GROWTH AND ENERGY STORAGE IN THE FORMING SHOOTS OF LARIX SUKACZEWII AND LARIX CAJANDERI IN THE MIDDLE TAIGA SUBZONE

1. 1 GROWTH AND ENERGY STORAGE IN THE FORMING SHOOTS OF LARIX SUKACZEWII AND LARIX CAJANDERI IN THE MIDDLE TAIGA SUBZONE Malyshev R.V. Institute of Biology of the Komi Science Centre Ural Division RAS; malrus@ib.komisc.ru

2. 2 The goal of our work was to carry out a comparative study of the metabolic activity in the shoots of the three larch geographic cultures Larix sukaczewii and Larix cajanderi growing in the middle taiga subzone Plesetsk Yakutsk Nizhny Novgorod

3. 70 cm 1cm 3 Object of the investigation The object of the study is the top of the larchshoots of the current year. Plants were 5 years old. The plants were grown in the nursery which is located in the vicinity of Syktyvkar. Larix sukaczewii seeds were collected from trees growing near Nizhny Novgorod (57° 30 'LN, 45° 10' LE) and Plesetsk (63° 05 'LN, 40° 21' LE). Seeds of Larix cajanderi were collected near Yakutsk (66° 45 'LN, 123° 21' LE).

4. 4 Model of growth rate (Hansen e. a., 1994) DHBRSG=455Rco2-q A comparative study of species was carried in the period from May to August. In order characterizing the metabolic rate measurements of respiration and metabolic heat rate were carry out. Amount of stored energy in the shoots was evaluated using the method of calorimetry and mathematical model of growth (Hansen e.a., 1994). This model allows to calculate growth rate of plants based on respiration and heat evaluation measurements. In the mathematical form this model is expressed by the equation: Energy losses Growth rate of a plant or quantity of reserved energy The total energy amount from oxidation of a substrate ∆HBRSG – growth rate [µW / mgdry weight] 455–the constant is from Thornto’s rule and is equal to the average heat of combustion of organic compounds per mole of O2 [µW /nmol О2]. Rco2– CO2 production rate[nmol/ mgdry weights] q – metabolic heat rate[µW/mgdry weight]

5. Mikrocalorimeter «Biotest-2»: А – multichannel calorimetric block, B – containers, C - schema of the container. B А C Sample NaOH vessel with NaOH 5

6. 6 Respiration rate (А), metabolic heat rate (В) inLarix cajanderishootat 20 ºC А Results of the investigation have revealed that shoots metabolism intensity goes down during the vegetation period. It is clearly shown by the example of Larix cajanderi. The greatest intensity of shoots respiration and metabolic heat rate was in May. These parameters decreased by 60% to the middle of June. The metabolism activity decrease during the period is accompaniedwith the termination of needle growth. It’s well known that larch shoots begin to form the shoot after termination of needle growth. The increasing of respiration and heat rate intensity likely reflects activation of metabolism in period from the middle of June till the middle of July. Respiration and heat rate in the shoot apex declined in August when shoots growth was completed. 0.08 0.06 Rco2– CO2 production ratenmol/ mg DW s 0.04 0.02 0 August May June July В 15 10 q, µW/mgDW 5 0 May June July August

7. 7 Growth rateofLarix cajanderishootat 20 ºC The estimation of stored energy amount on the base of respiration and metabolic heat rate data was revealed that the greatest storage of energy in the Larix shoots was in May. During June, energy storage in shoots decreased by 75%. In July it was revealed small peak of the growth rate, and then the activity of storage process decreased insignificantly. 25 20 15 ∆HВRSG, µW/mgDW 10 5 0 May June July August

8. 25 (Larix cajanderi) Yakutsk (Larixsukaczewii) Plesetsk 20 15 ∆HВRSG, µW/mgdry weight 10 5 0 May June July August 8 Growth rate of Larch shoot at 20 ºC The dynamics of energy storage process in shoot apex of Larix sukaczewii was similar to Larix cajanderi during the vegetation period. But in May the Larix cajanderi shoot tops characterized by more energy storage rate as comparing with Larix sukaczewii. This fact can indicate more intensive needle growth of Larix cajandei at beginning of vegetation period.

9. 9 Growth rate of Larix sukaczewiishoot at 20 ºC 20 Comparing of Larix sukaczewii shoots originated from Plesetsk and Nizhniy Novgorod shows that difference in energy storage rate between this individuals was insignificant. At the beginning of vegetation the tendency of more intensive energy storage in Larix sukaczewii shoots originated from Nizhniy Novgorod was revealed. Nizhny Novgorod 15 Plesetsk 10 ∆HВRSG, µW/mgdry weight 5 0 May June July August

10. 10 Conclusions 1.The seasonal pattern growth rate as process of energy storage in the apexes of the current year shoots of Larix cajanderi and Larix sukaczewii was revealed. It was shown that the maximal rate of energy storage in May at the beginning of bud growth was observed. Growth of current year shoots deceased to August. Tendency to higher rate of energy storage in buds of Larix cajanderi as compared to Larix sukaczewii was in May. 2.Small increase of energy storage rate during June reflects the enhancement of the shoot linear growth. 3.There are no significant differences in the rate of energy storage between the current shoots of Larix sukaczewii from Nizhny Novgorod and from Plesetsk.

11. I’d like to thank Alexey Leonardovich Fedorkov for providing experimental materials and assistance in analyzing the results. Thanks for attention!