Timing irrigation to suit citrus phenology: a means of reducing water use without compromising fruit yield and quality?

2007 ◽  
Vol 47 (1) ◽  
pp. 71 ◽  
Author(s):  
R. J. Hutton ◽  
J. J. Landsberg ◽  
B. G. Sutton

This paper addresses the question of whether a citrus crop has the same need for water at all stages of development or whether it is possible to withhold water at times when the crop is less sensitive to water stress, thus, reducing total water use and improving water use efficiency while still maintaining yield. To answer this question water applied by irrigation was reduced by up to 33% relative to standard full irrigation by extending the intervals between applications from 3 to 17 days during fruit growth stages II and III in the annual growth cycle. As expected, the longer intervals resulted in greater depletion in soil moisture and significant water stress developed as soil water deficits approached the lower limits of plant available water. Stressed trees exhibited mean pre-dawn water potential (ψl) values of –0.93 MPa and midday ψl values decreased to between –2.0 and –2.5 MPa. Periodic soil water deficits in late summer and autumn reduced shoot growth, but fruit yield was unaffected, and there was no evidence of reduced canopy size. Water use efficiency (mass of fruit produced per unit water applied) improved, but fruit growth was extremely sensitive to moisture stress and extended irrigation intervals in summer and autumn reduced fruit size. Fruit juice quality was also affected, as there was an increase in both total soluble solids and juice acidity, but the practical consequences of these were limited because there were only small changes to the sugar : acid ratios. This work has demonstrated that deficient irrigation during summer can be used to manipulate growth and reduce water use, but at the risk of a marginal reduction in fruit size.

2005 ◽  
Vol 85 (4) ◽  
pp. 877-888 ◽  
Author(s):  
Paul G. Jefferson ◽  
Herb W. Cutforth

Crested wheatgrass (Agropyron cristatum L. Gaertn.) and alfalfa (Medicago sativa L.) are introduced forage species used for hay and grazing by cattle across western Canada. These species are well adapted to the semiarid region but their long-term responses to water stress have not been previously compared. Two alfalfa cultivars with contrasting root morphology (tap-rooted vs. creeping-rooted) and two crested wheatgrass (CWG) cultivars with different ploidy level (diploid vs. tetraploid) were compared with continuously cropped spring wheat (Triticum aestivum L.) for 6 yr at a semiarid location in western Canada. Soil water depletion, forage yield, water use efficiency, leaf water potential, osmotic potential and turgor were compared. There were no consistent differences between cultivars within alfalfa or CWG for variables measured. However, these two species exhibit different water stress response strategies. Leaf water potential of CWG was lower during midday stress period than that of alfalfa or wheat. Alfalfa apparently had greater capacity to osmotically adjust to avoid midday water stress and maintain higher turgor. Soil water use patterns changed as the stands aged. In the initial years of the trial, forage crops used soil water from upper layers of the profile. In later years, soil water was depleted down to 3 m by alfalfa and to 2 m by crested wheatgrass. Alfalfa was able to deplete soil water to lower concentrations than crested wheatgrass or wheat. Soil water depletion by wheat during the non-active growth season (after harvest to fall freeze-up) was much less than for CWG or alfalfa as expected for annual vs. perennial crops. As a result, more soil water was available to wheat during its active growth period. In the last 3 yr, the three species depleted all available soil water. Forage yield responses also changed over time. In the initial 3 yr, crested wheatgrass yielded as much as or more than alfalfa. For the last 3 yr of the experiment, alfalfa yielded more forage than crested wheatgrass. Forage crops deplete much more soil water during periods of aboveground growth dormancy than wheat. Water use efficiency of crested wheatgrass declined with stand age compared with fertilized continuous spring wheat. Alfalfa exhibited deep soil water extraction and apparent osmotic adjustment in response to water stress while CWG exhibited tolerance of low water potential during stress. Key words: forage yield, soil water, water potential, water use, water use efficiency, drought


1986 ◽  
Vol 13 (4) ◽  
pp. 523 ◽  
Author(s):  
JM Morgan ◽  
AG Condon

Genotypic differences in turgor maintenance in wheat were shown to be associated with differences in grain yield in the field at both high and Low water deficits. High water deficits were produced by growing plants in field plots using water stored in the soil at sowing, and excluding rain with a rain cover. At low water deficits plants received rainfall, and irrigation was supplied before and immediately after sowing, at tillering, at jointing, at ear emergence, and during grain filling. Yield differences were analysed in terms of harvest index, water use, and water use efficiency. Water use was calculated from changes in soil water contents. At high water deficits all three factors were associated with differences in turgor maintenance. However, only the variations in water use and harvest index could be logically associated with differences in turgor maintenance. Analysis of the soil water extraction data showed that the differences in water use efficiency were due solely to differences in water use at depth while surface water losses were the same, i.e. the ratio of transpiration to soil evaporation would have been higher in low-osmoregulating genotypes. At low water deficits, no differences were observed in harvest index, though there were non-significant correlations between turgor maintenance and total water use efficiency or total water use. A similar result was obtained when the water use and yield data were related to osmoregulation measurements made in the glasshouse. It is therefore concluded that effects of turgor maintenance or osmoregulation on grain yield were primarily associated with differences in water use which were, in turn, due to differences in water extraction at soil depths between 25 and 150 cm.


