0486-B4

Intraspecific remote hybridization of Siberian pine (Pinus sibirica Du Tour) at the Clone Plantation in Krasnoyarsk Forest-steppe

G.V. Kuznetsova ¹

Abstract

Experiments in intraspecific hybridization of Siberian pine just of this species but of different origin have been carried out at the clone plantation in Krasnoyarsk forest- steppe. Crossings were realized using the principle of ecologo- geographical remoteness of populations. Siberian pine clones chosen as an object for crossing were of good growth and constant reproductive ability in the many- year cycle. In the result of the analysis the characteristics of hybrid female cones (weight, linear size, number of developed scales) and seeds (number, weight, seed fullness, viability) the positive influence of the controlled pollination at such a combination of climatypes is stated. At studying hybrid growing climatypes resulting from crossing climatypes of the plain and mountain populations, also heterosis signs have been revealed.

Introduction

Hybridization of forest tree species alongside with selection and reproduction of the best plus trees is one of the basic methods of forest selection directed to wood efficiency increase as well as to improvement of their qualitative structure. Works in artificial inter- and intraspecific hybridization both of deciduous and coniferous tree species obtained a large development.

Realization of artificial interspecific crossings of Pinus sibirica Du Tour with Pinus koraiensis Siebold et Zucc. (Demidenko, Urusov, Il'itchev, 1982; Urusov, 1988; Тitov, 1995) and with Pinus pumula (Pall.) Regel (Sokolov, 1972) had no positive result. In this respect the crossings of Pinus sibirica with Pinus cembra L. are interesting, in result of which viable seeds were obtained (Тitov, 1999).

Breeding the economically valuable hybrids depends on selecting parental pairs very much. The theories of genetic balance and superdominating connect the appearance of hybrid power with inherited distinctions of parents. At hybridization of forest tree species the principle of selecting the pairs in degree of ecologo-geographical remoteness of parents is successfully used. The obtained hybrids have an accelerated growth and a more rich seed fruiting.

Intraspecific crossing between remote climatypes has a great practical interest for obtaining a great number of hybrid seeds of the first generation. Moreover, the problems of obtaining hybrid seeds from intraspecific crossings Pinus sibirica remain still poorly studied. However, in the result of geographically remote hybridization of Pinus sibirica the heterosis can appear in the first generation, and the posterity of these hybrids can be later vegetatively reproduced what will allow to develop the recommendations for obtaining hybrid seeds at forest seed plantations.

Materials and Methods

The experiments in geographical hybridization of Pinus sibirica were carried out in 1986 at the clone plantation of this species but of different origin in Krasnoyarsk forest-steppe. The clone Siberian pine plantation was established in the year 1965 using Scots pine (Pinus sylvestris) natural regeneration as a stock. The parent trees of Siberian pine for the clone plantation were thoroughly selected, only those with a good cone crop during many years. Pollen of grafted Pinus sibirica trees collected in the year 1986 with the viability 69,6 - 82,6% was used. A free cross-pollination of parent trees of each variant was used as a control.

The following combinations were applied at crossing:

• The 1-st variant - Yermakovsky climatype, 500 m a.s.l., (Krasnoyarsk krai, 53 ⁰ 10' N, 95 ⁰ 20'E) x Baikit climatype (Evenkia, 61 ⁰ 40' N, 50 ⁰ 05' E);
• the 2-nd variant - Verkh-Katunsky climatype, 1000 m a.s.l. (the Mountain Altai, 50 ⁰ 43' N, 86 ⁰ 06' E) x Yermakovsky climatype, 1500 m a.s.l. (Krasnoyarsk krai);
• the 3-rd variant - Коzylsky climatype, 200 m a.s.l. (Krasnoyarsk krai, 56 ⁰ 38' N, 91 ⁰ 30' E) x Yermakovsky climatype, 1500 m a.s.l.;
• the 4-th variant - Yermakovsky climatype, 500 m a.s.l. (Krasnoyarsk krai) x Angarsky climatype, 500 m a.s.l. (Irkutsk oblast, 53 ⁰ 01' N, 102 ⁰ 25' E).

Results and discussion

Hybrid cones from the tested trees resulted from all the crossings were collected in August 1987. The cones of the same trees after a free pollination were picked for the control. Survival of hybrid cones varied from 10 up to 54%. The analysis of collected hybrid cones has shown that all they in all the crossing variants turned to be larger in weight and size (length, width) than the control cones from parent trees.

Studying the quality of seeds from the cones of different crossing variants (Table 1) has shown that the weight of developed seeds was higher in the variants №№ 1, 3 and 4. Seed fullness in the variant № 4 was much higher than in the control one. In the control N4 variant the 39 % of empty seeds were revealed what resulted from insufficient pollination. In the variant № 3 a high percent of seeds with polyembrions (in the experiment - 37 % and in the control - 38,8 %) was noted what is related to the influence of parent tree heredity. Low seed viability was observed in seeds of all the crossing combinations (from 36,3 % up to 51 %), and in the control one with a free pollination it was 29,5- 50%. In the variant № 2 at crossing the mountain populations the seed viability was lower since the hybrid seeds had, mainly, a small germ 0,1 - 0,2 mm. Number, weight of developed seeds of the variants №№ 1, 2, 3 exceeded those ones of the control variant. The weight of 1000 seeds in all the variants was higher than that one in the control.

