Root distribution of cactus pear genotypes under different soil water replacement levels

Abstract

Knowledge of the cactus pear root distribution system can improve management of the plant by defining the areas of soil best suited to fertilizer application and the installation of soil moisture sensors under irrigation. Thus, the aim of the present study was to assess the root distribution of cactus pear genotypes under different water replacement levels. To that end, a field experiment was conducted in a randomized block design, using genetic material from two cactus pear genotypes (Opuntia fícus-indica Mill. and Nopalea cochenillifera Salm-Dyck) and six water replacement levels based on reference evapotranspiration - ET0 (T1, no irrigation; T2, 15%; T3, 30%; T4, 45%; T5, 60% and T6, 75% of ET0), arranged in split-plot, with irrigation treatments allocated to the plots and the genetic material to the sub-plots, and three replicates. The roots of the cultivars were collected for analysis of root length density (RLD) 390 days after planting. The RDL of very fine roots declines as depth and distance from the plant base increases and total, fine, small and medium RDL rise at higher water replacement levels; 75% of ET0 near the plant base increases RDL; all the root diameter classes are concentrated at a distance of 0-0.20 m from the plant base and depth of 0.10 to 0.25 m; the RDL percentage is higher for the Gigante genotype and Miuda exhibits better root distribution.

Root Distribution, Nutrient Concentration and Accumulation in ‘Gigante’ Cactus Pear Irrigated With Saline Water

“…The highest RDL values for very fine roots in plots irrigated with high-salinity water at 33% ETo with a 3-d II and at 50% ETo with a 2-d II formed a group, while the remaining treatments were grouped with lower RDL values (Table 4). Castro et al (2021) also found no differences in RLD of small root class with an increase in the percentage of soil water replacement level; however, they found an increase in RLD of very fine and fine root classes up to the irrigation level of 75% of ETo.…”

“…Castro et al (2021) also found a higher concentration of all classes of 'Gigante' and 'Miuda' forage cactus pear's roots at a distance of up to 0.20 m from the base of the plant and at a depth of 0.10 to 0.25 m. The results of these authors corroborate those obtained in the present study, with the concentration of the cactus pear root system in the first 0.15 m deep and at shorter distances from the plant. This consolidates the technical recommendations for the crop, such as applying fertilizers close to the plant to increase nutrient-use efficiency by improving nutrient uptake and utilization by plants.1 ** -Significant at p ≤ 0.01 and * -Significant at p ≤ 0.05 by the t test.…”