Current state of hemp breeding in C.I.S. L. G. Rumyantseva and N. K. Lemeshev
Vavilov Institute of Plant Industry (VIR), 42 B. Morskaya St., St Petersburg 190000, Russia
In the course of the last 30 years, the amount of land used in hemp production area in the former USSR as well as present-day Russia has been incessantly decreasing. Prior to the disintegration of the USSR, hemp was produced on 50-60 thousand hectares. However, the reduction in crop acreage was basically due to a mistaken government economic strategy, in which they preferred to purchase hemp fibre abroad, spending the equivalent of over US $200 million per year instead of developing domestic production. This policy resulted in the absence of complex harvest and post-harvest mechanized procedures and in insufficient funding of hemp breeding programmes.
Despite these constraints, a number of regions (Poltava, Oryol, Krasnodar, etc.) produced good yields of fibre (1.0-1.2 tons/hectare) and seed (0.6-0.8 tons/hectare).
Breeding also progressed. Conventional breeding techniques were applied: hybridization, followed by continuous family/group selection. In later stages of seed production, mass selection methods were used.
The unceasing 20 year systematic selection for higher fiber content, performed at the All-Union Research Institute of Bast Crops (in Glukhov, Ukraine), increased this parameter by 13.8%, achieving a total plant fiber content of 35-37% in a number of varieties.
These breeding programmes were based on the accessions of the plant genetic resources collection of the Vavilov Institute (VIR). For instance, cv. Yuzhnosozrevayushchaya Odnodomnaya 14 (YUSO-14) produced by the Institute was bred by family/group selection methods on progeny from crosses of female YUSO-1 (VIR Cat. no. 429*) and pollen from the monoecious Bernburg hemp of the former East Germany. This resulting cultivar now covers nearly half of the present hemp production area of Russia and is fairly uniform in its sexual expression, monoecious pistillate hemp accounting for up to 90% of the plants. Agricultural production of this strain yielded 1.0-1.2 tons of fiber and 1.3-1.5 tons of seed per hectare.
Cv. YUSO-16 has been bred from the French monoecious hemp cultivar Fibrimon 56 (VIR 537*). This cultivar is notable for a low cannabinoid content and a long vegetative period. Average fibre yield is 2.0 tons/hectare and seed yield is 1.0-1.2 tons/hectare.
Cv. Dneprovskaya Odnodomnaya 6, a southern hemp cultivar, has been obtained by hybridization of the Hungarian cultivar Szegedy 9 (VIR 437) with Fibrimon 56 (VIR 537*), followed by family/group selection. This cultivar has high fibre yield (31.5%) and a seed yield of 0.55 ton/hectare. Plant height is up to 2.5 meters.
One of the priorities for the next few years of hemp breeding may be to obtain cultivars without active drug substances. In the initial breeding phase, the recommended cultivars with low cannabinoid content will be YUSO-14, YUSO-16 and Dnepropetrovskaya Odnodomnaya 6. The next phase will be marked by developing the cultivar Yuzhnosozrevayushchaya Odnodomnaya (YUSO-31), which contains half the THC content and ripens 5-6 days earlier than YUSO-14, but gives the same yields. An even lower cannabinoid content has been noticed in cv. Zolotonozhskaya YUSO-11.
In recent years, the Krasnodar Research Institute of Agriculture has accomplished a series of experiments on breeding southern hemp with an absence of active cannabinoids. Selection of southern hemp without cannabinoids has been closely linked to breeding for higher fibre content and yield. This breeding was based on the families identified by means of multiphase family/group selection in the hybrid Szegedy 9 (VIR 437) X Krasnodarskaya 56 with individual analysis of each plant for its seed weight, stem fibre content and flower cannabinoid content, followed by testing of the identified families. Ten phases of selection resulted in a dioecious cultivar of southern hemp, Kuban, having a vegetative period of 160 days, only 20% of the THC content of the Krasnodarskaya 35 standard, a fibre content of 28.3%, a seed yield of 0.35 ton/hectare and a plant height of 260 cm. This cultivar is being produced commercialy on an area of 3,000 hectares.
