Plant water parameters and the remote sensing R
                     1300/R
                     1450 leaf water index: controlled condition dynamics during the development of water deficit stress

The kinetics of protein incorporation from newly-absorbed nitrogen (N, de novo protein synthesis) was estimated by 15N tracing in 18-week-old white clover plants (Trifolium repens L. cv. Regal) during 7 d of water-deficit treatment. The physiological relationship between kinetics and accumulation of proline and ammonia in response to the change in leaf-water parameters was also assessed. All leaf-water parameters measured decreased gradually under water deficit. Leaf and root dry mass was not significantly affected during the first 3 d when decreases in leaf-water parameters were substantial. However, metabolic parameters such as total N, proline and ammonia were significantly affected within 1 d of commencement of water-deficit treatment. Water-deficit treatment significantly increased the proline and NH3–NH4+ concentrations in both leaves and roots. There was a marked reduction in the amount of N incorporated into the protein fraction from the newly absorbed N (NANP) in water-deficit stressed plants, particularly in leaf tissue. This reduction in NANP was strongly associated with an increased concentration of NH3–NH4+ in roots (P≤0.05) and proline (P≤0.01) in leaves and roots. These results suggest that proline accumulation may be a sensitive biochemical indicator of plant water status and of the dynamics of de novo protein synthesis in response to stress severity.

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Optimizing irrigation and determining the most sensitive development stage to drought in barley (Hordeum vulgare L.) in a semi-arid environment

Acta Botanica Croatica ◽

10.37427/botcro-2020-011 ◽

2020 ◽

Vol 79 (1) ◽

pp. 87-94

Author(s):

Leila Romdhane ◽

Nicola Dal Ferro ◽

Amor Slama ◽

Leila Radhouane

Keyword(s):

Water Potential ◽

Water Deficit ◽

Leaf Water Potential ◽

Yield Components ◽

Stem Elongation ◽

Leaf Water ◽

Water Deficit Stress ◽

Growth Stages ◽

Development Stages ◽

Three Stages

Rising temperatures and increasing water scarcity, which are already important issues, are expected to intensify in the near future due to global warming. Optimizing irrigation in agriculture is a challenge. Understanding the response of crop development stages to water deficit stress provides an opportunity for optimizing irrigation. Here we studied the response of two barley varieties (Rihane, Martin), to water deficit stress at three development stages (tillering, stem elongation, and heading) by measuring water status and grain yield components in a field experiment in Tunisia. The three stages were selected due to their importance in crop growth and grain development. Water deficit stress was initiated by withholding water for 21 days at the three stages with subsequent re-watering. Water deficit led to a progressive decrease in leaf water potential. In both varieties, heading was the stage most sensitive to water deficit. Leaf water potential measurements indicated that water deficit stress was more severe during heading, which to some extent may have influenced the comparison between growth stages. During heading, the number of ears per plant and weight of a thousand grains were reduced by more than 70% and 50%, respectively compared with stress at tillering. Comparison of yield components showed differences between the two barley varieties only when the water deficit was produced during the tillering stage.

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Non-Contact Measurement Methods of Detecting Plant Water Deficit Stress for Space Flight Growth Chamber Application

10.4271/2004-01-2455 ◽

2004 ◽

Author(s):

Hans-Dieter Seelig ◽

David M. Klaus ◽

Louis S. Stodieck ◽

Alexander Hoehn

Keyword(s):

Water Deficit ◽

Space Flight ◽

Measurement Methods ◽

Growth Chamber ◽

Water Deficit Stress ◽

Plant Water ◽

Contact Measurement ◽

Plant Water Deficit

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Response to terminal water deficit stress of cowpea, pigeonpea, and soybean in pure stand and in competition

Australian Journal of Agricultural Research ◽

10.1071/ar07155 ◽

2008 ◽

Vol 59 (1) ◽

pp. 27 ◽

Cited By ~ 15

Author(s):

A. A. Likoswe ◽

R. J. Lawn

Keyword(s):

