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Constitutive water-conserving mechanisms are correlated with the terminal drought tolerance of pearl millet [Pennisetum glaucum (L.) R. Br.].

Kholová J, Hash CT, Kakkera A, Kocová M, Vadez V - J. Exp. Bot. (2009)

Bottom Line: In addition, Tr measured in detached leaves (g water loss cm(-2) h(-1)) from field-grown plants of the parental lines showed lower Tr values in tolerant parents.These results demonstrate that constitutive traits controlling leaf water loss under well-watered conditions correlate with the terminal drought tolerance of pearl millet.Such traits may lead to more water being available for grain filling under terminal drought.

View Article: PubMed Central - PubMed

Affiliation: International Crops Research Institute for Semi-Arid Tropics, Patancheru, Andhra Pradesh, India.

ABSTRACT
Pearl millet, a key staple crop of the semi-arid tropics, is mostly grown in water-limited conditions, and improving its performance depends on how genotypes manage limited water resources. This study investigates whether the control of water loss under non-limiting water conditions is involved in the terminal drought tolerance of pearl millet. Two pairs of tolerant x sensitive pearl millet genotypes, PRLT 2/89-33-H77/833-2 and 863B-P2-ICMB 841-P3, and near-isogenic lines (NILs), introgressed with a terminal drought tolerance quantitative trait locus (QTL) from the donor parent PRLT 2/89-33 into H77/833-2 (NILs-QTL), were tested. Upon exposure to water deficit, transpiration began to decline at lower fractions of transpirable soil water (FTSW) in tolerant than in sensitive genotypes, and NILs-QTL followed the pattern of the tolerant parents. The transpiration rate (Tr, in g water loss cm(-2) d(-1)) under well-watered conditions was lower in tolerant than in sensitive parental genotypes, and the Tr of NILs-QTL followed the pattern of the tolerant parents. In addition, Tr measured in detached leaves (g water loss cm(-2) h(-1)) from field-grown plants of the parental lines showed lower Tr values in tolerant parents. Defoliation led to an increase in Tr that was higher in sensitive than in tolerant genotypes. The differences in Tr between genotypes was not related to the stomatal density. These results demonstrate that constitutive traits controlling leaf water loss under well-watered conditions correlate with the terminal drought tolerance of pearl millet. Such traits may lead to more water being available for grain filling under terminal drought.

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Related in: MedlinePlus

Relationship between the normalized transpiration rate (NTR) and the fraction of transpirable soil water (FTSW) of two pearl millet genotype pairs: H77/833-2 and PRLT 2/89-33, and ICMB 841-P3 and 863B-P2 (H77/833-2, ICMB 841-P3—sensitive; PRLT 2/89-33, 863B-P2—tolerant) during the vegetative (a, b) and reproductive (c, d) stage in 2007. The FTSW thresholds where transpiration initiated its decline were calculated with a plateau regression procedure from SAS. Then the regression lines of the relationships between NTR and FTSW were drawn by fitting NTR to FTSW data above and below the respective threshold for transpiration decline in each genotype and assessment stage.
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fig1: Relationship between the normalized transpiration rate (NTR) and the fraction of transpirable soil water (FTSW) of two pearl millet genotype pairs: H77/833-2 and PRLT 2/89-33, and ICMB 841-P3 and 863B-P2 (H77/833-2, ICMB 841-P3—sensitive; PRLT 2/89-33, 863B-P2—tolerant) during the vegetative (a, b) and reproductive (c, d) stage in 2007. The FTSW thresholds where transpiration initiated its decline were calculated with a plateau regression procedure from SAS. Then the regression lines of the relationships between NTR and FTSW were drawn by fitting NTR to FTSW data above and below the respective threshold for transpiration decline in each genotype and assessment stage.

Mentions: At the vegetative stage, the transpiration started declining at FTSW values ranging between 0.49 and 0.30 (Fig. 1a, b). In fact, threshold values were higher for sensitive H77/833-2 and ICMB 841B-P2 than for PRLT 2/89-33 and 863B-P2 at the vegetative stage. In contrast, at the reproductive stage the transpiration dropped at similar FTSW values ranging between 0.26 and 0.35 (Fig. 1c, d) in all genotypes (Table 3).


