Structural features of endocarpial sclerenchyma valves and its role in soybean pod dehiscence (report II)

The problem of instability of soybean varieties to untimely pod dehiscence remains unsolved, which which raises the need for new anatomical features governing this phenomenon. Promising is the use of the aw of homologous series of N. I. Vavilov in the study of the causes of resistance to shattering in other species of legumes in order to find the same forms in soybeans. Study the anatomical structure of pods in eight accessions of cultivated and wild soybeans, and five species of other species of legumes with different resistance to shattering was carried out in VNIIMK, Krasnodar, in 2012-2014. Anatomy endocarpial sclerenchyma evaluated in 25 pods of each accessions or legume species. It is shown that the longitudinal crack in the ventral sutures are initially shatter zones and arise due to shrinkage of tissues in mature soybean pods. Diagonal layer of drying sclerenchyma in the endocarp accumulates physical and mechanical stresses, which lead to the pods dehiscence and twisting of the valves. Angles of sclerenchyma fibers inclination in cultivated and wild soybean close to the diagonal (« 45°), which determines the appearance of the maximum torque of torsional strain in the valves. Deformation of valves continues until sclerenchyma fiber alignment along the longitudinal axis of rotation. In such legume species as black locust, Judas tree, Russian liquorice and honey locust with indehiscent or later dehiscent pods scleren- chyma fibers in the valves are located under the more or less acute angles compared with soybean, which reduces the stress caused by torsional deformation and provides increased resistance to pods dehiscence. It is shown that the resistance to shattering at the line of soybeans D-1809 TD provides increased angles endo- karpial sclerenchyma, as in legume species with slightly dehiscent pods, which confirms the presence of soybean homologous overlap with other types of legume species on this trait.