The intensity of photosynthesis of the surface of columnar apple-tree in the conditions of Kyiv

Abstract

The aim of the study was to determine the intensity of the photosynthetic apparatus of the leaves and to identify the adaptive potential of plants of columnar varieties and compare them with traditional apple varieties. Using the luminescent methods of analysis, in the particular photo- and thermal induction of chlorophyll fluorescence, the functional state of the photosynthetic apparatus was diagnosed. The SMF-2 apparatus excited and recorded the fluorescence spectra in a specific area of the leaf surface, the individual fluorescence changes resulting from the action of light or heating. Fluorescence emission was recorded in the spectrum range of 500–800 nm. Fluorescence changes (caused by temperature) were recorded for the stationary level of light induction of fluorescence by heating the sheets from 20 to 80 °C.

The concentration of chlorophylls was determined at the end of July when the leaf was formed, but its aging had not begun. The leaves were selected in eightfold repetition from complex fruit formations placed on different age sections of the trunk with the same level of light. Alcohol extraction of pigments of 96% ethanol solution was used. The optical density of the alcohol extract was determined using a photoelectric photometer KFC-3-01- "ZOMZ". The contents in the Chla and Chlb sheets (at 649 and 665 nm) were calculated using the formulas of Kh.N. Pochinok.

High-yielding trees are marked by the intense flow of metabolic processes, which are accompanied by the accumulation of peroxide compounds that activate cellular processes of foam acidosis and extrusion. The accumulation of peroxides decreases the stability of the membranes of the photosynthetic apparatus, which is controlled by the time range between the appearance of fluorescence-induced β- and γ-waves. A shorter time interval between the occurrence of these fluorescence changes may indicate, higher potential productivity of apple plants under optimal growing conditions. The intensity of membrane transport processes is lower in less productive plants. The level of peroxide compounds in them is also lower, which possibly causes such plants high stability of membranes of green plastids and is reflected in the overestimated values of temperature-time index tγ-β.

Subject to favorable agri-environmental factors (especially illumination), the ratio of the maximum amplitude γ-wave to β (F^680γt / F^680βt) in varieties of common apple should be greater than 2.0. The ratio shows the level of tension of the membrane transport bonds during the course of photosynthetic reactions. In plants with openwork and correspondingly better-lighted crown, this indicator is usually higher than in plants with dense leaf cover.

Our studies showed that the leaves of plants of the ordinary variety Idared, which were one-year-old growth, had the highest intensity of photosynthesis according to the ratio F^680γt / F^680βt; in the leaves of three-year, Difficult fruit spurss decreased the intensity of photosynthesis by 25%, in six-year - up to 45%.

Almost the same ratio of amplitudes of thermally induced waves leaves the Difficult fruit spurss of all age sections of apple trees of the variety Tantsivnytsia. In leaves of 16-year-old Difficult fruit spurs, the intensity of photosynthesis was 17% higher than shoot elongation. In Bolero, a decrease in the F^680γt / F^680βt ratio was observed in leaves placed on four- to eight-year-old Difficult fruit spurs; this was due to the thickening of the crown in the area. For the Sparta variety, the highest level of intensity of membrane transport processes is inherent in the leaves located on the four-year-old section of the trunk, in other sections this is 20% lower.

The efficiency of the process of photosynthesis depends on the quantitative content of green pigments in the leaf and the ratio of their forms. The above ratio reflects the structural organization of the chloroplasts and the potential of the plant to adapt to changes in environmental conditions, primarily light. In the studied varieties observed variation in the content of Chla in leaves from 5.05 to 8.09 mg / g crude mass; significantly exceeded the control grade Sparta. The much lower content of Chla was characterized by all the common varieties studied and the columnar Favorite and the President.

The content of Chlb in the leaves of the studied varieties of apple varied from 1.74 to 3.27 mg / g of crude mass. The least content of this pigment is the variety Favorite, the largest - Tantsivnytsia, and Sparta.

The total amount of Chla + Chlb pigments, depending on the variety, ranged from 6.69 to 11.17 mg / g of crude mass. Significantly higher values of this indicator were characterized by plants Sparta, the smallest - Paper, President and Favorite.

The highest Chla: Chlb, and therefore the lowest adaptability, is characterized by the Bilosnizhka variety; in the leaves of this variety, the number of Chla exceeded Chlb 3.03 times, while in the varieties Sparta, Tantsivnytsia - 2.48-2.55 times, which indicates the best adaptive properties of the latter varieties under these conditions. Significantly lower levels of Chla: Chlb relative to control were recorded in Sparta, other varieties were at the control level.