Foliar spray of phosphates induces growth increase and systemic resistance to Puccinia sorghi in maize

Abstract

A single foliar spray of 0-1 M phosphate salts solution was applied to the upper side of maize (cv. Jubilee) leaves 1,2 and 3 at the five-to six-leaf stage, 2-4 h before inoculation with Puccinia sorghi. This treatment induced systemic resistance against common rust as expressed by 98% reduction in the number of pustules of P. sorghi developed on leaves 5, 6 and 7, There was no damage or chlorotic stippling on the induced leaves (I, 2 and 3) as a result of the phosphate spray, A less effective, but still significant. reduction (90%) in the number of pustules was obtained when the foliar spray was applied 6 days before inoculation. One foliar spray of K2HPO4 on leaves 1,2 and 3.6 days before inoculation, stimulated plant growth regardless of inoculation. The foliar spray on the day of inoculation was less effective in stimulating growth. Appropriate mixtures of phosphate solutions revealed that the level of protection was not necessarily dependent on the gradual changes in the pH of the solution. The possible dual use of phosphate salts as foliar fertilizers and as agents for induced resistance is discussed.

Foliar sprays of NPK fertilizers induce systemic protection againstPuccinia sorghi andExserohilum turcicum and growth response in maize

“…Similar data were reported for P. sorghi and E. turcicum, the causal organisms of common rust and northern leaf blight (NLB) in maize, respectively Reuveni, R. et al, 1994a;1994b]. Interestingly, potassium phosphate has recently been identified as the active component in the earlier papilla formation and resistance of barley to powdery mildew [Inoue et al, 1994].…”

“…The present data and our previous reports Reuveni, R. et al, 1994a; h after inoculation and were used for determination of NPK accumulation, as described in M&M, and Figure 6. The total number of pustules produced on leaves 9 and 10 was counted 14 days after inoculation.…”

Induction of resistance in chickpea (Cicer arietinum L.) against Ascochyta rabiei by applying chemicals and plant extracts

“…Different types of phosphate salt viz dibasic and tribasic sodium or potassium phosphates were highly effective in SAR induction with a pH value greater than 7 (Gottstein and Kuć, 1989). Foliar application of these phosphate salts induced systemic resistance (ISR) in cucumber (Descalzo et al, 1990), broad bean (Walters and Murray, 1992), grapevine (Reuveni and Reuveni, 1995), maize (Reuveni et al, 1994), pepper (Reuveni and Reuveni, 1995;Reuveni and Reuveni, 1998), and rice (Manandhar et al, 1998) against diversified pathogens belonging to various taxonomic groups. However, all the results are contradictory with our findings and there might be a difference in the selection of K salts or pH may be less than 7.…”

Managing Crop Disease through Cultural Practices

“…As with nitrogen, the effects of phosphorus on plant disease may be the result of direct effects on the pathogen, host plant metabolism, leading to effects on pathogen food supply, and effects on plant defences (Walters & Bingham, 2007). Indeed, foliar application of phosphate salts has been shown to induce resistance to pathogens in a range of crop plants, including cucumber (Mucharromah & Kuc, 1991), broad bean (Walters & Murray, 1992), grapevine (Reuveni & Reuveni, 1995), maize (Reuveni et al, 1994) and rice (Mandahar et al, 1998).…”