Grape-based residue as a substrate in Oncidium baueri Lindl. acclimatization

Abstract The use of agricultural residues as a substrate is a promising option for orchid acclimatization, which is a critical stage of micropropagation. Thus, this study aimed to evaluate the use of grape residue S-10 Beifort®, isolated or mixed with other agricultural residues, in the acclimatization of Oncidium baueri Lindl. Five treatments were studied (S-10 Beifort®; S-10 Beifort® + carbonized rice husk (CRH); S-10 Beifort® + coconut fiber (CF); S-10 Beifort® + CRH + CF; CRH + CF), with four replications containing 10 seedlings each. After 120 days, the highest survival rate occurred with the mixture CRH + CF (62.5%). The mixture of S-10 Beifort® with CRH provided a greater shoot length (3.7 cm), not differing from the mixture of the three substrates (2.9 cm). S-10 Beifort® + CRH and the mixture of the three substrates ensured greater root length (3.8 cm). The mixture of the three residues provided the highest average of fresh and dry mass accumulation. The pH variation between the substrates was from 5.2 to 6.3, while S-10 Beifort® presented the highest electrical conductivity (2030 μS cm-1) and the mixture of this material with carbonized rice husk presented the highest water retention capacity. The use of a mixture of S-10 Beifort® with carbonized rice husk or with carbonized rice husk and coconut fiber (1:1:1) is indicated for the acclimatization of Oncidium baueri Lindl.