Intraspecific variation in the resistance to flooding and drought in populations of Paspalum dilatatum from different topographic positions

Abstract

Many studies have analysed plant responses to flooding or drought separately, without addressing the relations between plant resistance to each of these factors. In this paper, we compare the responses to drought and flooding under glasshouse conditions of three populations of Paspalum dilatatum, a perennial C grass dominant at different positions along a topographic gradient in the flooding pampa of Argentina. Our results showed that flooding effects on yield were negative on an upland, null on an intermediate, and positive on a lowland population, whereas drought reduced yield equally across populations, showing that resistance to flooding was not related to resistance to drought at a population level. Drought decreased height and aerenchyma, and increased the proportion of roots, while flooding had opposite effects on these traits. The responses of the single clones that made up each population showed a positive relation between the resistances to both factors: along the ecocline formed by 58 clones, those more resistant to drought were also more resistant to flooding. In addition, the combined resistance of each clone to both factors was negatively related to yield at field capacity, (i.e. the most resistant clones were less productive) and unrelated to the proportion of roots and aerenchyma. This result agrees with predictions of Grime's plant strategy theory and differs from a few previous studies, which showed negative relations between the resistances to flooding and drought among genera and species.

Evaluation of Bermuda grass (Cynodon dactylon (L.) Pers.) and Bahia grass (Paspalum notatum Flugge) for short-term drought tolerance targeting low-maintenance landscaping

“…In the present study, drought did not have any impact on absolute change in root biomass in both species. Similar results have been reported by Loreti and Oesterheld (1996) with Paspalum dilatatum. Results from this study corroborate earlier findings (Huang and Gao, 2000) in that, high biomass fraction was partitioned in to roots during drought.…”

Tolerance to flooding in five Brachiaria brizantha accessions

“…Even grass species with a known tolerance to flooding show a shift in carbon allocation from below-to above-ground components under flooding (Naidoo & Naidoo, 1992;Naidoo & Mundree, 1993;Baruch, 1994a;Loreti & Oesterheld, 1996;Dias-Filho & Carvalho, 2000). The reason for that is the deleterious effect flooding has on root formation and growth and the induction of root decay it causes (Kozlowski, 1997).…”

Acquisition and allocation of resources in two waterlogging‐tolerant grasses

“…These results support previous work on P absorption in waterlogged P. dilatatum plants (Rubio et al, 1997), where it was found that waterlogging increases P uptake per unit root as a consequence of (i) an increase in specific root length ; (ii) an increase in the intrinsic uptake capacity of each unit of root biomass (higher V max ; lower K m ) ; and (iii) an increase in soil P availability. A primary effect of soil waterlogging on these and many other tolerant plants is to produce a root system with more porosity, and this factor is presumably important to the increase in specific root length (Loreti & Oesterheld, 1996). It has been suggested that decreased soil penetration resistance under waterlogging conditions also contributes to the increase in specific root length (Rubio et al, 1997).…”