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ŠUMARSKI LIST 5-6/2018 str. 52     <-- 52 -->        PDF

production was very low in 2013 in the control ramets and the ramets with pruned terminal shoots, the cones were not counted.
The analysis of variance conducted for the young seed orchard revealed that year-treatment interaction was significant both for conelet and cone production, and while the volume index and block were statistically significant for conelet production, the rest of the factors were non-significant (Table 8). No statistically significant difference was found for conelet or cone production with respect to treatment (control ramets, pruning of terminal shoots). It was found that volume index had an impact on conelet production, whereas diameter and volume index had no impact on cone production.
In the old seed orchard, mean height, diameter at breast height and volume index declined in ramets pruned by three and five nodes. The decline was larger in ramets pruned by five nodes. The decrease in volume index occurred in parallel with the shortening in height. Therefore, it was assumed that the decline in volume index may be due to the shortening of height, since the crown diameters remained more or less the same. On the other hand, in ramets pruned by three nodes and five nodes, diameter at breast height was found to be 1.0 cm and 1.6 cm lower, respectively, compared to the control ramets. The reduction in diameter at breast height was in parallel with the degree of pruning. The reduction in diameter at breast height was considered to be a result of the reduction in the top surface, hence in the rate of photosynthesis.
After two years, the average height of the control rametswas 117 cm and 176 cm tallerthan the ramets pruned by three and five nodes respectively. In 2008, heights in ramets pruned by three and five nodes were reduced by 25% (184 cm) and 39% (302 cm), respectively, while the control ramets were 202 cm and 283 cm taller than ramets pruned by three and five nodes. In the six years,since the first pruning, it was found that the difference between the heights of the control ramets and ramets pruned by three nodes and five nodes declined to 85 cm and 107 cm, respectively. In other words, the growth in the height of the pruned ramets was proportionally higher than the growth in the control ramets.
In the old seed orchard, cone production was higher in 2012 than 2013. Since cone production was high both in the control and pruned ramets, it was assumed that 2012 was a year of high seed yield. On the other hand, ramets pruned by three nodes reached a higher average number of cone production than control ramets in 2012. However, when 2012 and 2013 are considered together, there was no explicit trend in terms of cone production either in the control ramets or in the pruned ramets. In fact, only the year factor was found to be statistically significant in the analysis of variance, which was likely due to 2012 being a year of high yield, as previously mentioned. No difference was also found between treatments in the old Turkish red pine seed orchard in the preliminary study covering the period 2009-2011 (Alan et al. 2011). Similarly, in a 14-year-old lodgepole pine (Pinus contorta Douglas.) seed orchard, no significant difference was found in terms of cone production with respect to height (Stoehr et al. 1995). But, in a 20-year-old Turkish red pine clone park, 15% pruning was found to increase the number of female flowers and cones compared with the control clones (Sengun and Semerci 2002). Likewise, in a 17-year-old white spruce (Picea glauca (Moench) Voss.) seed orchard where two to five nodes were pruned, it was determined following a four-year period after pruning that the pruning of three and four nodes resulted in an increase in cone production (Nienstaedt 1981). In the study of Turkish red pine by Sengun and Semerci (2002), only one year’s cone crops were counted, a more moderate top pruning was used, aflat topping method was applied instead, and the evaluation was carried out at the clonal level. So, the difference observed in the study of Turkish red pine (Sengun and Semerci 2002) might be due to one or more of these factors. On the other hand, the increase in cone production in white spruce with pruning (Nienstaedt 1981) might be due the difference in species.
In the middle-aged seed orchard, the heights of ramets were shortened by 18% through pruning. While the difference between mean height of control and pruned ramets was 159 cm in 2012, it was 58 cm in 2015. Although the control ramets remained taller for the entire four-year period, it was seen that pruned ramets grew proportionally faster.
The second pruning age (12 years) of the middle-aged seed orchard was close to the first pruning age (15 years) of the old seed orchard. In the middle aged Turkish red pine seed orchard, the spacing used (5×5) was narrower than the one generally used (7×7, 8×8, 9×9), and thinning was planned in the future. Since the volumes of control ramets decreased, it was assumed that the crown diameters of pruned ramets grew larger. In a similar study, Copes and Bordelon (1994) identified more extensive growth at the crowns of pruned trees in two Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) seed orchards aged 17 and 22 years. On the other hand, in a western hemlock (Tsuga heterophylla (Raf.) Sarg.) seed orchard, it was found that severe (50%) and moderate (25%) pruning eliminated or considerably delayed the need for thinning (Ross 1989). It was determined that pruning also substitutedfor a certain extent the need for thinning in the middle-aged seed orchard, based on the crown development and the increase in