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  • Author or Editor: M. F. Handy x
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Abstract

Using wet-digestion as a standard, leaf samples of orange (Citrus sinensis (L.) Osbeck cv. Valencia) and Schefflera actinophylla Harms were dry-ashed at 500° and 700°C to demonstrate analytical sensitivity of the Schefflera nutrient elements to ashing temperature. Citrus leaf samples dry-ashed at 500° showed only a significant analytical loss in Fe, but dry-ashing at 700° showed substantial losses in Zn, and K. Schefflera leaf samples dry-ashed at 500° showed substantial losses in Cu, Fe, and Mn. Samples dry-ashed at 700° showed high to very high losses in Ca, Mg, Na, Zn, Cu, Mn, and Fe. Use of an analytical method established for one plant species was clearly not applicable to others without verification.

Open Access

Abstract

Zn and K loss was related to increasing temperature, and Cu, Fe, Mg, and P loss was related to the residual carbon in the ash of a standard routine check and reference sample of ‘Valencia’ orange leaves (Citrus sinensis (Linn.) Osbeck). Only Zn showed both loss due to volatilization and analytical loss related to increasing amounts of residual carbon. Mn and Na did not show a clear response to time, temperature, or sample size; B showed a response only at the highest temperature. The magnitude of differences was small, but the measured differences were very highly significant, indicating consistency due to treatment under given sets of conditions.

In a proven dry-ashing procedure widely accepted for citrus leaves in California, best results were obtained when citrus tissue materials were ashed at 550°C for 8 hr, and when sample size was not greater than 2.5 g.

Open Access

Abstract

Major nutrients removed by ‘Valencia’ orange fruit were N, K, Ca, P, and Mg. Amounts of N, Ca, and B were higher; Zn and Mn were lower than those reported for Florida oranges. Relatively small amounts of applied nutrients were found to be removed by the fruit. P, K, Ca, Mg, Zn, Mn, Cu, and Fe tended to be immobilized in the soil (either by direct application or decay of leaves and other plant parts), availability depending on soil pH. Leaching of N, largely as NO3, should always be minimized.

Open Access

Abstract

The effects of Fe-deficiency and Mn-deficiency in macadamia leaves on the accumulation of free amino acids and total amino acids (free plus protein amino acids) were studied in water vs. sand culture. Leaves showing severe Fe-deficiency symptoms contained substantially higher concentrations of free histidine, aspartic acid, threonine, serine, glutamic acid, proline, alanine, valine, and tyrosine than analogous control leaves. The sum of the individual free amino acids were 177% higher in the Fe-deficient leaves than in the control leaves.

Mn-deficient leaves, containing .0003% Mn, had significantly higher concentrations of free aspartic acid, threonine, glutamic acid, proline, alanine, valine, isoleucine, leucine, tryosine, and phenylalanine than analogous control leaves. The sum of the free amino acids in Mn-deficient leaves was 85% higher than in the analogous leaves from the control plants.

In chlorotic Fe-deficient leaves the concentrations of total lysine, histidine, ammonia, arginine, aspartic acid, methionine, and leucine were significantly higher than in control leaves.

Mn-deficient leaves contained significantly higher amounts of total lysine, histidine, ammonia, aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, methionine, isoleucine, leucine and phenylalanine than control leaves.

The concentrations of free lysine, histidine, aspartic acid, glutamic acid, proline, alanine, and valine were higher in the leaves of plants grown in sand culture. The total ammonia, threonine, methionine, leucine, tyrosine, and phenylalanine were lower in the leaves of plants grown in water culture. Total arginine was higher in leaves from the sand culture.

There were several significant interactions between treatments and culture media on the accumulation of free and total amino acids in the Fe- or Mn-deficient leaves.

Open Access

Abstract

Samples were taken from grapefruit Citrus paradise Macf. cv. Marsh, Valencia orange Citrus sinenesis L. Osbeck, and lemon Citrus limetta, ‘Risso’ trees growing in the field in the Citrus Research Center, Riverside, California. Quantitation of 17 protein and 18 nonprotein amino acids of citrus leaves were evaluated for comparative effects of sample drying-methods on the 3 citrus species.

Freeze-dried leaves contained significantly higher amounts of nonprotein, and lower amounts of protein amino acids, than the analogous leaves that were oven-dried. This indicates that citrus leaves must be enzymatically deactivated immediately after sampling and kept in a frozen condition in preparation for analysis. Otherwise, accurate assessment of amino acids in the leaves at sampling would not be obtained.

Grapefruit and ‘Valencia’ orange leaves contained higher concentrations of glutamic acid, aspartic acid, leucine, lysine, and arginine than of other protein amino acids. Lemon leaves contained more substantial amounts of glutamic acid, arginine, aspartic acid, leucine, and glycine.

The nonprotein amino acids proline, serine, alanine, and aspartic acid were found in more substantive amounts in grapefruit and ‘Valencia’ orange leaves, 77 and 69 percent, respectively, of the sum of nonprotein amino acids determined. In lemon leaves, proline, arginine, lysine, serine, and alanine were found to be more concentrated. These 5 nonprotein amino acids constituted 79% of the total of those determined. Proportionally, lemon leaves contained a larger fraction of nonprotein amino acids than grapefruit or ‘Valencia’ orange leaves.

Open Access

Abstract

Citrus leaves from plants supplied with low soil oxygen showed a decreased sum of protein amino acids, while the free amino acids sum increased. Leaves from Phytophthora spp. infested plants contained a higher free amino acids sum than uninfested. The orange leaves, Citrus sinensis L. Osbeck cv. Atwood navel, contained a higher sum of protein amino acids than lemon leaves, Citrus limon L. Burm. cv. Prior Lisbon, although both of these species were budded on sweet orange rootstock, Citrus sinensis L. Osbeck cv. Bessie. Leaves from the orange scion contained lower concn of glutamic acid, glycine, valine, isoleucine, and leucine, and higher aspartic acid and phenylalanine than the lemon leaves. The sum of the free amino acids in the orange leaves was higher than in lemon leaves. Significant interaction effects on free cystine, methionine, and tyrosine were caused by Phytophthora spp. infestation in the 2 species.

Open Access

Abstract

Protein amino acids in leaves of Phytophthora spp.-infested or noninfested plants were not affected measurably. Leaves from plants supplied with low soil oxygen levels contained significantly less protein amino acids: lysine, histidine, aspartic acid, threonine, serine, glutamic acid, glycine, alanine, valine, isoleucine, leucine, tyrosine, and phenylalanine but more arginine than analogous leaves of plants supplied with normal soil oxygen concn.

The leaves of Phytophthora-infested plants contained significantly lower concn of nonprotein amino acids: threonine, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine but higher concn of arginine and aspartic and glutamic acids. The nonprotein amino acids: lysine, arginine, aspartic acid, and pro line were higher, while threonine and glutamic acid were lower, in seedling leaves supplied with low soil oxygen than those in leaves on plants supplied with normal soil oxygen.

The protein and nonprotein proline, and the sum of nonprotein amino acids increased in leaves of noninfested plants, while decreasing in leaves of infested plants, with a decreasing level of soil oxygen to roots.

Substantive amounts of protein amino acids found in citrus seedling leaves were glutamic acid, aspartic acid, proline, leucine, and arginine; those of nonprotein amino acids were proline, arginine, serine, lysine, and aspartic acid. These amounts represent, respectively, 50 and 90% of the sum.

Open Access