Determination of Nitrogen, Phosphorus, and Potassium in Leaf Tissue. Application of Micromethods

Rootstocks have been shown (7,8, 9,11,13) to exert an influence on tree growth, disease resistance, and fruit quality factors of various types of citrus. Recent work in California (5,6) in which the leaves of orange, grapefruit, and lemon trees on a large number of different rootstocks were analyzed for several nutritive elements, strongly suggests that the amounts of these minerals in the scion leaves may be affeeted by the rootstock used.Since one of the objectives of the nutritionial research program at this station is an attempt to associate the mineral composition of citrus leaves with tree performance, fruit quality, and fertilizer utilization, it is desirable to know as much as possible about the effect of rootstock on the mineral content of the leaves. Some information on eleven nutrient elements has been obtained with Valencia orange trees on six different rootstocks, under Florida conditions, and is presented herewith. Materials and methodsA rootstock test with Valencia orange was laid out in a randomized block arrangement in 1942 by other members of this station staff for the purpose of comparing the six rootstocks in respect to their effect on various aspects of tree growth, yield, and fruit quality. The rootstocks used were sour orange (Citrus Aurantiurm), Rough lemon (C. Linton), Rusk citrange (Poncirts trifoliata x C. sinensis), Bowen grapefruit (C. paradisi), Cleopatra mandarin (C. reticulata) and Parson Brown (sweet) orange (C. sinensis). The budded trees were two years old when the experiment started, and had been in the field five years when leaves were taken for analysis in late July, 1947. The soil is Lakeland fine sand located near Tavares, Florida. A complete mixed fertilizer (N, P, K, Mg, Mn, Zn, Cu, and B) was applied uniformly to all plots three times each year. During the first three years applications were made manually, while a mechanical distributor was used for the last two years. Dolomitic limestone was applied uniformly to the entire experimental area at intervals in amounts sufficient to maintain the acidity of the soil at about pH 5.5. No nutritional sprays were applied at any time.Thirty-six 6-months-old leaves from non-fruiting shoots of the spring flush were collected in a uniform manner from each plot of three trees, with nine replications for each rootstock. The leaves were throughly scrubbed in a neutral detergent solution (sodium lauryl sulphate), rinsed four times in distilled water, dried to constant weight at 500 C, ground to a fine powder in a semi-micro Wiley mill provided with a nickel-coated

Section: Methodsmentioning

confidence: 99%

The Influence of Rootstock on the Mineral Composition of Valencia Orange Leaves

Smith¹,

Reuther²,

Specht³

1949

“…The nucleotides released in the reaction were estimated using a Perk.in-Elmer Model 139 UV-VIS Spectrophotometer at a wavelength of 250 mu after unhydrolyzed RNA was (precipitated by the stop solution (2 …”

mentioning

confidence: 99%

Ribonuclease Activity of Stressed Tomato Leaflets

Dove

1967

Siwninary. Homogenates of leaflets of desiccated tomato plants show increased ribonuclease activity compared to homogenates of turgid controls. Much of this increase is iindependent of changes in translocation to and from the leaflet. Interruption of translocation through living cel'ls by detachment of leaflets or steam damage to the petiolules prodluces increased ribonuclease activity, but this activity is increased further when excised leaflets are allowed to wilt. Increases in rihonuclease often parallel or precede increases in the soluble nitrogen content. Further increases in activity occur when excised leaves become yellow. Exposure of leaflets to CO,-,free air has little effect on activity at low-light intensitv (120 ft-c). These results suggest that water stress directly affected ribontuclease activity at the cellular level.Increased ribonuclease activity results from various physiological disturbances inl leaves. Kessler and co-workers found greater activity in homogenates of leaves stressed by zinc deficiency (6) and dehydration (4) thani in homogenates of unstressed controls. Ribonuclea;e activity of apple leaves increases with leaf age (5). However, barley leaf discs show less ribonuclease activity when they are floated on water ( 11). These data aDparently confl,ict wvith the w idelv-held belief that detachment of leaflets causes an acceleration of normal patterns of senescence (14).TranSlocation between leaves and the remainder of the pDlant body is often redutced during drought (110, 13) and the assimilation of CO, is also reduced (1). Changes 'in ribonuclease activity during drought may tlherefore be a dlirect response to dehydration of leaf cells or may result from changes in the immediate cellular environment brought about by factors such1 as stomatal closure and reduced translocation.

“…Material for nitrogen and ash determinations was rapidly dried in a forced draft oven according to the method of LooMIs and SHULL (24). Dried tissue ground to 60 mesh was used for determination of total nitrogen including nitrates by the micro-Kjeldahl method of KOCH and MCMEEKIN (18) which has been found appropriate for plant tissue (8,20,42 and relatively stiff. The acute angle of insertion of the petiole w^ith the stem and the upward bending of the lamina to form a V-shaped position with the midrid were very characteristic ( fig.…”

mentioning

confidence: 99%

Effects of Photoperiod and Nitrogen Supply on Growth and Reproduction in the Gherkin

Hall¹

1949

In view of the fragmentary knowledge of and growing interest in the ontogeny of cueurbits, an experiment was undertaken to trace certain metabolic and formative processes during the life cycle of a representative species of this family. Though many species of cucurbits are known to be dayneutral in respect to flowering, their growth and certain aspects of reproduction are, nevertheless, known to be highly responsive to day lenlgth and nitrogen supply (10,11,12,38). Hence, contrasted conditions of day length and nitrogen nutrition were employed in the experiment in order to identify as far as possible plant responses associated with each of these variables. The common gherkin, Cucumis anguria (2), was selected for the experiment on the basis of the essentially day-neutral character of its flowering response, convenience of plant size and brevity of its life cycle.