Water stress augments silicon-mediated resistance of susceptible sugarcane cultivars to the stalk borer Eldana saccharina (Lepidoptera: Pyralidae)

Abstract

Silicon (Si) can improve resistance of plants to insect attack and may also enhance tolerance of water stress. This study tested if Si-mediated host plant resistance to insect attack was augmented by water stress. Four sugarcane cultivars, two resistant (N21, N33) and two susceptible (N26, N11) to Eldana saccharina Walker were grown in a pot trial in Si-deficient river sand, with (Si+) and without (Si-) calcium silicate. To induce water stress, irrigation to half the trial was reduced after 8.5 months. The trial was artificially infested with E. saccharina eggs after water reduction and harvested 66 days later. Silicon treated, stressed and non-stressed plants of the same cultivar did not differ appreciably in Si content. Decreases in numbers of borers recovered and stalk damage were not associated with comparable increases in rind hardness in Si+ cane, particularly in water-stressed susceptible cultivars. Overall, Si+ plants displayed increased resistance to E. saccharina attack compared with Si- plants. Borer recoveries were significantly lower in stressed Si+ cane compared with either stressed Si- or non-stressed Si- and Si+ cane. Generally, fewer borers were recovered from resistant cultivars than susceptible cultivars. Stalk damage was significantly lower in Si+ cane than in Si- cane, for N21, N11 and N26. Stalk damage was significantly less in Si+ combined susceptible cultivars than in Si- combined susceptible cultivars under non-stressed and especially stressed conditions. In general, the reduction in borer numbers and stalk damage in Si+ plants was greater for water-stressed cane than non-stressed cane, particularly for susceptible sugarcane cultivars. The hypothesis that Si affords greater protection against E. saccharina borer attack in water-stressed sugarcane than in non-stressed cane and that this benefit is greatly enhanced in susceptible cultivars is supported. A possible active role for soluble Si in defence against E. saccharina is proposed.

Plant species diversity for sustainable management of crop pests and diseases in agroecosystems: a review

“…On the other hand, Kvedaras et al (2007) found that silicon (Si) provided greater protection against attacks by the sugarcane stem borer Eldana saccharina in water-stressed cane than in unstressed cane (see also "Section 9.3").…”

Silicon in Plant Tolerance Against Environmental Stressors: Towards Crop Improvement Using Omics Approaches

“…Results showed that the Si-applied sorghum plants could extract a large amount of water from drier soils and can maintain a higher stomatal conductance. Silicon was also shown to improve the resistance of sugarcane to water stress [14]. In maize, Si enhanced the efficiency of water use upto 35% and reduced the oxidative membrane damage [15].…”

Impact of silicon on various agro-morphological and physiological<br>parameters in maize and revealing its role in enhancing water stress<br>tolerance

“…Pei et al (2010) reported that in case of wheat, grown in water stress conditions, Si application stimulates antioxidant defense. Kvedaras et al (2007) have shown that the Si does not only enhance the tolerance to water stress but also improves the resistance of sugarcane plants to insect attack (Stalk borer). Gong et al (2006) determined that the application of silicates in the saline culture improves the growth of shoots and correlated it with the Si deposition in the exodermis and endodermis in rice (Oryza sativa L.) seedlings.…”