Abstract
Neotropical savannas are exposed to recurrent dry periods of varied duration, and forage grasses must be able to cope with such temporal stresses to maintain productive pastures. This study compared leaf water relations and net photosynthesis under drought of five perennial Brachiaria species: the tufted B. brizantha (CIAT 6780), the semi-stoloniferous B. decumbens (CIAT 606) and B. mutica, and the stoloniferous B. humidicola (CIAT 679) and B. dictyoneura (CIAT 6133). Plants of the five grasses were grown in large pots and subjected to drought by suspending watering until first wilting symptoms (14 days for B. brizantha, B. decumbens and B. mutica, and 29 days for B. humidicola and B. dictyoneura). Afterwards, they were re-watered and a second soil dry cycle was imposed. Time trends in leaf water potential (Ψl), relative water content (RWC), osmotic potential at full turgor (Ψ0 100), stomatal conductance (Gs) and net photosynthesis (A) of stressed (DT) plants were compared to those of well-irrigated (CT) plants. Predawn Ψl in DT plants decreased to a minimum of −1.5 and −2.0 MPa in B. brizantha and B. mutica, compared to −2.5 to −3.0 MPa in B. decumbens, B. humidicola and B. dictyoneura. RWC decreased up to 50% in B. brizantha, compared to 75% in the other species. In B. humidicola, B. dictyoneura and in a lesser extent, B. decumbens, leaves of DT plants adjusted osmotically, by an apparent accumulation of nutrient solutes, at a rather constant ratio of turgid to dry weight of the tissue. Calculated osmotic adjustment ranged between 0.38 (B. decumbens) to 0.87 MPa (B. humidicola). This adjustment in Ψ0 100 was in some cases maintained 7 days after re-watering. In B. brizantha and B. mutica, Gs and A were significantly affected by drought, with maximum reduction percentages at the second drought period of 65 and 80%, respectively. The corresponding reduction in B. decumbens was 53 and 55%, respectively; whereas in B. humidicola and B. dictyoneura Gs and A were reduced less than 20%. In all species, re-watering allowed for the water relations (except Ψ0 100) and photosynthetic activity of leaves of DT plants to reach values comparable to those of CT plants. Results are discussed in term of root morphology and soil water extraction pattern, as well as leaf traits that may contribute to withstand drought under moderate soil water stress.
Similar content being viewed by others
References
Baruch Z 1994 Responses to drought and flooding in tropical forage grasses. II. Leaf water potential, photosynthesis rate and alcohol dehydrogenase activity. Plant Soil 164, 97–105.
Baruch Z and Fernández D S 1993 Water relations of native and introduced C4 grasses in a Neotropical Savanna. Oecologia 96, 179–185.
Baruch Z and Fisher M 1991 Factores climáticos y de competencia que afectan el desarrollo de la planta en el establecimiento de una pastura. In Establecimiento y renovación de pasturas. Eds. C Lascano y J Spain. pp. 103–142. CIAT, Cali, Colombia.
Baruch Z, Ludlow M M and Davies R 1985 Photosynthesis responses of native and introduced grasses from Venezuelan savannas. Oecologia 67, 288–293.
Bittman S and Simpson G M 1989 Drought effects on water relations of three cultivated grasses. Crop Sci. 29, 992–999.
Blum A, Mayer J and Golan G 1989 Agronomic and physiological assessments of genetic variation for drought resistance in sorghum. Aust. J Agric. Res. 40, 49–61.
Bouyoucos G J 1954 New type of electrode for plaster of paris moisture blocks. Soil Sci. 78, 339–242.
Buldgen A and François J 1998 Physiological reactions to imposed water deficit by Andropogon gayanus cv. Bisquamulatus and Cenchrus ciliaris cv. Biloela in a mixed fodder crop. J. Agric. Sci. 131, 31–38.
Chaves M M, Maroco J P, Pereira J S 2003 Understanding plant responses to drought: from genes to the whole plant. Funct. Plant Biol. 30: 239–264.
Fisher M J and Kerridge P C 1998 Agronomía y Fisiología de las especies de Brachiaria. In Brachiaria: Biología, Agronomía y Mejoramiento. Eds. J W Miles B L Maass and C B do Valle. pp. 46–57. CIAT. Cali, Colombia. EMBRAPA/CNPGC. Campo Grande, Brasil.
