Dependences between Beginning of Mulberry Vegetation and Air Temperature in Northwest Bulgarian Conditions

Z. PETKOV

Sericultural Experiment Station, BG-3000 Vratza, Bulgaria

Abstract

PETKOV, Z., 2000. Dependences between beginning of mulberry vegetation and air temperature in Northwest Bulgarian conditions. Bulg. J. Agric. Sci., 6: 303-306

Some dependences between beginning of mulberry vegetation and air temperature were analysed at Vratza (Northwest Bulgaria) conditions. In the spring mulberry vegetation has been started earliest in Morus alba and Morus latifolia species and for this an average 89 – 91 days from the beginning of the year and 158.74 – 180.82⁰C sum of effective temperatures were necessary. Some complicated dependencies between period till beggining of mulberry vegetation, average temperature for this period and sum of effective temperatures were detected. The correlation between sum of effective temperatures and average temperature for the period till vegetation starting was negative, between period till beginning of vegetation and average temperature was negative also and between sum of effective temperatures and period till vegetation starting was positive with varying degree. The results obtained could be used for mulberry varieties dividing into practice in Northwest Bulgarian conditions.

Key words: mulberry, beginning of vegetation, air temperature, correlation, regression