Response of orchard 'Washington Navel' orange, Citrus sinensis (L.) Osbeck, to saline irrigation water. I. Canopy characteristics and seasonal patterns in leaf osmotic potential, carbohydrates and ion concentrations

1989 ◽  
Vol 40 (2) ◽  
pp. 359 ◽  
Author(s):  
J Lloyd ◽  
H Howie
Keyword(s):  
Leaf Area ◽  
Irrigation Water ◽  
Osmotic Potential ◽  
Citrus Sinensis ◽  
Soluble Sugars ◽  
Seasonal Patterns ◽  
Navel Orange ◽  
Washington Navel ◽  
Leaf Osmotic Potential ◽  
Chloride Concentrations

Effects of irrigation water salinity on tree canopy volume, leaf area, rates of leaf abscission and production, as well as seasonal patterns in leaf osmotic potential (=), starch, soluble sugars and sodium and chloride concentrations were determined for 24-year-old 'Washington Navel' orange trees (Citrus sinensis [L.] Osbeck) on sweet orange (C. sinensis) rootstock. Trees had been irrigated with water containing either 5 or 20 mol NaCl m-3 for 5 years prior to measurements.Trees irrigated with 20 mol NaCl m-3 had a greater number of vegetative flushes in spring. This occurred at the expense of flowering, as numbers of reproductive and mixed flushes were reduced by salinity. Despite a high number of vegetative buds on trees irrigated with 20 mol NaCl m-3, leaf area was still less than low salinity trees.Extensive abscission of spring flush leaves occurred from mid-summer onwards for trees irrigated with 20 mol NaCl m-3. This was not a consequence of leaf water deficit, as more negative leaf osmotic potentials resulting from increased foliar sodium and chloride concentrations resulted in maintenance of leaf turgor. Excessive concentrations of sodium and/or chloride may have been responsible for abscission observed. Some acclimation of foliage to salinity was evident.Irrespective of salinity treatment, leaf osmotic potential became more negative as the season progressed. This was partly due to increased concentrations of soluble sugars in foliage during autumn and winter. Levels of soluble sugars and starch were consistently lower in leaves on trees irrigated with high salinity water, indicating that production rather than utilization of carbohydrate may limit citrus productivity under saline conditions.

Response of orchard 'Washington Navel' orange, Citrus sinensis (L.) Osbeck, to saline irrigation water. II. Flowering, fruit set and fruit growth

1989 ◽  
Vol 40 (2) ◽  
pp. 371 ◽  
Author(s):  
H Howie ◽  
J Lloyd
Keyword(s):  
Leaf Area ◽  
Citrus Sinensis ◽  
Fruit Set ◽  
High Salinity ◽  
Starch Content ◽  
Fruit Growth ◽  
Leaf Abscission ◽  
Navel Orange ◽  
Washington Navel ◽  
Floral Differentiation

Flowering, fruit set and fruit growth of 'Washington Navel' orange fruit was monitored on 24-year-old Citrus sinensis trees on Sweet orange rootstocks that had been irrigated with either 5 or 20 mol m-3 NaCl for 5 years preceding measurements.Trees irrigated with high salinity water had reduced flowering intensities and lower rates of fruit set. This resulted in final fruit numbers for trees irrigated with 20 mol m-3 being 38% those of trees irrigated with 5 mol m-3 NaCl. Final fruit numbers were quantitatively related to canopy leaf area for both salinity treatments.Despite little difference between trees in terms of leaf area/fruit number ratio, slower rates of fruit growth were initially observed on high salinity trees. This effect was not apparent during the latter stages of fruit development. Consequently, fruit on trees irrigated with 20 mol m-3 NaCl grew to the same size as fruit on trees irrigated with 5 mol m-3 NaCl, but achieved this size at a later date. Measurements of Brix/acid ratios showed that fruit on high salinity trees reached maturity standards 25 days after fruit on low salinity trees.Unimpaired growth of fruit on high salinity trees during summer and autumn occurred, despite appreciable leaf abscission, suggesting that reserve carbohydrate was utilized for growth during this period. Twigs on high salinity trees had much reduced starch content at the time of floral differentiation in winter. Twig starch content and extent of floral differentiation varied in a similar way when examined as a function of leaf abscission. This suggests that reduced flowering and fruit set in salinized citrus trees is due to low levels of reserve starch, most of which has been utilized to support fruit growth in the absence of carbohydrate production during summer and autumn.

