RESPONSE OF MEXICAN WILD HUSK TOMATO (Physalis spp.) TO OSMOTIC POTENTIAL IN HYDROPONICS

Abstract

The osmotic potential (Ѱ_o) of nutrient solutions can influence growth and production; however, the effect is a function of the magnitude of Ѱ_o and the demand or the absorption capacity of each species. The objective of this research was to evaluate growth and yield of Mexican wild husk tomato (Physalis spp.) at different osmotic potentials in the nutrient solution. Accessions 7b, 9b, 17b and Philadelphia were evaluated with Ѱ_o of -0.018, -0.036 and -0.054 MPa under greenhouse conditions and hydroponics. The effect of treatments at 30, 60 and 90 days after transplant (DAT) was quantified through measurements of plant height, stem diameter, number of flowers per plant and readings for the intensity of the green color of leaves, or SPAD (Soil Plant Analysis Development) readings. The percentage of fallen flowers was determined at 90 DAT, and during one month the percentage of fruit set, number of fruits per plant and weight of fruits were quantified. In general, all traits were affected by the Ѱo of the nutrient solution and by plant material. Plant height, stem diameter, number of flowers, and SPAD readings were higher as nutrient solution concentration increased (lower Ѱ_o). However, the percentage of fallen flowers, fruit set, fruit number and fruit weight were lower when plants were exposed to -0.054 MPa. Accession 9b reached a larger height, and 17b increased its diameter more than other materials. Accessions 9b and 17b increased the number of flowers; 7b and 17b registered the highest percentage of fallen flowers, 7b had the highest SPAD readings, and the highest yield was achieved with accession 9b. All genotypes showed reduced growth with -0.018 MPa in the nutrient solution, and with high osmotic potential fruit yield decreased. The intermediate level (0.036 MPa) is the appropriate osmotic potential for fruit production. Accession 9b was the most suitable for fruit production under greenhouse conditions as it showed the highest number of fruits and yield.