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Intact Plant, Callus and Field Grain Yield Responses of Tepary Bean to Drought
Author(s) -
Mohamed M. F.,
Tawfik A. A.
Publication year - 2007
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.2007.00237.x
Subject(s) - transpiration , photosynthesis , stomatal conductance , shoot , biology , relative growth rate , agronomy , dry weight , horticulture , drought tolerance , water use efficiency , osmotic pressure , dry matter , leaf area index , specific leaf area , phaseolus , botany , growth rate , mathematics , geometry
Abstract In a field trial involving four tepary lines ( Phaseolus acutifolius A. Gray), NE#8A and NE#19 produced higher grain yield than NE#5 and NE#7 under both well watered and drought conditions. However, NE#8A is considered more resistant than NE#19 in terms of drought sensitivity index. Greenhouse investigations on intact plants indicated no differences among the four lines in leaf and stem dry mass, and leaf area. Root depth did not strictly differentiate lower‐yielding from higher‐yielding lines. In contrast to lower‐yielding lines, however, plants of higher‐yielding ones allocated greater dry matter (DM) in roots in response to imposed water stress. Distinctly, NE#19 had the greatest root : shoot (R : S) while NE#8A characterized by high net photosynthesis. Both NE#8A and NE#19 showed reduced leaf area : root dry mass ratio, stomata conductance and transpiration rate. Consequently, these two lines showed no significant changes in leaf relative water content while photosynthetic water‐use‐efficiency increased in response to water stress. Calli derived from leaf and root tissues of higher‐yielding lines exhibited low initial osmotic potential (ψ s ). These calli did not show alterations in ψ s , DM% and relative growth rate (RGR) when subjected to water stress. Although leaf‐ and root‐derived calli of lower‐yielding lines exhibited osmotic adjustment, they suffered water stress in terms of elevated DM and reduced RGR. Overall, results suggest that dehydration‐avoidance mechanisms conditioned by increased root mass and stomata resistance accompanied with low initial cellular ψ s sustained high grain yield of tepary under limited water supply.