scholarly journals Sugar/osmoticum levels modulate differential abscisic acid-independent expression of two stress-responsive sucrose synthase genes in Arabidopsis

1999 ◽  
Vol 344 (2) ◽  
pp. 503-509 ◽  
Author(s):  
Annabelle DÉJARDIN ◽  
Lubomir N. SOKOLOV ◽  
Leszek A. KLECZKOWSKI
Keyword(s):  
Signal Transduction ◽  
Abscisic Acid ◽  
Cold Stress ◽  
Osmotic Potential ◽  
Sucrose Synthase ◽  
Cellular Response ◽  
Expression Profiles ◽  
Soluble Sugars ◽  
Leaf Osmotic Potential ◽  
Detached Leaves

Sucrose synthase (Sus) is a key enzyme of sucrose metabolism. Two Sus-encoding genes (Sus1 and Sus2) from Arabidopsis thaliana were found to be profoundly and differentially regulated in leaves exposed to environmental stresses (cold stress, drought or O2 deficiency). Transcript levels of Sus1 increased on exposure to cold and drought, whereas Sus2 mRNA was induced specifically by O2 deficiency. Both cold and drought exposures induced the accumulation of soluble sugars and caused a decrease in leaf osmotic potential, whereas O2 deficiency was characterized by a nearly complete depletion in sugars. Feeding abscisic acid (ABA) to detached leaves or subjecting Arabidopsis ABA-deficient mutants to cold stress conditions had no effect on the expression profiles of Sus1 or Sus2, whereas feeding metabolizable sugars (sucrose or glucose) or non-metabolizable osmotica [poly(ethylene glycol), sorbitol or mannitol] mimicked the effects of osmotic stress on Sus1 expression in detached leaves. By using various sucrose/mannitol solutions, we demonstrated that Sus1 was up-regulated by a decrease in leaf osmotic potential rather than an increase in sucrose concentration itself. We suggest that Sus1 expression is regulated via an ABA-independent signal transduction pathway that is related to the perception of a decrease in leaf osmotic potential during stresses. In contrast, the expression of Sus2 was independent of sugar/osmoticum effects, suggesting the involvement of a signal transduction mechanism distinct from that regulating Sus1 expression. The differential stress-responsive regulation of Sus genes in leaves might represent part of a general cellular response to the allocation of carbohydrates during acclimation processes.

scholarly journals The Role of Carbohydrates in Active Osmotic Adjustment in Apple under Water Stress

1992 ◽  
Vol 117 (5) ◽  
pp. 816-823 ◽  
Author(s):  
Zhongchun Wang ◽  
Gary W. Stutte
Keyword(s):  
Water Stress ◽  
Malus Domestica ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Soluble Sugars ◽  
Sugar Alcohol ◽  
Apple Trees ◽  
Mature Leaves ◽  
Leaf Osmotic Potential

