Short-term spectral indication of the salinity effects on avocado rootstocks growth caused with ground and regenerated wastewater irrigation.

Abstract

An avocado rootstocks were grown in a pot experiment with lysimeters to evaluate the effect of three irrigation options: groundwater (GW), regenerated wastewater (RWW), and a 1:1 mixture of both (GW/RWW-1:1). Plant water and salt stress assessment was carried out using leaf non-destructive and destructive methods during the fifth and sixth months of the experiment. The avocado leaf blade area decreased by the end of observations in the GW/RWW-1:1 and RWW treatments by 1.2 and 1.5 times compared to the groundwater option. The water saturation deficit was mainly 1.4–1.7 times more in GW/RW-1:1 and RWW than in GW. The lowest levels of chlorophyll a, chlorophyll b and carotenoids were at the treatment with 100% regenerated water. 50% level using of mix consisted of ground and regenerated water (GW/RW-1:1) took intermediate pigments content. The highest positive correlations were observed for relationship between EC and DSWI2 > WBI >DSWI1 > MSI (rp = 0.300, 0.286, 0.230, 0.185, respectively; p ≤ 0.05). A negative correlation was observed for correlation between W1 and EC (rp = -0.283; p < 0.001). Only the PBI index showed a positive correlation with the EC (rp = 0.224; p = 0.007). On the other hand, a negative correlation was found for MCARI1 = MTVI > R780/R740 > VREI1 (rp = -0.330, −0.273, and −0.238, respectively; p ≤ 0.001).