Differences in photosynthetic and transpiration activity of bine and branch leaves of hop plant (Humulus lupulus L.)

Abstract

This paper evaluates photosynthetic and transpiration rate of bine and branch leaves of hop (cultivar 'Agnus'). Monitoring of photosynthetic rate helps us determine phases of vegetation and environmental conditions under which plants are most active, most productive, or what influences their activity. By measuring, using LC pro+ (ADC Bio Scientific Ltd.), we detected that branch leaves show a higher rate of photosynthesis than bine leaves. Branch leaves' photosynthetic rate in the period 2011-2013 ranged between 120-184% compared with bine leaves. However, we did not find any dependence of yield on the rate of photosynthesis during the experiment. In some years when lower photosynthetic rate was measured, higher yields were achieved than in years with higher photosynthetic activity. Yield formation is therefore a multifactorial complex, involving main influence of year and weather conditions. Photosynthetic rate of bine leaves ranged from 3.29 to 8.33 μmol CO2 m(-2) s(-1). Photosynthetic rate of branch leaves ranged from 6.05 to 9.89 μmol CO(2) m(-2) s(-1). Transpiration rate of branch leaves ranged between 104-119% compared with bine leaves.