Application of partial rootzone drying to improve irrigation water use efficiency in grapefruit trees

2010

An experiment on regulated deficit irrigation (RDI) was performed during two growing seasons (2007 and 2008) in a drip-irrigated orchard of Navelina/Cleopatra in Senyera (Valencia, Spain). Two RDI treatments, where water application was reduced to 40% and 60% of the «irrigation dose» (ID), were carried out during the initial fruit enlargement phase (Stage II, 17 th July to 2 nd September). The rest of the year they were irrigated at 110% ID. These treatments were compared with a control, where irrigation was applied without restriction during the whole year at 110% ID. The ID was obtained from the evapotranspiration data, as well as from the characteristic variables of drip irrigation for the specific experimental orchard. The effects of the treatments on yield, fruit quality, and vegetative growth are discussed in relation to tree water status (midday stem water potential, Ψ st). Minimal Ψ st values reached in the treatment with the highest stress intensity were-1.71 and-1.60 MPa in 2007 and 2008 respectively. These Ψ st values reached as a consequence of the water reduction in the RDI summer treatments applied in this study did not affect yield or fruit quality, allowing water savings between 16% and 23%. In conclusion, water restriction during summer, and once «June drop» has finished, favours the better use of water resources by Navelina citrus trees, achieving an increase of water use efficiency (between 14% and 27% in this case), provided that an appropriate irrigation in autumn allows for tree recovery.

Agronomy for Sustainable Development, 2011

Citrus is a crop of major economic importance in Spain, cultivated during the dry season when irrigation is essential to guarantee yields of high quality. As water resources are progressively more insufficient, more effective water management in agriculture is crucial. Deficit irrigation in many agricultural crops has frequently proved to be an efficient tool for improving water-use efficiency. We hypothesise that, despite the effectiveness of deficit irrigation, the most suitable strategy in citrus orchards remains to be defined for Mediterranean environment. In this study, for the period from 2006 to 2008, a 12-year-old orange orchard, Citrus sinensis L. Osb. cv. Navelina, grafted onto Carrizo citrange, C. sinensis L. Osb.×Poncirus trifoliata L. Osb., were subjected under two deficit-irrigation strategies defined as follows: (1) low-frequency deficit irrigation applied according to the plant-water status, and (2) sustained-deficit irrigation with a water-stress ratio of 0.6, defined as the ratio of actual water-limited supply in this treatment related to the water supply of the control treatment. The control treatment was irrigated at 100% of ET C for the entire irrigation season (ET C : crop evapotranspiration). Midday stem-water potential (Ψ stem) and stomatal conductance (g S) were used to estimate the water status of the trees. The lowest Ψ stem and g S values were registered in the deficit-irrigation treatments with a seasonal pattern consistent with the irrigation dynamics applied in each case. Ψ stem and g S values significantly differed from those of the control trees. Although the integrated stress levels were similar in deficit-irrigation treatments, differences in yield and fruit quality were found, having a more positive response to low-frequency deficit irrigation with an increase of 25% in yield in comparison to the sustaineddeficit irrigation treatment. Here, we thus demonstrate the significant differences in water productivity. Indeed, water productivity parameter not only depends on the amount of water, but also on the irrigation strategy applied, which promoted substantial water savings without significant impact on yield. The present study highlights that lowfrequency deficit irrigation should be adopted as a most appropriate strategy for achieving sustainable water management and attains reasonable yields and improves quality in citrus orchards under Mediterranean semiarid climate.

Agricultural Water Management, 2014

Regulated deficit irrigation (RDI) has been assessed in a wide number of fruit crops. However, few are the studies dealing with long-term RDI strategies. In this work, we assessed the response of 'Clementina de Nules' citrus trees to summer RDI treatments [RDI-1, irrigated at 50% of crop evapotranspiration (ETc) and RDI-2, irrigated at 35% ETc] during six consecutive seasons (2007)(2008)(2009)(2010)(2011)(2012). Although water restrictions were applied according to reductions over ETc, threshold values of stem water potential (−1.3 to −1.5 MPa in the RDI-1 treatment and −1.5 to −1.7 MPa in the RDI-2) were also considered for scheduling deficit irrigation. Results showed that the water stress imposed in the RDI-2 treatment had a noticeable impact on fresh fruit weight, reducing yield and economic return over the six years and more so during the first two years in comparison to a control treatment irrigated at 100% ETc during the whole season. The RDI-1 strategy had a lower impact than the RDI-2 treatment on the fresh fruit weight and did not significantly reduce yield or the economic return over the six seasons. RDI improved fruit quality particularly in the most stressed treatment by increasing the total soluble solids and titratable acidity. RDI also reduced vegetative growth although the reduction was not proportional to the level of stress reached by trees. On average for the six years, the relative trunk growth and pruning weight in both RDI treatments were reduced around 20% in comparison with the control trees. Long-term deficit irrigation did not lead to a noticeable accumulation of salts in the root zone. Overall, these results show that the RDI-1 strategy here studied can be successfully applied during six consecutive seasons in commercial 'Clementina de Nules' orchards allowing water savings of 15% without any detrimental effect on tree performance.

