Abstract
The aim of this study is to be investigated “Yield - irrigation depth” relationship for white breading rose in the conditions of Kazanlak’s Valley (south part of Bulgaria). The field experiment was carried out during 2009 - 2011 period with following variants: 1) without irrigation; 2) irrigation with 50% of the irrigation depth; 3) irrigation with 75% of the irrigation depth; 4) full irrigation (100% of calculated irrigation depth). This relationship is established in two directions - for blossom and for oil, using the degree equation: Yi=1-(1-Yd)x(1-xi)n, (where Yi is the yield by irrigation depth xi, Yd - yield without irrigation, xi - relative irrigation depth and n - exponent). The results show that used equation presents very accurately the change of the yield depending on level of the irrigation depth. The value of “n” is from 1.0 to 1.2 and R>0.94. There is linear relationship (by R2>0.8), which allows predicting the yield of oil by data for yield of blossom.