Effect of water supply on canopy temperature, stomatal conductance and yield quantity of processing tomato (Lycopersicon esculentum Mill.)

Abstract

Tomato (Lycopersicon esculentum Mill.) is one of the most extensively cultivated horticultural crops in the world.Water supply is important for yield quantity and quality. The aims of the present study were 1) to evaluate the canopy temperature and the stomatal conductance on processing tomato substances with different water supply, 2) to investigate the effect of different water supply on yield quantity. There were two irrigated treatments, one of them was the reguralry irrigated plant stand which got 333 mm water during investigated period, including the precipitation and the other was the cut off substance which means the irrigation (drip) was stopped at the beginning of the ripening process and there was a control as well which got 189 mm precipitation. The canopy temperature was measured row by row with a Raytek MX 4 type infrared remote thermometer. The stomatal conductance was measured by Delta-T AP4 type porometer. There were significant differences between the control and irrigated plants according to the water supply which was formulated the canopy values. The plants with a deficient water supply were decreased the transpiration rate, therefore its cooling effect didn’t show up. The regularly irrigated tomato plants’ yield exceeded the unirrigated ones more than twice. It is emerged from the study that the irrigation has a positive effect on the amount of the harvestable yield in this year type.

Physiological Responses of Selected Vegetable Crop Species to Water Stress

“…If soil water content is sufficient for the plant stand, the difference between canopy temperature and air temperature is zero or negative, but if the plants suffer from water stress this value is positive. An increase of 1 • C in canopy temperature related to a 10% decrease in the transpiration [31]. Size and stomatal density of genotypes are different thereby the transpiration varies in intensity which correlates with the difference of the canopy temperature of plants.…”

“…Helyes et al [31] found a close correlation between the stress degree days (SDD) and yield of tomatoes. If the canopy temperature exceeded the air temperature (at noon), transpiration was reduced, which indicated water stress and resulted in yield reduction and quantity.…”

“…Tomatoes are most sensitive to water deficiency at fruit setting and intensive fruit development periods [3], when the increasing water stress resulted in a 25 to 50% decrease in the yield [10,[26][27][28][29]. During early flowering of tomatoes, water scarcity causes flower shedding and lack of fertilization [30], and during fruit setting, plants with small sized fruits are produced [10,31].…”

“…Under water stress conditions, the canopy temperature of tomatoes was only higher than the air temperature by 1.8 • C, while it was significantly lower (0.6 • C) under optimal water supply conditions [92]. Air temperature had a small impact on the canopy temperature of tomatoes grown under regular irrigation and cut-off stand (i.e., irrigation was stopped 30 days before harvest) (r 2 = 0.60; r 2 = 0.55), however, the canopy temperature of water stressed plants increased with rising air temperature (r 2 = 0.59) ( Figure 3) [31]. A close correlation between canopy temperature and leaf water potential of maize was established [80] and the lowest CWSI values were measured between 10:00 and 11:00 and the highest ones between 12:00 and 13:00 [95].…”

“…x FOR PEER REVIEW 9 of Relationship between the air and canopy temperature for the Kecskeméti jubileum tomato variety under rain-fed (thin line), cut-off (broken line) and regularly irrigated (thick line) conditions Source: Helyes et al[31].…”