Mango Stem Response under Different Irrigation Regimes

ABSTRACT Mexico has dominated the international mango trade having high yields and excellent fruit quality. The use of soil, plant and environmental sensors can monitor plant hydric status and optimize water application. Linear resistance dendrometers were developed and installed in a high-density 8-year old commercial mango orchard during two seasons; 10 in 2019 and 40 in 2020. Stem diameter fluctuations were acquired every 10 minutes to obtain maximum diameter (MXD), minimum diameter (MND), morning slope (MS) and afternoon slope (AS). Mango stem response during flowering, fruit-fall and fruit-growth was analyzed after applying daily irrigation (DI) or reduced deficit irrigation (RDI). Yield was similar for both treatments, but water use efficiency was higher with deficit irrigation. A new variable known as negative integral (NI) was obtained from the dendrometer signature after adding all the values between 8:00 and 18:00. NI provided a stem shrinkage magnitude, peaks attributed to transpiration and slopes showing flow transport to and from the trunk. NI presented a high correlation of 0.85 against T7 during the flowering stage for RDI-1. If NI crossed zero, a severe stress was present; a high AS present in the evening, indicates nutrient solution provided to fruits. Fruit yield depends on panicle number and fruit-drop during the first production stages, being RDI-1 more efficient in retaining fruits.