Production of hemiparasitic plant seeds and its use

(Working Group No. 2 - coordinator Assoc. Prof. Stanislav Hejduk)

Project team develops certificated technology of hemiparasitic plant seed production of genus Rhinanthus. Seeds of Rhinanthus are not widely available yet, but it is known that these plants can be used to convert existing high and thick (productive) grasslands into the lower and sparse vegetation of dicotyledonous forbs. In the last two decades, Rhinanthus has been experimentally used in England to lower productivity and promote the vegetation diversity of meadows and highway slopes. This technology, however, has not spread, due to poor establishment of the used species (Rhinanthus minor - Little yellow rattle) in new places and also because of the high price of the seed.

Our observations show that the related species Rhinanthus alectorolophus - Greater yellow rattle, Czech native species (formerly weed of cereals), is able to grow in most grassland types. In addition, Rhinanthus alectorolophus is a rapidly growing species with a huge production of seeds, which gives good prospects for commercial seed production and large-scale application of the technology. By 2018, registration of new varieties of Rhinanthus is planned for market purposes. To meet this goal, negotiations were initiated with employees of the Central Institute for Supervising and Testing in Agriculture (hereinafter abbreviated KZZ). Seeds of selected genotypes of Rhinanthus alectorolophus as well as other promising species R. major were sown along with the host plant Lolium multiflorum (Italian ryegrass) in the containers for the implementation of DUS tests (distinctness, uniformity and stability).

Until now the multiplication of Rhinanthus seeds was going on in the stands of Calamagrostis epigejos in forest clearings, and these stands are technically difficult to adjust for sowing and harvesting. Thus, field experiment with nine cultural species of grasses and four species of legumes was started in September 2015 in order to identify the suitable host species for commercial seed production of hemiparasitic Rhinanthus. In November, seeds from both Rhinanthus species were sown inside these experimental monocultures. The plot size is 4 m2 and it is a triplicate experiment. Results to date suggest that 1 ha of agricultural land could annually produce 400 to 500 kg of Rhinanthus alectorolophus seeds. This fact makes, in the current state of soil preparation, harvesting and seed cleaning prices, good assumptions that the price of Rhinanthus seed could cost 3-4 EUR per 1 kg, which is the level of cultural grasses seed prices.

Treatment of grassland with Rhinanthus proceeds as follows. After autumn sowing of 500 seeds (i. e. about 2 g) per 1 m2, Rhinanthus within one or two subsequent growing seasons suppresses growth of productive grasses. This indirectly supports especially forbs with rosette leaves which are effective in defending against Rhinanthus haustoria (suction root organs). This change of species composition will thus lead to a very significant reduction of total aboveground biomass production (up to half). Whereas Rhinanthus is an annual plant, it is totally dependent on its host (grasses), after suppression of vegetation it also retreats and opens the space for spontaneous colonization of other plant species. At the same time it releases its nutrients from biomass for newcoming species. With a wealth of litter on the soil surface and soil structure stabilization with decaying grass roots, there is no danger of erosion in the meantime before the development of dicotyledonous forbs.

© 2016, Pavla Mladkova