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Abstract
Introduction
Scots pine (Pinus sylvestris L.) is one of the main forest species and an important source of timber. Considerable efforts are making for the selection and testing of its varieties by the productivity. Despite this, little emphasis has been placed on the issues of Scots pine resistance against adverse environmental factors. Resin productivity is one of the most stable and available for studying characteristic of the Scots pine. It is presumed to be related to the productivity and resistance to plant diseases, in particular, to the annosum root rot. The volume of outflowing resin is used as an effective and reliable criterion to estimate the intensity of physiological processes in trees.
The aim of our study was to evaluate the progenies of the synthetic Scots pine populations by the set of features, including resin productivity, in the variety tests in the Left-bank Forest-Steppe zone of Ukraine.
Materials and Methods
The 20-year-old candidates to synthetic variety-populations were surveyed in the variety test of Scots pine in the Gutyanske Forest Enterprise in the Kharkiv region. Progenies from nine clonal seed orchards (CSO) and from one permanent forest seed stand (PFSS) as well as their regional control variants from the corresponding regions, namely Kharkiv, Kyiv, Rivne and Volyn regions, were studied. Mensuration and breeding characteristics and state and level of resin productivity were estimated for 20 trees of each variant. The progeny grown from the seeds collected in the Gutyanske Forest Enterprise was used as a local control for all the variants.
The diameters and heights of the trees were measured according to generally accepted methods; the breeding category and the state category were determined according to the classification developed in URIFFM. Resin productivity was estimated by the method of trunk micro-wounding. On this basis, trees were divided into five categories, from very low to high resin productivity. The percentage of “conditionally resistant trees” with the diameters equal and larger than the average control, and at the same time of the average and higher categories of resin productivity, were determined in the variants. The average indicators of the investigated characteristics were evaluated from 1 to 5 points and their value was determined for each variant. The variants with the highest number of points were considered as “perspective”. The amplitudes of the indicators variability of the studied characteristics were evaluated and the statistical validities of the differences between the variants were determined.
Results
At the age of 20, three out of ten potential variety-populations exceeded local control by the heights and diameters. The variants from the Kharkiv and Kyiv regions were the best by the breeding structure and state category. Only one candidate to the variety-population exceeded the local control by the level of resin productivity; the rest were 2–19 % lower. In seven variants, the proportion of trees with higher resistance to phytopathology, in particular, to the annosum root rot, were higher (Pst = 45…50 %) than in the control (Pst = 40 %). The correlation between the resin productivity and the growth characteristics were weak: for diameter r = 0.32 ± 0.055; for height r = 0.17 ± 0.057.
Conclusions
Among the investigated candidates to synthetic variety-populations, we identified the following variants with total points of 18…19 as “promising” ones: Prikhilky-1, Prikhliky-2, Geographical, and Kyiv-3. The number of points was recorded to decrease with increasing distance from the test site to the progenies origin westwards. The results of integrated point assessment of candidates to variety-populations indicated the feasibility of using seeds from clonal seed orchards and permanent forest seed stands to create planted stands to be productive and potentially resistant to plant diseases.
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