Changes in yield characteristics among various seed
generations of hemp variety USO-14

V. P. Sitnik

Institute of Fibre Crops, 45 Lenina Street, Glukhov 245130, Ukraine

Sitnik, V.P. 1995. Changes in yield characteristics among various seed generations of hemp variety USO-14 Journal of the International Hemp Association 2(2): 79-82.
          Yield parameters of the non-drug hemp variety USO-14 were studied.  Reproductions of various seed lots and the same seeds from different years, obtained as a result of a new method of seed selection, were tested.  Seed yield was not altered up to the second generation while stem and fibre yield were not altered up to the fourth generation.  It was found that a variety’s potential productivity remains the same during this period of its industrial use.

Introduction

          The expression of the yield potential of a variety depends on the quality of the seed material, which is affected amongst others by agro-technical measures.  All agricultural crops, including hemp, are characterised by biological variability when reproduced and used industrially (Remeslo 1972, Gulyaev and Guksov 1978, Demkin 1971).  It has been previously reported that stem and fibre yield of monoecious and dioecious hemp varieties decrease with the number of propagations of elite seeed (Virovets 1971, Demkin and Bondarenko 1971).  In the 1990’s, to solve the problem of drug use, the Institute of Bast Crops and affiliated scientific and research institutions obtained the highly productive and non-drug hemp varieties USO-14, USO-16, USO-31, Zolotonoshskaya-13, Dneprovskaya monoecious-6, and Zenitsa.  To maintain all the valuable biological and economic characteristics of these new monoecious hemp varieties at all phases of their cultivation, a system of seed multiplication was elaborated (Senchenko, Sitnik et al. 1988).  It included a group of nurseries and seed lots, wherein selection and propagation of improved hemp varieties took place.  We studied the influence of this new system of seed multiplication on seed characteristics.

Table 1.  Yields (tons/ha) of hemp crops grown from seed of different seed generations (Variety USO-14) average for 1992-1993.

Materials and Methods
          We investigated seeds of different reproductions of the monoecious hemp variety USO-14.  The seeds of the plant nursery of the family testing of hemp variety USO-14 (harvest of 1986, 1987, 1988 and 1989) were propagated according to a new method of seed-growing up to the second and third reproductions.  The propagation was carried out in the following succession: plant nursery of the families (the seeds of the best families selected for their economic and biological characteristics), superelite (the seeds destined for growing elite), elite (the seeds grown in research establishments and destined for propagation in production), first reproduction, second reproduction and third reproduction (the seeds following elite in the link of seed growing propagation).  Thus by 1992 we had received five lots of superelite seeds of the harvests of 1987, 1988, 1989, 1990 and 1991, respectively, four lots of elite seeds (1988, 1989, 1990 and 1991), three of the first reproduction (1989, 1990 and 1991), two of the second reproduction (1990 and 1991) and one of the third reproduction (1991).  To maintain the viability of seeds which had been accumulated since 1987, they were stored at the critical moisture without oxygen in polyethylene bags.
          In 1992-1993, all seed lots of superelite, elite, first, second and third reproduction were sown in field conditions to determine their biological and productive characteristics.  Experiments were carried out in four randomised repetitions.  The area of the plots was 25 m². The seeds were sown at a density of 60/m² and at 45 cm row width.  The change in yield and biological characteristics was determined by comparing the reproductions of each initial seed lot and by comparing different seed lots of the same reproduction.

Table 2.  Sexual structure of hemp grown from seeds of different generations. Content of Sexual Types* (%)

* A new classification of sexual types of monoecious hemp, worked out in the 1990s (by N. D. Migal).  It suppliments the classifica-tion by Grishko, von Sengbusch, Bredemann.  The genotypes of sexual types of monoecious hemp are not identical to the genotypes of the same sexual types of dioecious hemp.

Results and Discussions
          The yields of fifteen seed lots of different reproductions and years are given in Table 1.  It shows that seed reproductions, including the first one, do not differ much for seed productivity.  Some seed yield decrease was found in the second and third reproductions.  This could result either from the deterioration of the varietal purity of these reproductions or from the change of their sex structure (Table 2).  In the third reproduction, the proportion of male plants was 21-35 %.  In preceding reproductions, the proportion of male plants was lower.  According to the new system of seed-growing, hemp seeds of the third reproduction were not sown for industrial use.  A different result was found regarding the effect of seed reproduction on stem and fibre yield.  The yield of dry stem and fibre did not depend on seed generation.  The stem yield from elite seed (1988) was 5.24 ton/ha, its progeny in the third reproduction yielded 5.83 ton/ha.  Elite yield of 1989 was 5.30 ton/ha correspondingly.  According to data presented in Table 1, there were no differences in the stem productivity among superelite, elite, first, second and third reproduction seeds produced in 1989, 1990 and 1991.  Exceptions are the yields of superelite seed lots produced in 1987 and 1988.  Long seed storage influenced vigour, simultaneity of germination and yield of those seeds.  In the plots with seed produced in 1987 and 1988, seedlings appeared 2-3 days later and plant development until the phase of budding was delayed for 3-5 days (Table 3), which could negatively influence the yield.
          The response of fibre yield was similar to that of stem yield (Table 1), fibre content of the stems was not affected.  Having compared biological and yielding characteristics of superelite seed propagations harvested in 1987, 1988, 1989, 1990 and 1991, we observed that over five years, varietal characteristics of the hemp variety USO-14 did not deteriorate, sometimes they even improved, except for the distribution of sexual types.
          While studying these fifteen different hemp seed lots it is notable that seed, stem and fibre yields are very similar.  Conditions of cultivation did not significantly influence seed yielding ability in spite of the fact that the seeds were produced in different years and under different environmental conditions.

Table 3.  Results of phenological observation on superelite sowings of the variety USO-14.

References

• Demkin A.P., 1971.  O sisteme semenovodstva konopli i posevnikh kachestvakh eyo semyan (About system of hemp seed-growing and seeds quality).  In : Questions of selection and seed-growing of hemp and kenaf Urozhaj, Kiev : 67-78 (in Rus.).
• Demkin A.P. and Bondarenko A.D., 1971.  Reproduktsiya, tipichnost steblestoya i urozhajnost volokna konopli (Reproduction, plant stand typicalness and hemp fibre productivity).  In Seed and seed-growing, N1 : 51-53 (in Rus.).
• Gulyaev G.V. and Guksov R.L., 1978.  Selektsiya i semenovodstvo polevikh kultur (Selection and seed-growing of field crops) Kolos, Moskva : 435 (in Rus.).
• Remeslo V.N., 1972.  Selektsiya i semenovodstvo zernovikh kultur (Selection and seedgrowing of cereals).  Urozhaj, Kiev : 302 (in Rus.).
• Senchenko G.I., Sitnik V.P. et al., 1988.  Proizvodstvo sortovikh semyan konopli (Production of high-quality hemp seeds).  Agropromizdat, Moskva, 24 (in Rus.).
• Virovets V.G., 1971.  Izuchenie productivnosti razlichnikh reproduktsij semyan konopli (Study of productivity of different hemp seed reproductions.  Synopsis of thesis).  Glukhov : 24 (in Rus.).