EFFECT OF TROPIMEZCLA, BASED ON MICROBIAL INOCULANTS, ON THE DEVELOPMENT, PROTECTION AND PRODUCTIVITY OF ONION CROP (Allium cepa).
The onion crop or head onion (Allium cepa) is extended among Colombia and is one of the most important vegetables due to its economic income and nutritional supply (calcium, phosphorus, vitamins A and B), used for fresh consumption and industrial edible products. Although the onion crop develops very well at dry conditions, low relative humidity, high solar radiation and water supply, the bulb formation is affected by photoperiod, temperature, foliage damage and specially the mineral nutrition.
At present, compounds that promote plant development have been applying and evaluating, increasing the root development, reducing damage from pests and diseases and promoting a better use of water and nutrient absorption, which is traduced in agrochemicals reduction, throughout the use of environmentally friendly biological products that give protection to the plants.
The biological control play an important place within plant disease management practices to control soil pathogens, mainly of the genera Rhizoctonia, Sclerotium, Pythium, Phytophthora, Fusarium and others. There are fungi as the genus Trichoderma which can compete with pathogenic fungi, while the yeast Saccharomyces cerevisiae has showed great ability to control plant diseases and synthesize antibiotic compounds and their suspension cells or culture filtrates inhibit spore germination and appresorium formation of Colletotrichum and other pathogens.
The fungi Beauveria y Metarhizium are widely recognized as entomopathogens of more than 60 species of insects of different orders in different crops and the fungus Paecilomyces has a confirmed action on numerous nematodes that attack many crops. The mix of these fungi and other microorganisms has showed improvement of soil microbial characteristics, reduction of plant pathogens points, improvement of nutrient absorption, production of antibiotics, control of nematodes, improvement of the immune system of the plant, tolerance to the water stress and reduction of at least 20% the use of chemical fertilizers. As a result, different doses of commercial product TROPIMEZCLA were evaluated. The results showed that the action of TROPIMEZCLA on the fresh weight of the aerial part of the plants, confirm the protective action of TROPIMEZCLA due to the foliage protection during the whole development of the crop; TROPIMEZCLA promoted commercial bulbs size which have market guarantee and good value.
To conclude, two sprayings of the product must be made at 2.5 a 3.0 K/ha dose; the first one must be sprayed over the built beds, incorporating the microbial inoculant at 5-8 cm depth, just before the transplantation and the second, at bulb thickness and before or after mineral fertilization.