INFLUENCE OF SOWING TIME ON THE EXPRESSION OF BARLEY AND WHEAT PLANTS PHYSIOLOGY

Tipically, in our autumn wheat and barley have sown in a relatively wide range, due to variuos causes: climate (Slater, 1976), management etc. To clarify what would be the most appropriate range for the plants to know the physiology of the most favorable, decadal have experienced many moments of sowing several years. Period was thus between Sept. 10 and Nov. 1 (6 points sowing). Plants were studied by several indices for physiology expression (Stoy, 1969) i.e. leaf area index (LAI), the photosynthetic potential by leaf area duration (LAD), net assimilation rate (NAR) and grain yield. Among these features were found match, but on the contrary, some are even contradictory. Thus, if the maximum LAI of wheat was obtained from Oct. 1 (9.2 m2 leaf/m2 soil), the maximum photosynthetic potential was still to Oct. 1 (1.48 km2 leaf x day), and maximum net assimilation rate was obtained in Oct. 10 (6.63 g d.m./m2 /day). LAI of barley was Oct. 1 (7.4 m2 leaf/m2 soil), maximum LAD Sep. 20 (1.11 km2 leaf x day), and maximum NAR Oct. 10 (7.05 g d.m./m2 /day). In these conditions, the maximum grain production was formed for wheat in Oct. 1 with an extension until Oct. 20. Winter barley was maximum in Oct. 1 with an extension from Sept. 20 until Oct. 10.