NEGATIVE CORRELATION BETWEEN THE AMOUNT OF RESPIRED SUBSTRATE AND THESHOOT ROOT RATIO IN DARK-GROWN BARLEY SEEDLINGS/

Spring barley plants (Hordeum vulgare L., cv. Koral) were cultivated i n full darkness in one of the following nutrient solutions for 21 days : distilled water (control), KNO3, Ca(NO3)2, KH2PO4, MgSO4, NaCl. Samp lings were made during the period of fast substrate export from the ke rnel (days 5 to 8 from the start of gemination) and by the end of the experiment (days 20 and 21) when the kernel utilizable substrate was e xhausted. Nutrient solutions significantly affected both shoot and roo t growth, shoot/root ratio and the amount of respired substrate. The p lants in the KNO3 solution respired the least amount of available subs trate (17.8 mg plant-1) whereas those from MgSO4, Ca(NO3)2 and distill ed water used 22.3,22.1 and 21.4 mg plant-1, respectively. Tle lowest shoot/root ratio was found in plants from the distilled water (1.50) a nd Ca(NO3)2 (1.73), whereas the highest ratio (3.25) was found in plan ts grown in KNO3. Because of differences in respiration rate per unit dry mass between shoot and root, nutrient availability may primarily a ffect dry matter distribution between shoot and root and lead to diffe rences in the amount of substrate respired per plant.