Abstract
This study evaluated the growth and gas exchanges of guava, cv. ‘Paluma’ cultivated in salinized soil and subjected to different nitrogen (N) doses in a protected environment in the municipality of Campina Grande-PB. The experimental design was randomized blocks, in a 5 x 4 factorial arrangement with three replicates, and the treatments resulted from the combination of five salinity levels in the soil saturation extract - ECse (2.15, 3.15,4.15, 5.15 and 6.15 dS m-1) and four N doses (70, 100, 130 and 160% of the recommended N dose). The dose referring to 100% of N corresponded to 541.1 mg of N dm-3 of soil. At 120 and 180 days after (DAT), plant growth was evaluated based on stem diameter (SD), leaf area (LA) and number of leaves (NL). At 210 DAT, the following variables of leaf gas exchanges were evaluated: stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E) and CO2 assimilation rate (A). ECse above 2.15 dS m-1 reduced stem diameter, leaf area, number of leaves, stomatal conductance, internal CO2 concentration, transpiration and CO2 assimilation rate, in both evaluation periods. N dose above 70% of the recommendation (378.7 mg N dm-3 of soil) did not mitigate the deleterious effects caused by the salt stress on the growth and gas exchanges of guava plants.
Highlights
Guava (Psidium guajava L.) is a fruit crop widely cultivated in the Southeast and Northeast regions of Brazil, and is a highly profitable activity with great potential for expansion
Among various processes affected by salinity, it is known that water absorption by plants and gas exchanges are negatively affected due to the reduction in the osmotic potential
The soil was classified as eutrophic Regolithic Neosol, with loamy sand texture, collected in the 0-30 cm layer in the municipality of Esperança-PB, whose physical and chemical characteristics (Table 1) were determined according to methodologies described by Donagema et al (2011)
Summary
Guava (Psidium guajava L.) is a fruit crop widely cultivated in the Southeast and Northeast regions of Brazil, and is a highly profitable activity with great potential for expansion. Soil salinization is a critical factor for plant production in protected environments, due to the low tolerance to salinity of commercial plants (Eloi et al, 2011; Medeiros et al, 2012). In a protected environment there is an accumulation of certain ionic species, such as the cations Na+, Ca2+ and Mg2+ and the anions Cl- and SO42-, affecting plant water consumption, lowering the osmotic potential in the soil and decreasing the water potential of the plants, besides causing ionic toxicity due to excess of Cl-, Na+ and Ca2+, among others. The excess of sodium salts, besides causing damage to the soil’s physical properties, results in generalized reduction of growth in the cultivated plants, leading to serious damage to agricultural activity (Cavalcante et al, 2010). According to Távora et al (2001), in the initial growth stage guava can be classified as sensitive to salinity, with threshold salinity in the soil saturation extract of 1.2 dS m-1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
