Irrigation with saline water increased the concentration of salts in the soil and caused reductions in the absolute and relative growth rates of West Indian cherry, in the period from 30 to 515 days after transplanting.
In relation to the mean fruit mass of West Indian cherry fruits (Figure 3C), the highest value (5.98 g [fruit.sup.-1]) occurred in plants irrigated using water with the lowest salinity level (0.8 dS [m.sup.-1]), being statistically higher than the value (2.08 g [fruit.sup.-1]) observed in plants under irrigation with ECw of 3.8 dS [m.sup.-1].
Reduction in MFM due to water salinity is consistent with the absolute and relative growth rates for the diameter of rootstock and scion of West Indian cherry plants (Figures 1 and 2) and expresses the response of the decrease in the osmotic potential and/or excessive accumulation of ions in the protoplasm (Flowers et al., 2014).
Irrigation with saline water of up to 3.8 dS [m.sup.-1] did not affect the water status of the West Indian cherry plants.
The high salinity of irrigation water reduces gaseous exchange activity and increases the percentage of damage in the leaf cells of West Indian cherry plants.
The 40% increase over recommended dose of nitrogen increases the synthesis of chlorophyll b and carotenoids in the West Indian cherry plant when irrigated with saline water of up to 2.2 dS [m.sup.-1].
Initial fluorescence (Fo) and maximum fluorescence (Fm) of West Indian cherry were reduced by 21.49 and 15.48% as water salinity increased from 0.8 to 3.8 dS [m.sup.-1] respectively (Figures 2A and B).
Variable fluorescence in West Indian cherry plants irrigated with low-salinity water (0.8 dS [m.sup.-1]) decreased linearly as K doses increased, with a reduction of 22.78% in the Fv in plants fertilized with 125% of the K recommendation in comparison to those subjected to 50%, which represents a reduction of 162.50 electrons [quantum.sup.-1] (Figure 3A).
Therefore, it can be inferred that the photosynthetic apparatus of West Indian cherry plants irrigated with 3.8 dS [m.sup.-1] water (Figure 3B) is compromised by salt stress, since these plants had Fv/Fm values of 0.63 electrons [quantum.sup.-1].
Increment of N dose in the P/N combinations stimulated maximum fluorescence (Fm) and variable fluorescence (Fv) in west indian cherry plants under 100:140% P/N, and these indices were 9.03 and 12.17% higher in the treatment 100:140 P/N compared with plants in the control treatment (100:100% P/N) (Figure 1B and C).
Absolute and relative growth rates of the rootstock and number of leaves of west indian cherry plants were influenced by the increase in irrigation water salinity, showing a quadratic behavior, in which the highest values of absolute growth, relative growth and number of leaves, 0.17 mm day1, 0.018 mm m[m.sup.-1] [day.sup.-1] and 1,071 leaves, respectively, were obtained at ECw levels of 1.68, 1.80 and 1.22 dS [m.sup.-1], respectively (Figure 2A, B and C).
It is observed that the slight increment in water salinity positively influenced the growth of west indian cherry plants, probably due to the addition of calcium and magnesium, which are essential to plant development.