DROUGHT-TOLERANT MAIZE GENOTYPES INVEST IN ROOT SYSTEM  AND MAINTAIN HIGH HARVEST INDEX DURING WATER STRESS

ABSTRACT – Drought is considered the primary limitation to agriculture and, can reduce grain yield by up to 60%when occurs at pre-flowering in maize. In this context this research, aimed to understand the maize genotypes behaviorto drought management and carbon partitioning between grain production and structures to maintain hydration whensubmitted to drought. Maize genotypes tolerant (DKB390 and P30F35) and sensitive (BRS1010 and 2B710) to droughtwere grown in a greenhouse using two water conditions: irrigated and stressed. Water deficit was imposed atpre-flowering and maintained for twelve days. Leaf water potential, gaseous exchange and male and female floweringinterval were evaluated. At the end of the cycle, production components and root/shoot ratio dry weight were evaluated.Drought-tolerant genotypes used root system as a mechanism of tolerance to drought, which ensure greater efficiencyin absorption and loss of water and, consequently, greater stomatal conductance during the drought, compared to thesensitive-genotypes. In addition, drought-tolerant genotypes showed greater stability in the source-sink relationship,exhibiting higher photosynthetic rate and harvest index.Keywords: water stress, carbon partitioning; root/shoot ratio dry weight, gas exchanges, Zea mays.GENÓTIPOS DE MILHO TOLERANTES À SECA INVESTEM EM SISTEMA RADICULARE MANTEM ALTO ÍNDICE DE COLHEITA DURANTE O ESTRESSE HÍDRICORESUMO- A seca é considerada restrição primária à agricultura, e no milho, quando ocorre no pré-florescimento,pode reduzir o rendimento de grãos em até 60%. Neste contexto, objetivou-se entender como genótipos de milhocontrastantes para tolerância à seca, gerenciam o particionamento de carbono entre produção de grãos e estruturasde manutenção da hidratação durante a seca. Para isso, em casa de vegetação cultivaram-se genótipos de milhotolerantes (DKB390 e P30F35) e sensíveis (BRS1010 e 2B710) à seca, em duas condições hídricas: irrigadonormal e déficit hídrico. No pré-florecimento foi imposto o déficit hídrico, que foi mantido por doze dias.Posteriormente avaliou-se o potencial hídrico foliar, trocas gasosas e intervalo de florescimento masculino e feminino.No final do ciclo, avaliaram-se os componentes de produção e a razão raiz/parte aérea. Constatou-se que, genótipostolerantes utilizaram preferencialmente sistema radicular como um mecanismo de tolerância à seca, o que garantiu aesses genótipos, maior eficiência entre a absorção e perda de água e, consequentemente, maior condutância estomáticadurante a seca, em relação aos genótipos sensíveis. Além disso, os genótipos tolerantes apresentaram maior equilíbrioem suas relações fonte e dreno, exibindo maiores taxa fotossintética e índice de colheita.Palavras-chave: estresse hídrico, particionamento de carbono, razão raiz/parte aérea, trocas gasosas, Zea mays.

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DROUGHT-TOLERANT MAIZE GENOTYPES INVEST IN ROOT SYSTEM AND MAINTAIN HIGH HARVEST INDEX DURING WATER STRESS

Revista Brasileira de Milho e Sorgo ◽

10.18512/1980-6477/rbms.v15n3p450-460 ◽

2016 ◽

Vol 15 (3) ◽

pp. 450 ◽

Cited By ~ 3

Author(s):

RONIEL GERALDO AVILA ◽

PAULO CESÁR MAGALHÃES ◽

AMAURI ALVES DE ALVARENGA ◽

ALYNE DE OLIVEIRA LAVINSKY ◽

CLEIDE NASCIMENTO CAMPOS ◽

...

