Nopalito and forage productivity of Opuntia spp. and Nopalea sp. (Cactaceae) growing under green-house hydroponics system.

摘要

The aim of this research was to assess the year-long productivity (nopalito and fodder) of Nopalea cochenillifera, Opuntia ficus-indica, O. robusta ssp. larreyi and O. undulata x O. tomentosa, growing under green-house hydroponics. Cladodes were harvested when they reached the tender nopalito size (growth stage 1, GS1), developed cladode size (GS4), or one of two intermediate stages (GS2 and GS3), regardless of their chronological age. Productivity was determined by dividing total production by the number of days that passed from the first sprout to the last harvest. Productivity increased (p<0.001) exponentially with growth stage in O. undulata x O. tomentosa, O. ficus-indica and N. cochenillifera, and linearly in O. robusta ssp. larreyi. As nopalito, the productivity of Opuntia (21 and 31 kg DM ha-1 day-1 for GS1 and GS2, respectively) doubled that of Nopalea, although this difference did not achieve statistical significance. In stages GS3 and GS4, O. robusta ssp. larreyi and O. undulata x O. tomentosa showed the highest productivity (p<0.05), 63 and 57, and 82 and 93 kg DM ha-1 day-1, respectively, although the latter rose significantly from GS3 to GS4. Biomas-accumulation pattern for treatments fit sigmoid model, which is characteristic of perennial species. With the harvest criterion adopted, the interval between harvests depended on the species and increased, on average, from 10 days in GS1 to 28 days in GS4. Cactus pear productivity depended on the species, and was likely associated with the daily and seasonal temperature variations in its natural habitat. Differences in productivity were more evident at the genus level. Productivity rose as larger cladodes were harvested, but with different rates between species. Nopalito productivity was similar in the four species, but they differed in forage productivity.