Hemp breeders mastered a method which made it possible to identify cannabinoid content by thin-layer chromatography of selected leaves from each crop during the period from budding to flowering. This led to the establishment of the Transpollination Direction Nurseries (TDN) where plants were discarded or selected in accordance with precise data on their THC contents. In 1990, application of this method resulted in such new cultivars as YUSO-42 and YUSO-45, with THC contents of 0.004 and 0.007%, respectively.
Recently, a rapid method for plant cannabinoid content analysis has been developed on the basis of a qualitative reaction, and this has now been introduced into practice. It takes just 10-13 seconds to analyze each plant in the field before budding. Thus it is now possible to discard cannabinoid-containing plants before budding, greatly increasing the efficiency of selection against this trait and allowing a wider range of initial breeding stock. It should be noted that breeding for the absence of cannabinoids is accompanied by strict control over commercially valuable traits, despite the fact that practically no interrelationship between yield and cannabinoid content has been established.
Hemp is cultivated primarily for fibre production, but hemp seed is also important. Seeds contain approximately 30-35% oil, which is used widely for industrial purposes and in food production. Optimum ratios of the fatty acids depend on the purpose of the oil. Industrial utilization requires a quick-drying oil with a high content of polyunsaturated linoleic and linolenic fatty acids. These fatty acids are also highly desirable for human nutrition, but their chemical lability causes them to spoil easily in the presence of air and light. This imparts an unpleasant flavor to mishandled oils and requires special precautions to preserve oil freshness.
The Department of Industrial Crops of the VIR in cooperation with the Biochemistry Laboratory have analyzed 100 hemp accessions of different origins, including 48 domestic and 52 foreign varieties acquired by the VIR which are characterized by good fibre quality and low drug content. Plantings were performed in the fields of the Ustimovka Experimental Station of the VIR (Poltava Province, 1983-1985). In spite of the plant varieties being from widely diverse origins, the variability in their seed fatty acid content was not large. Average data reported for three years revealed that palmitic content varied from 5.8 to 7.4%, stearic acid from 1.6 to 3.0%, oleic acid from 10.6 to 15.3%, linoleic acid from 55.6 to 59.5%, and linolenic acid from 16.2-24.3%.
Relatively high in linoleic acid (over 22%) were the accessions from Uzbekistan (VIR 455*), Armenia (VIR 482), Hungary (VIR 548*), and the cultivars Maikopskaya 1 (VIR 491*), Dneprovskaya 4 (VIR 510), Dneprovskaya 5 (VIR 511). High oil content (over 35%) was identified in the accessions from Daghestan (VIR 524), Karachaevo-Cherkessia (VIR 525), Hungary (VIR 481, VIR 535), Yugoslavia (VIR 479*) and cv. Maikopskaya 1 (VIR 491*).
Hemp breeding faces a series of complex problems which may be solved by wide utilisation of the global hemp germplasm collection stored at VIR. For this purpose, it would be necessary to perform in depth and complex studies of the accessions in this collection, especially of the monoecious drug-free varieties identified for their earliness. Research should aim to identify sources of flexibility, firmness and other fibre quality traits, including disease and pest resistance, and sources of variation in oil yield and quality. It is necessary to create varieties with more economically valuable traits by individual selection, applying the express method of cannabinoid content evaluation, and to perform hybridization with the purpose of uniting all required parameters in a single genotype. This would result in obtaining early ripening monoecious materials for breeding, which would also possess high productivity and high quality of fiber and oil.
It is necessary to conduct research on the genetics of sexual, technological and biochemical characteristics, lack of which impedes the efficiency of hemp breeding.
* = Accessions no longer maintained in the VIR collection. The remainder of the accessions noted in this article are threatened with extinction. A concerted effort must be made to preserve these valuable accessions for future breeders.