NITROGEN AND PROTEIN CONTENT COMPARED BETWEEN NEW LEAVES AND RIPES OF GUARANAZEIRO CULTIVARS UNDER DIFFERENT PRODUCTION SYSTEMS

Abstract

Seeking subsidies to understand the preference of pest insects and microorganisms for young tissues, newly expanded leaves of seven cultivars of guaranazeiro were collected in September 2018 and, from the same cultivars, collected new leaves, in April 2019, in the municipalities Amazonas from Maués, Presidente Figueiredo and Manaus, in plots of ten plants of each cultivar, in each location, in three different systems: a) Embrapa production system (Pereira, 2005); b) Jayoro production system (Santos et al., 2018) and, c) Integrated production system (Santos et al. 2018), in a total of 21 treatments. Locations were considered as repetitions. The samples were dried in a forced ventilation oven and the nitrogen quantified following the Kjeldahl semimicro method. There were no significant differences between cultivars for N content, neither in new leaves nor in mature leaves. However, the average among cultivars of N levels in young leaves (44.39 g kg-1) was 44.92% higher than the average in mature leaves (24.45 g kg-1). There was no production system effect for N in new leaves. On the other hand, for N in mature leaves, the integrated and Jayoro systems were positioned first, not differing from each other, followed by the Embrapa system. The crude protein contents (N x 6.25) contained in the young leaves and in the mature leaves did not reveal significant differences between the cultivars, but in the new leaves it was much higher. The average among the seven cultivars revealed a protein content of 27.74% in new leaves and 15.28% in mature leaves, an average of 44.92% more for new leaves. Production systems did not induce differences in protein content in new leaves, whereas in mature leaves the Integrated and Jayoro systems stood out and did not differ, followed by Embrapa.