Suchergebnisse

Phosphorus is part of several organic compounds in plant metabolism such as nucleotides and phosphoproteins, in addition to participating in metabolism and energy storage. This study aimed to evaluate the response of peach trees cv. Sensação to phosphate fertilization and establish the critical level of this nutrient in soil and leaves. The experiment was conducted in the 2016 and 2017 cycles in a commercial orchard located in Morro Redondo, RS, Brazil. The experimental design was a randomized block design with four replications. Peach trees were fertilized with increasing doses of phosphorus (P) of 0, 20, 40, 60, and 80 kg ha?1 of P2O5 as triple superphosphate. In the two evaluated cycles, samples of soil at a depth of 0–20 cm and leaves were collected to determine mineral contents. The data were submitted to analysis of variance by the F test (P < 0.05), and when the effects were significant, regression equations were adjusted. P application increased the contents of this nutrient in the soil. Leaf P contents were not affected by fertilization, as well as productivity and yield components. Thus, the critical level of P in soil and peach leaves could not be established. In soils where P contents are classified as medium and high, there is no need to apply this nutrient.

Forms of aluminum (Al) present in the solution of tropical and subtropical soils can cause toxicity in rootstocks and peach cultivars, impairing growth and productivity. This can be minimized by growing Al-tolerant rootstocks and cultivars. However, this is not sufficiently known, especially because plant breeding programs do not always consider tolerance as a selection variable for genetic materials. The study aimed to (a) select cultivars and clonal selections of Al-tolerant peach rootstocks, (b) identify variables that confer Al tolerance for use in genetic improvement programs, and (c) propose critical levels (NC) and ranges of toxicity (TF) of Al in relation to morphological variables of the root system. The experimental design was completely randomized, comprising a factorial of 13 (cultivars and clonal selections) x 2 (with and without Al) with three replications. Own-rooted 'BRS Mandinho' peach seedlings (without rootstock) and grafted seedlings of 'BRS Mandinho' on different cultivars and clonal rootstock selections were cultivated in a hydroponic system, composing two levels for the Al factor (absence and presence at 100 mg L−1). The morphological variables of the canopy and root system, Al accumulation in tissues, translocation factor, and the critical level (NC) and toxicity range (TF) of Al in the roots were evaluated. Rootstocks FB-SM-09-43, JB-ESM-09-13, SAS-SAU-09-71, SS-CHI-09-40, 'Sharpe' and VEH-GRA-09-55 were tolerant at high Al concentrations. The NC of Al in the roots in relation to the root surface area of peach rootstocks was 1400 mg Al kg−1, and the FT was between 1200 and 1500 mg Al kg−1.