The response of the perennial teosinte Zea diploperennis (Poaceae) to nitrate availability

Zen diploperennis is a perennial Mexican teosinte with favourable clonal pr opagation characteristics. Being a species of che genus Zen it is used in m aize breeding programs as a source of virus' resistance and other genetic t raits, including regeneration capacity. Determination of optimal growth con ditions of this species is important from the perspective of its potential as a forage crop as well as its potential use in breeding programs and gene tic engineering. The responses of 2-month old Z. diploperennis plants to ni trate availability were investigated. Significant differences have been fou nd in the growth, CO2 exchange (photosynthesis, respiration), chlorophyll a nd nitrogen concentration between plants grown at high (HN) and low (LN) ni trate supply. At HN, the plants grew faster than those cultivated at LN. Ra tes of photosynthesis, leaf respiration, root respiration (including the no nphosphorylating alternative pathway), quantum yield, photosynthetic nitrog en-use efficiency, concentration of chlorophylls and some growth parameters (total biomass, specific leaf area, leaf mass ratio and shoot mass ratio) were higher for the plants at HN. At both HN and LN, we found relatively hi gh values of PNUE.