Ecological Engineering & Environmental Technology

In our experiment we have studied the effects of partial root-zone drying (PRD) on plant physiological response, plant soil water dynamics, yield and fruit quality of mature clementine trees (Citrus clementina) during the irrigation seasons 2017 and 2018 in an orchard located in Triffa plain (north-east Morocco). Two irrigation treatments were applied: (i) full irrigation where trees were irrigated with enough water to replace 100% of crop evapotranspiration (ETc), and (ii) alternate partial root-zone drying (PRD) with trees irrigated at 75% ETc (applied on one side of the root-zone while the other side was kept dry, alternating the sides every week). Results show that PRD at 75% of crop water demand (ETc) decreased the fruit yield by 17% in 2017 and 7% in 2018 compared with the Full irrigation treatment and did not induce significant loss of crop yield. The PRD irrigation treatment, induces not only a reduction of the wetted soil volumes and transpiration rate, but also represented the highest Irrigation Water Use Efficiency (IWUE) with an increase of 11 and 21% for 2017 and 2018 respectively. Both fruit size and fruit weight decrease significantly in PRD treatment by 12-10% and 11-12% compared to Full irrigation respectively for 2017 and 2018. Titrable acidity (TA) and total soluble solids percentage (TSS) increased significantly in PRD fruit by 9-11% and 1.2-1.4% respectively for 2017 and 2018. Juice percentage decreased significantly in the first year for PRD treatment by 6% whereas in 2018 the PRD fruit had the highest juice percentage with significant difference of 3% compared to Full irrigation statically significant. Results show clear difference of rooting between irrigation strategies with an increase of the root number by the PRD treatment.

Agricultural Water Management, 2010

Four strategies of deficit irrigation based on a different water-stress ratio (WSR) applied in each phenological stage, and a control treatment were implemented in 11-year-old citrus trees (Citrus sinensis L. Osb. Cv. Navelina) grafted onto carrizo citrange (C. sinensis L. Osb. Â Poncirus Trifoliata L. Osb.). The midday stem-water potential and stomatal conductance were measured during the periods considered, and these parameters were used to estimate the plant-water status. Integrated stem-water potential (C Int) and integrated stomatal conductance (g Int) were calculated for all treatments and used as a waterstress indicator for the crop. Reference equations were formulated to quantify the relations between water-stress indicators (WSR, C Int , g Int) and the crop response, expressed as yield, yield components, and fruit-quality parameters under limited seasonal water availability. Significant differences in yield were found in the second year of experiment between the stressed treatments and control, although these differences were evident during the first year. The main effects were detected in treatments with a water-sever stress applied during the flowering and fruit-growth phases. When this degree of stress was applied during the maturity phase, it was reflected mainly in fruit-quality parameters (total soluble solids, and titrable acidity). These results lead to the conclusion that, in mature orange trees, deficit irrigation affects yield and fruit quality, while enabling water savings of up to 1000 m 3 ha À1. Therefore, yield declined on average 10-12% but boosted water productivity 24% with respect to the fully irrigated treatment. Regarding the water-stress indicators used, C Int and g Int showed highly significant correlations with the yield and fruit-quality parameters.