Keyword(s):

Water Stress ◽

Root System ◽

Dry Weight ◽

Carbon Partitioning ◽

Drought Tolerant ◽

Shoot Ratio ◽

Root Shoot Ratio ◽

Maize Genotypes ◽

Female Flowering ◽

Source Sink

ABSTRACT – Drought is considered the primary limitation to agriculture and, can reduce grain yield by up to 60% when occurs at pre-flowering in maize. In this context this research, aimed to understand the maize genotypes behavior to drought management and carbon partitioning between grain production and structures to maintain hydration when submitted to drought. Maize genotypes tolerant (DKB390 and P30F35) and sensitive (BRS1010 and 2B710) to drought were grown in a greenhouse using two water conditions: irrigated and stressed. Water deficit was imposed at pre-flowering and maintained for twelve days. Leaf water potential, gaseous exchange and male and female flowering interval were evaluated. At the end of the cycle, production components and root/shoot ratio dry weight were evaluated. Drought-tolerant genotypes used root system as a mechanism of tolerance to drought, which ensure greater efficiency in absorption and loss of water and, consequently, greater stomatal conductance during the drought, compared to the sensitive-genotypes. In addition, drought-tolerant genotypes showed greater stability in the source-sink relationship, exhibiting higher photosynthetic rate and harvest index.Keywords: water stress, carbon partitioning; root/shoot ratio dry weight, gas exchanges, Zea mays.GENÓTIPOS DE MILHO TOLERANTES À SECA INVESTEM EM SISTEMA RADICULARE MANTEM ALTO ÍNDICE DE COLHEITA DURANTE O ESTRESSE HÍDRICORESUMO- A seca é considerada restrição primária à agricultura, e no milho, quando ocorre no pré-florescimento, pode reduzir o rendimento de grãos em até 60%. Neste contexto, objetivou-se entender como genótipos de milho contrastantes para tolerância à seca, gerenciam o particionamento de carbono entre produção de grãos e estruturas de manutenção da hidratação durante a seca. Para isso, em casa de vegetação cultivaram-se genótipos de milho tolerantes (DKB390 e P30F35) e sensíveis (BRS1010 e 2B710) à seca, em duas condições hídricas: irrigado normal e déficit hídrico. No pré-florecimento foi imposto o déficit hídrico, que foi mantido por doze dias. Posteriormente avaliou-se o potencial hídrico foliar, trocas gasosas e intervalo de florescimento masculino e feminino. No final do ciclo, avaliaram-se os componentes de produção e a razão raiz/parte aérea. Constatou-se que, genótipos tolerantes utilizaram preferencialmente sistema radicular como um mecanismo de tolerância à seca, o que garantiu a esses genótipos, maior eficiência entre a absorção e perda de água e, consequentemente, maior condutância estomática durante a seca, em relação aos genótipos sensíveis. Além disso, os genótipos tolerantes apresentaram maior equilíbrio em suas relações fonte e dreno, exibindo maiores taxa fotossintética e índice de colheita.Palavras-chave: estresse hídrico, particionamento de carbono, razão raiz/parte aérea, trocas gasosas, Zea mays.

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Cluster and principle component analyses of maize accessions under normal and water stress conditions

Journal of Agricultural Sciences Belgrade ◽

10.2298/jas1501033m ◽

2015 ◽

Vol 60 (1) ◽

pp. 33-48 ◽

Cited By ~ 4

Author(s):

Hafiz Mustafa ◽

Jehanzeb Farooq ◽

E Ejaz-Ul-Hasan ◽

Tahira Bibi ◽

Tariq Mahmood

Keyword(s):

