Gemma Víllora

Improving the Mineral Nutrition in Grafted Watermelon Plants: Nitrogen Metabolism

Watermelon (Citrullus lanatus [Trumb.] Mansfeld cv. Early Star), was used as scion grafted onto three cultivars of pumpkin (Cucurbita pepo L. cvs. Brava, Shintoza and Kamel) used as rootstocks and ungrafted Early Star plants were used as control. The rootstocks showed a high capacity for N uptake and transport to the scion where N reduction and assimilation improved growth of the scion in grafted plants with respect to the control.

Yield improvement in zucchini under salt stress: determining micronutrient balance

Zucchini plants (Cucurbita pepo L. var. Moschata) grown in pots under greenhouse conditions were supplied with differing amounts of NaCl (0, 20, 40, and 80 mM). The foliar concentrations of Cl, Fe, Mn and Zn increased in response to rising NaCl levels. The Cu concentrations in leaves were highest in the 0 mM NaCl treatment. In fruits, concentrations of Cl, total Fe and extractable Mn increased with higher levels of NaCl. Fruit yield was increased only by NaCl at 80 mM. Length and fresh weight of fruit tended to increase with increasing NaCl rate, and fruit dry weight proved greatest at 80 mM. The activities of catalase and ascorbic acid oxidase assayed in fruits showed an inverse relationship with the salt concentrations applied. In this context, it is useful to determine the effect of NaCl on the micronutrient concentration, given that the improvement of crop watered with saline water enhances the micronutrient profile. Thus, at 80 mM NaCl treatment improved the micronutrient levels in the shoot, and significantly increased the micronutrient density in the edible part of this crop.

Zucchini growth, yield, and fruit quality in response to sodium chloride stress

Abstract Zucchini (Cucurbita pepo L. cv. Moschata) plants were grown in a pot experiment under greenhouse conditions at Almeria (Southeastern Spain) in 1994 and 1995. Sodium chloride (NaCl) added to the irrigation water at 0 (control), 0.25, 0.50, and 1.0 g L‐1 and complemented with a fertilizer solution. Yield was determined on number and weight (kg) of fruit per plant. The hidric content (%W) per fruit was calculated using fruit fresh and dry weights. Fruit diameter, fruit length, and fruit firmness were also measured. Electrical conductivity, soluble solids concentration, titratable acidity, and pH as well as non‐structural carbohydrates concentration were determined. Zucchini yield, quality, and quantity increased as NaCl concentration was increased to 1 g L‐1. This cultivar appears to suitable to be grown in coastal locations where soil and irrigation water contain salt concentration that limit the growth of other crops less tolerant to salinity.

Nitrogen and phosphorus metabolism and yield of capsicum plant (Capsicum annuum L. cv. Lamuyo) in response to increases in NK fertilization

Abstract Capsicum plants were grown under controlled conditions and submitted to individual fertilization with varying rates of NK. N was applied as NH4NO3 (N1: 6 g m‐2, N2: 12 g m‐2, N3: 18 g m‐2and N4: 24 g m‐2) and K as K2SO4 (K1: 4 g m‐2, K2: 8 g m‐2and K3: 12 g m‐2), resulting in 12 treatments of the corresponding crosses between the different rates of N and K. Applying high rates of N and K led to an increase in the absorption and translocation of NO to the shoot, however, the trend of the NR in the two assays studied (NRc and NRi) and that of NH indicate that this latter ion was the main N form assimilated by the plant. The products resulting from this process, mainly proteins, increased with higher N and K rates, which also gave rise to the maximum leaf concentrations of organic and total P forms, while inorganic P was unaffected. The acid phosphatase activity proved to be a good indicator of the nutritional status of P. Finally, yield in Kg plant‐1 was maximum at N3K1, whereas the greatest number of fruits were maximum at the N4K3 rate.Capsicum plants were grown under controlled conditions and submitted to individual fertilization with varying rates of NK. N was applied as NH 4 NO 3 (N 1 : 6 g m -2 , N 2 : 12 g m -2 , N 3 : 18 g m -2 and N 4 : 24 g m -2 ) and K as K 2 SO 4 (K 1 : 4 g m -2 , K 2 : 8 g m -2 and K 3 : 12 g m -2 ), resulting in 12 treatments of the corresponding crosses between the different rates of N and K. Applying high rates of N and K led to an increase in the absorption and translocation of NO to the shoot, however, the trend of the NR in the two assays studied (NRc and NRi) and that of NH indicate that this latter ion was the main N form assimilated by the plant. The products resulting from this process, mainly proteins, increased with higher N and K rates, which also gave rise to the maximum leaf concentrations of organic and total P forms, while inorganic P was unaffected. The acid phosphatase activity proved to be a good indicator of the nutritional status of P. Finally, yield in Kg plant -1 was maximum at N 3 K 1 , whereas the greatest number of fruits were maximum at the N 4 K 3 rate.

Nutritional diagnosis of fig tree leaves

Abstract Fig trees (Ficus carica L. cv. Pellejo Duro) were sampled during four consecutive years (1992–95). Nutrient element concentrations, fruit yield, and optimal ranges for the nutrient elements and physiological parameters were determined.

