Calcium Uptake by Excised Maize Roots and Interactions With Alkali Cations

Abstract

Abstract. Ca2+ uptake was studied in short-term experiments using 5-day-old excised maize roots. This tissue readily aborbs Ca2', and inhibition by dinitrophenol and low temperature shows that the process is metabolically mediated. The uptake of Ca2+, like that of other cations, is influenced by the oounter ion, the pH and concentration of the ambient solution, and the presence of other cations. Materials and MethodsAll experiments were conducted with 6-cm apical segments of primary roots. The 5-day-old maize seedlings (Zea mays, cv. Dekalb 441) were grown as follows: 150 g of seed were surface sterilized with 2.5 % HO2. for 2 min to minimize fungal growth, rinsed, and soaked in aerated, distilled water for 6 hr. Aft'er soaking, the seeds were distributed on cheesecloth-covered, stainless-steel screens suspended over 7 liters of 2 X 10-4 M CaSO4. The culture solution was aerated continuously and was renewed after 3 days. The seedlings were grown in the dark in growth chambers maintained at 270.The excised roots were held in several liters of aerated, distilled water prior to treatment. After thoroughly mixing the roots, samples were removed and gently blotted on absorbent tissue paper to remove excess water. One-gram root samples were rinsed. briefly with distilled-deionized water and transferred to 1-liter treatment solutions, except where treatment concentrations were less than 0.1 meq/l in which case 10 liters of solutions were used. All solutions were aerated throughout the 24-hr absorption period.

Exotic Annual Grasses in Western Rangelands: Predicting Resistance and Resilience of Native Ecosystems to Invasion (Draft)

“…This finding was followed up by Harner and Harper (1973), Pederson and Harper (1979), Woodward et al (1984) and McKnight et al (1990) to explain patterns of plant distribution in natural vegetation in the arid western US. Other studies also support the observations that high levels of Mg and Ca can restrict plant uptake of K in both the laboratory and the field (Kahn and Hanson 1957, Epstein 1961, Elzam and Hodges 1967, Maas 1969, Garcia et al 1999, Sinanis et. al 2003.…”

Absorption of Magnesium and Chloride by Excised Corn Root

“…DeKalb 441). The roots were obtained from 5-day-old seedlings that were dark-grown in 0.2 mi CaSO, according to the procedure described previously (10). The preparation and treatment of the roots are also indicated therein, except for the following minor modifications: (a) to minimize leaching of the excised roots prior to treatment, the roots were held between several layers of damp cheesecloth rather than in distilled water and (b) both growth and treatment temperatures were maintained at 30 C, except when temperature was a variable.…”

“…One species that meets these requirements is corn. Unlike the plant tissues mentioned above, excised corn roots actively absorb CaW+ (3,10), as well as Mg'+. This study was undertaken to characterize the general features of Mg2`and Cl-uptake by this tissue and to determine the effects of Ca2+ under various treatment conditions.…”

Aluminum Effects on Calcium Fluxes at the Root Apex of Aluminum-Tolerant and Aluminum-Sensitive Wheat Cultivars

“…These techniques may not be best suited for studying Al effects on Ca2+ uptake; i.e. because Ca2+ fluxes can vary considerably, both along the roots and with time (5,6,15,26), Al effects on Ca2+ transport in specific localized regions of the root, such as the apex, may be very important in understanding the mechanisms of Al toxicity.…”