Histological anomalies in stems of common and runner beans (Phaseolus vulgaris L. and Ph. coccineus L.) treated with pendimenthalin

Abstract

Common beans (Phaseolus vulgaris L.) 'Augustynka' and 'Złota Saxa' and runner beans (Ph. coccineus L.) 'Blanka' and 'Eureka' were seeded on loess-like soil containing 1.6% of organic matter, and sprayed with pendimethalin at the dose of 1650 g•ha-1 ' immediately after seeding in the middle of May. The herbicide inhibited shoot growth and caused enlargement of the stem at the soil level. Observations made in light and scanning electron microscope showed that in the swollen parts of the stem, the diameter of cortical parenchyma cells was bigger, the thickness of phloem layer was irregular, phloem fibers were less lignified, and the xylem cylinder was asymmetrical. In stems of 'Augustynka', 'Złota Saxa' and 'Eureka' cultivars, the thickness of secondary xylem and the diameter of vessels were reduced. Some vessels and tracheids were positioned transversely and obliquely to the stem axis and had an arched shape. Cell walls were less lignified and had a smaller number of pits. The largest number of histological anomalies was found in stems of the 'Augustynka' and 'Złota Saxa' cultivars.