Biochemical components of wild relatives of chickpea confer resistance to pod borer, Helicoverpa armigera

Efforts are being made to develop chickpea varieties with resistance to the pod borer, Helicoverpa armigera for reducing pesticide use and minimizing the extent of losses due to this pest. However, only low to moderate levels of resistance have been observed in the cultivated chickpea to this polyphagous pest. Hence, it is important to explore wild relatives as resistance sources to develop insect-resistant cultivars. Therefore, we studied different biochemical components that confer resistance to H. armigera in a diverse array of wild relatives of chickpea. Accessions belonging to wild relatives of chickpea exhibited high levels of resistance to H. armigera as compared to cultivated chickpea genotypes in terms of lower larval survival, pupation and adult emergence, decreased larval and pupal weights, prolonged larval and pupal developmental periods and reduced fecundity of the H. armigera when reared on artificial diet impregnated with lyophilized leaf powders. Amounts of proteins and phenols in different accessions of chickpea wild relatives were significantly and negatively correlated with larval weight, pupation and adult emergence. Phenols showed a negative correlation with pupal weight and fecundity, but positive correlation with pupal period. Total soluble sugars showed a negative correlation with larval period, but positive correlation with pupation and pupal weight, while tannins showed a positive correlation with larval weight, pupation and adult emergence. The flavonoid compounds such as chlorogenic acid, ferulic acid, naringin, 3,4-dihydroxy flavones, quercetin, naringenin, genistein, biochanin-A and formononetin that were identified through HPLC fingerprints, exhibited negative effects on survival and development of H. armigera reared on artificial diet impregnated with lyophilized leaf powders. The wild relatives with diverse mechanisms of resistance conferred by different biochemical components can be used as sources of resistance in chickpea breeding programs to develop cultivars with durable resistance to H. armigera for sustainable crop production

Review on ultra-high temperature boride ceramics

Ceramic materials having melting points higher than 3000 °C and suitable for structural applications at above 2000 °C are commonly known as Ultra-High Temperature Ceramics (UHTCs). Several transition metal di-borides, possessing the desired combinations of thermo-mechanical, physical and chemical properties, form an important sub-class of the UHTCs. Over the last couple of decades, there has been a growing interest for UHTCs in general, and for the transition metal di-borides in particular, due to the increasing demands in hypersonic aerospace vehicles, atmospheric re-entry vehicles and energy applications. However, problems pertaining to sintering, moderate fracture toughness and experimental challenges associated with reliably measuring the elevated temperature properties, as well as the properties that determine the performances at the actual service conditions, have limited their widespread applications. This paper comprehensively reviews the various routes/techniques, including the advanced ones, as adopted for the synthesis and densification of the di-borides. The effects of sinter-additives and reinforcements on the densification, microstructure and various properties, including elevated temperature properties have been discussed in critical terms. Due attention has been paid towards understanding the challenges associated with the experimental measurements of the high temperature properties under extreme environmental conditions and the very recently developed techniques for the same. Some of the existing and futuristic applications of transition metal di-borides have also been discussed. Finally, the review concludes with an outlook towards some of the outstanding issues