Leaf Temperature ◽

Root Density ◽

Stress Conditions ◽

Root Weight ◽

Positive Correlation ◽

Drought Tolerant ◽

Shoot Ratio ◽

Root Shoot Ratio ◽

Maize Genotypes ◽

Breeding Programmes

In the current set of an experiment, forty maize genotypes were assessed for drought associated traits. For evaluation of these traits, PC and correlation analyses were employed to obtain suitable parents that can be further exploited in future breeding programmes. Correlation analysis revealed some important associations among the traits studied. Fresh root length had positive and significant associations, but leaf temperature had a significant negative correlation with root density at both 40% and 100% moisture levels while root density had negative association at 100% and positive correlation at 40% moisture level with chlorophyll content. The positive correlation among these yield contributing traits suggested that these characters are important for direct selection of drought tolerant high yielding genotypes. Principal component (PC) analysis showed first 4 PCs having Eigen value >1 explaining 86.7% and 88.4% of the total variation at 40% and 100% moisture levels respectively with different drought related traits. Cluster analysis classified 40 accessions into four divergent groups. The members of clusters 1 and 2 may be combined in future breeding programmes to obtain genotypes/hybrids that can perform well under drought stress conditions. Members of cluster 3 may be selected on the basis of root density, leaf temperature, dry root weight and root shoot ratio by weight and can be combined with members of cluster 4 due to higher leaf temperature and root shoot ratio by length. The results showed that the germplasm having a wide genetic diversity can be thus utilized for future breeding programme to obtain drought tolerant maize genotypes/ hybrids for adaptation to water scarce areas. This article has been retracted. Link to the retraction <a href="http://dx.doi.org/10.2298/JAS1603303E">10.2298/JAS1603303E</a>

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Putative Mechanisms of Drought Tolerance in Maize (Zea mays L.) via Root System Architecture Traits

Annual Research & Review in Biology ◽

10.9734/arrb/2019/v32i230079 ◽

2019 ◽

pp. 1-19 ◽

Cited By ~ 1

Author(s):

A. M. M. Al-Naggar ◽

M. M. Shafik ◽

M. O. A. Elsheikh

Keyword(s):

Water Stress ◽

Drought Tolerance ◽

Root System ◽

Root Architecture ◽

Dry Weight ◽

Grain Filling ◽

Tolerance Index ◽

Root Branching ◽

Crown Root ◽

Drought Tolerant

Identifying maize genotypes with favorable root architecture traits for drought tolerance is prerequisite for initiating a successful breeding program for developing high yielding and drought tolerant varieties of maize. The aims of the present study were: (i) to identify drought tolerant genotypes of maize at flowering and grain filling, (ii) to interpret the correlations between the drought tolerance and root architecture traits and (iii) to identify the putative mechanisms of drought tolerance via root system traits. An experiment was carried out in two years using a split plot design with three replications. The main plots were assigned to three water stress levels, namely: well watering (WW), water stress at flowering (WSF) and water stress at grain filling (WSG), and sub-plots to 22 maize cultivars and populations. Drought tolerance index (DTI) had strong and positive associations with crown root length (CRL), root circumference (RC) and root dry weight (DRW) under both WSF and WSG, a negative correlation with brace root whorls (BW), and positive correlations with crown root number (CN) under WSF and brace root branching (BB) and crown root branching (CB) under WSG. These root traits are therefore considered as putative mechanisms of drought tolerance. The cultivars Pioneer-3444, SC-128, Egaseed-77, SC-10 and TWC-324 showed the most drought tolerant and the highest yielding in a descending order; each had a number of such drought tolerance mechanisms. Further investigation should be conducted to determine the underlying root mechanisms contributing to the selection of water-efficient hybrids of maize.

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Competition between drought-tolerant upland rice cultivars and weeds under water stress condition

Planta Daninha ◽

10.1590/s0100-83582013000200006 ◽

2013 ◽

Vol 31 (2) ◽

pp. 291-302 ◽

Cited By ~ 5

Author(s):

F.B. Cerqueira ◽

E.A.L. Erasmo ◽

J.I.C. Silva ◽

T.V. Nunes ◽

G.P. Carvalho ◽

...

