Effects of gametocides on male sterility and breeding traits in monoecious hemp

Abstract

Manual castration in monoecious hemp hybridization is complicated by long development and anthesis of numerous male flowers in an inflorescence. Chemical castration significantly facilitates the crossing process.

The aim and tasks of the study were to establish specifics of gametocide influence on male sterility and breeding traits in modern monoecious hemp varieties of the Central Russian eco-geographic type.

Material and methods.In theresearch, we used 1,3-dibromopropane, dibutylphthalate and ethephon (solution of 2-chloroethylphosphonic acid). Single/double treatment of hemp plants (60 plants per treatment) was performed using water extracts of various concentrations in the following phase of the plant development: ten leaves, budding, beginning of anthesis. Effects of the agents on the growth and development was evaluated by changes in the total and technical length, stem diameter, stem weight, fibre weight, fibre content, seed weight per plant, 1000-seed weight, sex structure.

Results and discussion.The test gametocides affected male sterility and productivity traits of hemp. The efficacy of treatment depended on the concentration (dose) and phenological phase of plant development. Both varieties under investigation, Hliana and Hlesiia, formed a sufficient number of hybrid seeds per plant for further research and reproduction.

Conclusions. Double treatment of hemp during the ten-leaf and beginning of anthesis phases with dibutylphthalate at the concentrations of 2.0 and 1.0% was proved to be efficient. Almost 100% chemical castration of male flowers can be attained by treating them with 0.3–0.6% ethephon (2-chloroethylphosphonic acid, 1,440–2,880 mg/L) at the dose of 30 ml/m² in the ten-leaf phase before budding and beginning of differentiation of reproductive organ tissues in meristematic zones.