PHENOLOGICAL AND PHYSIOLOGICAL CHARACTERIZATION OF A WILD POPULATION OF PITAYO (Stenocereus queretaroensis (Weber) Buxbaum) ASSOCIATED WITH VESICULARARBUSCULAR MYCORRHIZAS

Pitayos (Stenocereus spp.) are columnar cacti that grow in the wild and under cultivation. Their edible fruits are sold in local markets. Those populations have received little investigation, even though pitayo is an important component of tropical and subtropical deciduous forests. In this work we examine the seasonal variation in soluble sugars, inorganic phosphorus and climatic factors in relation to colonization by VAM-fungi in wild plants of S. queretaroensis, in order to determine the physiological and environmental conditions present at the time that the symbiotic relation begins and during its development. Our observations revealed that the increase in soil water content at the beginning of the summer (june), stimulated the formation of rain roots, and mycorrhyzal spore germination, favoring the colonization of this type of roots by VAM fungi. Root growth was the conspicuous vegetative event during the summer season; the other phenophases (vegetative growth, reproductive growth) occur during the dry season, so root colonization by VAM-mycorrhizae does not coincide with the main vegetative and reproductive phenophases. Thus mycorrhizae development does not compete for resources with the main metabolic sinks. The development of root colonization by VAM mycorrhizae coincides with the increase in the content of phosphorus and soluble sugars in the stems of pitayo. On the other hand, reducing sugars in the rain roots decrease during the process of colonization. The hyphae of mycorrhizal fungi only enter rain roots that have a cortex with parenchyma cells. Mycorrhizal colonization decreases once the rain roots start the maturation process at the end of summer, a process that is accompanied by substantial suberization of the epidermis and the hypodermis.

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Autores principales:	Arceta-González, Irma Esther, Pimienta-Barrios, Eulogio, Zañudo-Hernández, Julia, Olalde-Portugal, Victor
Formato:	Digital revista
Idioma:	spa
Publicado:	Colegio de Postgraduados 1999
Acceso en línea:	https://www.agrociencia-colpos.org/index.php/agrociencia/article/view/1586
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