Yield, water use efficiency, and yield response factor in carrot crop under different irrigation depths / Produtividade, eficiência no uso da água e fator de resposta em produção de cenoura sob diferentes lâminas de irrigação

The aim of the present study was to evaluate the effect of different irrigation depths on the yield, water use efficiency (WUE), and yield response factor (Ky) of carrot (cv. 'Brasília') in the edaphoclimatic conditions of Baixada Fluminense, RJ, Brazil. Field trials were conducted in a Red-Yellow Argisol in the 2010-2011period. A randomized block design was used, with 5 treatments (depths) and 4 replicates. Depths were applied by drippers with different flow rates, and the irrigation was managed by time domain reflectometry (TDR) technique. The reference (ETo) and crop (ETc) evapotranspiration depths reached 286.3 and 264.1mm in 2010, and 336.0 and 329.9mm in 2011, respectively. The root yield varied from 30.4 to 68.9t ha-1 as a response to treatments without irrigation and 100% replacement of the soil water depth, respectively. Values for WUE in the carrot crop varied from 15 to 31kg m-3 and the mean Ky value was 0.82. The mean values for Kc were obtained in the initial (0.76), intermediate (1.02), and final (0.96) stages. Carrot crop was influenced by different water depths (treatments) applied, and the highest value for WUE was obtained for 63.4% of soil water replacement.(AU)

O objetivo deste estudo foi avaliar o efeito de diferentes lâminas de irrigação na produtividade, na eficiência de uso da água (EUA) e no coeficiente de resposta de produção (Ky) da cenoura (cv. 'Brasília') ao déficit hídrico do solo, nas condições edafoclimáticas da Baixada Fluminense-RJ. Ensaios de campo foram conduzidos em 2010 e 2011, em um Argissolo Vermelho-Amarelo, usando um delineamento em blocos casualizados, com 5 tratamentos (lâminas) e 4 repetições. As lâminas foram aplicadas por gotejadores com diferentes vazões e o manejo da irrigação foi realizado com a técnica da TDR. As lâminas de evapotranspiração de referência (ETo) e da cultura (ETc) totalizaram 286,3 e 264,1mm, em 2010, e 336,0 e 329,9mm, em 2011, respectivamente. A produtividade de raízes variou de 30,4 a 68,9t ha-1 como resposta aos tratamentos sem irrigação e com 100% de reposição da lâmina de água no solo, respectivamente. Os valores de EUA no cultivo da cenoura variaram de 15 a 31kg m-3 e o Ky médio foi de 0,82. Foram obtidos os valores médios de Kc nas fases inicial (0,76), intermediária (1,02) e final (0,96). A cultura da cenoura foi influenciada pelas diferentes lâminas aplicadas (tratamentos) e a maior EUA foi obtida para o tratamento com reposição de 63,4% da água do solo.(AU)

Water extraction variability in the banana root zone affects the reliability of water balance

Spatial and temporal variability of soil water extraction from the root zone affect soil water balance determination. The number of sensors installed in the root zone in studies addressing water balance is still set arbitrarily. This study provided an investigation of the water extraction process by banana (Musa spp.) roots by (i) determining the variability of water extraction from the banana tree root zone, (ii) detecting differences in the estimation of evapotranspiration (ET) by the soil water balance method when the number of soil profiles monitored in the roots zone varies, (iii) and; determining the minimum number of Time Domain Reflectometry (TDR) probes needed to obtain ET precision and accuracy similar to that determined by a drainage lysimeter. The field experiment was conducted in Cruz das Almas, in the state of Bahia, Brazil, where a drainage lysimeter was installed on a banana plantation. The water extraction in the banana root zone was quantified by the water content variations monitored in 72 points by TDRs, with measurements at 15-min intervals. The variability of water extraction in the banana root zone was medium to high. The range of variability affects the reliability of the crop evapotranspiration calculation by the soil water balance method. To prevent an overestimation of banana evapotranspiration, the water extraction in the soil profile must be monitored with at least 16 TDR probes installed at a minimum distance of 0.9 m and a minimum depth of 0.7 m.

Water extraction variability in the banana root zone affects the reliability of water balance

Spatial and temporal variability of soil water extraction from the root zone affect soil water balance determination. The number of sensors installed in the root zone in studies addressing water balance is still set arbitrarily. This study provided an investigation of the water extraction process by banana (Musa spp.) roots by (i) determining the variability of water extraction from the banana tree root zone, (ii) detecting differences in the estimation of evapotranspiration (ET) by the soil water balance method when the number of soil profiles monitored in the roots zone varies, (iii) and; determining the minimum number of Time Domain Reflectometry (TDR) probes needed to obtain ET precision and accuracy similar to that determined by a drainage lysimeter. The field experiment was conducted in Cruz das Almas, in the state of Bahia, Brazil, where a drainage lysimeter was installed on a banana plantation. The water extraction in the banana root zone was quantified by the water content variations monitored in 72 points by TDRs, with measurements at 15-min intervals. The variability of water extraction in the banana root zone was medium to high. The range of variability affects the reliability of the crop evapotranspiration calculation by the soil water balance method. To prevent an overestimation of banana evapotranspiration, the water extraction in the soil profile must be monitored with at least 16 TDR probes installed at a minimum distance of 0.9 m and a minimum depth of 0.7 m.(AU)