Keyword(s):

Water Stress ◽

Leaf Area ◽

Stress Condition ◽

Upland Rice ◽

Total Concentration ◽

Dry Weight ◽

Rice Cultivars ◽

Drought Tolerant ◽

Water Stress Condition ◽

Water Conditions

The objective of this study was to evaluate the competitiveness of two cultivars of upland rice drought-tolerant, cultured in coexistence with weed S. verticillata, under conditions of absence and presence of water stress. The experiment was conducted in a greenhouse at the Experimental Station of the Universidade Federal de Tocantins, Gurupi-TO Campus. The experimental design was completely randomized in a factorial 2 x 2 x 4 with four replications. The treatments consisted of two rice cultivars under two water conditions and four densities. At 57 days after emergence, were evaluated in rice cultivars and weed S. verticillata leaf area, dry weight of roots and shoots and total concentration and depth of roots. Was also evaluated in rice cultivars, plant height and number of tillers. Water stress caused a reduction in leaf area, the concentration of roots and vegetative components of dry matter (APDM, and MSR MST) of rice cultivars and Jatoba Catetão and weed S. verticillata. The competition established by the presence of the weed provided reduction of all vegetative components (MSPA, and MSR MST) of cultivars and Jatoba Catetão. It also decreased the number of tillers, the concentration of roots and leaf area. At the highest level of weed competition with rice cultivars, a greater decrease in vegetative components and leaf area of culture, regardless of water conditions.

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IDENTIFICATION OF DROUGHT TOLERANT WHEAT GENOTYPES UNDER WATER DEFICIT CONDITIONS

International Journal of Research -GRANTHAALAYAH ◽

10.29121/granthaalayah.v4.i2.2016.2830 ◽

2016 ◽

Vol 4 (2) ◽

pp. 206-214 ◽

Cited By ~ 1

Author(s):

Zaid Chachar ◽

N. A. Chachar ◽

Q.I. Chachar ◽

S.M Mujtaba ◽

G.A Chachar ◽

...

Keyword(s):

Water Stress ◽

Seed Germination ◽

Osmotic Stress ◽

Root Length ◽

Dry Weight ◽

Shoot Length ◽

Wheat Genotypes ◽

Maximum Reduction ◽

Drought Tolerant

Climate change is emerging phenomena and causing frequent drought which lead to scaricity of water, which ultimately nagetively affecting wheat (Triticumaestivum L.) yield all around the world. The aim of this study was to explore the potential deought tolerant wheat genotypes for candidate genes exploration. This study was conducted during the year 2014-2015 at Plant Physiology Division, Nuclear Institute of Agriculture (NIA) Tandojam. The six wheat genotypes (cv. MT-1/13, MT-2/13, MT-3/13, MT-4/13 Chakwal-86 and Khirman) were investigated for their response at germination and seedling stage under different water stress treatments (0, -0.5, -0.75 and -1.0 MPa) in controlled conditions. The results of experiments with reference to genotypes revealed that genotype Chakwal-86 shows maximum seed germination (82.58 %), while the genotype Khirman shows maximum shoot length (7.23 cm), root length (15.1 cm), shoot fresh wt. (5.85 g 10-1shoots), root fresh wt. (3.45 g 10-1roots), shoot dry wt. (1.33 g 10-1shoots), root dry wt. (0.69 g 10-1roots). Among the genotypes tested Khirman and MT-4/13 are the tolerant genotypes had the potential to perform better under drought conditions, whereas MT-4/13 and Chakwal-86 were moderate tolerant under water stress conditions. Moreover, the genotypes i.e. MT-1/13 and MT-2/13 are the sensitive genotypes under drought environment. It is concluded from present in-vitro studies that osmotic stress significantly reduced the seed germination shoot/root length fresh and dry weight in all six wheat genotypes. The maximum reduction was found at higher osmotic stress induced by PEG-6000 (-1.0 MPa) significantly.

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Dissecting the effects of nitrate, sucrose and osmotic potential on Arabidopsis root and shoot system growth in laboratory assays

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2011.0230 ◽

2012 ◽

Vol 367 (1595) ◽

pp. 1489-1500 ◽

Cited By ~ 36

Author(s):

Peter Roycewicz ◽

Jocelyn E. Malamy

Keyword(s):

