Root Growth Rate Analysis in Four Opuntia ficus-indica (L.) Mill. Varieties

Abstract

The present research was carried out with the objective to determine the time in the emission of roots, the growth rate, and the morphological differences of roots (length, diameter, and dry weight of roots) of four varieties of cactus pear Opuntia ficus-indica (Liso forrajero, Villanueva, Jalpa and Copena V-1) cultivated under controlled conditions and established in glass containers with sand as substrate, under a completely randomized design with six replications of four plants per replication. The time in the emission of the first roots of each variety was measured, while the daily growth rate of roots was measured during the first 14 days after the establishment of the cladodes. At 54 days after the establishment, a destructive sample was carried out to measure the length, the diameter, and the dry weight of roots, as well as the visual evaluation of the roots density. The results showed a differential among varieties in all variables. The time (in days) of the emission of roots of cactus pear showed differences among varieties, where the Liso forrajero variety was the more premature and Copena V-1 was the tardiest. An inverse relation between roots emission time and growth rate of roots was found because Copena V-1 showed the higher growth rate but presented a greater time in the emission of these, while Liso forrajero variety showed the lower growth rate but the lesser time in its emission. The length, the diameter, and the dry weight of roots showed a significant differential among varieties, whereas the variety Villanueva showed the greater values in the three variables.