A. Sanchez

A daily rhythmic model for ph and volume from xylem sap of tomato plants

Abstract Ten‐day‐old tomato plants (Lycopersicon esculentum Mill. cv. Rambo) were transplanted in a NFT special system. The experiment was repeated three consecutive times. Each experiment consists of three replicates. The experiments were carried out first with 30‐day‐old plants and subsequently with plants which were 45‐days‐old. The sap flux rates (V) vary considerably during the day at both harvest dates and there was has highly significant correlation (p>0.999) with the chronophysiological rhythm (Halberg, 1969) which has the highest rates in the day and the lowest rates at night. The pH rhythm, which shows an opposite behavior of the sap flux rate, is related to organic anion equivalents (C‐A). A markedly difference in the behavior of C‐A values occurred at both harvest dates. The model presented in this paper may provide a framework for the explanation of short and long term V and pH fluctuation of xylem sap. The changes in the pH of the xylem sap are probably normally buffered, but may have the po...

Physiological plant age dependent biochemical indicators and physiological parameters of iron nutrition

Iron indicators were studied in two crop species, tomato and cucumber, of different sink (fruit) characteristics but similar in terms of phenological stages: flowering, fruit development, early ripening, foliar senescence and fruit senescence. Leaves were sampled every two weeks throughout the period of maximum fruit production in order to determine biochemical indicators and physiological parameters known to fluctuate as the plant develops. Total phenols and σ-diphenols increased as the leaf aged, whereas peroxidase levels did not change with plant age. Catalases and chlorophylls became scarcer as the leaf approached senescence in both tomato and cucumber. The inorganic and soluble fractions of P declined in tomato but remained unchanged in cucumber, while P bound to DNA structures increased with physiological leaf age in both crops. The phosphorylated lipid-bound P fraction also increased as the plant aged. Both the soluble and the organic Ca fraction became higher in the leaf of both species as this organ approached senescence. Total Fe levels increased with plant age, while soluble Fe levels decreased.

Influence of plant age on mature leaf iron parameters

Abstract The change of several biological and physiological indicators was studied in mature leaves of muskmelon plants (Cucumis melo L. cv. Galia) during the biological cycle. Plants were grown under greenhouse conditions, using differential fertilization with N, P, and K, and irrigation with brackish water. We measured total and soluble Fe and Mn, total and soluble Fe index, endogenous and Fe‐ and Mn‐inflitrated catalase and peroxidase and aconitase activities in leaves in an attempt to trace possible Fe deficiencies. The Fe‐Index is defined as follows: Fe Index = [(10P + K) 50]/Fe, where: P and K as % d.w. and Fe as μg/g d.w. The physiological indicators (Fe Index) was markedly raised at the beginning of the biological cycle, indicating that foliar samples contained high concentrations of P and K, which may have induced Fe deficiency. The Fe Index decreased steadily during the biological cycle, indicating that fertilizer was applied correctly. Comparisons of endogenous and Fe‐ and Mn‐infiltrated enzyma...

Iron indices and micronutrients in deciduous fruit trees

Abstract Perennial deciduous plants were studied during their vegetative cycles. Leaves were sampled regularly every 15 days throughout this period in order to determine total and soluble iron (Fe) indices, physiological balances, and micronutrient levels. Analysis of variance and coefficients of variation were high for Fe indices and micronutrients between samples. The values of interaction between variables were not high. The optimium value of total Fe index ranged from 0.72–0.74 in almond to 1.11–1.14 in pomegranate. Optimum values for soluble Fe index ranged from 0.77–0.83 in almond to 1.18–1.29 in pear. Similar ranges were observed for soluble and total micronutrients and ternary groups. The evolution of the physiological ternary groups demonstrates ionic imbalances in apple in total Fe and manganese (Mn) as a result of excess levels of total zinc (Zn) during the final phase of fruit development. During this phase, total and soluble Fe and Mn also show significant interactions in persimmon. In apple,...

Influence of nitrogen, phosphorus, and potassium fertilization on foliar pigments in muskmelon plants

Abstract The effect of nitrogen (N), phosphorus (P), and potassium (K) fertilization on chlorophyll a and b, carotenes, and anthocyanin was studied in muskmelon plants (Cucumis melo L. cv. Galia) during their biological cycle. Plants were grown under greenhouse conditions using differential fertilization with N, P and K, and irrigation with brackish water. We measured chlorophyll a and b, carotenes, anthocyanin, and total and soluble magnesium (Mg) and iron (Fe) contents. No relationship was found between the rate of fertilizer applied and the content of these pigments. Our results revealed that a relationship does exist between the foliar content of chlorophyll a and Fe, irrespective of the fertilizer treatment applied. However, only a relationship between chlorophyll b and Mg in the P treatments was found. The fact that the chlorophyll content was related to the N and K treatments could be due to a slight deficiency induced by Mg. The phenological stage of specific parameters was studied, resulting in t...

