Cold stress at seedlings stage of buckwheat optimizes development of both roots and aboveground biomass and limits the excessive vegetative growth interfering with seed formation (an analytical review)

Abstract

Buckwheat, sown in warmed soil, quickly sprouts, grows and successfully competes with annual weeds. However, such agronomic practice does not always lead to a good grain yield, because a powerful, abundantly flowering buckwheat plants often give only a minimal amount of seeds due to a lack of moisture in the upper layer of soil during flowering. This behavior of buckwheat is described as "overgrowth (with poor seed formation)". This phenomenon is caused by the relative weakness of the root system of this species: the specific feature of buckwheat is a very fast transition to formation of secondary roots, which gives advantages at the first stages of development, but restricts the roots growth later. Buckwheat flowering is stretched in time. First half of this developmental stage which is most important for the grain yield is coincided with the most intensive vegetative growth. The lowered temperature at the seedlings stages slows the growth of the aboveground biomass and accelerates the growth of the roots that at later stages favorably affects the conditions for seeds development and, respectively, the grain yield. It explains why early sowing time is favorable for the grain yield of buckwheat.