Rootstock‐mediated changes in xylem ionic and hormonal status are correlated with delayed leaf senescence, and increased leaf area and crop productivity in salinized tomato

Abstract

Tomato crop productivity under salinity can be improved by grafting cultivars onto salt-tolerant wild relatives, thus mediating the supply of root-derived ionic and hormonal factors that regulate leaf area and senescence.A tomato cultivar was grafted onto rootstocks from a population of recombinant inbred lines (RILs) derived from a Solanum lycopersicum ¥ Solanum cheesmaniae cross and cultivated under moderate salinity (75 mM NaCl). Concentrations of Na + , K + and several phytohormones [abscisic acid (ABA); the cytokinins (CKs) zeatin, Z; zeatin riboside, ZR; and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC)] were analysed in leaf xylem sap in graft combinations of contrasting vigour. Scion leaf area correlated with photosystem II (PSII) efficiency (Fv/Fm) and determined fruit productivity. Xylem K + (but not Na + ), K + /Na + , the active CK Z, the ratio with its storage form Z/ZR and especially the ratio between CKs and ACC (Z/ACC and Z + ZR/ACC) were positively loaded into the first principal component (PC) determining both leaf growth and PSII efficiency. In contrast, the ratio ACC/ABA was negatively correlated with leaf biomass. Although the underlying physiological mechanisms by which rootstocks mediate leaf area or chlorophyll fluorescence (and thus influence tomato salt tolerance) seem complex, a putative potassium-CK interaction involved in regulating both processes merits further attention.

Effects of grafting combinations on the nutritional composition of pepper fruit

“…The changes in scion characteristics have been mainly related to a higher capacity fo water and nutrient uptake by the vigorous roots of rootstocks [5,20,22] and/or translocation of endogenous hormones or other metabolites between the rootstock and scion [30,31]. In order to determine the putative effects of the promising rootstocks 'Charlot' and 'Foc' on pepper fruit quality parameters, the representative sweet peppers 'Almuden' and 'Coyote' were used as scions and fruit from grafted, self-grafted, and ungrafted plants, collected at similar maturity stages, were processed for analysis.…”

Some rootstocks improve pepper tolerance to mild salinity through ionic regulation

“…However, the direct relation between K + homeostasis and salinity tolerance has not been well-established [1]. In some species, Na + can be balanced by a higher K + concentration [36], while in other plants, tolerance is due to the capacity of roots to maintain K + transport in the xylem, as in tomatografted plants [37,38].…”

Differences in photosynthetic performance and its correlation with growth among tomato cultivars in response to different salts

“…However, the correlation found between photosynthesis and growth for specific cultivars has not been analysed, and this analysis is especially necessary when we consider the diverse cultivars that have been tested. Leaf growth inhibition under salt stress may be regulated by hormones or their precursors [25], and Albacete et al [2] M A N U S C R I P T…”