Effect of Saline Environment on Yield and Smut Disease Severity of Different Corn Genotypes (Zea mays L.)

Abstract

The effects of salitie irrigation water on growth, yield, smut index and leaf CI content were investigated under field conditions. The plants were grown in 1994 and 1995 and artificially infected with U. maydis-spore-suspension at V^ and V,o leaf stages. The severity was rated on a 1-9 scale, whenever the symptotns appeared. The results showed that superior growth, greater yield performance, associated with lower smut incidence and leaf Cl contents were generally observed on Taba than its counterparts. Increasing salinity exhibited significant increases in leaf CI and induced marked inhibition on growth, yield and SI data. The salt sensitivity of corn genotypes, as revealed from the comparison of the slope of linear regression equations, was related to 1.00: 1.19; 1.42 for cvs Taba, 310 and 320, respectively. The differential yield response with respect to SI data proved that smut susceptibility was inversely related to salt tolerance concept. The data of Cl-disease interaction showed that smut reactions of highly susceptible and resistant genotypes (cvs 320 and Taba) were hardly monitored by plant Cl content, revealing that disease resistance is genetically controlled. Conversely, the progressive modifications of smut reaction, accompanied by CI accumulation in the moderately susceptible genotype 310 proved that disease resistance was environmentally conditioned by salt stress.

Responses to combined abiotic and biotic stress in tomato are governed by stress intensity and resistance mechanism

“…It is thus of great importance to examine plant responses to combinations of abiotic and biotic stress factors, important variables that are relevant to crop yields (Soliman and Kostandi, 1998; Kissoudis et al , 2014). …”

“…Field crops are grown under the same variable conditions; however, as they are bred and selected under relatively controlled conditions, several trade-offs might have been overlooked that can result in negative interactions under field conditions ( Brown and Rant, 2013 ; Hückelhoven et al , 2013 ; McGrann et al , 2014 ). It is thus of great importance to examine plant responses to combinations of abiotic and biotic stress factors, important variables that are relevant to crop yields ( Soliman and Kostandi, 1998 ; Kissoudis et al , 2014 ).…”

Combined biotic and abiotic stress resistance in tomato

“…Observations of the effects of abiotic stress on foliar pathogens are on the other hand mixed, with studies reporting either enhanced (Achuo et al 2006;Wiese et al 2004), or decreased resistance (Roubtsova and Bostock 2009;Sanogo 2004). Abiotic stress severity can affect responses to abiotic and biotic stress combinations (Soliman and Kostandi 1998), and therefore the outcome of the interaction may be dependent on the specific environmental conditions under which it occurs.…”

“…and Cl -up to levels that were toxic for the fungus (evidenced by the increased fungal growth under salt stress). The severity of the stress can influence the magnitude of impact of another stress (Soliman and Kostandi 1998). Preliminary results in our laboratory indicated that the impact of salt stress on PM growth may depend on the severity of the applied stress (unpublished results).…”

Effects of different levels of saline water on infection of tomato by Botrytis cinerea, the causal agent of gray mold

“…Many studies concluded that exposure of plants to salinity stress can significantly increase the susceptibility of tomato to root knot nematode (Endongali and Ferris, 1982;Maggenti and Hardan, 1973), and to increase the susceptibility of citrus and chrysanthemum to Phytophthora root rots (Blaker and MacDonald, 1986;MacDonald, 1984;Swiecki and MacDonald, 1988). Soliman and Kostandi (1998) showed that maize had varying susceptibility to smut disease caused by Ustilago maydis under different concentrations of NaCl. The low levels of salinity (25-50mM) could increase the severity of phytophthora root rot of tomato with high Na:Ca ratios (10:1) (Bouchibi et al, 1990); Phytophthora (Roubtsova and Bostock 2009;Sanogo, 2004), F. oxysporum f. sp.…”