Salinity is one of the modern agriculture major obstacles, causing several physiological disturbances in plants, adversely affecting its growth and development. Therefore, some techniques are required in order to alleviate the negative effects of salinity stress on plants, as for example an adequate nitrogen fertilization. The aim of this study was to assess the ecophysiological responses of sugar apple plants (Annona squamosa L.) submitted to different salinity levels and nitrogen fertilization doses. The experimental design was a randomized block in an incomplete factorial scheme, with five electrical conductivities of the irrigation water (ECw: 0.5, 1.01, 2.25, 3.49 and 4.0 dS m-1) and five nitrogen doses (0, 101, 350, 598.2 and 700 mg dm-3), with four replicates, generated from the Box Central Composite experimental design matrix. Through a daily course, it was observed variations in gas exchange, chlorophyll content and fluorescence parameters. The gas exchange, chlorophyll content and fluorescence parameters were measured on photosynthetically active leaves. There was significant interaction between the salinity levels (ECw) and nitrogen doses for the chlorophyll indexes. The electrical conductivity of the irrigation water caused significant negative effects on chlorophyll fluorescence. Therefore, it can be stated that the sugar apple plants ecophysiology varies through the day and that salinity affects its chlorophyll content and fluorescence.

Cinco genótipos de amendoim de diferentes hábitos de crescimento foram submetidos a estresse hídrico moderado durante 7 dias em casa de vegetação. O plantio foi feito em vasos de 15 litros contendo solo e substrato (Plantmax®), otimizados para a cultura. O delineamento experimental adotado foi inteiramente casualizado, com esquema bi-fatorial 5 × 2 (5 genótipos × 2 tratamentos hídricos), com cinco repetições. As atividades enzimáticas da SOD, CAT, APX e GPX foram analisadas, além do acúmulo de carboidratos, amido e prolina. Em função do déficit hídrico submetido, verificou-se aumento nas atividades da SOD e da CAT em todos os genótipos, tanto nas folhas quanto na raiz, destacando-se as cv. 55 437 e BR 1 e a linhagem LBM Branco. O acúmulo de prolina e redução do teor de amido foram verificados em todos os genótipos, em resposta ao déficit hídrico, porém o teor de carboidratos foi elevado só nos materiais mais tolerantes. Em função das respostas obtidas, destacam-se como materiais mais tolerantes as cultivares 55 437 e BR 1, seguidas por LBM Branco. LBR Branco tem comportamento intermediário e LViPE 06 é o material mais sensível. Five peanut genotypes, with different growth habits were submitted to moderate water stress in a greenhouse for seven days. Seeds were planted in 15-litre pots containing soil and a substrate (Plantmax®), both optimized for the crop. The adopted experimental design was completely randomized, using a 5 x 2 bi-factorial scheme(5 genotypes × 2 water treatments) with five replications. The enzymatic activities of SOD, CAT, APX and GPX were analyzed, as well as the carbohydrate, starch and proline. An increased activity was shown in SOD and CAT enzymes for all genotypes submitted to water stress, in both leaf and root, especially in the 55 437 and BR1 cultivars and also in LBM Branco line. Proline accumulation and reduced starch were verified in all stressed genotypes, but carbohydrate content was increased just in tolerant materials. Based on results, 55 437 and BR1 were more tolerant to water stress, followed by LBM Branco. The LBR Branco shows intermediate behavior and LViPE- 06 was more sensitive

Erythrina velutina Willd. (common name: mulungu) is a deciduous, heliophyte found in the semi-arid region of northeastern Brazil. To evaluate the growth and water relations of mulungu seedlings in soils with different degrees of moisture content, an experiment was carried out under greenhouse conditions using four water treatments (100%, 75%, 50% and 25% of the field capacity- FC). Predawn (Ψpdw) and midday leaf water potential (Ψmdw), relative water content (RWC), plant height, number of leaves, stem diameter, leaf area (LA), specific leaf area (SLA), leaf area ratio (LAR), dry matter in different organs, biomass partitioning and root:shoot ratio were evaluated. No differences were detected between treatments for Ψpdw after 30 days; however, at midday, control plants and those under 75% FC underwent a greater reduction in Ψmdw than plants cultivated with 50% and 25% FC. After 90 days, only the plants under 50% FC exhibited a reduction in Ψmdw. RWC was reduced at midday, but there were no differences between treatments. Nearly all growth parameters were reduced due to water deficit, especially in the plants with 25% FC, as determined by the number of leaves, stem diameter, plant height, LA, SLA and dry mass in several organs. LAR and root:shoot ratio were not affected. Mulungu seedlings seem to have developed rusticity to overcome intermittent droughts with no change in the pattern of dry matter distribution. The maintenance of turgor pressure seems to be more associated to a reduction in the growth ratio than a reduction in leaf water potential.