Variations in fruit micronutrient contents associated with fertilization of cucumber with macronutrients

Rates of N, P and K were used to compare the effects on iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and chloride (Cl) as well as the response of some biochemical indicators of micronutrient status in leaves and fruits of greenhouse-grown cucumbers (Cucumis sativus L. cv. Brunex F1). The treatments were as follows: NH4NO3 (5, 10, 20, 40 g/m 2 ); PO4H3 (8, 16 g/m 2 ); and K2SO4 (20, 40 g/ m 2 ). Control plants were supplied only with organic matter (manure from plant debris). The treatments N20, P16 and K40 favored the highest leaf biomass, whereas N40, P8 or P16 and K40 produced the lowest fruit biomass. The best treatments to promote phytoaccumulation of Fe and Mn in fruits were N10, P16 and K40. The fruit Cu, Zn and Cl accumulations were increased by fertilizer compared to the control. Foliar and fruit catalase activities help to indicate the nutritional status of Fe and Mn in cucumber, but, peroxidase and ribonuclease activities did not by themselves prove sufficiently informatives. # 2002 Elsevier Science B.V. All rights reserved.

Temperature in relation to phosphorus nutrition in Chinese cabbage.

Abstract Chinese cabbage plants [Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50] were cultivated experimentally for two years (1993 and 1994) using a semi‐forcing technique of floating rowcovers, polyethylene (T1), polypropylene (T2), versus no floating row‐covers, control (T0). Five samplings were made, taking four plants per each replication and total phosphorus (P) (Ptotal), inorganic P (Pi), and calculated organic P (Porg) were determined as well as foliar acid phosphatase activity (FAPA). The aerial and root temperatures of the treatments T1 and T2 exceeded those of T0. The Ptotal concentration showed no significant variations with treatment, whereas the Pi concentrations increased in Ti and T2 and Porg decreased in both treatments with respect to T0. The FAPA was influenced a similar way as Pi, raising with temperature. The contents (mg plant‐1) of Ptolal, Pi, and Porg were greater in T1 and T2 than in T0, and this could be due to the fact that the highest temperatures (root and aerial zone) generated by the plastic rowcovers favored the absorption of P, thereby boosting FAPA and the fresh and dry weights, and yield.

Plant nitrogen characteristics of a semi‐salt‐tolerant zucchini variety to sodium chloride treatments

Abstract Plants of a Zucchini (Cucurbita pepo L. var. Moschata) cultivar considered to be semi‐salt‐tolerant were grown in artificial soil in 1‐m containers under greenhouse conditions with differing supplies of sodium chloride (NaCl) [0 (T0), 30 (T1), 60 (T2) or 120 (T3) g m‐2 plot‐1] during the entire growth cycle. These plants were used to determine the concentrations of nitrogen (N) forms and fractions, together with antagonistic anions in both leaves and fruits. The ammonium (NH4) concentration increased and nitrate (NO3) concentration decreased in both leaves and fruits, and chloride (Cl) concentration increased while sulphate (SO4) concentration decreased in both leaves and fruits with NaCl treatments. Organic‐N concentration in leaves increased according to the soil salinity treatments, while in the fruit there was a slight increase at low salinity, although values returned to those of the control when soil salinity increased. In leaves there was an increase in proline concentrations when salinity...

Applications in sustainable production

Capsicum plants grown under controlled conditions underwent crossed fertilization with N (four levels) and K (three levels) totalling 12 combination of NK dosages. The plants were sampled throughout their growth cycle and the leaves were analyzed to measure total and soluble Ca and Mg, and their fractions. Soluble Mg showed its lowest leaf level in the treatment N 4 K 3 , whereas the highest value was obtained at N 1 K 3 . Total Mg has the maximum leaf levels at N 1 K 2 , whereas the lowest levels occurred in the treatment N 2 K 1 The various fractions of Mg showed different degrees of importance and in the present study the order of importance was: Pectate-Mg Inorganic-Ca > Pectate-Ca Residual-Ca > Phosphate-Ca.Abstract Capsicum plants grown under controlled conditions underwent crossed fertilization with N (four levels) and K (three levels) totalling 12 combination of NK dosages. The plants were sampled throughout their growth cycle and the leaves were analyzed to measure total and soluble Ca and Mg, and their fractions. Soluble Mg showed its lowest leaf level in the treatment N4K3, whereas the highest value was obtained at N1K3. Total Mg has the maximum leaf levels at N1K2, whereas the lowest levels occurred in the treatment N2K1. The various fractions of Mg showed different degrees of importance and in the present study the order of importance was: Pectate‐Mg<Residual‐Mg<Organic acid anion‐Mg<Organic anion‐Mg<Chlorophyll‐Mg. Soluble Ca showed its lowest leaf level in the treatment N3K3, whereas the highest value was obtained at N4K1. Total Ca has the maximum leaf levels at N4K3, whereas the lowest levels occurred in the treatment N1K2. The increasing NK supply directly or indirectly affects the integration of the ionic forms of Ca in plant tissues as Ca was integrated in proportions which indicated the growing conditions of the crop, with the following order: Oxalate‐Ca > Inorganic‐Ca > Pectate‐Ca ≈ Residual‐Ca > Phosphate‐Ca

Phosphorus supply influences the molybdenum, nitrate and nitrate reductase activity in eggplant

Summary Greenhouse experiments were conducted for two years (1993-1994) with eggplants being supplied H3PO4 as the P source (1 mM, 2 mM and 4 mM) to study its influence on Mo distribution and on aspects of nitrate metabolism and fruit quality. The NO3– and Mo in leaf blades, petioles and fruits as well as foliar in vivo nitrate reductase (NR; E.C. 1.6.6.1) activity were analysed. P application at levels exceeding 1 mM P altered the NO3– and Mo status and distribution in the above-ground organs of eggplant. The 4 mM P treatment induced the highest NO3– accumulation in leaf blades and lowered transport to the fruits. Moreover, lower P (1 and 2 mM) supplies led to increased NO3– concentration in fruits. The 4 mM P treatment induced a greater Mo concentration in the fruit, whereas the soluble form of Mo was nearly equally distributed between the shoot organs.