Effect of fertilization levels, age and canopy height of Lycopersicon hirsutum on the resistance to Myzus persicae

The effects of different levels of fertilization with nitrogen and potassiu m (NK), height within the canopy and plant age of Lycopersicon hirsutum f. glabratum (PI 134417) C. H. Mull and L. esculentum on the density of foliar cristalliferous idioblasts and trichomes, and on the levels of 2-tridecano ne (2-TD) and 2-undecanone (2-UD) and their influence on the resistance to Myzus persicae (Sulzer) were investigated. NK levels were inversely related to densities of trichomes and cristalliferous idioblasts in L. esculentum, but only to densities of cristalliferous idioblasts in L. hirsutum. Tricho me density increased with increasing height within the canopy and with plan t age in L. esculentum and L. hirsutum. Density of cristalliferous idioblas ts in L. hirsutum increased with canopy height reaching a maximum at mid-he ight within the canopy in opposition to L. esculentum in which a small decr ease in density with height within the canopy was found. There was also a s mall decrease of idioblast density with increasing plant age for L. esculen tum, while a greater and opposite variation took place in L. hirsutum. L. e sculentum has mainly non- glandular leaf trichomes (90%), while L. hirsutum has mainly glandular trichomes (97%). The main glandular trichomes of L. h irsutum are producers of 2-TD and 2-UD, whose leaf content increases with i ncrease of trichome density. A negative effect of 2-TD concentration and cr istalliferous idioblast density on the survival and longevity of M. persica e was observed. Since L. hirsutum presented much higher levels of 2-TD and cristalliferous idioblast density than L. esculentum, L. hirsutum seems a p romising source of resistance to M. persicae for tomato breeding programs.