Water salinity, nitrogen and phosphorus on photochemical efficiency and growth of west indian cherry

Abstract

The objective of this study was to evaluate the interaction between water salinity and doses of nitrogen and phosphorus on chlorophyll a fluorescence and on the growth of West Indian Cherry (‘acerola’) plants in the initial growth stage. The research was carried out in a protected environment, in lysimeters filled with Regolithic Neosol of loamy clay texture and low initial phosphorus content. The experiment was conducted in a randomized block design, arranged in a factorial scheme with two factors, five levels of electrical conductivity of the irrigation water - ECw (0.6, 1.4, 2.2, 3.0 and 3.8 dS m-1) and four proportions of the recommendation of phosphorus/nitrogen - P/N (100:100, 140:100, 100:140 and 140:140% P/N of recommendation), with three replicates, and each plot consisted of one plant. Water salinity above 2.2 dS m-1 decreases the quantum efficiency of photosystem II and the growth of west indian cherry plants. Increase in nitrogen and/or phosphorus supply improves the energy stability of west indian cherry plants by reducing the effects of salt stress on the quantum efficiency of photosystem II. The increase of 40% in the nitrogen dose increased the chlorophyll a fluorescence, but did not influence the plant growth.

Saline water and potassium fertilization in cultivation of grafted west indian cherry BRS 366 Jaburu

“…As plants are irrigated with saline water, the salt content in the soil increases and exceeds the tolerable limit, and the growth rate of most species progressively decreases, given the difficulty to absorb water due to the reduction in the osmotic potential of the soil solution (GURGEL et al, 2003). Sá et al (2018), studying the growth of the West Indian cherry cv. 'BRS 366 Jaburu' under saline conditions (ECw: 0.6 to 3.8 dS m -1 ), observed reduction in the absolute and relative growth rates for the rootstock and scion as a function of water salinity from 1 to 150 days after transplanting.…”

Growth and production components of West Indian cherry cultivated with saline waters and potassium fertilization

“…The reduction in growth rate is also due to the deleterious effect of excess salts on plant metabolism, because the excess of soluble salts in the root zone causes a reduction of turgor, with consequent decrease in cell expansion (Khalid & Silva, 2010). Sá et al (2018), evaluating the effects of water salinity (ECw: 0.6; 1.4; 2.2; 3.0 and 3.8 dS m -1 ) on the growth of West Indian cherry plants, also observed that increase in ECw led to reduction in the absolute and relative growth rates of stem diameter, in the period from 1 to 150 days after transplanting.…”

“…Thus, knowledge on the degree of tolerance of crops to salinity may allow the use of waters with a high concentration of salts, a common situation found in the semi-arid region of Northeast Brazil (Nobre et al, 2010;Souza et al, 2017). For this purpose, it is necessary to conduct studies in order to identify salinity-tolerance indices of crops, including West Indian cherry, aiming to establish the degree of restriction of certain types of water for irrigation (Lima et al, 2014), because there are few studies in the literature with this fruit crop under salt stress conditions in the post-grafting stage (Sá et al, 2017(Sá et al, , 2018.…”

Morphophysiological aspects of young Calotropis procera plants submitted to different shading levels

“…Fm refers to the condition in which the reaction centers of PSII reached their maximum capacity, i.e., when all the quinone was totally reduced, thus, some plants present increases in Fm as a mechanism of acclimatization to shading, aiming at maximizing light absorption [25], a fact that contrasts to the one observed in the present study. Fv, on the other hand, refers to the potential active energy in PSII, which leads us to deduce that the increasing shading levels induced a low activity of PSII and dissipation of excitation energy as heat [26].…”