Published in Scientific Papers. Series B, Horticulture, Vol. LXV, Issue 2
Written by Kostadin KOSTADINOV, Radoslav CHIPILSKI, Stoyan FILIPOV, Nadezhda SHOPOVA
The climate change that has occurred in the last three decades is also present for the region of Plovdiv in Bulgaria. Increase of annual average air temperature and temperature values during winter and early spring has been recorded in comparison to the (1961-1990) referent period in Plovdiv region. The lettuce development was researched in a greenhouse in the Agricultural University- Plovdiv. During the lettuce growth six different variants were used: no fertilizer, one chemical, and four organic fertilizers. The effect of the different organic fertilizers was studied through physiological parameters and vegetative behavior of plants. This paper analyzed changes in functional activity of the plant photosynthetic apparatus and productivity of variants with different fertilizers in an unheated greenhouse. The ratio between photosynthetic active radiation (PAR) and quantum yield (qY-Fv/Fm) of PS II was more effective in dark-adapted leaves for the organic fertilizer variants, compared to the no fertilizer variant. No significant difference was observed in the values of the minimal fluorescence Fo in reaction centers of PS II after the dark-adaptation of leaves from the different fertilizer variants. It was estimated the higher value of the chlorophyll content index (CCI) for organic and chemical fertilizers compared to the no fertilizer variant. The main biometric parameters were studied.
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