ENVIRONMENTAL-EFFECTS ON THE ACCUMULATION OF HYDROXAMIC ACIDS IN WHEAT SEEDLINGS - THE IMPORTANCE OF PLANT-GROWTH RATE

The effects of temperature and photoperiod on accumulation of hydroxam ic acids (Hx) in wheat (Triticum aestivum L.) seedlings were evaluated under laboratory conditions. Hx concentrations were significantly hig her at higher temperatures. No such clear trend was found for the phot operiod effect. The significant effect of temperature and photoperiod on growth rate of seedlings and the significant positive correlation b etween growth rate prior to analysis and levels of Hx, suggested that environmental effects on Hx accumulation were at least partially media ted through their effect on plant growth rate. After uncoupling the ef fect of environmental conditions from the effect of plant growth rate by statistical means the effect of temperature on Hx was no longer sig nificant. Therefore, temperature effect was fully mediated by plant gr owth rate. Implications of the patterns found are discussed in issues of plant-defense general theories.