SUBSTRATE AND FERTILIZATION IN THE QUALITY OF Myrocarpus frondosus SEEDLINGS

Abstract

Myrocarpus frondosus is a native species with high commercial timber value. Thus, the objective of this research was to evaluate the quality of seedlings of Myrocarpus frondosus in the nursery and to indicate the most adequate substrate and fertilization for the production of seedlings. The experiment was conducted in a completely randomized design, with four replications, in a factorial scheme, composed of four combinations of substrates: S1-100% commercial substrate (CS); S2 - 80% CS and 20% carbonated rice husk (CRH); S3 - 60% CS and 40% CRH; S4 - 40% CS and 60% CRH, and four fertilizations: NF – No fertilization; CRF – controlled release fertilizer (ammonium sulfate, simple superphosphate and potassium chloride); RRF – ready release fertilizer and micronutrients. Physical and chemical analyses were performed on the substrate. At 300 days after emergence, the following morphological variables were evaluated: (height, stem diameter, H/SD ratio, leaf area, root length, aerial dry mass, root dry mass, total dry mass, Dickson quality index) and the physiological variables chlorophyll a, chlorophyll b, carotenoids, initial fluorescence, maximum fluorescence, Fv/Fm ratio and electron transport rate). Regardless of the substrate and fertilization, slow growth of the species was observed, even for the best treatment, which was verified from the height (17.87 cm) and stem diameter (2.62 mm). The use of the commercial substrate (40%) with carbonated rice husk (60%) associated with the concentration of 6 g L-1 of controlled release fertilizer is recommended, since they present the best results for the morphological and physiological variables in the nursery in general.

Sowing time and substrate in the production of ipê-mirim seedlings

“…The availability of water in the substrate is a fundamental part of the processes of root and leaf emission, as well as the transport of water and nutrients via the xylem, providing conditions for the production of photoassimilates necessary for the growth and initial development of the seedling (Masiero et al, 2019). The function of the substrate is to provide adequate conditions for the development and growth of the plant root system (Aimi et al, 2019) T. stans proved to be nutrient dependent both in the initial phase of seedling emergence and in the subsequent development of the seedlings, as the highest averages of morphological characteristics were obtained in enriched substrates, mainly and the lowest averages in sand and vermiculite, substrates considered inert (Table 3). The substrate composition can change emergence, initial growth and the content of photosynthetic pigments, modifying the capture of radiant energy and influencing the amount of assimilates produced (Afonso et al, 2017).…”

“…Electrical conductivity, on the other hand, refers to an indication of the concentration of salts in the solution and provides a parameter for estimating the amount of nutrients present in the substrates (Pêgo et al, 2019) and, according to Gabira et al (2020), high values can negatively affect plant root growth, significantly influencing seedling quality. Aimi et al (2019) emphasize that the physical condition is important because the substrate must be porous, thus avoiding the lack of oxygen, and water availability to the roots. Sand presents high and vermiculite with low density (Kämpf, 2000), being verified for sand a density of 1333 kg m -3 and for vermiculite, 159 kg m -3 (Stumpf et al, 1999).…”