Soil Science Society of America Journal, 2014

All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Water Use in Drip-and Microsprinkler-Irrigated Citrus Trees Soil & Water Management & Conservation A ccurate estimation of plant water use could improve irrigation management (Gutierrez et al., 1994; Morgan et al., 2006), leading to a better understanding of plant-water interactions (Ham et al., 1990). Lysimetry, water balance, and crop evapotranspiration (ET c) have been used in Florida to estimate citrus water use with microsprinkler irrigation on a field scale without partitioning evaporation and transpiration from the ET component (Obreza and

2000

Long-term field experiments were carried out between 1985 and 1988 to determine the effect of different irrigation intervals and pan coefficients on the fruit and trunk growth rates and yield of mature grapefruit trees grown in the Eastern Mediterranean Region of Turkey in a medium-light textured soil. Two different irrigation intervals (I1=15 and I2=25 days), and pan coefficients (k1=0.60 and

European Journal of Horticultural Science, 2019

Introduction 'Valencia' is a late orange (Citrus sinensis L. Osbeck) cul-tivar in which fruit develop across a year, ranging from fruit-set in late spring of the current year to full ripening in the next spring. This means that for a short time we can find both fruit at stage I and stage III (Iglesias et al., 2007) on the same tree. For this peculiar circumstance, growth rate of current-season 'Valencia' oranges may be influenced by the presence/absence of previous-season, nearly mature fruit. In particular, the presence of older fruit may reduce growth Summary Background-Partial rootzone drying is an irrigation strategy known for increasing water use efficiency without significantly affecting tree water status. 'Valencia' oranges have a very long development period and nearly mature fruit and new fruitlets may be present at the same time on the tree, competing for water and assimilates. Objectives-The present study investigates the effect of recurrent deficit irrigation and fruit harvest on tree water status and fruitlet growth of 'Valencia' orange. Methods-Forty-eight adult trees were exposed to three irrigation treatments for seven years (2007-2013): irrigation with 100% of ETc (CI), continuous deficit irrigation (DI, 50% of CI) and partial root-zone drying (PRD, 50% of CI on alternated sides of the root-zone). In spring 2014, stem water potential (Ψ stem) and continuous measurements of sap flow and fruitlet growth were recorded before (May) and after (June) the harvest of mature fruit. Results-No differences in Ψ stem were found among irrigation treatments, while Ψ stem was lower in June than in May at midday. In both May and June, sap flow density (not sap flow per tree) was higher in DI than in CI and PRD trees suggesting more efficient water uptake/transport in the former. In May, DI and PRD fruit showed lower daily relative growth rate (RGR) than CI fruit due to a possible shortage of carbon and nutrients. After removing mature fruits, differences among irrigation treatments were canceled. Sap flow was directly related to fruit RGR at low sap flow rates, but inversely related to RGR at high sap flow rates. Conclusions-Our data show that the presence of maturing fruit does not impact the water status of 'Valen-cia' trees, while it may transiently limit fruitlet growth (by source limitation) in deficit irrigated trees.

2012

Wallace and Batchelor (1997) showed the main options for improving WUE in different categories, engineering, agronomy, management and institutional improvements. Although it is not possible to discuss all the options listed in detail by these authors, three of the options are of particular interest. Concerning engineering improvements, there are several irrigation systems to water crops that can reduce application losses and improve application uniformity.

Agricultural Water Management, 2020

Brazil stands out in world citrus production, as it is responsible for the largest cultivated area and production amounts. In the last decade, Sao Paulo State fruit yield improved due to adoption of technologies such as irrigation and fertilization. Considering the need for improving yield, quality and water resources sustainable use in agriculture, the aim of this study was to evaluate the effect of deficit irrigation on Pêra-IAC orange fruit yield, juice quality and water use efficiency. The experiment was carried out in a Pera sweet orange grafted onto Sunki mandarin orchard. Water was applied by drip irrigation system and there were five treatments testing different irrigation depths: T100-100 % of crop evapotranspiration (ETc), T75-75 % ETc, T50-50 % ETc, T25-25 % ETc and T0-rainfed. Six replications per treatment were randomized in blocks for statistical analysis. Fruit yield was evaluated by weighing all fruits per tree and quality characteristics were monitored by samplings during maturation period until harvest. Five harvesting years were evaluated, from 2013/14-2017/18. Results were tested by analysis of variance, Tukey's means test and Scott-Knott grouping test (α = 0,05). Irrigation improved fruit yield in three out of five seasons, even when applying only 25 % of ETc. Irrigation yield increments ranged from 15 to 64 % when compared to rainfed treatment. Deficit irrigation improved fruit quality compared to the full-irrigated trees (T100), as it resulted in lower acidity and higher maturation index. After five seasons, fruit yield in irrigated treatments was increased by 30.8 % compared to the rainfed. Water use efficiency showed that deficit irrigation applying 50 % ETc is an interesting strategy for increasing yield, quality and saving water.