The aim of the study was the determination the effect of foliar application of growth regulator containing Ti (Tytanit®), on Lolium multiflorum morphometry, photosynthetic activity, chlorophyll content and chemical composition of dry matter. A pot experiment was carried out in a plant breeding room of Siedlce University, Poland, in 2019. The experimental units were as follows: I) control – plants sprayed with distilled water; II) plants sprayed with 0.02% Tytanit concentration; III) plants sprayed with 0.04% Tytanit concentration; IV) plants sprayed with 0.06% Tytanit concentration. The following parameters were determined: the shoots number, the number and the length of leaf blades, the length of roots, the dry weight of roots, the dry weight of plants per pot and the content of chlorophyll a and b in leaf blades. In addition, maximum and actual efficiency of the leaf photosystem, photochemical and non- photochemical quenching coefficients and the content of total protein, crude fibre, monosaccharides, crude fat, crude ash, Ca, Mg, P, K and the ratio of K/(Ca + Mg), and Ca/P in the dry matter of plants were determined. Used in controlled conditions, the regulator contributed to the growth of most morphological characteristics, improved photosynthetic activity, increased the concentration of chlorophyll a and b, and

Permanent grasslands are the most environment-friendly way of using agricultural lands. Apart from producing fodder, grasslands play many other important non-productive functions. Biodiversity is the key factor decisive for their high natural and productive values. Grasslands play an important role in water retention. Not all types of grasslands may be used agriculturally. Out of 16 types of habitats, 10 may be used for production, the others are biologically valuable. The surface area of permanent grasslands in Poland has markedly decreased during the last decade. Now, they constitute slightly more than 20% of agricultural lands occupying 3127.8 thous. ha (in 2019) including 2764 thous. ha of meadows and 363.8 thous. ha of pastures.

The content of structural carbohydrates and lignin are important assessment criteria of the feed value of meadow plants. It is affected by many independent factors, including among others its development stage during the harvest as well as climatic conditions, especially the amount of rainfall. During the years 2014–2016, plant samples were harvested at weekly intervals, respectively five times from late April to late May. The effect of harvest date on cellulose, hemicelluloses and lignin contents was evaluated. The chemical composition of plants was varied, depending not only on harvest date but also on the year of study. Regardless of the course of meteorological conditions in subsequent growing seasons, the increase of cellulose (from 236.5 to 297.9 g∙kg–1 DM), hemicelluloses (from 159.3 to 210.8 g∙kg–1 DM), and lignin (from 31.5 to 43.1 g∙kg–1 DM) in the following dates of harvest were observed. These parameters were also positively correlated with the total rainfall from the begging of vegetation season to the date of plants sampling (R2 = 0.65, 0.12 and 0.44 for cellulose, hemicelluloses and lignin, respectively), and with the average daily air temperature in the moment of harvest (R2 = 0.66, 0.32 and 0.52 for cellulose, hemicelluloses and lignin, respectively). The cellulose and lignin content, regardless of the harvest date, were significantly higher in the first year of the study (2014), when moisture conditions for plant development were optimal.