Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- Lavandula multifida response to salinity: Growth, nutrient uptake, and physiological changesPublication . Garcia-Caparros, Pedro; Llanderal, Alfonso; Pestana, Maribela; Correia, Pedro José; Teresa Lao, MariaFern leaf lavender (Lavandula multifida L.) is a perennial shrub native to Almeria with known medicinal properties, which grows in saline soils that are increasingly present in the Mediterranean region. However, the effects of salinity on the mineral nutrition and physiology of L. multifida are unknown. In the present study, we evaluated the salt resistance of this species and compared it with other members of the Lamiaceae. Plants of L. multifida were grown in pots in a mixture of sphagnum peat-moss and Perlite, and treated with five different NaCl concentrations [10 (control), 30, 60, 100, and 200 mM NaCl] over a period of 60 d. The effects of different levels of salinity on mineral nutrient and osmolyte concentrations and on biomass were evaluated. Our results show that L. multifida plants were able to grow with 60 mM NaCl without significant biomass reduction. Na+ and Cl- were the main contributors to the osmotic potential in both roots and leaves, whereas total soluble sugars (TSS) and proline made only a small contribution. The concentrations of TSS and proline showed different trends in the different organs: in roots, both showed the highest concentrations at 60 mM NaCl, whereas in leaves TSS increased and proline decreased with increasing salt stress. To survive salinity, L. multifida plants increased salt excretion (Na+ and Cl-) by leaves at 100 and 200 mM NaCl and leaf succulence at 60, 100, and 200 mM NaCl. Excessive accumulation of Na+ and Cl- was avoided by shedding leaves. Our results indicate that L. multifida is better adapted to salinity compared to other members of the Lamiaceael, a consideration that is particularly relevant for their growth in and saline areas.
- The use of macronutrients and water in marginal Mediterranean areas: the case of carob-treePublication . Correia, P. J.; Martins-Loução, M. A.Carob-tree (Ceratonia siliqua L.) is a sclerophyllous leguminous tree species widely cultivated in whole Mediterranean basin. The fruits (a dry pod) are normally used after crushing to separate seed and pulp, and the seed endosperm is processed to obtain a mucilaginous gum, which is then used in a wide range of commercial food products as a thickener and stabilizer. Contrary to other traditional crops, there is an increasing demand for carob products, which represents a potential benefit to farmers and a diversification of farm incomes. However, current information about the ecology of this crop has not yet been integrated and so there are some doubts about the correct management of natural resources, like water and soil nutrients, in order to improve productivity. These items are particularly important in Mediterranean areas where growth and yield are mostly limited by both climatic and edaphic conditions. In this short communication, some data concerning water and nutrients use (particularly nitrogen) in carob-tree are reviewed.
- Evaluation of carob tree productivity during a 30-year period, in relation to precipitation and air temperaturePublication . Correia, Pedro José; Cota, Tania; Pestana, MaribelaWater availability for irrigation of intensive crops will become a major problem in southern Iberia. One of the tools to sustain land use under water shortage is to choose crops well adapted to those environmental stress conditions featuring low water demand. The aim of this paper is to explore several relationships between climatic variables and the fruit production of carob-tree (yield) in a series of 30 consecutive years (1985-2015) referred to one single orchard. Precipitation and air temperature were the selected variables and regression models were tested. It was not possible to find any relations between yield and temperature, but precipitation during the hydrological year was inversely and significantly related to yield (Model 1- R-2 = 0.18). A close analysis indicated that rainfall registered during autumn was particularly effective, since higher yields were obtained in the years with less rainfall registered in the period September + October + November (SON) (Model 2; R-2 = 0.21). Although the air temperature effect was not found significant, mean values between 22.0 and 24.5 degrees C during SON were crucial to flowering and yield. Model 2 was validated using an independent data set considering 3 years, and the calculated yields were overestimated by 18.6% and 4.0% in two consecutive seasons. Moreover, Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios predict a precipitation decrease for SON period in the region, which may create favorable conditions for insect pollination and fruiting success.
- Seasonal variations of leaf water potential and growth in fertigated carob-trees (Ceratonia siliqua L.)Publication . Correia, P. J.; Martins-Loução, M. A.Variations of predawn and midday leaf water potential and relative growth rates were studied in mature carob trees (Ceratonia siliqua L. cv "Mulata") submitted to a fertigation experiment. Three levels of irrigation were tested: 0%, 50% and 100%, based on daily standard evaporation values. For each irrigation level two nitrogen amounts were applied - 21 and 63 kg N ha-1 year-l as ammonium nitrate. The experiment was run between July 91 and August 1993. Measurements of leaf water potential and absolute branch length increments were made at monthly intervals, during the entire experimental period or during seasonal growth, respectively. Leaf water potential was related to soil volumetric water content, maximum and minimum air temperature and daily evaporation. Predawn leaf water potentials were always higher than - 1.1 MPa. Midday leaf water potential values presented very large seasonal variations and very low values independent of treatments. The low leaf water potentials observed for the fertigated trees during summer, suggest that this parameter may be related not only to the evaporative demand but also to growth investment. The amount of fertigation was positively correlated with vegetative growth increment and fruit production. Practical implications for irrigation schedules of leaf water potential patterns together with drought adaptation mechanisms of carob tree are discussed.
- Relationships between nutrient composition of flowers and fruit quality in orange trees grown in calcareous soilPublication . Pestana, M; Beja, Pedro; Correia, PJ; De Varennes, A; Faria, EATo determine if flower nutrient composition can be used to predict fruit quality, a field experiment was conducted over three seasons (1996-1999) in a commercial orange orchard (Citrus sinensis (L.) Osbeck cv. 'Valencia Late', budded on Troyer citrange rootstock) established on a calcareous soil in southern Portugal. Flowers were collected from 20 trees during full bloom in April and their nutrient composition determined, and fruits were harvested the following March and their quality evaluated. Patterns of covariation in flower nutrient concentrations and in fruit quality variables were evaluated by principal component analysis. Regression models relating fruit quality variables to flower nutrient composition were developed by stepwise selection procedures. The predictive power of the regression models was evaluated with an independent data set. Nutrient composition of flowers at full bloom could be used to predict the fruit quality variables fresh fruit mass and maturation index in the following year. Magnesium, Ca and Zn concentrations measured in flowers were related to fruit fresh mass estimations and N, P, Mg and Fe concentrations were related to fruit maturation index. We also established reference values for the nutrient composition of flowers based on measurements made in trees that produced large (> 76 mm in diameter) fruit.