MAGUEY BAGASSE WASTE AS SUSTAINABLE SUBSTRATE IN SOILLESS CULTURE BY MELON AND TOMATO CROP

The soilless culture of vegetables in protected environments has increased in southern Mexico. However, the use of materials such as mineral wool or perlite as substrates is expensive and unsustainable. Therefore, the use of alternative, local materials such as the waste from mescal and coconut industries, including maguey (Agave spp.) bagasse, coconut fruit fiber and dust, as well as non-metallic mining products, such as vermiculite, is desirable. In this study, the physical, chemical and biological properties of vermiculite, coconut fiber, and maguey bagasse were determined, and their potential for cultivating melons (c.v. 'Magno F1') and tomatoes (Mill. c.v. 'Don Raúl') was evaluated. Moreover, 13 different substrates, based on combinations of the aforementioned materials, were analyzed. Materials were characterized at the Oaxaca Unit of the National Polytechnic Institute, and experiments were conducted in a multi-tunnel greenhouse in a randomized block design. Results indicated that materials possessed a narrow particle size distribution, where the lowest percent weight was observed for coarse particles (>2 mm), resulting in a low coarseness index. Alternatively, the highest percent weight was observed in medium particles (0.25 mm). Values of apparent density, total porosity, electrical conductivity, and germination rate of lettuce seeds were acceptable for soilless substrates. The highest yield of tomatoes (12.4 kg m^-2 was observed on a substrate composed of 25% coconut dust and 75% vermiculite. In contrast, a mixture of 25% maguey bagasse and 75% vermiculite produced the highest yield of melons (3.1 kg m^-2). Moreover, the concentration of total soluble solids was not affected by the substrates. In conclusion, mixtures of maguey bagasse and/or coconut dust with vermiculite are superior to pure materials and can be used for the soilless cultivation of melons and tomatoes.