Substratos orgânicos para a produção de batata-semente

Abstract

Potato cultivation in agroecological systems is of great importance for family farming. However, the high cost and low availability of seed potatoes are limiting factors for the expansion of the crop. The aim of this work was to formulate and select organic substrate, promoter of vegetative and reproductive development, for the production of seed potatoes. Survival, leaf growth rate, gas exchange and agronomic variables of potato were evaluated in four experiments with the cultivars Aracy, Ágata and Aracy-ruiva. Seed potato sprouts were used as propagative units. The first experiment was carried out with the propagation of cv. Aracy on 16 (S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15 and S16) organic substrates. Among the 16 substrates evaluated, eight (S1, S2, S3, S8, S9, S10, S11, S15) were selected for promoting greater tuber development and compared with the commercial substrate. In the first experiment (cv. Aracy), plant survival was 60% (S7); 80% for substrates S10, S14, S15 and S16 and 100% for substrates S1, S2, S3, S4, S5, S6, S8, S9, S11, S12 and S13. In the second experiment (cv. Aracy) substrates S3, S8, S10, S11 and S15 provided plant survival equal to or greater than the commercial substrate (60%). In the third experiment (cv. Ágata), plants grown on substrates S3, S9, S10, S11 and S15 had 100% survival, equivalent to the commercial substrate. In the fourth experiment (cv. Aracy-Ruiva) substrates S2, S3, S9, S11 and commercial provided 100% plant survival. In the first and sec-ond experiment (cv. Aracy) the plants developed in the S8 substrate had a higher leaf growth rate. In the experiment with cv. Ágata, substrate S11 provided a higher growth rate. In the experiment with cv. Aracy-ruiva, higher growth rate was observed for plants in the S9 sub-strate. The instantaneous efficiency of carboxylation (EiC) in plants of cv. Aracy from the second experiment was higher in plants grown in S8, S15, S1 and commercial substrates. The plants of cv. Aracy-ruiva cultivated on S15, S8, S2 and commercial substrates have a higher internal concentration of CO2 (Ci); and those grown on S3 substrate have higher instantane-ous water use efficiency (EiUA). The eight selected substrates provided similar development of mass, diameter and length of the tubers produced by the cultivars, when compared to the commercial substrate. Regarding the number of tubers, only in the experiment with cv. Ágata, a statistical difference was observed for this variable, with plants developed in substrates S11, S10, S8, S1, S9, S15 and commercial in greater numbers. No difference was found between the macronutrient contents (N, P, K, Ca and Mg) of the tubers of cv. Aracy evaluated in the first experiment for plants grown on substrates S1, S2, S3, S8, S9, S10, S11, S15. Among the substrates evaluated, substrate S11 is indicated for the production of seed potatoes, as it pro-motes the survival, vegetative and reproductive development of cvs. Aracy, Ágata and Aracy-ruiva.