Constitutive water-conserving mechanisms are correlated with the terminal drought tolerance of pearl millet [Pennisetum glaucum (L.) R. Br.].

Kholová J, Hash CT, Kakkera A, Kocová M, Vadez V - J. Exp. Bot. (2009)

Relationship between the normalized transpiration rate (NTR) and the fraction of transpirable soil water (FTSW) of two pearl millet genotype pairs: H77/833-2 and PRLT 2/89-33, and ICMB 841-P3 and 863B-P2 (H77/833-2, ICMB 841-P3—sensitive; PRLT 2/89-33, 863B-P2—tolerant) during the vegetative (a, b) and reproductive (c, d) stage in 2007. The FTSW thresholds where transpiration initiated its decline were calculated with a plateau regression procedure from SAS. Then the regression lines of the relationships between NTR and FTSW were drawn by fitting NTR to FTSW data above and below the respective threshold for transpiration decline in each genotype and assessment stage.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2803210&req=5

fig1: Relationship between the normalized transpiration rate (NTR) and the fraction of transpirable soil water (FTSW) of two pearl millet genotype pairs: H77/833-2 and PRLT 2/89-33, and ICMB 841-P3 and 863B-P2 (H77/833-2, ICMB 841-P3—sensitive; PRLT 2/89-33, 863B-P2—tolerant) during the vegetative (a, b) and reproductive (c, d) stage in 2007. The FTSW thresholds where transpiration initiated its decline were calculated with a plateau regression procedure from SAS. Then the regression lines of the relationships between NTR and FTSW were drawn by fitting NTR to FTSW data above and below the respective threshold for transpiration decline in each genotype and assessment stage.
Mentions: At the vegetative stage, the transpiration started declining at FTSW values ranging between 0.49 and 0.30 (Fig. 1a, b). In fact, threshold values were higher for sensitive H77/833-2 and ICMB 841B-P2 than for PRLT 2/89-33 and 863B-P2 at the vegetative stage. In contrast, at the reproductive stage the transpiration dropped at similar FTSW values ranging between 0.26 and 0.35 (Fig. 1c, d) in all genotypes (Table 3).

Bottom Line: In addition, Tr measured in detached leaves (g water loss cm(-2) h(-1)) from field-grown plants of the parental lines showed lower Tr values in tolerant parents.These results demonstrate that constitutive traits controlling leaf water loss under well-watered conditions correlate with the terminal drought tolerance of pearl millet.Such traits may lead to more water being available for grain filling under terminal drought.

View Article: PubMed Central - PubMed

Affiliation: International Crops Research Institute for Semi-Arid Tropics, Patancheru, Andhra Pradesh, India.

ABSTRACT
Pearl millet, a key staple crop of the semi-arid tropics, is mostly grown in water-limited conditions, and improving its performance depends on how genotypes manage limited water resources. This study investigates whether the control of water loss under non-limiting water conditions is involved in the terminal drought tolerance of pearl millet. Two pairs of tolerant x sensitive pearl millet genotypes, PRLT 2/89-33-H77/833-2 and 863B-P2-ICMB 841-P3, and near-isogenic lines (NILs), introgressed with a terminal drought tolerance quantitative trait locus (QTL) from the donor parent PRLT 2/89-33 into H77/833-2 (NILs-QTL), were tested. Upon exposure to water deficit, transpiration began to decline at lower fractions of transpirable soil water (FTSW) in tolerant than in sensitive genotypes, and NILs-QTL followed the pattern of the tolerant parents. The transpiration rate (Tr, in g water loss cm(-2) d(-1)) under well-watered conditions was lower in tolerant than in sensitive parental genotypes, and the Tr of NILs-QTL followed the pattern of the tolerant parents. In addition, Tr measured in detached leaves (g water loss cm(-2) h(-1)) from field-grown plants of the parental lines showed lower Tr values in tolerant parents. Defoliation led to an increase in Tr that was higher in sensitive than in tolerant genotypes. The differences in Tr between genotypes was not related to the stomatal density. These results demonstrate that constitutive traits controlling leaf water loss under well-watered conditions correlate with the terminal drought tolerance of pearl millet. Such traits may lead to more water being available for grain filling under terminal drought.

Show MeSH
Related in: MedlinePlus