Keywords: Sechium edule (Jacq.) Sw., calcareous, chlorosis, mycorriza.
The initial nutrimental deficiency symptoms associated to the loss of the plant vigor and fruit color of Sechium edule (Jacq.) Sw., locally called White Chayote, were reproduced under greenhouse conditions to evaluate response to nutriment addition and microsymbiont inoculation. The soil used was from Actopan, Veracruz, Mexico, and was subdivided into layers at 0-30, 30-60, 60-90 cm and mixture of total profile to determine fertility. For every 30 liters of soil layer, 8.29 g (NH4)2SO4, 1.0 g of Ca3(PO4)2, 4.4 g of K2SO4, 1.15 g of FeSO4, MnSO4 and ZnSO4, and 0.75 g of sulfur, 40 g of Glomus intraradices (MA) and Azospirillum brasilense were applied. Plant height, chlorophyll, total biomass, and CO2 assimilation were evaluated; in addition, X-ray analyses were performed in cuttings from the fourth internode below the apical bud of the main stem. The soil showed Cl-, SO42-, HCO3-, Na+ soluble compounds and pH of up to 7.9. In addition, values of P, Ca2+ and Mg2+ of 5.6, 50.3 and 4.7 times, respectively, above the consigned values for the species were found. Plants sown in the soil of the 0-30 layer showed the highest growth compared with the 30-60, 60-90 levels and total profile mixture. The nutrients mixed with MA, as well as with MA and A. brasilense, was statistically significant. The control plant showed crystals made of P, Ca, S, Si, Na, Mg obstructing the stem xylem bundles. The experimental evidence showed that the initial symptoms associated to White Chayote, were due mainly to nutrimental deficiencies, which was more evident in the levels of soil below 0-30 cm.