Root System ◽

Osmotic Potential ◽

Wide Spectrum ◽

System Size ◽

Growth Media ◽

Target Tissue ◽

Shoot Ratio ◽

Root Shoot Ratio ◽

Shoot System ◽

The Impact

Studying the specific effects of water and nutrients on plant development is difficult because changes in a single component can often trigger multiple response pathways. Such confounding issues are prevalent in commonly used laboratory assays. For example, increasing the nitrate concentration in growth media alters both nitrate availability and osmotic potential. In addition, it was recently shown that a change in the osmotic potential of media alters the plant's ability to take up other nutrients such as sucrose. It can also be difficult to identify the initial target tissue of a particular environmental cue because there are correlated changes in development of many organs. These growth changes may be coordinately regulated, or changes in development of one organ may trigger changes in development of another organ as a secondary effect. All these complexities make analyses of plant responses to environmental factors difficult to interpret. Here, we review the literature on the effects of nitrate, sucrose and water availability on root system growth and discuss the mechanisms underlying these effects. We then present experiments that examine the impact of nitrate, sucrose and water on root and shoot system growth in culture using an approach that holds all variables constant except the one under analysis. We found that while all three factors also alter root system size, changes in sucrose and osmotic potential also altered shoot system size. In contrast, we found that, when osmotic effects are controlled, nitrate specifically inhibits root system growth while having no effect on shoot system growth. This effectively decreases the root : shoot ratio. Alterations in root : shoot ratio have been widely observed in response to nitrogen starvation, where root growth is selectively increased, but the present results suggest that alterations in this ratio can be triggered across a wide spectrum of nitrate concentrations.

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Greenhouse production of Echinacea purpurea (L.) and E. angustifolia using different growing media, NO3−/NH4+ ratios and watering regimes

Canadian Journal of Plant Science ◽

10.4141/p05-167 ◽

2006 ◽

Vol 86 (3) ◽

pp. 809-815 ◽

Cited By ~ 5

Author(s):

Youbin Zheng ◽

Mike Dixon ◽

Praveen Saxena

Keyword(s):

Water Stress ◽

Medicinal Plant ◽

Leaf Area ◽

Production System ◽

Echinacea Purpurea ◽

Root Production ◽

Total Biomass ◽

Greenhouse Production ◽

Shoot Ratio ◽

Root Shoot Ratio

Current field cultivation and wild-harvest methods for the medicinal plant Echinacea are struggling to meet the requirements for a high-quality, uniformly produced crop for human consumption. To help meet this challenge, the potential of using a greenhouse production system for Echinacea production was explored. Echinacea purpurea (L.) Moench and angustifolia DC. var. angustifolia plants were grown in three types of greenhouse production systems: (1) deep flow solution culture (D), (2) pots with either Pro-Mix (P) or (3) sand (S). Plants were irrigated with one of three nutrient solutions containing NO3−/NH4+ ratios of 7:1, 5:1 or 3:1, respectively. The plants grown in the Pro-Mix and the sand systems were either well-watered or subjected to periodical water stress. The results obtained after 12 wk of growth showed that Echinacea root production in the greenhouse systems was comparable with or better than that in the field. Based on root and total biomass production, the Pro-Mix system was the best production system for both E. angustifolia and E. purpurea. In most cases, the NO3−/NH4+ ratio did not have significant effects on the growth of either species. When effects were seen, however, higher NO3−/NH4+ levels generally resulted in greater leaf area, root and total biomass, and a higher root/shoot ratio. Mild periodic water stress did not affect the root/shoot ratio or the root biomass in either species. The application of a periodic water stress reduced leaf area of both species, but a reduction in total biomass was only observed in E. purpurea. Key words: Echinacea, greenhouse production, hydroponic production, medicinal plant, NO3−/NH4+ ratio, water stress

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Production Techniques for Highrise™ and Seedling Live Oak

Journal of Environmental Horticulture ◽

10.24266/0738-2898-20.2.127 ◽

2002 ◽

Vol 20 (2) ◽

pp. 127-132

Author(s):

Edward F. Gilman ◽

Ann Stodola ◽

Michael D. Marshall

Keyword(s):

