Tomato water stress index as a function of irrigation depths

Abstract

A B S T R A C TInfrared thermometry allows evaluating plants under water stress, by measuring the canopy temperature, without the need of physical contact with the leaves. The aim of this study was to determine the water stress index of the tomato crop for industrial processing (Hybrid 'BRS Sena'), as a function of irrigation depths applied by subsurface drip irrigation, in Southern Goiás, Brazil, in 2015 and 2016. The experiment was conducted in a randomized block design, with four replicates. The treatments consisted in five irrigation depths: 50, 75, 100, 125 and 150% of crop evapotranspiration. The water stress index of the tomato crop was evaluated using two methodologies, as a function of the canopy temperature, air temperature and other local meteorological parameters, as well as the relationship between water stress index and crop yield. Theoretical and empirical methods estimate CWSI similarly in tomato. In the hottest hours of the day, even under adequate soil moisture conditions, the 'BRS Sena' tomato showed CWSI above 0.2. CWSI is a good indicator to evaluate the water status of the tomato crop for industrial processing and to recommend the moment of irrigation. The higher the CWSI, the lower the yield of 'BRS Sena' tomato.Índice de estresse hídrico de tomateiro em função de lâminas de irrigação R E S U M OA termometria infravermelha permite avaliar o estresse hídrico das plantas através da medição da temperatura do dossel, sem necessidade de contato físico com as folhas. Objetivou-se neste trabalho determinar o índice de estresse hídrico do tomateiro industrial (híbrido BRS Sena) em função de lâminas de irrigação aplicadas por gotejamento subsuperficial, na região Sul de Goiás, nos anos 2015 e 2016. O delineamento experimental foi em blocos ao acaso, com quatro repetições. Os tratamentos consistiram de cinco lâminas de irrigação, iguais a 50, 75, 100, 125 e 150% da evapotranspiração da cultura. Avaliou-se o índice de estresse hídrico do tomateiro por meio de duas metodologias, em função da temperatura no dossel, temperatura do ar e demais parâmetros meteorológicos locais, e também a relação dos valores do índice de estresse hídrico com a produtividade da cultura. Os métodos teórico e empírico estimam de maneira semelhante o CWSI no tomateiro. Nas horas mais quentes do dia, mesmo em condições de umidade adequada no solo, o tomateiro BRS Sena apresentou CWSI acima de 0,2. O CWSI é um bom indicativo para avaliar o estado hídrico do tomateiro industrial e indicar o momento de realizar a irrigação. Quanto maior o CWSI, menor foi a produtividade do tomateiro BRS Sena.

Tomato yield as a function of water depths and irrigation suspension periods

“…The results of yield corroborate those found by Koetz et al (2008), Moreira et al (2012) and Silva et al (2018), in Cerrado area of Jataí, Ipameri and Morrinhos in Goiás, with the hybrid 'Heinz 9498' , cultivar 'Hypeel' and hybrid 'BRS Sena' , respectively. These authors concluded that, under water deficit, tomato yield is compromised.…”

“…Similar results were found in Italy by Patanè et al (2011), who observed that irrigation suspension before harvest leads to lower crop yields and that irrigation during the entire cycle of tomato plants cause higher yields, and in Morrinhos, GO, by Silva et al (2018), who concluded that the higher the water stress index, the lower the yield of the hybrid 'BRS Sena' .…”

“…In Italy, Patanè et al (2011) concluded that, under water deficit, industrial tomato yield is severely compromised and that irrigation during the entire cycle promotes higher yields, whereas longer periods of irrigation suspension prior to harvest lead to lower yields, due to lower fruit weight and abortion of flowers and fruits. In Morrinhos, GO, Silva et al (2018) concluded that the higher the water stress index of the crop, the lower the yield of the industrial processing tomato hybrid ('BRS Sena').…”

Decision Support System for Variable Rate Irrigation Based on UAV Multispectral Remote Sensing

“…Secondly, the CWSI/K c inversion model (VI-Kc/VI-CWSI) is built for specific districts and crops. Different crops have different optimization VI-Kc/VI-CWSI model [24,25]. Different districts with the same crop also have different VI-Kc/VI-CWSI [26].…”

Physiological Responses of Coffee Tree Under Different Irrigation Levels

“…The use of infrared thermometry as indicative of the leaf water potential has already been studied for several crops such as: bean (Asemanrafat & Honar, 2017), eggplant (Çolak et al, 2015), citrus (Gonzalez-Dugo et al, 2014), coffee (Craparo et al, 2017), grape (Bellvert et al, 2014), cotton (Cohen et al, 2015), tomato (Ramírez et al, 2015;Silva et al, 2018) and others.…”