Water Deficit ◽

Water Status ◽

Leaf Water ◽

Water Deficit Stress ◽

Pure Stand ◽

Leaf Water Status ◽

Test Species ◽

Dehydration Tolerance ◽

Dehydration Avoidance ◽

Leaf Survival

The response to terminal water deficit stress of three grain legumes, soybean, cowpea and pigeonpea, was evaluated in plants grown in large tubes, in competition with either the same species or one of the other two species. The aim was to explore how species differences in drought response affected water use, growth and survival of plants in pure stand and in competition. Two plants, comprising the test species and its competitor, were grown in each tube. Water was withheld 26 days after sowing by which time each plant had at least three fully expanded trifoliolate leaves. Leaf water status and plant growth were measured through destructive samples when 80% and 90% of the estimated plant available water (PAW) was depleted and at plant death, while PAW depletion, node growth and leaf survival were monitored at 2–3 day intervals until the last plants died (61 days after water was withheld). In pure stand, the rate of PAW depletion was initially slowest in cowpea despite its much larger leaf area, and fastest in soybean. Node growth was most sensitive in cowpea, ceasing at 65% PAW depletion compared with 85% PAW depletion in pigeonpea and soybean, so that the latter two species produced relatively more nodes after water was withheld. However, senescence of the lower leaves was most rapid in soybean and slowest in cowpea. Cowpea and pigeonpea extracted almost all PAW and died an average 18 days and 14 days, respectively, after maximum PAW depletion. In contrast, soybean died before 90% of PAW was depleted and so in pure stand used less water. There were otherwise only minor differences between the species combinations in the timing and maximum level of PAW depletion. The ability of cowpea and pigeonpea to maintain leaf water status above lethal levels for longer was achieved through different means. Cowpea relied primarily on dehydration avoidance and maintained tissue water status higher for longer, whereas pigeonpea demonstrated greater dehydration tolerance. While significant levels of osmotic adjustment (OA) were identified in soybean and pigeonpea, OA appeared to be of limited benefit to leaf survival in soybean. Pigeonpea invested significantly more total dry matter (TDM) in roots than either cowpea or soybean. Cowpea survived longest in pure stand whereas pigeonpea and soybean survived shortest in pure stand, suggesting that the dehydration avoidance response of cowpea was more effective in competition with like plants whereas the dehydration tolerance strategies of pigeonpea and soybean were least effective when competing against like plants. On average, TDM per plant ranked in the order cowpea > soybean > pigeonpea, largely reflecting initial differences in plant size when water was withheld. However, there was an inverse relation between TDM of a species and that of its competitor, so that in effect, water not used by a given plant to produce TDM was used by its competitor and there were no differences in TDM production per tube.

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Water deficit stress induces different monoterpene and sesquiterpene emission changes in Mediterranean species. Relationship between terpene emissions and plant water potential

Chemosphere ◽

10.1016/j.chemosphere.2006.10.029 ◽

2007 ◽

Vol 67 (2) ◽

pp. 276-284 ◽

Cited By ~ 88

Author(s):

E. Ormeño ◽

J.P. Mévy ◽

B. Vila ◽

A. Bousquet-Mélou ◽

S. Greff ◽

...

Keyword(s):

Water Potential ◽

Water Deficit ◽

Water Deficit Stress ◽

Plant Water ◽

Mediterranean Species ◽

Species Relationship ◽

Plant Water Potential ◽

Emission Changes

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Next generation phenotyping for developing climate resilient rice varieties

ORYZA- An International Journal on Rice ◽

10.35709/ory.2019.56.s.2 ◽

2019 ◽

Vol 56 (Special Issue) ◽

pp. 92-105

Author(s):

Rabi N Sahoo ◽

C Viswanathan ◽

Gopal Krishna ◽

Bappa Das ◽

Swati Goel ◽

...

Keyword(s):

Remote Sensing ◽

Water Deficit ◽

Multispectral Imaging ◽

Sugar Content ◽

Stress Index ◽

Water Deficit Stress ◽

Next Generation ◽

Crop Water Stress Index ◽

Non Invasive ◽

Rice Genotypes

Present paper deals with different components of next generation phenomics for characterizing rice genotypes for water deficit stress. Major sensors used in the study were non-imaging hyperspectal remote sensing, thermal imaging at ground platform and RGB and multispectral imaging sensors from drone platform. Different spectral indices were evaluated along with new proposed index and different multivariate models were studied for non-invasive estimation of relative water content (RWC) and sugar content in rice plant using spectral reflectance data collected in spectral range 350 to 2500 nm. Spectral data were further used for spectral discrimination of rice genotypes. Crop water stress index derived from thermal images acquired for rice genotypes could well characterize the drought resistant and sensitive genotypes. Initial study on field phenotyping through drone remote sensing using multispectral and RGB sensor was also explored to capture differential response of genotypes, trait and heat map mapping. All developed protocols as reliable alternative to conventional methods are fast, economic and non-invasive and in use in plant phenomics centre for high throughput plant phenotyhping for water deficit stress studies.

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The effect of root hairs under drought in open field conditions

10.5194/egusphere-egu21-6332 ◽

2021 ◽

Author(s):

Maria Marin ◽

Deborah S Feeney ◽

Lawrie K Brown ◽

Muhammad Naveed ◽

Siul Ruiz ◽

...

