Growth of Trickle‐Irrigated Tomato as Related to Rooting Volume and Uptake of N and Water 1

Abstract Information about responses of plants in general, and of tomato ( Lycopersicum esculentum Mill.) in particular, to various trickle‐irrigated soil volumes is meager. This information is essential in planning water rates and geometries and in scheduling drip irrigation systems. Our objective was to study root development and distribution in a sandy soil in the field under three trickle irrigation regimes; yields, dry matter production, water and N content in the root zone and N uptake by the tomato were all evaluated in relation to root development. Irrigation frequency increases from one to three irrigations per day produced a significant increase in dry matter yield, but decreased fresh fruit yield. A seasonal application of 620 mm compared to 320 mm, both applied as one irrigation per day, did not increase dry fruit yield, but increased fresh fruit yield by a factor of 1.46. The main factor that contributed to the different response of the plants to the irrigation treatments, was the root weight and distribution in the soil during the growth period. In the once‐a‐day irrigation treatments, the root weight declined at the time of fruit filling, which caused a delay in production, while when irrigating three times a day, that decrease was not observed, and fruit dry matter production occurred at a higher rate. This response produced a greater final dry matter yield. In all the treatments the rapid fruit filling period was followed by a 55‐day period of slow dry matter production, which, in turn, was followed by an enhanced production rate.