Flowering variation of a young Scots pine (Pinus sylvestris L.) clonal seed orchard based on years

Abstract

In this research, it was tried to determine the male and female flower yield in young clonal seed orchard (YCSO) with the expectation that the flowering variation would be decreased among years, clones and ramets thanks to aging. The measurements were made on five ramets for each of 30 clones in four years in a Scots pine (Pinus sylvestris L.) seed orchard. The orchard, originated from the Araç-Dereyayla seed stand in Kastamonu, was established in 1995 by using two years-old grafts in Kastamonu, located northwestern Black Sea region of Türkiye. The examined characters were number of male (NMF), and female flowers (NFF). When the four-year of data from the YCSO was evaluated, mean values from NMF and NFF among the clones were significant and variation of the ramets was high. The coefficient of variation (Cv) from the NMF of the clones gradually decreased with the subsequent years (Cv2006=147.54%, Cv2010=59.04%), whereas the Cv in the NFF did not show any decrease with the same years. In addition, there were significant differences among the years as to the NMF, and NFF. Over the four years, the NMF was significantly lower than that of the NFF, and even in some years the NFF was doubled compared with the NMF (NMF2006=65.9; NMF2007=314.29; NMF2008=427.85; NMF2010=115.73 & NFF2006=123.80; NFF2007=604.68; NFF2008=394.62; NFF2010=196.72). Abundant flowering periods seen in natural stands were also observed in the male and female flowers of the clonal seed orchards. For the studied seed orchard high variation both among the clones and the ramets indicates the high selection capacity in the breeding programs. The bigger variation among the ramets confirm that the genotypes have responded against the heterogeneity of growing area in seed orchard or the ramets have not reached the optimum flowering period. These results have shown the importance of the practices which increase the flowering yield and effectiveness of fertilization in YCSO.