Greenhouse grown 2-year-old potted `Jonathan' apple trees (Malus domestica Borkh.) were subjected to various levels of water stress in February. Midday leaf water potential (ψW), leaf osmotic potential (ψS), soluble sugars, and starch contents of mature leaves were measured throughout the development of water stress to determine whether active osmotic adjustment could be detected and whether carbohydrates were involved. Active adjustments of 0.6 MPa were observed 3 and 5 days, respectively, after water stress was initiated. Leaf turgor potential (ψP) could not be maintained through the osmotic adjustment when ψW dropped below -1.6 MPa. Sorbitol, glucose, and fructose concentrations increased while sucrose and starch levels decreased significantly as water stress developed, strongly suggesting that sugar alcohol and monosaccharide are the most important osmotica for adjustment. Sorbitol was a primary carbohydrate in the cell sap and accounted for > 50% of total osmotic adjustment. The partitioning of newly fixed W-labeled photosynthates in mature leaves was not affected by water stress immediately after the 30-min 14CO2 treatment. All the W-labeled carbohydrates decreased in the labeled leaves very rapidly after 14CO2 labeling. The decrease in 14C-sorbitol was greater than the decrease in other carbohydrates under both well-watered and stressed conditions. After 24 hours of water stress, however, the percentage of 14C-sorbitol increased while the percentages of sucrose, starch, glucose, and fructose decreased significantly with increasing levels of stress. The ratio of 14C-sorbitol in leaves with ψW = -3.5 MPa to leaves with ψW = -0.5 MPa was significantly higher than that of 14C-sucrose, 14C-glucose, W-fructose, or 14C-starch.

scholarly journals Growth, yield and fruit quality of 'Washington Navel' orange on four rootstocks during the first four years of production.

1969 ◽  
Vol 85 (3-4) ◽  
pp. 143-149
Author(s):  
Félix M. Román-Pérez ◽  
Agenol González-Vélez
Keyword(s):  
Puerto Rico ◽  
Fruit Quality ◽  
Citrus Sinensis ◽  
Growth Yield ◽  
Tree Canopy ◽  
Navel Orange ◽  
Washington Navel ◽  
Canopy Volume ◽  
Swingle Citrumelo

Performance of the rootstocks 'Swingle citrumelo', 'Naronja' and mandarins 'Cleopatra' and 'Sun Chu Sha' on 'Washington Navel' orange [Citrus sinensis (L.)] was evaluated at Corozal and Isabela, Puerto Rico, during the first four years of production. Mean number of fruit per tree was significantly different between locations and among rootstocks for 1996-97 and 1997- 98. Data were not taken in 1998-99 because of damage caused by Hurricane Georges. The first two years the amount of fruit was significantly higher at Corozal than at Isabela, with Swingle producing greatest fruit yield. In 1999-00 (fourth year of production) no significant differences between locations were detected for tree canopy volume. Significant differences for internal fruit quality were detected between locations and among rootstocks for acidity, brix/acidity ratio and pH. No significant differences were observed for brix between locations or among rootstocks.

The development of cuttings of the Washington navel orange to the stage of fruit set. I. The development of the rooted cutting

1961 ◽  
Vol 12 (6) ◽  
pp. 1050 ◽  
Author(s):  
CT Gates ◽  
D Bouma ◽  
H Groenewegen
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Normal Growth ◽  
Dry Weight ◽  
Navel Orange ◽  
Rooted Cutting ◽  
Woody Perennial ◽  
Plant Parts ◽  
Shoot Initiation ◽  
Washington Navel

The development of rooted cuttings of the Washington Navel orange through two cycles of growth is described, and the effects of phosphorus nutrition and the relative value of nitrate and ammonium as sources of nitrogen are assessed. Alternation of shoot and root development over the period of the experiment was observed. There appeared to be no build up of dry matter reserves in the plant tops before new shoot initiation, but rather a rhythmic distribution between root and shoot of the dry matter assimilated. The initiation of new shoots was followed by a rapid increase in leaf area, by an increase in dry matter per unit leaf area, by a rapid increase in whole plant dry weight, and by higher growth rates. In this latter respect, the behaviour of this woody perennial contrasts with the normal growth pattern of annuals, where the growth indices tend to fall with time. Phosphorus shortage delayed plant development, so leading to lower dry weight values in all plant parts. No differences in growth due to nitrate or ammonium as sources of nitrogen could be detected.

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