**2. Materials and methods**

#### **2.1. Objects**

This chapter reflects research that was conducted at the Russian Research Institute of Floriculture and Subtropical Crops, Laboratory of Biotechnology, Physiology and Biochemistry of Plants in 1989–2016.

Within the research the following objects were used:


#### **2.2. Methods**

from 350 to 700 nm and bacteria from 350 to 900 nm). All higher plants contain chlorophyll *a*

32 Photosynthesis - From Its Evolution to Future Improvements in Photosynthetic Efficiency Using Nanomaterials

In addition, there are two more bacteriochlorophylls contained in the cells of photosynthetic bacteria: chlorophyll found in diatom algae and chlorophyll *d* in red algae. Yellowing or chlorosis of the leaves is a result of their inability to increase or maintain the content of chlorophyll. Numerous studies have found that this phenomenon depends on a number of internal and external factors (genetic characteristics, temperature, water regime, mineral nutrition, etc.) [6–9]. Along with the green pigments in the chloroplasts, chromatophores contain pigments belonging to the group of carotenoids. Carotenoids represent the yellow and orange pigments of aliphatic structures, derivatives of isoprene. Carotenoids are contained in all higher plants and many microorganisms. These are the most common pigments with various functions, the main ones being: (1) participation in the absorption of light as accessory pigments and (2) to protect the chlorophyll molecules from photooxidation, which is irreversible. Perhaps the

The biggest differences in the content of photosynthetic pigments are due to the location where plants are growing. Quantitative content and qualitative composition of pigments and the change of their ratio in the leaves are all important characteristics of the physiological condition of the plants and their photosynthetic apparatus, including the orientation of adaptive responses when exposed to stressful conditions. However, the current data found in the scientific literature concern the pigment system of plants within different botanical/ geographical zones, in particular a few pigment apparatus of the plants in the subtropical zone that are growing in Russia. At the same time, in the early stages of ontogenesis of the plants of the subtropical zone, it was necessary to adapt simultaneously to two stress factors: high insolation and changes in hydrothermal (particularly hydrological) conditions during the course of the year. The question is: how does adaptation relate primarily to the photosyn-

Thus, since the total amount of photosynthetic pigments varies considerably depending on the locus of the plants and dynamics of their accumulation, which are affected by many factors, we investigated the content of photosynthetic pigments in leaves within a number of subtropical crops grown in the conditions of Russia's damp subtropics. This chapter presents the results of studies of the pigment apparatus of leaves within subtropical plants such as tea (*Camellia sinensis* L.), Actinidia sweet or kiwifruit (*Actinidia deliciosa* Chevalier), and hazelnut (*Corylus pontica* C. Koch), which have an important agronomic value in the subtropics of Russia, as well as decorative subtropical shrubs such as hydrangea large leaf (*Hydrangea macrophylla* [Thunb.] Ser.) and weigela (*Weigela* × *wagneri* L. H. Bailey) of interest in the field of landscape design and urban landscaping.

This chapter reflects research that was conducted at the Russian Research Institute of Floriculture and Subtropical Crops, Laboratory of Biotechnology, Physiology and Biochemistry of Plants

carotenoids take part in oxygen exchange in photosynthesis [7, 10].

and *b* [4, 5].

thetic apparatus?

**2. Materials and methods**

**2.1. Objects**

in 1989–2016.

The contents of photosynthetic pigments were determined once a month in the extract of green leaves by the method of Shlyk [11]. The allocation of chlorophylls and carotenoids used acetone in the solvent. The density of the extract on a spectrophotometer was measured at the wavelengths corresponding to the absorption ima of chlorophyll *a* (662 nm) and *b* (664 nm) in the red region of the spectrum and at the wavelength of maximum absorption of carotenoids (440.5 nm). When calculating the number of pigments, calculations using Ziegler and Egle formulas were used.


The sample volume for the studied crops—35–60 pieces with each option—and the selection of laboratory tests to complete the assessment should be carried out with the exposure of the bush (i.e., with four sides).

In varietal evaluation work of photosynthetic pigments, leaf selection is carried out with three to four bushes of each variety, taking into account the principle of selection mentioned above.

The program STATGRAPHICS Centurion XV and mathematical software package MS Excel 7.0 were applied during the processing of research materials and evaluation of experimental results. The following parameters using ANOVA statistics were used: coefficients of data variation,construction of the correlation and regression matrix, and estimation of least statistical difference (LSD [*P* ≤ 0.05]).
