Screening of Chickpea Germplasm for Resistance to Fusarium Wilt Under Sick-Plot Conditions

Abstract

Fusarium wilt, caused by Fusarium oxysporum f. sp. ciceris, is among the most damaging soil-borne diseases of chickpea, and the sick plot has long been the workhorse of resistance screening: a field in which inoculum has been built up so that susceptible plants reliably die. This narrative review asks how far a resistance call made in such a plot can be trusted. It draws on published work on the races of the pathogen, the genetics of resistance, the sources of resistant germplasm, the available molecular markers and the statistics of field trials, and it reports no new data. The main difficulty is instability. Races differ in aggressiveness and symptom type, soil temperature and inoculum density alter the speed and extent of wilting, and sick plots are rarely uniform, so a line that looks resistant in one season or field may wilt in another. Genotype-by-race interaction adds a further layer, because a line resistant to one race can be fully susceptible to another. We argue that a single sick-plot score is best treated as a provisional observation, to be confirmed by repetition, spatial adjustment, race-specific testing and, where available, marker information, and we set out what a transparent screening report should contain.