2019 ◽  
Vol 37 (3) ◽  
pp. 309-314
Author(s):  
Dalva Paulus ◽  
Ivan Carlos Zorzzi ◽  
Fabiana Rankrape

ABSTRACT Water deficit or water excess can affect development and yield of vegetables. The objective of this study was to evaluate the effect of different soil water stress ranges for Chinese cabbage (Brassica pekinensis) in a protected cultivation. The researches were carried out at the Olericulture Sector of Universidade Federal Tecnologica do Paraná between April and July, 2015 and January and April, 2016. Two Chinese cabbage cultivars were analyzed (Eikoo and Kinjitsu) with four soil water stress range (13-17, 23-27, 33-37 and 43-47 kPa) moments of irrigation indicative parameters. The trial design was completely randomized, with four replications, in a factorial scheme. For head fresh mass, a soil stress range of 13-17 kPa resulted in higher yield (527.2 g/plant), in the first research. In the second one, ‘Eikoo’ showed higher productivity in the stress range 13-17 kPa (70.7 t ha-1). About water use efficiency, higher values were obtained, 42.1 kg m-³ in the first research and 47.3 kg m-³ in the second one with Kinjitsu and Eikoo cultivars, respectively, in the stress range 13-17 kPa. ‘Eikoo’ had a higher productivity than ‘Kinjitsu’ in the second research (summer), but in the first one (autumn-winter) these differences were not expressive. The use of stress ranges as indicative of irrigation return time between 13-17 kPa is suitable for Chinese cabbage crop.


Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 373
Author(s):  
Shuang Li ◽  
Yun Xie ◽  
Gang Liu ◽  
Jing Wang ◽  
Honghong Lin ◽  
...  

Soil erosion could change the effective storage of soil moisture and affected crop water use efficiency (WUE). To quantitative study differences in the WUE of soybean and the crop’s response to water stress for soils with different degrees of erosion in northeastern China, three erosion degrees—(1) lightly, (2) moderately and (3) severely—eroded black undisturbed soils and four years (from 2013 to 2016) of soybean pot experiments were used to control soil water content (100%, 80%, 60%, and 40% field capacity (FC)) and observe the crop growth processes. To study the relationships between erosion–water use–productivity, the following results were achieved: (1) the optimal water content was 80% FC for lightly eroded soil (L) and 100% FC for both moderately (M) and severely (S) eroded soil. Yield (Y) was best in M with the value of 3.12 t ha−1, which was 4.6% and 85.5% higher than L and S, respectively. Under the conditions of adequate water supply, there was no significant change in Land M, but the values were significantly different for the S ( p < 0.05). (2) Y and biomass (B) were sensitive to water stress except in the branching stage. (3) The values of WUEY and WUEB for the three eroded soils were the best at 80% FC. The stress coefficient (SF) values of the three eroded soils were not significantly different. In the flowering and pod formation stage, the SF reached the maximum under waterlogging stress. While the water shortage stress reached the maximum in the seed filling stage, the soil water content decreased by 10%, and the WUEB decreased by 15%, which was 2.5 times more powerful than the waterlogging stress. This study indicated the change in soybean growth with respect to the water response caused by soil erosion, and provided a scientific basis and data for the reasonable utilization of black soil with different erosion intensities. The results also provided important parameters for the growth of simulated crops.


2008 ◽  
Vol 56 (2) ◽  
pp. 109 ◽  
Author(s):  
Katy E. Sommerville ◽  
Jennifer Read

Nothofagus cunninghamii (Hook.) Oerst. and Atherosperma moschatum Labill. co-occur in cool-temperate rainforest across the wetter parts of Tasmania and Victoria, Australia, but A. moschatum extends to drier areas than N. cunninghamii. Possible reasons include differential tolerance of drought and fire or dispersal capacity. Here, we compare these species in their responses to water deficits. Differences in seedling survival, leaf tissue damage, shoot water relations, stomatal sensitivity, allocation of biomass and the long-term water-use efficiency of each species in response to water stress were investigated. N. cunninghamii showed traits typical of a high-water-use species, such as high stomatal conductance, a strategy that is not surprising in a rainforest species. However, it also displayed an exceptional ability to draw water from the soil and longer seedling roots, allowing replacement of water lost, at least in the short term. A. moschatum showed a more conservative water-use strategy, surviving greater internal dehydration with less damage, and displaying greater stomatal sensitivity to drought and long-term water-use efficiency in trees. The apparently superior long-term drought resistance of A. moschatum may in part explain its more common occurrence in drier regions than N. cunninghamii, at least in Tasmania, while the capacity of N. cunninghamii to survive short but severe periods of water stress correlates well with its higher position in the canopy and greater exposure to sunlight and desiccating winds. However, there is little evidence to suggest that the absence of N. cunninghamii from the rainforests of eastern Victoria is due to drought. We also suggest that the water-use strategy of N. cunninghamii may relate not just to surviving water deficits, but to maximising annual carbon gain in a temperate climate that is, on average, driest during the warmest time of the year.


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