an inappropriate photoperiod for the crossbreeding of 'Bima Brebes' and 'Biru Lancor.' Out of 30, 17 plants showed symptoms of Fusarium wilt disease. Meanwhile, the 13 resistant individuals exhibited similarities with the male parent 'Biru Lancor' during ISSR molecular analysis, suggesting that the male parent may play a role in transmitting disease resistance. The selection of parental individuals and crossbreeding factors are crucial for successful shallot crossbreeding. This study bears significant implications for further development of shallot crossbreeding, potentially leading to new disease-resistant cultivars.