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Interview
Professor Dr. Iv·n BŪcsa, the breeder of Kompolti hemp


Iv·n BŪcsa is the eldest and one of the most successful active hemp breeders of Europe. For 40 years, he improved eight state-registered fibre hemp varieties, four of which are still cultivated. The improvement of the first unisex hybrids (pure female F1 originating from a monoecious x dioecious crossing) and the development of Bredemann's idea and method are linked with his name.

During his career he bred only dioecious and unisex hybrids. He used monoecious varieties only as crossing partners because he was convinced (later proven by experimental evidence) that the monoecious varieties produce lower yields than the dioecious ones due to a 20 % inbreeding depression. He also improved the chlorophyll-deficient yellow-stemmed and the spherical ornamental varieties that characterise the extensiveness of his breeding work.

We introduce here a part of this multifarious and rich life-work via interview (12 October 1994).


Journal of the IHA: When was hemp introduced to Hungary?

Iv·n BŪcsa: We don't know exactly. The Slavic people, who inhabited what is now Hungary up 'till about 900 AD, probably cultivated hemp. The first written reference to hemp is found in a royal customs bill of Esztergom from 1198 AD (At the time Esztergom was the capital of Hungary, where the kings of the first dynasty ruled). In this 800-year old customs document written in Latin, hemp was mentioned together with flax. At the time, hemp was not imported into Hungary but was an age-old native crop. Until 1860-1870 hemp was grown and processed solely by peasants. After that time, Italian hemp cultivars, which were grown and processed on an industrial scale, were introduced into Hungary. Until 1960, peasant and industrial hemp production coexisted. The forced collectivisation of agriculture in 1960 caused the disappearance of hemp production by peasants.

JIHA: How did you get interested in hemp breeding?

IB: In 1949, at the beginning of my career, I was appointed as the assistant of Dr. Rudolf Fleischmann, who founded the Kompolt Research Institute in 1918 and who started working with hemp in 1920. His cultivar "Fleischmann" was very famous in all of Eastern and Central Europe. It replaced the Italian cultivars Carmagnola and Bolognese which were grown until then. Our cultivar "Kompolti" initially originated from "Fleischmann". After Fleischmann's death in 1951 his 'inheritance' was divided between the three breeders working at Kompolt. As I was the youngest of the three, I got the two crops the others did not want: hemp and alfalfa. Hemp was not an easy crop to do breeding work on, as there was not much literature available. At that time only German and Russian literature was available.

JIHA: Why have you bred dioecious cultivars while many other hemp breeders have developed monoecious cultivars?


Iv·n BŪcsa (Photo R.C. Clarke.)


IB: The natural state in which hemp appears was and is dioecious. Monoeciousness is artificial in hemp, it can only exist with the help of man, and without selection, the dioecious state will return in two or three generations. It is therefore very hard and demanding to keep 90 to 95 % monoeciousness during seed multiplications. Apart from that, however, monoecious hemp is appropriate only when the crop is grown for so-called double use, i.e. when both stem and seed are harvested. This is the case in France and in the former Soviet Union, where most crops are grown for double use. In a dioecious crop, the male plants will be strongly deteriorated when the crop is harvested at seed ripeness, so in this case one needs monoecious cultivars. In Hungary and its neighbouring countries, like formerly in Italy, this double use is unknown. Here fibre hemp is grown as a dense crop which is harvested at the time of male flowering ("green hemp"), while seed production takes place in crops grown at a low plant density and with completely different growing techniques. For this 'classic' use monoecious cultivars are of no use, so we never bred a monoecious cultivar.

Furthermore, monoeciousness has two large disadvantages. In the first place, all monoecious cultivars which I tested over the last 20 to 25 years yielded 10 to 20 % less than dioecious cultivars. This is caused by the possibility of self-pollination and the resulting inbreeding. With model experiments and with biometric determinations we have established that 20-25 % of self-pollination takes place in monoecious hemp, and this is the cause of the lower stem yield. In the second place, in monoecious hemp, the genetic progress for fibre content is slow, because the so-called Bredemann principle can not be used. The Bredemann principle consists of the rapid determination of fibre content in male plants before they flower, so that only the males with the highest fibre content are allowed to pollinate the female plants. In a breeding garden (nursery) of one hectare, I have 15,000 to 20,000 plants and I need only the very best 50 to 100 males for the pollination. (This can be compared to breeding of dairy cows, where a few hundred extremely good bulls inseminate all the cows of an entire country.) In monoecious hemp this approach can not be used, so the rate of genetic progress is only 50 % or less of that in dioecious hemp. In spite of these disadvantages, we use a monoecious hemp cultivar in breeding, but only as a parent for unisexual hemp.

JIHA: Which brings up the next question: why did you develop a unisex cultivar?

