[The influence of stress on xylogenesis of Scotch pine in Siberia]
2007
Sudachikova, N.E. | Milutina, I.L. | Romanova,L.I.,Russian Academy of Sciences. Siberian Branch, Krasnoyarsk (Russian Federation). The V.N. Sukachiev Inst. of Forest Science
A comparative study of biometric characteristics and the elements of annual ring of stem wood in 8-13 years old Scotch pine seedlings in Central Siberia in a cowberry and motley grass pine forest on humic pod soil in the subzone of the South Taiga (the Emeljanovsky district, the Krasnodar Krai) under natural and experimental conditions imitating the conditions of permafrost, drought and waterlogging in the rhizosphere the cold, water and hypoxic stresses inhibited the growth of needles to a greater degree than that of shoots. The greatest affection on the biometric characteristics of trees had a delay in defrosting in the root range: the shoot lengths decreased 3-4 times, needles – 2 times. In the experiment imitating a soil drought, a longitudinal increase of axial organs (terminated and branch shoots) reduced by 10% only, whereas the needle lengths – by 25%. An inundation reduced the shoot lengths inconsiderably, while the length of needles decreased by 34%. These stresses in the rhizosphere induced a nonspecific decrease in the width of annual rings in the stemwood due to the smaller number of tracheids in a radial row and the radial size of early tracheids as well. For example, in the variant with a shortened shoot the number of tracheids of an annual rings is 67% of the control, the sizes of early tracheids reduced to 65% of the control. The specificity of water deficit manifested itself in a thickening of cell walls in early and late wood by 11 and 31%, respectively, and in an increase in the share of late wood by 7%. Root hypoxy also increased the share of late wood by 7%, the cold stress decreased the width of the late wood layer by 9% and by 28-39% the thickness of cell walls. The mechanical damages of roots induced a decrease in the with of annual rings due to a diminution of the diameter of early tracheids by 22%, the number of late tracheids in the radial row by 22% and the thickness of the cell walls by 15%
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