Root architecture affected by pear degeneration in relation to rootstock and soil characteristics

The functionality of the roots has both physiological-productive and phytosanitary implications for pear in high density orchards. The dynamic equilibrium that exists between the root system and the above ground system is known: the functionality of one part is conditioned by the health of the other. It is no coincidence that many of the agronomic operations carried out in the field (such as irrigation, fertilization, soil tillage, weed control) aim to create an environment suitable for root growth and absorption. In 8 farms in Emilia Romagna (Italy) with cases of pear tree degeneration, a study about the impact of different factors on the root system has been carried out: different pear rootstocks (pear and quince clones) grafted with Abbé Fétel (in one case, self-rooted), and two different types of irrigation systems (drip and under-foliage sprinkling) were investigated in commercial orchards with problems of pear tree degeneration. The soil samples were collected in 2021 at a depth of 0-30 cm at 30 cm distance from the trunk along the row. The architecture analysis of the roots and the analysis of microbial biomass and respiration were carried out. An interaction was observed between sample origin, microbial activities, and root architecture with possible consequences in the response of pear plants to anomalous seasonal trends (summer temperatures above normal and reduced rainfall). The superficial root systems are in fact very sensitive to high soil temperatures and temporary asphyxia induced by localized irrigation and anomalous microbial activity.