scholarly journals How Do Crops Balance Water Supply and Demand when Water Is Limiting?

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 208
Author(s):  
Andrew Borrell ◽  
Barbara George-Jaeggli ◽  
Erik van Oosterom ◽  
Graeme Hammer ◽  
Emma Mace ◽  
...  
Keyword(s):  
Water Supply ◽  
Leaf Area ◽  
Supply And Demand ◽  
Crop Improvement ◽  
Limiting Factor ◽  
Crop Species ◽  
Stay Green ◽  
Canopy Development ◽  
Improvement Programs ◽  
Water Supply And Demand

Plants are sessile organisms requiring mechanisms that enable them to balance water supply and demand in dry environments. Demand (D) is largely driven by canopy size (transpirational leaf area), although differences in transpiration per unit leaf area also occur. Supply (S) is primarily driven by water capture via the root system. Drought stress can be defined as the situation where supply of water cannot meet demand of the crop, such that water availability is the limiting factor for biomass accumulation. Under such conditions, plants will need to reduce D in order to meet the limited S, access more water to increase S, or increase the efficiency with which water is utilised. We used sorghum, a model C4 crop species, to demonstrate how the stay-green trait can modulate canopy development and root architecture to enhance adaptation. We show how stay-green positively impacts the balance between S and D under post-flowering drought, including insights at the molecular level. We provide examples of how canopy and root traits impact the S/D balance in other cereals under water limitation. For example, on the supply side, the extent of genetic variation for root angle (RA) has been evaluated in sorghum, wheat and barley, and genomic regions associated with RA have been mapped. Furthermore, the relationship between RA and grain yield has been explored in barley and sorghum field trials. The capacity to manipulate components of S and D to optimise the S/D balance should assist crop improvement programs to develop enhanced ideotypes for dry environments.

scholarly journals Water: the most important ‘molecular’ component of water stress tolerance research

2013 ◽  
Vol 40 (12) ◽  
pp. 1310 ◽  
Author(s):  
Vincent Vadez ◽  
Jana Kholova ◽  
Mainassara Zaman-Allah ◽  
Nouhoun Belko
Keyword(s):  
Water Stress ◽  
Water Supply ◽  
Water Deficit ◽  
Plant Traits ◽  
Supply And Demand ◽  
Limiting Factor ◽  
Management Options ◽  
Major Drawback ◽  
Water Stress Tolerance ◽  
Water Supply And Demand

Water deficit is the main yield-limiting factor across the Asian and African semiarid tropics and a basic consideration when developing crop cultivars for water-limited conditions is to ensure that crop water demand matches season water supply. Conventional breeding has contributed to the development of varieties that are better adapted to water stress, such as early maturing cultivars that match water supply and demand and then escape terminal water stress. However, an optimisation of this match is possible. Also, further progress in breeding varieties that cope with water stress is hampered by the typically large genotype × environment interactions in most field studies. Therefore, a more comprehensive approach is required to revitalise the development of materials that are adapted to water stress. In the past two decades, transgenic and candidate gene approaches have been proposed for improving crop productivity under water stress, but have had limited real success. The major drawback of these approaches has been their failure to consider realistic water limitations and their link to yield when designing biotechnological experiments. Although the genes are many, the plant traits contributing to crop adaptation to water limitation are few and revolve around the critical need to match water supply and demand. We focus here on the genetic aspects of this, although we acknowledge that crop management options also have a role to play. These traits are related in part to increased, better or more conservative uses of soil water. However, the traits themselves are highly dynamic during crop development: they interact with each other and with the environment. Hence, success in breeding cultivars that are more resilient under water stress requires an understanding of plant traits affecting yield under water deficit as well as an understanding of their mutual and environmental interactions. Given that the phenotypic evaluation of germplasm/breeding material is limited by the number of locations and years of testing, crop simulation modelling then becomes a powerful tool for navigating the complexity of biological systems, for predicting the effects on yield and for determining the probability of success of specific traits or trait combinations across water stress scenarios.

