The aim of this study was to evaluate the efficiency of nutrient uptake, accumulation, distribution and use, and its relationship with growth variables, chlorophyll content, and root and shoot dry-weight partitioning in the ‘Okinawa Roxo’ peach rootstock, submitted to different nutrient solutions and substrates. The experimental design was completely randomised, with four treatments and five replications. The treatments were T1: Ns1 = Souza et al. nutrient solution (2011), applied to a sand substrate; T2: Ns2 = Hoagland and Arnon (1950), applied to a sand substrate; T3: Commercial Substrate + H2O; and T4: Control, Sand + H2O. Ninety days after transplanting (DAT), morphological, physiological and nutritional parameters were determined in the ‘Okinawa Roxo’ rootstock, together with the correlation between nitrogen concentration and nitrogen balance index, and the chlorophyll content and index. The greatest zinc content was detected in the shoots of the ‘Okinawa Roxo’ plants, at more than 80% of the accumulated total. Treatments T1 and T2 (nutrient solutions Ns1 and Ns2 respectively) made it possible to obtain ‘Okinawa Roxo’ plants with the best morphophysiological characteristics, being ready for grafting three months after transplanting in a greenhouse. The use of the Ns1 nutrient solution resulted in greater efficiency in the uptake and use of the nutrients nitrogen (N), potassium (K) and iron (Fe). The N and Total Chlorophyll concentrations in the leaves of the red-leaved peach tree can be estimated indirectly with a chlorophyll meter, and are an accurate indication of the nutritional status of the plant in relation to nitrogen content.

The cultivar 'G × N-9' is an almond x peach hybrid rootstock, the main characteristic of which is resistance to several root-knot nematodes (Meloidogyne spp.). Although its propagation by hardwood cutting in the fall is recommended, optimization of 'G × N-9' in vitro propagation is currently needed. Thus, the objective of this study was to evaluate the effect of the cytokinins [6-benzylaminopurine (BAP) and Kinetin (KIN)], and the carbohydrate sources (sucrose and sorbitol) on shoot proliferation and elongation, as well as the influence of indole-3-butyric acid (IBA) on in vitro rooting and acclimatization of 'G × N-9' rootstock. This study reports enhanced on shoot proliferation and elongation based on the interaction between BAP and KIN. When comparing the effects of sorbitol and sucrose, sorbitol at 15 and 30 mg L −1 was the most effective for the induction of shoot proliferation (5.75 ± 0.19 and 6.39 ± 0.21 shoots per explant, respectively). The highest number of roots per explant was in QL medium supplemented with 0.6 and 1.2 mg L −1 IBA. After 30 days of acclimatization, the treated-plants with 1.2 mg L −1 IBA showed the smallest root length, but the higher number of roots per explant (8.35 ± 0.41). The successful acclimatization of plantlets depended on the use of IBA during in vitro culture, to induce a healthy and well-developed root system.

Flordaguard' has shown great potential as a standard rootstock for peach. The aim of this study was to examine the influence of Murashige & Skoog (MS) medium and modified MS-½N medium (half Nitrogen content), explant type and angle orientation on the culture medium, as well as 6-benzylaminopurine (BAP) concentrations on in vitro shoot proliferation in 'Flordaguard' rootstock. Explants cultured in MS-½N medium showed higher averages for number of lateral shoots and elongated shoots. The maximum average length of lateral shoots was obtained using doublephase medium. The 3.0 mg L -1 BAP induced the highest number of lateral shoots per explant (3.38 ±0.57). Whereas the higher number of lateral shoots elongated (1.75 ±0.10 cm) occurred at concentrations until 2.0 mg L -1 BAP. The study corroborated the importance of a 50% reduction in both NH 4 NO 3 and KNO 3 content in the cultured medium to improvein vitro propagation of 'Flordaguard' peach rootstock.