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Abstract
“White Rose” potato plants were grown in modified Hoagland’s solution at concentrations of 0 to 16 meq/1 of K. After 32 days of growth, 16 plant parts were taken for analysis. The K status of the potato plant was reflected best by the second leaf below the flat top (Fig. 1). This leaf was the recently matured leaf of the plant, was relatively easy to sample, and did not differ greatly in K concentration from the first, third, and fourth leaves. The critical K value at a 10% reduction of growth was 2.3% for the petiole tissues and 1.1% for the blade tissues.
Abstract
Potato plants were grown outdoors in pots containing Alvolite, a low K material, under low and high K conditions. The blades of recently matured leaves were relatively constant in K concentration, whereas the petioles changed rapidly with growth and K supply. Sodium was largely excluded from the leaf tissue while Ca and Mg were higher with low K supply. Tubers under high and low K nutrition changed only from about 2.0 to 1.3% K, respectively, and the values of Na, Ca, and Mg were very low, ranging from only 0.06 to 0.30%. Therefore, an analysis of tubers is not useful in plant analysis.
The degree of K deficiency can be estimated by following the rate of K decline in reference to the K critical level of 2.3% for the petiole and 1.1% for the blade tissues as illustrated by present results and of a field experiment.
Abstract
Tomato plants (Lycopersicon esculentum L. cv. VF 145-21-4) in the greenhouse developed over a 5-week period from seedling to early bloom stage, increased in fresh and dry weight of shoots and roots, in plant height, and internal NO3-N concentration in relation to the NO3 supply of the culture solution. Increases in NO3-N varied among plant parts: roots < stem < petiole > blade. Growth of shoots was related to NO3-N concentration in plant parts. A petiole from a young mature leaf, leaf 2, was the best indicator of N status of the plant. Its critical value for N deficiency was 275 ppm of NO3-N (dry wt) when estimated at a 10% reduction in growth. A tentative critical value for use under field conditions was set at 500 ppm. Movement of NO3 was primarily unidirectional from the petiole to the blade, with little return movement to the stem and upward to younger petioles.
Abstract
‘White Rose’ potato plants (Solanum tuberosum L.) grown outdoors in water cultures with 0 to 16 meq/1 Mg displayed deficiency symptoms 30 days after transplanting ranging from severe to none. Corresponding growth reduction was caused by Mg stress. Critical concentrations in plant tissues for Mg deficiency were 0.06% Mg, dry wt basis, for the petiole and 0.09% for the blade of recently matured leaves.
Magnesium stress lowered the Mg concentration of petioles and blades much more than that of the fibrous roots. It had no appreciable effect on K but it decreased Na in most plant parts. Magnesium stress increased Ca in the fibrous roots and petioles but decreased it in blades. It increased nitrate-N in all tissues, and increased PO4-P in the fibrous roots and petioles but decreased it in blades. All petioles, as a rule, were much higher in K, Na, NO3-N, and soluble PO4-P than the blades. Our results indicated that the minerals interacting with Mg depend on the plant part analyzed.