Keyword(s):

Water Potential ◽

Water Deficit ◽

Open Field ◽

Leaf Water Potential ◽

Root Hair ◽

Root Hairs ◽

Leaf Water ◽

Plant Water ◽

Clay Loam ◽

Wild Type

Root hairs represent an attractive target for future crop breeding, to improve resource use efficiency and stress tolerance. Most studies investigating root hairs have focused on plant tolerance to phosphorus deficiency and rhizosheath formation under controlled conditions. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. Although root hairs and rhizosphere are assumed to play a key role in regulating plant water relations, their effect on plant water uptake has been rarely investigated. As such, this study aimed to experimentally elucidate some of the impacts that root hairs have on plant performance under field conditions and water deficit. A field experiment was set up in Scotland for two consecutive years, in 2017 (a typical year) and 2018 (the driest growing season ever recorded at this site), under different soil textures (i.e., clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Measurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance. This resulted in less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot phosphorus accumulation. Specifically, minimum leaf water potential differed significantly (P = 0.021) between the wild type (-1.43 MPa) and its hairless mutant (-1.76 MPa) grown in clay loam, with the mutant exhibiting greater water stress. In agreement with leaf water potential measurements, at the peak of water stress, leaf abscisic acid concentration was significantly (P = 0.023) greater for the hairless mutant (394 ng g-1) than the wild type (250 ng g-1) grown in clay loam soil. Under water deficit conditions, in clay loam soil, shoot phosphorus accumulation in the wild type (2.49 mg P shoot-1) was over twice that in the hairless mutant (1.10 mg P shoot-1). Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought. While yield of the hairless mutant significantly (P = 0.012) decreased from 2017 to 2018 in both clay (-26%) and sandy (-33%) loam soils, no significant differences were found between years in the yield of the wild type. Therefore, selecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder&#8217;s dilemma of trying to simultaneously enhance both productivity and resilience. To our knowledge, the present findings provide the first evidence of the effect of root hairs under drought in open field conditions (i.e., real agricultural system). Therefore, along with the well-recognized role for P uptake, maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change.

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Rootstocks and Plant Water Relations Affect Sugar Accumulation of Citrus Fruit Via Osmotic Adjustment

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.129.6.0881 ◽

2004 ◽

Vol 129 (6) ◽

pp. 881-889 ◽

Cited By ~ 39

Author(s):

Graham H. Barry ◽

William S. Castle ◽

Frederick S. Davies

Keyword(s):

Water Deficit ◽

Water Relations ◽

Osmotic Adjustment ◽

Fruit Size ◽

Soluble Solids ◽

Water Deficit Stress ◽

Sugar Accumulation ◽

Plant Water Relations ◽

Plant Water ◽

Sucrose Hydrolysis

Citrus rootstocks have well-known effects on tree size, crop load, fruit size, and various fruit quality factors. Fruit from trees budded on invigorating rootstocks are generally larger with lower soluble solids concentration (SSC) and titratable acidity compared to fruit from trees budded on less invigorating rootstocks. Although it is unclear how rootstocks exert their influence on juice quality of Citrus L. species, plant water relations are thought to play a central role. In addition, the larger fruit size associated with invigorating rootstocks and the inverse relationship between SSC and fruit size implies that fruit borne on trees on invigorating rootstocks have lower SSC due to dilution effects in larger fruit. To determine how rootstock type affects sugar accumulation in fruit of Citrus species, controlled water-deficit stress was applied to mature `Valencia' sweet orange [C. sinensis (L.) Osb.] trees on Carrizo citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] or rough lemon (C. jambhiri Lush.) rootstocks. Withholding water from the root zone of citrus trees during stage II of fruit development decreased midday stem water potential and increased the concentrations of primary osmotica, fructose and glucose. Sucrose concentration was not affected, suggesting that sucrose hydrolysis took place. Increased concentrations of sugars and SSC in fruit from moderately water-stressed trees occurred independently of fruit size and juice content. Thus, passive dehydration of juice sacs, and concentration of soluble solids, was not the primary cause of differences in sugar accumulation. Controlled water-deficit stress caused active osmotic adjustment in fruit of `Valencia' sweet orange. However, when water-deficit stress was applied later in fruit development (e.g., stage III) there was no increase in sugars or SSC. The evidence presented supports the hypothesis that differential sugar accumulation of citrus fruit from trees on rootstocks of contrasting vigor and, hence, plant water relations, is caused by differences in tree water status and the enhancement of sucrose hydrolysis into component hexose sugars resulting in osmotic adjustment. Therefore, inherent rootstock differences affecting plant water relations are proposed as a primary cause of differences in sugar accumulation and SSC among citrus rootstocks.

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