In the result of the analysis of cone characteristics (the weight, linear sizes, number of developed scales), as well as quality of seeds (the number, weight, seed fullness, viability) a positive influence of the controlled pollination at this combination of Siberian pine climatypes was revealed in all the crossing variants. The advantage showed itself in the best formation of cones, also in formation of the increased number of full seeds.

Hybrid seeds as well as seeds from a free pollination were sown in 1988 after the stratification. The percent of germinated hybrid seedlings in all the crossing variants was much higher (from 50 to 80 %) than that one from a free pollination (15- 36 %). The variability of cotyledon number in seedlings of all the crossing variants was small. No large distinction in the cotyledon number in seedlings of all the crossing variants was revealed.

Studying the growth of hybrids resulted from Siberian pine climatype crossings (Table 2) has shown that the hybrid seedlings of the variants №№ 1, 3, 4 exceeded seedlings from a free pollination in growth, increment, diameter and needle length. The hybrids from the crossing of the plain and mountain populations of Siberian pine (the variant № 3) have the best growth, all the characteristics are higher by 50% than those ones of seedlings from a free pollination, and higher by 5- 42% than those ones of other hybrid seedlings. Seedlings of the variant № 1, the crossing of the southern and northern populations of Siberian pine, have absolutely good characteristics. The hybrids of the combination № 3 have visual signs of heterosis, they surpass the control ones by 50% in growth and needle length. The hybrids of the variant № 4 have a less growth in comparison with the variants № 1 and № 3, but nevertheless they exceed the control variant in all the characteristics.

A special attention should be paid to the variant № 2, it means the hybrids from the crossing the mountain populations of Siberian pine. In this variant the seedlings from a free pollination are distinguished for their growth. One should believe that at crossing mountain populations no significant growth effect was shown at this stage. The above-mentioned data (Table 2) reflect average distinctions in hybrid growing. However, if to compare the maximum growing hybrid seedlings of Siberian pine with the maximum growing control seedlings, then the difference in their growth is even more, the first ones exceed more than by 50%.

Conclusions

Our studies of intraspecific hybridization of Siberian pine at the clone plantation have shown an opportunity of obtaining geterotic hybrids of the first generation from crossing the remote ecotypes of this species. Further results of systematic observations of these hybrid growing will have a great interest. The genetic nature of geterosis is absolutely not studied yet. Opinions about the duality and complexity of heterosis nature are discussed. There is also an opinion that activity of the growth substances has an importance for general role of genetic factors. In this connection one more opinion is said that the fast growth at successful crossings, and generally, producing the hybrid power are undoubtedly the result of deep and complex changes in metabolism of the whole system of growth regulators and enzymes (Ivannikov, 1980).

Hence, the increment in a trunk diameter and height is realized due to activity of exchange products in structures of meristem cell using a genetic apparatus. Therefore for the further strategy of Siberian pine selecting we will study an influence of parent components in hybrids obtained at clone plantation by the method of dispersion analysis of signs, also by studying the influence of heterozygosity in separate genes on the effect of geterosis using an isoenzyme analysis etc.).

References

Demidenko V.P., Urusov V.M., Il'itchev U..N. The main tendencies of selecting Siberian pines of Siberia// Problems of a complex utilization of Siberian pine forests. Proceedings of scientific conference, September 9-10, 1981, Tomsk, 1982.: P.138-141.

Ivannikov S.P. Breeding and utilization of poplars in the USSR and abroad. - Moscow, 1971. Rotoprint.

Titov E.V. Clone test of Siberian pines // Lesnoye khozyaistvo - 1995, 6: P.25-26.

Titov E.V. An unique object of heterotic selecting Siberian pine in Bryansk oblast // Proceedings of international scientific conference. Bryansk, 1999.:P.69-71.

Sokolov S.Y. On biology of Siberian pine (Pinus sibirica Du Tour). Siberian pine in the European north of the USSR. Leningrad.: Nauka, 1972.: P.6-20.

Urusov V.M. Genesis of vegetation and efficient nature utilization in Far East. Vladivostok, 1988., 103 p.

Table 1 - Characteristics of Siberian pine seeds of hybrid origin

Table 2 - Growth of hybrid Siberian pine seedlings in Krasnoyarsk forest- steppe (numerator - 9 years, denominator - 4 years)

¹ V.N.Sukachev Institute of Forest, SB RAS, 660036, Akademgorodok, Krasnoyarsk, Russia
E-mail: [email protected], [email protected]