scholarly journals Light Quality Environment and Photomorphological Responses of Young Olive Trees

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 369
Author(s):  
Federico J. Ladux ◽  
Eduardo R. Trentacoste ◽  
Peter S. Searles ◽  
M. Cecilia Rousseaux
Keyword(s):  
Leaf Area ◽  
Light Quality ◽  
Plant Morphology ◽  
Cultivar Differences ◽  
Crop Species ◽  
Area Index ◽  
Canopy Development ◽  
Morphological Responses ◽  
Olive Trees ◽  
G Ratio

Tree densities have increased greatly in olive orchards over the last few decades. In many annual crop species, increased density reduces the horizontal red/far-red (R/FR) and blue/green (B/G) ratios during canopy development even before direct shading occurs, and such changes are known to alter plant morphology. This study with olive trees evaluated: (1) whether the leaf area index (LAI) of neighboring trees modifies the light quality environment prior to a tree being directly shaded and (2) the potential morphological responses of three olive cultivars to changes in light quality. Increasing LAI using different spatial arrangements of potted, three-year-old trees reduced the horizontal R/FR ratio more than that of the B/G ratio. Cultivar-specific responses to low R/FR ratio were observed for individual leaf area and aboveground/belowground biomass ratio using laterally positioned FR mirrors or green fences. No statistically significant responses were detected in response to green vegetation fences that reduced both horizontal R/FR and B/G ratios, but a cluster analysis grouped together the overall morphological responses to both FR mirrors and green fences. These results in olive trees suggest that cultivar differences in response to light quality may be relevant for understanding adaptation to dense orchards and identifying cultivars best suited to them.

scholarly journals A Probabilistic Approach for Characterization of Sub-Annual Socioeconomic Drought Intensity-Duration-Frequency (IDF) Relationships in a Changing Environment

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1522 ◽  
Author(s):  
Hadi Heidari ◽  
Mazdak Arabi ◽  
Mahshid Ghanbari ◽  
Travis Warziniack
Keyword(s):  
Water Supply ◽  
Mixture Model ◽  
Supply And Demand ◽  
Probabilistic Approach ◽  
Water Model ◽  
Drought Risk ◽  
Drought Intensity ◽  
Water Supply And Demand ◽  
Intensity Duration Frequency

Changes in climate, land use, and population can increase annual and interannual variability of socioeconomic droughts in water-scarce regions. This study develops a probabilistic approach to improve characterization of sub-annual socioeconomic drought intensity-duration-frequency (IDF) relationships under shifts in water supply and demand conditions. A mixture Gamma-Generalized Pareto (Gamma-GPD) model is proposed to enhance characterization of both the non-extreme and extreme socioeconomic droughts. Subsequently, the mixture model is used to determine sub-annual socioeconomic drought intensity-duration-frequency (IDF) relationships, return period, amplification factor, and drought risk. The application of the framework is demonstrated for the City of Fort Collins (Colorado, USA) water supply system. The water demand and supply time series for the 1985–2065 are estimated using the Integrated Urban water Model (IUWM) and the Soil and Water Assessment Tool (SWAT), respectively, with climate forcing from statistically downscaled CMIP5 projections. The results from the case study indicate that the mixture model leads to enhanced estimation of sub-annual socioeconomic drought frequencies, particularly for extreme events. The probabilistic approach presented in this study provides a procedure to update sub-annual socioeconomic drought IDF curves while taking into account changes in water supply and demand conditions.

Water-Stressed Pakistan

Asian Survey ◽  
2019 ◽  
Vol 59 (6) ◽  
pp. 1116-1136
Author(s):  
Amit Ranjan
Keyword(s):  
Water Supply ◽  
Supply And Demand ◽  
Agriculture Sector ◽  
Available Water ◽  
Water Supply And Demand

The widening gap between water supply and demand is the biggest threat and challenge before Pakistan. Of the available water, much is polluted. Both scarcity and pollution threaten the agriculture sector, on which the country’s economy depends.

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