Screening of Fig Varieties for Rootstocks Resistant to Soil Sickness

Abstract

Several fig varieties (Ficus carica L.) were tested as rootstocks for resistance to soil sickness. Exp. 1. Scions of 'Masui Dauphine' ('San Piero' sensu Condit, 1955) were grafted on potted rooted cuttings of 21 fig varieties grown for 3 years in a soil with a history of soil sickness. The trees grew poorly and formed root galls induced by root-knot nematodes (Meloidogyne incognita Kofoid et White). Scion growth on 'King' and 'Conadrid' stocks was uniformly vigorous, and had less growth inhibition than those on 'Masui Dauphine' (control stock). The root gall indices, which varied with rootstock variety, with 30% on 'King' as minimum, did not correlate with shoot growth. Therefore, the index fails as an indicator of susceptibility to soil sickness. Exp. 2. Twenty fig varieties were grown for 1 year in an experimental field with soil sickness and then for 2 more years after grafting with scion of 'Masui Dauphine'.'Zidi' and 'Biter Abiod' stocks promoted more vigorous scion growth than 'Masui Dauphine' (control stock) did. 'King' was initially weak but became relatively vigorous. Exp. 3. 'Masui Dauphine' grafted on 'Zidi', 'Biter Abiod', 'King', and own-rooted 'Masui Dauphine' were grown in 6 different farms. The trees grafted on 'Zidi' were vigorous in every field, even those with soil sickness, and with 3-year-old trees, 'Zidi' had no influence on fruit quality, such as Brix and skin color. Thus, we conclude that 'Zidi' is a suitable rootstock for its tolerance to soil sickness.