Abstract:

The effect of exogenous applications of potassium (K), calcium (Ca),
and nitrogen (N) on the susceptibility of four banana cultivars to Banana
Xanthomonas wilt (BXW) was studied. Murashige and Skoog
(MS) medium with normal concentrations of K at 783 mg/liter, Ca at
121 mg/liter, and N at 841 mg/liter was modified to contain various
concentrations of K, Ca, and N. Each nutrient was varied singly, each
with three replicate experiments. The concentrations were K at 78,
157, 391, 783, 1,565, and 3,913 mg/liter; Ca at 12, 24, 60, 121, 241,
and 603 mg/liter; and N at 84, 168, 420, 841, and 1,682 mg/liter. Plantlets
were generated in vitro on normal MS medium and later exposed to the nutrient concentrations for a total of 8 weeks. Thereafter, they
were artificially inoculated with Xanthomonas campestris pv. musacearum
using an insulin syringe. In each nutrient, plantlets exposed to
higher nutrient concentrations significantly (P < 0.0001) accumulated
more nutrient in their tissues compared with those exposed to lesser
nutrient concentrations. Wilt incidences were significantly reduced,
and incubation periods (time from inoculation to appearance of first
disease symptoms) increased, with increasing nutrient application. The
study lays a background for in vivo studies aimed at management of
BXW using nutrients, such as fertilizer application.