Influence of fertiliser treatment on apple fruit composition and physiology

Abstract

The contents of total phosphorus, ethanol-soluble phosphorus, ethanol-insoluble phosphorus, magnesium, calcium, and potassium were determined in tissue of apple fruits from trees receiving no fertiliser (U) and from trees receiving the fertiliser treatments N, P, NP, and NPK (N=2Ib sulphate of ammonia, P=41b superphosphate, and K=llb sulphate of potash per tree per year). In comparison with tissue from U fruit, tissue from P fruit possessed higher total, ethanol-soluble, and ethanol-insoluble phosphorus contents and a slightly lower potassium content. Treatment N resulted in increased levels of calcium and potassium but a markedly reduced phosphorus content. Calcium, magnesium, and phosphorus levels were elevated as a result of treatments NP and NPK; the latter treatment also resulted in a higher potassium content. Incidence of internal breakdown was negatively correlated with total and ethanol-soluble phosphorus contents, but not with the contents of magnesium, calcium, or potassium.

The Effect of Calcium on Respiration of Apples1

“…Letham (9) noted that, P, had an effect similar to that observed by us for Ca. Phosphorus could effectively counteract the increased respiration caused by N. He used a similar explanation to that which we are using for the Ca effect.…”

“…The similarity of effects of Ca and P on respiration is easily u n d e rsta n d a b le . Calcium interacts with phospholipid membranes whereas P is an integral part of these membranes (8,9).…”

“…The increase in decarboxylation of malate, however, does not account for the increase in total respiration of the low-Ca fruit. Lethan (9) reported that fruit from high-N trees was higher in respiration throughout the growing season and matured several days earlier than did fruit of other treatments. We suspect that low-Ca apples also have a higher in respiration and mature faster.…”

Calcium Concentration of ‘Spartan’ Apple in Relation to Amount of Senescent Breakdown in Individual Fruits1

“…Breakdown has been found.to be associated also with low P levels in New Zealand in the 'Sturmer' apple but not with Ca, Mg or K (3).…”

“…Homogeneity X 2, with 2 df, was 0.723, with P = 0.3-0.5, showing that all 3 sets of data were true estimators of the recombination value. 3 Male-sterility and leaf type. The F2 population from 'Calmar' ms x 6583fr gave information on the linkage between achene color and leaf type and on a second linkage between leaf type and male sterility (Table 2).…”