IB: After the collectivization of agriculture in Hungary in the early sixties, the farmers were no longer interested in producing hemp seed, an activity which has not been mechanized until the present day. As a result of this, seed for sowing became scarce and the hemp industry had to import poor-quality land races from Turkey. From the research conducted by McPhee, von Sengbusch and Hoffmann we know that when a monoecious hemp plant pollinates a dioecious female the offspring (F1) consists for over 90 % of females, for 3-5 % of monoecious plants bearing mainly female flowers and for only 2-3 % of true males. This small number of males however is sufficient to ensure adequate pollination of the crop. As the stand consists mainly of seed-bearing (female + monoecious) plants, with the same habit, we called it unisexual hemp. Such a stand yields 60 - 80 % more seed than a dioecious cultivar. The seed produced on this stand (F2) is used as sowing seed for fibre production. We called this cultivar "UNIKO-B". It is, in fact, a "single-cross" between Kompolti and Fibrimon, but it is the F2 generation which is commercialized. Von Sengbusch and Hoffmann described the phenomenon, but they did not think of its practical use. In Kompolt we make the cross between Kompolti and Fibrimon on a surface of 5 hectare (ha), this yields 2,500 kg of F1 seed. The F1 seed is sown on a surface of 500 ha, yielding 400,000 kg of F2 seed, which is used to sow 3,000-3,500 ha of fibre hemp.

Unisexuality also can be used to exploit the effect of heterosis which occurs when Chinese and European (Kompolti) cultivars are crossed. This heterosis can increase stem yield by 8-15 %. To be able to cross two cultivars we have to construct a female parent which is "male sterile", a unisexual F1 can be used as such. In order to obtain a unisexual chinese line we used Fibrimon as the donor, which was backcrossed many times until we obtained a monoecious line with a Chinese habit. We crossed this line with the original dioecious Chinese cultivar to obtain a unisexual Chinese F1. This F1 was crossed with Kompolti hemp to obtain Kompolti Hybrid TC. The stem yield of Kompolti Hybrid TC is 5-8 % higher than that of Kompolti. The unisexual Chinese F1 has an unsurpassed seed yield potential of up to 1,500-1,600 kg per ha.

JIHA: You made Kompolti Hybrid TC by crossing populations. Do you think much can be gained by using inbred lines to make hybrids?

IB: I can not answer this question because I never made inbred lines. It takes too long to make inbred lines and it is technically very difficult.

JIHA: What techniques did you use to develop your cultivars which have the highest fibre content of all existing hemp cultivars?

IB: As I explained in response to an earlier question, I used the Bredemann principle, which consists of the rapid determination of fibre content in male plants before they flower, so that only the males with the highest fibre content are allowed to pollinate the female plants. In some of my cultivars bark content is 38 - 40 %, this corresponds to a bast fibre content of 32 - 34 %. If the bark content is higher than 40 % the crop may lodge.

JIHA: How important is fibre quality relative to fibre content?

IB: Fibre quality is negatively related to fibre content. As we continue to select for fibre content we unwillingly increase the proportion of secondary fibre, which has a negative effect on fibre quality.

JIHA: Do cultivars differ in fibre fineness? IB: In a study comparing several cultivars on a number of locations, we found that the differences in fibre fineness between the locations were bigger than the differences between the cultivars.

JIHA: How did you develop Panorama, the world's only ornamental hemp cultivar?

IB: In a grow out of hemp from Lebanon we found two or three short and strongly branched plants. This character was lost in the F1, it reappeared in the F2. Through breeding I obtained a pure variety. We also made a monoecious version, because for an ornamental cultivar it is preferable if there are no male plants which die early. Panorama was commercialized in Hungary in the 1980s, but it was not much sold.

JIHA: How did you develop Kompolti S·rgasz·r™, the yellow stem hemp cultivar?

IB: Yellow stem was a mutation from professor Hoffmann, it was very early and very short. I crossed and backcrossed it often with the normal Kompolti to improve its stem yield and fibre content. In the end, we reached a very high fibre content, but its stem yield remained 15 % inferior to that of Kompolti. The textile factory liked the yellow stem very much, because in poor weather conditions the yellow stems can be dried in sheafs instead of being dried on the field. If this is done with normal hemp it causes problems because the stems in the middle of the sheaf do not lose their green colour, which eventually has a negative effect on the fibre colour.

JIHA: Current hemp cultivars were developed for textile fibre production. Do you think it will be feasible to develop special cultivars for seed production or for paper production?

IB: For textile production, new cultivars are not needed, because we have maximum stem yield and maximum fibre content. For paper production the high-fibre cultivars are very suitable, the presence of secondary bast fibre is no problem in this case. For seed production we have unisex, the single cross mother of Hybrid TC. It can yield up to 1,600 kg/ha of seed.

JIHA: What is the present status of your hemp cultivars, which can be bought in commercial quantities and through whom?

IB: Currently available are Kompolti, UNIKO-B, Kompolti Hybrid TC (but this cultivar contains too much THC for growing it in the EU) and Fibriko, which is like Kompolti Hybrid TC but with Kompolti S·rgasz·r™ instead of Kompolti as the father. Fibriko is not yellow but its fibre quality is better than that of Kompolti Hybrid TC. The cultivars belong to the GATE Agricultural Research Institute, but the institute is not allowed to do business, so a company called Fibroseed was founded. Fibroseed sells seed and pays the royalties to the GATE Institute.

JIHA: What was the most important discovery or technique in the history of hemp breeding?

IB: The use of the Bredemann principle was the most important innovation, the second most important contribution to hemp breeding was the development of monoecious hemp and in the third place I would list the making of unisexual hemp.

JIHA: What would be the most important developments to help make hemp a main-stream agricultural crop?

IB: First the laws which forbid hemp growing in a large number of countries will have to be changed. In the second place technical innovation is needed, we need better machines for harvesting and for the entire processing chain.


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