Monitoring and control of plant water stress in processing tomatoes

Calado, A.M.; Monzon, A.; Clark, D.A.; Phene, C.J.; Ma, C.; Wang, Y.

Monitoring and control of plant water stress in processing tomatoes

1990

Effects of decreasing water application on water stress indicators of high frequency drip-irrigated processing tomatoes was studied at the Water Management Research Laboratory in Fresno, California. Irrigation treatments were arranged in a randomized block design to produce five levels of water stress: T1= 0.40 ETc; T2= 0.60 ETc; T3== 0.80 ETc; T4= 1.0 ETc; T5= 1.20 ETc. The irrigation for each treatment was controlled automatically by a desktop computer using the electronic fluid level sensor wich measured evaporation of water Class "A" evaporation pan. Several soil and plant parameters were systematically monitored either manualy or by computer. Results from this experiment indicate that (1) soil matric potentials sensors (SMPS) could be used to schedule and control irrigation. Simultaneous measurents avoid poor decisions based on a typical conditions. (2) Crop Water stress index method (CWSI) appears to be usefull to schedule/control irrigation or characterize water stress in tomato plants. A considerable variability was determined in this method. (3) Some statistical significant correlations were found between stem diameter changes and leaf water potential. Water applied, yield and tomato quality are also presented.

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