Produtividade agroeconômica de plantas de mandioquinha-salsa 'Amarela de Carandaí', pré-propagadas em recipientes de papel com diferentes substratos

Abstract

The lack of planting material has limited the expansion of the Peruvian carrot cultivation, therefore a better use of the seedlings in recommended. The aim of this work was to study the growth and survival of Peruvian carrot seedlings pre-propagated in paper containers filled with different substrates and study the effects of substrates on agro-economic productivity of plants from this species. The initial propagation of Peruvian carrot plants 'Amarela de Carandaí' was carried out with seedlings composed of shoots obtained from mother plants grown at the Medicinal Plant Garden in the previous harvest, that were maintained in a cold chamber and planted in containers made out of newpapers, filled with six substrates: T1 = 100% commercial substrate (C); T2 = 100% soil (S); T3 = 80% C + 20% S; T4 = 60% C + 40% S; T5 = 40% C + 60% S; and T6 = 20% C + 80% S. The six treatments were arranged in randomized block design with eight replications and experimental unit composed of 20 paper containers. The treatments applied in the field were the same six pre-planting treatments, arranged in a randomized block design, with four replications and experimental unit composed of 12 Peruvian carrot plants. At the initial propagation, the highest plant was 9.56 cm at 29 days after planting (DAP) and the survival rate was 35.37% at 36 DAP, when transplanting was conducted. The survival rate of the plants in the field was 67.65%. The highest values for plant height (34.09 cm), stem diameter (62.54 cm) and number of leaves (34.82) were observed in plants at 204 DAP. The average SPAD value was 36.34. The larger fresh leaf mass (9.54 t ha-1), shoots (13.53 t ha-1) and marketable roots (18.52 t ha-1) were obtained in T6 (treatment 6), and non-marketable roots (3.08 t ha-1) in T1 (treatment 1). The larger dry leaf mass (1.38 t ha-1), shoots (2.41 t ha-1), marketable roots (3.88 t ha-1) and non-marketable roots (0.67 t ha-1) were obtained in T6. Crown fresh and dry mass showed an overall average of 4,25 t ha-1 and 0.83 t ha-1, respectively. The largest marketable roots numbers (277,200 ha-1) were obtained in plants from T4 and T6 treatments, and non-marketable roots (415,800 ha-1) and shoots (1,059,300 ha-1) in T6. The largest marketable roots diameter (38.27 mm) and nonmarketable roots (21.91 mm) were produced by plants from T1. The longer lengths of marketable roots were in plants from T6 (10.16 cm) and non-marketable roots in T1 (5.72 cm). An agro-economic assessment showed that the estimated costs ranged in R$ 24,896.31, between the highest cost (R$ 103,195.94) in T1 and the lowest cost (R$ 78,299.63) in T2. It was concluded that the greatest productivity of marketable roots (18.52 t ha-1) and the highest net income (R$ 27,841.12) were the Peruvian carrot 'Amarela de Carandaí' plants propagated in paper containers filled with the mixture of 20% commercial substrate and 80% of soil.