R. Reuveni et al., FOLIAR SPRAYS OF NPK FERTILIZERS INDUCE SYSTEMIC PROTECTION AGAINST PUCCINIA-SORGHI AND EXSEROHILUM-TURCICUM AND GROWTH-RESPONSE IN MAIZE, European journal of plant pathology, 102(4), 1996, pp. 339-348
One spray of 0.1 M aqueous solutions of NPK fertilizers on the upper s
ides of maize leaves 1, 2, and 3, 2-4 h prior to inoculation, induced
systemic resistance (ISR) against northern leaf blight (NLB) caused by
Exserohilum turcicum and Puccinia sorghi which were developed on leav
es 4, 5, 6, and 7. ISR was expressed as a reduction in the number and
area of lesions of E. turcicum and in the number of sporulating or non
-sporulating pustules of P. sorghi on leaves 4, 5, 6, and 7. The reduc
tion in the number of NLB lesions ranged from 51% (KH2PO4) to 69% (K2H
PO4) and their size reduction ranged from 73% (KNO3) to 91% (K2HPO4) a
s compared with water prayed plants. The reduction in the number of pu
stules of P. sorghi ranged from 66 to 77%. Fertilizers consisting of v
arious combinations of N, P and K in every case induce similar levels
of protection in either host-pathogen system. The induced protection w
as evident regardless of the leaf position or the rate of NPK accumula
tion in the upper protected leaves. High fresh weight was detected in
the induced plants which expressed the greatest induced protection aga
inst NLB and common rust. The possible dual use of NPK fertilizers - t
o supply nutrients to plants foliarly and at the same time to activate
the mechanism(s) for induction of systemic protection to P. sorghi an
d E. turcicum in maize - is discussed.