RELATIONSHIPS BETWEEN NITROGEN SUPPLY AND DIFFERENT PHOSPHORUS AND CALCIUM FRACTIONS IN LEAVES OF TOMATO AND CUCUMBER PLANTS

ABSTRACT Tomato and cucumber plants were grown in a greenhouse with different N treatments (N1 7.5; N2; N3: 20; N4: 30 g/m2). Leaves were sampled every two weeks throughout the period of maximum fruit production to determine the different P fractions (inorganic P, organic P, lipidic P, RNA P, DNA P, and proteic P) and Ca fractions (soluble Ca, bound Ca, inorganic insoluble Ca, and organic insoluble Ca), obtained by extraction with different solvents. Inorganic and organic P were the largest fractions, representing 70% of total P in tomato (vs 10% RNA P; 8% of lipidic P; 7% of DNA P, and 5% of proteic P) and 55% in cucumber (vs. 15% of RNA P; 13% of lipidic P; 10% of DNA P, and 7% of proteic P). The highest concentration of lipid P was found with treatment N2 in both crop species. The organic insoluble Ca fractions together with the inorganic insoluble fraction made up 50% (tomato) and 80% (cucumber) of total Ca. Relationships between P and Ca fractions and macro-micronutrients were also studied. A positiv...

What constitutes a good iron indicator with brackish water and gypsum

Abstract Solanum rnelongena plants (eggplant/aubergine) were grown under greenhouse conditions in an artificial soil enriched in CaSO4 and organic matter, and fertilized with N and P in the irrigation water, which was strongly brackish. Physiologically mature leaves were sampled every 15 days to analyze physiological and biochemical parameters. The results showed that, given the rhizospheric conditions in our experiments, there was an increase in Mn at the expense of Fe, and total Fe index was influenced by total P and K concentration, and, to a lesser degree, by total Fe. In contrast, the soluble Fe index was most markedly affected by soluble Fe, which was the most influential component of this index. The Fe index is defined as follows: Fe index = (10P + K)50/Fe, where Fe = μg iron/g dry matter, P = % phosphorus in dry matter, and H = % potassium in dry matter. The total Fe index is calculated from total nutrients, whereas the soluble Fe index is obtained from soluble nutrients. Enzymatic activities fail...

Assessing critical nitrogen supply by means of nitrate reductase activity in tomato and cucumber plants

This work was performed in order to obtain information about the relation between plant N‐levels and yields by means in vivo nitrate reductase activity (NRA) determinations in leaves of tomato and cucumber. Plants were grown under glasshouse conditions in solutions containing different N‐levels. At different growth stages, leaves were sampled and NRA, total N and growth were determined. Ammonia and NO3‐N have a considerable influence on the NRA by way of the feedback mechanism and NRA was affected by growth stage. This, however, is dependent on nitrification conditions when soil is applied. In our conditions, maximum NRA values associated with maximum yield were approximately 3.40 ‐ 3.70 μmol NO2‐ formed (g fresh weight, hr)‐1 for tomato and 4.50 ‐ 4.70 μmol NO2 ‐ formed (g fresh weight, hr)‐1 for cucumber plants.

Ion balance and its evolution in cultivars of melon (cucumia melo L.) irrigated with brackish water

Abstract The present study compares ionic balance in 19 muskmelon cultivars grown under greenhouse conditions with the same system of fertilization‐irrigation. Each cultivar was studied in 4 replications distributed in a random block design. In all 20 plants were sampled in each replication of each cultivar every 15 days throughout the reproductive cycle, and analyzed inmediately afterward. Highly significant differences were noted for cations (C+) (Gold‐King 304 meq/100g d.w., Canario 183 meq/100g d.w., anions (A‐) (Cantaloupe 387 meq/100g d.w., Arava 272 meq/100g d.w.), and cations‐anions balance (C+‐A‐) (Gold‐King ‐6 meq/100g d.w., Rocher ‐157 meq/100g d.w., Canario ‐163 meq/100g d.w.), as well as for hydrogen ions (H+) forming capacity (Dorado and Gold‐King 88 meq/100 g d.w., Gallicum, Rocher and Canario 0 meq/100g d.w.). Differences in OH‐ formation were also notable (Polidor 243 meq/100g d.w., Makdimon 120 meq/100g d.w.). Consequently, fruit production among the different cultivars varied widely. Th...

Relationship between biochemical indicators and physiological parameters of nitrogen and physiological plant age

The families, Solanaceae and Cucurbitaceae, differ mainly in the size of the sink and the length of their biological cycle, although their phenological stages overlap in time to some extent. Leaves were sampled during the period of greatest metabolic activity, which coincided with a plural of morphological changes, in order to analyze nitrogen indicators and parameters. Nitrogen concentration decreased over time in the leaf, as did NO3-ions, dry weight, amino acids, total and soluble protein. NH4-ions, nitrate reductase and productivity peaked during the period of greatest metabolic activity, coinciding with flowering and the initial and final phases of fruit ripening, and were lowest during foliar senescence. Total and soluble vegetative index (relation between mobile N, P, K and immobile Ca, Mg) declined, and transient alterations coincided with certain morphological and metabolic changes. All physiological alterations during the different physiological stages were seen in both species regardless of the size of the sink, however the magnitude of the alterations was conditioned by the sink and by exogenous arid endogenous N levels. Organ senescence can be defined as a series of metabolic changes in the mature plant which include a decrease or increase in enzymatic activity, proteolyis, pigment degradation and death.