PLANT GROWTH KINETICS OF SUGAR CANE PLANTS PROPAGATED CONVENTIONALLY AND IN VITRO

Abstract

In México, sugarcane (Saccharum officinarum L.) is traditionally propagated in vegetative form by cuttings obtained from another plantation; frequently, not genetic or phytosanitary quality control is carried out, thus resulting in lower agroindustrial yield and greater phytosanitary problems. An alternative is the establishment of certified seedlings based on the use of homogenous, pathogen-free vitroplants with increased vigor. The objective was to evaluate sugarcane plantations reproduced conventionally vs. vitroplants, in regard to their kinetics of biomass growth and its distribution, and their relationship with some physiological efficiency indexes, in two of the most widely planted sugarcane varieties in the country, CP 72-2086 and MEX 69-290. The two varieties were propagated as hydrothermotreated cuttings at 50 ° C for 2 h, and as in vitro plants, and were planted at 10,416 plants ha-1. Treatments were compared in a 2 (varieties) x 2 (sources of propagules) factorial experiment arranged as split plots design with four replicates. Response variables were measured in six destructive samples, performed every 20 days, following 45 days after transplant (dat). Biomass was determined as dry weight of complete plants, and was segmented on the stem, root and leaf tissue. Results showed a slow initial growth of in vitro plants, compared to plants derived from conventional propagation. However, starting from 105 dat the in vitro plants showed greater biomass accumulation. In vitro plants formed 25 % more stems per strain (15) than conventional plants (12). According to the kinetics of biomass distribution, in the four treatments the stem was the organ that grew the most after the slow phase, and exceeded root and leaves growth; these differences were more evident for in vitro plants.