No abstract

Premature needle cast, affecting the needles on one-year old shoots, thus shrinks the size of green crown of Scots pines, and can cause reduction of increment or even death of trees, especially during first years of their growth. Aim of our study was to evaluate the lasting impact of pathological needle cast to young Scots pines and its implications for tree breeding. Assessment of needle cast damages in 5 grade scale and measurements of height were done repeatedly in Scots pine open pollinated progeny trial, consisting of 65 families, located in central part of Latvia. Proportion of saplings with different level of needle cast damage differed significantly between the years of impact: severely damaged were 51%, 30% and 17% of saplings in growing seasons 4, 5 and 6, respectively. Both the needle cast damage grade at current growing season, as well as height of the sapling before the needle cast infection (at the end of the third growing season) had a significant effect on its grade of needle cast damages in the next growing season. Cumulative level of needle cast damages at the age 4 to 6 years had significant negative effect on height of the saplings at the age of 12 years both at individual tree and family mean level, as well as on survival. Selection of best growing families in such trial would also lead to selection of genotypes least affected by the disease.

No abstract

Lodgepole pine ( var. Engelm.) has been extensively introduced in Scandinavia on less productive sites. Under a changing climate, it also has a high potential in the eastern Baltic region; still, its performance there has scarcely been reported. This study investigated the performance of 36 Canadian provenances in 14 trials in western Latvia. Tree dimensions showed notable provenance and provenance-by-environment variation, implying that local selection by provenance can be applied for improved yield. Southern provenances showed the best height growth, while southwestern (more oceanic) provenances excelled in diameter growth. Most of the quality traits were affected by provenance or provenance-by-environment interaction, yet the variation was lower than for the growth traits.Pinus contortalatifolia

In this study, oak specific chloroplast simple sequence repeat (SSR) markers were used to analyse Latvian and Belarusian oak (Quercus robur L.) population provenance and genetic structure. Chloroplast haplotypes were compared between Latvian and Belarusian pedunculate oak, and several common haplotypes were identified. The SSR haplotypes were compared to previously reported PCR-RFLP haplotypes, and haplotypes from the A (eastern European) and C (central European) lineages were identified. C lineage haplotypes were only found in the western region of Latvia. Haplotypes shared between Latvia and Belarus were all from the A lineage. Despite the much smaller population size of oak in Latvia in comparison to Belarus, the level of genetic diversity identified using the chloroplast SSR markers is similar. Provenance trials will need to be established in order to determine the suitability of Belarusian oak reproductive material for deployment in Latvia. Based on the results from this comparison of chloroplast haplotypes, as well as climatic similarities, it is probable that Belarusian oak material will be better suited to the eastern regions of Latvia compared to the western regions of Latvia.