Agrobiological peculiarities and prospects for valorification of woad, Isatis tinctoria L., in Moldova

Abstract

We studied agro biological peculiarities, chemical composition and nutritional value and evaluated the capacity to produce biogas from aerial biomass of the woad, Isatis tinctoria L., family Brassicaceae Burnett, which was cultivated on the experimental land of the Botanical Garden (Institute) of Academy of Sciences of Moldova. It was established that the species Isatis tinctoria, in the first growing season, was characterised by slow growth and development, produced a basal rosette of leaves and a strong taproot, but in the second growing season, it had an accelerated growth and development rate. This species started flowering 10-15 days earlier than oilseed rape, so, it was valuable for bees as a pollen source. In the flowering period (the second half of April), woad branched stalks reached up to 105-110 cm high, the natural forage yield reached 23.0 t/ha of natural forage with a high degree of foliage (50%), in the seed development period (the end of May) – 35.0 t/ha of natural forage. The chemical composition of solids of green mass of Isatis tinctoria in the flowering period is represented as follows: 20.18% raw protein, 4.46% raw fats, 32.40% raw cellulose, 12.25% minerals, 30.76% nitrogen free extracts, but in the seed development period – 12.00%, 3.08%, 38.83%, 8.56% and 37.53%, respectively. The nutritional value in the flowering period was 0.11 nutritive units/kg, 1.14 Mj/kg metabolizable energy and 165.6 g/ nutritive units digestible protein, but, in the seed development period – 0.14 nutritive units /kg, 1.43 Mj/kg and 100 g/ nutritive units gestible protein, respectively. The Isatis tinctoria silage prepared from wilted green mass harvested in seed development period, was distinguished by homogeneous dark-brown colour, pleasant smell of pickled cabbage, 0.23 nutritive units./kg and 2.30 Mj/kg metabolizable energy, 110 g/ nutritive units digestible protein, but corn silage – 0.30 nutritive units/kg, 2.64 Mj/kg and 40g/ nutritive units digestible, respectively. The calculated biogas capacity of woad can reach values of 438-464 l/kg organic substance with 54-56% methane. Taking into consideration the presented scientific results, the species Isatis tinctoria is promising as a crop with multiple utility for founding fodder-melliferous and melliferous-energy plantations, besides; it can be used for green manure.