Large Diameter ◽

Small Diameter ◽

Dry Weight ◽

Root Pruning ◽

Root Weight ◽

Quercus Virginiana ◽

Shoot Ratio ◽

Live Oak ◽

Root Shoot Ratio ◽

Production Techniques

Abstract Cutting propagated Quercus virginiana ‘QVTIA’ Highrise™ PP #11219 and seedling live oak required the same amount of time to prune to a dominant leader in the nursery. Highrise™ live oaks were more uniform in caliper, height and root ball characteristics than the seedling crop. Finished seedling trees had larger caliper than cutting propagated Highrise™ but height was similar. Root pruning horizontal roots alone or in combination with placing root pruning fabric under the liner at planting reduced dry weight of roots in the root ball by reducing large-diameter root weight and increasing small-diameter root weight. Trees produced by both methods of root pruning survived the digging process better than non root-pruned trees in the summer digging season. Seedlings had more root weight in the root ball and a higher root: shoot ratio than Highrise™ live oak. But Highrise™ had a 45% greater small diameter root: shoot ratio than seedling live oak, and more Highrise™ survived the digging process than seedlings. Highrise™ may not need root pruning during production if dug in the dormant season.

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Drought Tolerance Responses of Purple Lovegrass and ‘Adagio’ Maiden Grass

HortScience ◽

10.21273/hortsci.42.7.1695 ◽

2007 ◽

Vol 42 (7) ◽

pp. 1695-1699 ◽

Cited By ~ 5

Author(s):

Erin Alvarez ◽

S.M. Scheiber ◽

Richard C. Beeson ◽

David R. Sandrock

Keyword(s):

Water Stress ◽

Drought Tolerance ◽

Sandy Soil ◽

Dry Weight ◽

Miscanthus Sinensis ◽

Total Biomass ◽

Shoot Dry Weight ◽

Drought Tolerant ◽

Species Being ◽

Canopy Size

Nonnative Miscanthus sinensis Anderss ‘Adagio’ and native Eragrostis spectabilis (Pursh) Steud. were evaluated for drought tolerance in a rain-excluded landscape setting in sandy soil in response to irrigation application volumes of 0 L, 0.25 L, 0.5 L, or 0.75 L. As irrigation rates increased, plant mass, canopy size, and shoot-to-root ratios increased for both species, being greatest at the 0.75-L rate. Shoot dry weight, root dry weight, total biomass, and shoot-to-root ratios were greater for E. spectabilis than M. sinensis. Cumulative water stress integral was also greater for E. spectabilis. Greater growth in conjunction with higher cumulative water stress indicates the native E. spectabilis is anisohydric and more drought-tolerant than the isohydric nonnative M. sinensis.

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Influence of Day and Night Temperatures on Sweet Pepper Seedling Development

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.121.4.699 ◽

1996 ◽

Vol 121 (4) ◽

pp. 699-704 ◽

Cited By ~ 4

Author(s):

Yaping Si ◽

Royal D. Heins

Keyword(s):

Leaf Area ◽

Dry Weight ◽

Sweet Pepper ◽

Internode Length ◽

Stem Diameter ◽

Stem Length ◽

Shoot Dry Weight ◽

Shoot Ratio ◽

Root Shoot Ratio ◽

The Difference

Sweet pepper (Capsicum annuum `Resistant Giant no. 4') seedlings were grown for 6 weeks in 128-cell plug trays under 16 day/night temperature (DT/NT) regimes from 14 to 26 °C. Seedling stem length, internode length, stem diameter, leaf area, internode and leaf count, plant volume, shoot dry weight (DW), seedling index, and leaf unfolding rate (LUR) were primarily functions of average daily temperature (ADT); i.e., DT and NT had similar effects on each growth or development parameter. Compared to ADT, the difference (DIF, where DIF = DT - NT) between DT and NT had a smaller but still statistically significant effect on stem and internode length, leaf area, plant volume, stem diameter, and seedling index. DIF had no effect on internode and leaf count, shoot DW, and LUR. The root: shoot ratio and leaf reflectance were affected by DT and DIF. Positive DIF (DT higher than NT) caused darker-green leaf color than negative DIF. The node at which the first flower initiated was related to NT. The number of nodes to the first flower on pepper plugs grown at 26 C NT was 1.2 fewer than those of plants grown at 14 °C NT.

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