RELATIONSHIP AMONG YIELD AND YIELD COMPONENTS OF WINTER WHEAT (TRITICUM AESTIVUM L.) CULTIVARS, AS AFFECTED BY TILLAGE SYSTEMS

The relationships among grain yield and yield components of 6 winter wheat cultivars in Romania, as affected by two contrasting tillage systems (no tillage-NT and chisel tillage-CT) were studied during five growing seasons (2011/12-2015/16) at Fundulea, which is located in the middle of Eastern Romanian Danube Plain. In order to determine the relationship between the investigated traits, both correlation method and linear regression were used on the level of significance 5%, 1% and 0.1%, dependant variables being considered as already late formed features in ontogenesis. Under both NT and CT tillage systems, mean positive correlations between number of kernels per spike and individual kernel weight per spike (r = 0.783*** and r = 0.524**, respectively) and strong positive correlations between grain yield and number of spikes m(-2) (r = 0 .893*** and r = 0.905***, respectively) were established. Weak correlation between kernel weight per spike and thousand kernel weight (r = 0.379* and r = 0.456*, respectively) was also established. Due to lower nutrients availability in NT system versus CT system, one can ascertain a significant diminution of number of grains per spike and grain weight per spike together with spike density increasing. Under CT system versus NT system, the significant TKW diminution due to increasing of number of grains per spike could be attributed to the diminution of soil moisture preservation as follows of crop residue incorporation.