Abstract
The quantification of the hydric necessity for production of qualified seedlings is of extremely importance, and the substrate is a mediator of such influence. However, few studies are carried out in this context and, mainly, with native species as Luehea divaricata Mart. et Zucc., which presents elevated wood potential and for restoration of riparian forests. Thus, the work consisted in evaluating different substrates and irrigation schemes, in the survival and growing of seedlings, characterizing the hydric demand of the species, using factorial scheme composed by four formulations of substrate (100T: 100% turf (peat); 80T: 80% peat and 20% carbonized rice husk - CRH; 60T: 60% peat and 40% CRH; 40T: 40% peat and 60% CRH) and six irrigation schemes. Variables of survival, height, stem diameter, production of aerial dry mass, root and total, leaf area and Dickson Quality Index were evaluated. We observed elevated survival, height, stem diameter, aerial dry mass and leaf area in irrigation of 16 mm day-1, combined with the substrates 100T and 80T. The dry masses and Dickson Quality Index, independent of the irrigation scheme, reflected in a greater carbon accumulation. Thus, we concluded that the substrates based on peat, mixed with until 20% of CRH provide a greater seedling growth, making them available to the hardening and expedition more quickly, when associated to the irrigation scheme of 16 mm day-1. Luehea divaricata is a native species that can be considered with high hydric demand during the phase of seedling production.
Highlights
Luehea divaricata Mart. et Zucc., from family Malvaceae family, is a native species of South America, occurring in Brazil, Uruguay, Argentina, Paraguay (USDA, 2015) and Bolivia (Tropicos, 2015)
The analysis of these two variables (H and stem diameter (SD)) demonstrated the possibility of reducing the time of seedlings in a nursery to about 30 days, when we used up to 20% of carbonized rice husk (CRH) combined with the peat under any irrigation scheme (Figure 1 A and B), or with a minimum of 40% of peat at an irrigation intensity of 16 mm.day-1 (Figure 1 D and E); under these conditions, seedlings growth was sufficient for rapid expedition (H=25 cm, SD=3mm)
On analyzing the interaction between the factors on the 120th day, we observed that the greater values of H, SD, and LA for the L. divaricata seedlings occurred in the substrates 100% peat (100T) and 80% peat and 20% CRH (80T), in the irrigation of 16 mm.day-1 (Table 2), confirming the results observed throughout the experiment when analyzed independently
Summary
Luehea divaricata Mart. et Zucc., from family Malvaceae family, is a native species of South America, occurring in Brazil, Uruguay, Argentina, Paraguay (USDA, 2015) and Bolivia (Tropicos, 2015). Uncontrolled and overly extractive exploration of L. divaricata, associated with the reduction in forest area owing to an increase in other land use types, has led to a considerable reduction in the number of its specimens. In this context, Conson et al (2013) highlighted the importance of defining strategies for population conservation of L. divaricata, including the study of its genetic structure, bearing in mind its importance in reforestation programs. According to Sarmento and Villela (2010), concern regarding the environment has fostered an increase in the demand for seeds and seedlings of native species, which constitute basic inputs in recovery, improvement, and biotechnology programs. The production of quality seedlings with appropriate planting characteristics is essential for the development of technologies that favor satisfactory plant growth at low costs
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