Nitrate Transport Rate in the Xylem of Tomato Plants Grafted onto a Vigorous Rootstock

• Published in: Agronomy (Basel) Vol. 10; no. 2; p. 182
• Main Authors: Albornoz, Francisco, Pérez-Donoso, Alonso G., Leigh Urbina, Jorge, Monasterio, Matías, Gómez, Miguel, Steinfort, Úrsula
• Format: Journal Article
• Language: English
• Published: MDPI AG 27.01.2020
• Subjects: solanum lycopersicum × solanum habrochaites; stem hydraulic conductance; vessel diameter; xylem vessel density
• ISSN: 2073-4395; 2073-4395
• DOI: 10.3390/agronomy10020182

Vigorous interspecific rootstocks increase nitrogen (N) uptake in tomato plants but limited information is available on xylem transport rate. Non-grafted and self-grafted tomato plants cv. Attiya and plants grafted onto an interspecific hybrid, Kaiser, were grown under growth chamber conditions and subjected to two light levels, 400 or 800 µmol PAR m−2 s−1. Plant water uptake, xylem sap NO3− content, and stem hydraulic conductance (ks) were measured after two weeks of growth. Xylem vessel number and diameter were evaluated in cross-sectional stem cuts and the theoretical xylem hydraulic conductance (kh) was calculated. Only the light level modified the xylem NO3− content. Grafting reduced ks by 84% in comparison to non-grafted plants. The water uptake rate and xylem sap NO3− content were 4.02 ± 0.66 g H2O kg−1 DW h−1 and 12.78 ± 1.16 mM, respectively, across all grafting treatments. The rootstock has a higher kh because the vessel diameter is 79.3 ± 14.4 µm while in non-grafted plants it is 62.0 ± 10.1 µm. Nitrate concentration and transport rate changes accordingly to the plant’s growth rate. The vigorous rootstock relies on larger vessels to supply the required amounts of N.