Sistemas de produção, estratificação e qualidade de sementes de

Abstract

The peach tree is of great importance among the temperate climate fruit grown in Brazil. The commercial propagation of the species is traditionally carried out with the planting of the stones of the rootstock in the soil and subsequent grafting of the scion cultivar by active bud grafting. Thus, the quality and stratification of the stones are extremely important. In addition, the conventional production system presents numerous problems related to the sanity and development of the seedlings' root system. Given this context, two experiments were conducted during the 2020/2021 production cycle with the aim of improving the seedling production system of the crop. With the first work, the objective was to evaluate the quality of seedlings of the scion cultivars Chimarrita, BRS Fascínio and Maciel produced in three production systems: conventional, semi-hydroponic and in plastic bags. The rootstocks grown in this last system showed lower lateral ramifications, diameter and height when compared to the other systems. Semi-hydroponics provided seedlings with higher dry mass of tertiary roots, showing the quality of their root system, in addition to providing greater balance between the roots and the aerial part of the seedlings. With the seedlings cultivated in the conventional system, they obtained greater vigor in their aerial part and dry mass of roots due to the greater growth potential. In the second experiment, the objective was to evaluate the emergence and growth of 'Capdeboscq' peach rootstocks from seeds submitted to four periods of cold stratification (0, 15, 30 and 45 days) and separated into four intervals of mass (2.5 to 3.0; 3.1 to 3.5; 3.6 to 4.0 and 4.1 to 4.5 g). As the period of cold stratification increased, there was a positive effect in relation to the increase in emergence speed and speed index, in addition to the decrease in the average mean emergence time. With the improvement in the speed of the emergence process, both height and diameter of the seedlings submitted to 45 days of cold stratification were higher when compared to the three lower periods. The seed mass did not affect the mean emergence time and the growth in height and diameter of the rootstocks, however, the heaviest stones presented lower percentage and emergence speed and speed index when compared to the two smallest intervals of mass. It was concluded, therefore, that the semi-hydroponic system provides the production of peach seedlings with higher root system quality and that cold stratification is extremely important in improving the sexual propagation of peach rootstocks.