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a b s t r a c tPlant analysis plays a major role in fertilizer recommendations for perennial tree crops and vines. Plant analysis, however, does not quantify the rate of nutrients to apply. The approach developed in this work takes into account the content of the nutrients in grapevine parts and their dynamic within the plant to assist in the estimation of the amount of fertilizer to apply. Groups of three vines were cut at ground level on four different dates from September 14th to November 28th. On the first sampling date the vines were separated into trunk, cordons, canes, leaves and clusters for determination of dry matter content and elemental composition. On the following dates the vines were separated into the plant parts that were still present, since the clusters were only present on the first sampling date and the leaves on the first two. To assess the mobility of nutrients within the plant, samples of phloem vessels and sawdust of the entire trunk were taken as well as samples of chlorotic and green leaves. Nitrogen (N), potassium (K), phosphorus (P) and boron (B) showed mobility within the plant whereas calcium (Ca) and magnesium (Mg) did not. The removal of nutrients in clusters is critical for estimating N and K fertilizer rates. Clusters removed 19.9 kg N ha −1 and 28.7 kg K ha −1 . In the case of N, it is also important to assess the system's ability to recycle the nutrient contained in the leaves and canes which amounted to 49.4 kg N ha −1 . Phosphorus, calcium and magnesium applications might not justify being taken into account in the annual fertilization plan. Thus, the establishment of the fertilization programme should be a nutrient-specific exercise which takes into account all sources of information, including target yield and nutrient content in clusters, the vineyard management strategies influencing nutrient use efficiency from fallen leaves and prunings and soil testing and plant analysis.

Une expérience réalisée à Coruche (Portugal) sur une culture de tomate a permis de tester plusieurs critères de contrainte hydrique relatifs à la plante et à son microclimat. Le potentiel hydrique de base et la conductance stomatique sont des critères très sensibles à un arrêt de l'irrigation. Les critères microclimatiques (température et flux de surface) peuvent être intéressants, si certaines précautions relatives à la dimension de la parcelle étudiée sont prises. Le critère le plus sensible et le plus simple à déterminer est cependant le potentiel de base. On suggère par conséquent, de l'utiliser pour diagnostiquer les périodes de contrainte hydrique chez les plantes cultivées dans des conditions expérimentales voisines de celles étudiées ici.Mots clés additionnels : Potentiel hydrique foliaire, température radiative, résistance stomatique, rapport du flux de chaleur sensible au rayonnement net, tomate, irrigation. SUMMARY A study of several indicators of the water status of a tomato crop in a semi-arid region.An experiment conducted on a tomato crop at Coruche (Portugal) enabled the authors to test several water stress indicators for the plant and its microclimate. Predawn leaf water potential and stomatal conductance were very sensitive indicators of water stress. Microclimatic criteria (crop radiative temperature and parameters referring to fluxes above the canopy) could be useful provided certain precautions on the dimensions of the plot are taken. The most sensitive and easily determined of the indicators was, however, predawn leaf water potential. We therefore suggest its use as an appropriate diagnostic measure for water stress in cultivated plants grown under experimental conditions close to those studied here.Additional key words : Leaf water potential, radiative temperature, stomatal conductance, ratio of'sensible heat to net radiation, tomato crop, irrigation.

European chestnut is the most important cash crop in the highlands of NE Portugal. However, limited data on cropping technique are available to help farmers make decisions. This work is motivated by the lack of data related to chestnut response to fertilizer application. It reports results from a field fertilization trial consisting of the application of a combination of lime (L), nitrogen (N), phosphorus (P), potassium (K), and boron (B), namely LNPKB, NPKB, -NPKB, N-PKB, NP-KB, and NPK-B. Seedlings of chestnut were planted in June 2013 and grown for four growing seasons. Plant height, trunk diameter, and pruning wood were assessed every year and used as indicators of tree crop growth. Elemental leaf analysis and other tools [SPAD-502 chlorophyll meter; Field Scout CM 1000 NDVI (normalized difference vegetation index) meter, and the OS-30p+ fluorometer] were used to assess plant nutritional stresses. In January 2017 soil samples were collected at three depths (0-5, 5-10, and 10-20 cm) to determine several soil fertility parameters. The nonapplication of K and B reduced the tree crop growth and pruning residues. Leaf analysis revealed leaf K and B concentrations respectively in the NP-KB and NPK-B treatments to be in the deficient range previously established for chestnut. SPAD readings and NDVI detected the reduced availability of N associated with the -NPKB treatment but not the reduced plant growth associated with NP-KB or NPK-B treatments. The dark adaptation protocols of F V /F M , F V /F 0 , and OJIP measurements performed with the OS-30p+ fluorometer failed to diagnose the nutrient stresses detected by leaf analysis or the reduction in plant growth.

Phosphorus (P) application in olive orchards is very common in the Mediterranean basin although experimental evidence of crop response to applied P is practically non-existent. In this work soil P and tree P nutritional status of the olive groves of NE Portugal were assessed from a population of 1808 soil and 2252 leaf samples. Plant response to applied P was evaluated from two field and two pot experiments carried out with the cultivar 'Cobrançosa'. The analyses of soil and leaf samples of the olive orchards of the region indicate that P fertilizer recommendations should be based on leaf rather than on soil analyzes, since the latter seems to overestimate the need for P. The field and pot experiments hardly showed any positive response to P applications, which is a sign that the use of P fertilizer in olive can be substantially reduced. Nonetheless, in one pot experiment, P application significantly increased total dry matter yield during three consecutive years, in a strict association with higher tissue P concentrations and enhanced photosynthetic activity, as revealed by gas exchange and chlorophyll fluorescence traits. The experimental results also showed that the roots can uptake and store P when available in the soil, which may buffer the levels of P in the shoots. The acid phosphate activity can provide useful information but deserves caution in the interpretation of results since it depends not only on the availability of inorganic P in the soil, but also on the available organic substrate and pH.

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a b s t r a c tA natural source of nitrogen (N) is needed to increase soil fertility in traditional olive orchards and to maintain the N nutritional status of olive trees. With this aim, we studied the introduction of legume cover crops in two olive orchards, which were converted into mulches and left on the ground as phytomass after they had been cut. The experiments were carried out in Suç ães and Qta do Carrascal, NE Portugal, from October 2009 to January 2012. In Suç ães, the ground-cover treatments were lupine (Lupinus albus L.), a mixture of 11 self-reseeding annual legume species, natural vegetation fertilized with 60 kg N hm −2 and natural vegetation not fertilized. The treatments imposed in Qta do Carrascal were lupine, hairy vetch (Vicia villosa Roth.), a mixture of 11 self-reseeding annual legumes and natural vegetation. Soil N availability in the year following the establishment of the mulches was monitored by an in situ incubation technique. Olive yields and tree nutritional status were also measured. A peak of net N mineralization was recorded early in the autumn in the plots where the legume cover crops had been grown in the last season, in comparison with the natural vegetation plot. In the next spring, soil N availability was negligible even in the plots previously cropped with legume species. The effect of the legume cover crops on soil inorganic-N availability seems to have been slight and short-lived taking into account the high amounts of N contained in the mulched phytomass. The effect of legume cover crops on olive yield and leaf N concentration was statistically significant only in few occasions. The results of these experiments recommended some caution in the management of pure legume cover crops as a mulch in olive orchards due to the reduced transfer of N from legumes to olive trees.