Response of five citrus rootstocks to iron deficiency

Abstract

Citrus established in calcareous soils can be affected by iron (Fe)‐deficiency chlorosis which limits yield and the farmers' income. The degree of deficiency depends on the rootstock, but the resistance to Fe chlorosis still requires further investigation. To study physiological parameters of citrus rootstocks that could be used to evaluate resistance to Fe deficiency, plants of Troyer citrange (Citrus sinensis L. Osb. × Poncitrus trifoliata L. Raf.), Carrizo citrange, Volkamer lemon (Citrus volkameriana Ten. & Pasq.), alemow (Citrus macrophylla Wester), and sour orange (Citrus aurantium L.) were grown in nutrient solutions with 0, 5, 10, 15, or 20 μM Fe. For each rootstock, plant height, root and shoot dry weights, and concentration of Fe in the shoots and roots were measured at the end of the experiment. Chlorophyll (CHL) concentration was estimated throughout the experimental period using a portable CHL meter (SPAD‐502) calibrated for each rootstock. At the end of the experiment, CHL fluorescence parameters were measured in each rootstock with a portable fluorimeter. Maximal and variable fluorescence values indicated that the photochemistry of Troyer was more affected by a low concentration of Fe in the nutrient solution than that of other rootstocks. To compare rootstocks, the absolute CHL concentration was converted into relative yield by employing a scaling divisor based on the maximum value of total CHL in plants without Fe‐deficiency symptoms. Exponential models were developed to determine the minimum Fe concentration in nutrient solution required to maintain leaf CHL at 50% of the maximum CHL concentration (IC50). Models were also developed to assess the period of time the rootstocks were able to grow under Fe‐stress conditions before they reached IC50. Volkamer lemon and sour orange needed the lowest Fe concentration (between 4 and 5 μM Fe) to maintain IC50, and Troyer citrange had the highest Fe requirement (14 μM Fe). Citrus macrophylla and Carrizo citrange required 7 and 9 μM of Fe, respectively. Similarly, Volkamer lemon and sour orange rootstocks withstood more days under total Fe depletion or with a low concentration of Fe (5 μM Fe in nutrient solution) until they reached IC50, compared to the other rootstocks. The approach used led to a classification of the rootstocks into three categories, regarding their internal tolerance to Fe chlorosis: resistance (sour orange and Volkamer lemon), intermediate resistance (C. macrophylla and Carrizo citrange), and reduced resistance (Troyer citrange).

Influences of different iron levels on plant growth and photosynthesis of W. Murcott mandarin grafted on two rootstocks under high pH conditions

“…It is known that a low Fe supply negatively affects the chlorophyll content and other components of chloroplasts, which reduces growth capacity (De La Guardia and Alcantara, 2002). In the present study, it was observed that as iron doses rise, SPAD values increase, which is supported by other research findings (Pestana et al, 2001;De La Guardia and Alcantara, 2002;Pestana et al, 2011). This is because iron functions as a component of proteins in significant cellular events such as respiration and cell division; moreover, it has a role in the reduction steps of important biological events, such as transpiration and photosynthesis, and also in chlorophyll biosynthesis (Einsenstein and Blemings, 1998;Zocchi et al, 2007).…”

Efectos Del Enriquecimiento Con Selenio en Spad, Calidad De La Fruta Y Parámetros De Crecimiento De Plantas De Fresa en Un Sistema De Cultivo Sin Suelo

“…Esto da a entender que la aplicación del Se en plantas, como práctica cultural, se relaciona en parte con el tamaño de los frutos. Estudios anteriores realizados también en el cultivo de la fresa, como el de Correia et al (2011), han llegado a conclusiones similares, señalando además que ciertas prácticas culturales pueden influir en la composición nutricional de los frutos. De forma similar, el Se también se relaciona con la firmeza de la fruta.…”

“…En la Figura 2-A puede observarse una disminución de los valores de SPAD en hoja vieja desde la semana 18 a la semana 25, que se corresponde con el final del ciclo de cultivo. Tendencias similares han sido descritas por Pestana et al (2011), que sugirieron cambios en la concentración total de clorofila (mol m -2 ) de las hojas de plantas de fresa a lo largo del ciclo del cultivo. Según los resultados obtenidos se observó un efecto significativo de los tratamientos de Se y de las semanas sobre los valores de SPAD en hoja vieja.…”

Insights into Physiological Responses of the Halophyte Suaeda fruticosa to Simultaneous Salinity and Iron Deficiency

“…In our conditions, salt treatment under both Fe supply regimes apparently restricts iron uptake, as evidenced by the lower iron concentrations (mg g À1 DW) in leaves and to lesser extent in roots of salt-treated plants. These results could be explained by the dilution effect related to the biomass increase of salt-treated plants [44,45] rather by a salt-induced limitation of Fe uptake. This assumption is strengthened when analyzing data in terms of Fe content (mg plant À1 ) which show either significantly higher or constant values following salt treatment depending on the organ.…”