Fisher M J and Ludlow M M 1984 Adaptation to water deficits in Stylosanthes. In The biology and agronomy of Stylosanthes. Eds. H M Stace and L A Edye. pp. 163–179. Academic Press. Sydney, Australia.
Geerts P, Buldgen A, Diallo T and Dieng A 1998 Drought resistance by six Senegalese local strains of Andropogon gayanus var. bisquamulatus through osmoregulation. Trop. Grassl. 32, 235–242.
Guenni O, Marin D and Baruch Z 2002 Responses to drought of five Brachiaria species. I. Biomass production, leaf growth, root distribution, water use and forage quality. Plant Soil 243, 229–241.
Huang B 2000 Role of root morphological and physiological characteristics in drought resistance of plants. In Plant-environment interactions. Ed. R E Wilkinson. 2nd ed. pp. 39–64. Marcel Dekker, Inc., NY, USA.
Jones HG 1992 Plants and microclimate. A quantitative approach to environmental plant physiology. 2nd ed. Cambridge University Press, New York, USA. 428 pp.
Kalopos T, van den Boogaard R and Lambers H 1996 Effect of soil drying on growth, biomass allocation and leaf gas exchange of two annual grass species. Plant Soil 185, 137–149.
Losch R and Schulze E D 1994 Internal coordination of plant responses to drought and evaporational demand. In Ecophysiology of photosynthesis. Ecological Studies No. 100. Eds. E D Schulze and M M Caldwell. pp. 185–200. Springer-Verlag, Heildelberg, Germany.
Ludlow M M 1980a Adaptaive responses of stomata to water stress. In Adaptation of plants to water and high temperature stress. Eds. N C Turner and P J Kramer. pp. 123–138. Wiley Interscience, New York, USA.
Ludlow M M 1980b Stress physiology of tropical pasture plants. Trop. Grassl. 14, 136–145.
Ludlow M M and Ng T T 1976 Effect of water deficits on carbon dioxide exchange and leaf elongation rate of Panicum maximum var. trichoglume. Aust. J. Plant Physiol. 3, 401–413.
Ludlow M M, Chu A C P, Clements R J and Kerslake R G 1983 Adaptation of species of Centrosema to water stress. Aust. J. Plant Physiol. 10, 119–130.
Ludlow M M, Fisher M J and Wilson J R 1985 Stomatal adjustment to water deficits in three tropical grasses and a tropical legume grown in controlled conditions and in the field. Aust. J. Plant Physiol. 12, 131–150.
Morgan J M 1984 Osmorregulation and water stress in higher plants. Ann. Rev. Plant Physiol. 35, 299–319.
Nelson C J 1995 Photosynthesis and carbon metabolism. In Forages. An introduction to grassland agriculture. 5th ed. Vol. 1. Eds. R F Barnes, D A Miller and C J Nelson. pp. 31–43. Iowa State University Press, Ames, Iowa, USA.
Peake D C I, Stirk G D and Henzell E F 1976 Leaf water potentials of pasture plants in a semi-arid subtropical environment. Aust. J. Exp. Agric. Anim. Husb. 15, 645–654.
Pugnaire F I, Haase P, Incoll L D and Clark S C 1996 Response of the tussock grass Stipa tenacissima to watering in a semi-arid environment. Funct. Ecol. 10, 265–274.
Qian Y L, Fry J D and Upham W S 1997 Rooting and drought avoidance of warm-season turfgrasses and tall fescue in Kansas. Crop Sci. 37, 905–910.
Rao I M, Kerridge P C and Macedo M C M 1998 Requerimientos nutricionales y adaptación a los suelos ácidos de especies de Brachiaria. In Brachiaria: Biología, Agronomía y Mejoramiento. Eds. J W Miles B L Maass and C B do Valle. pp. 58–78. CIAT. Cali, Colombia; EMBRAPA/CNPGC. Campo Grande, Brasil.
SAS Institute 1989 SAS/STAT™. Guide for personal computers. Version 7. SAS Institute Inc. Cary, NC, USA. 1028 pp.
Scholander P F, Hammel H T, Hemmingsen A E and Broadstreet E D 1965 Hydrostatic pressure and osmotic potential in leaves of mangroves and some other plants. Proc. Nat. Acad. Sci. 52, 119–125.
Schultze-Kraft R and Teitzel J K 1992 Brachiaria mutica (Forsk.) Stapf. In Plant Resources of South-East Asia. N° 4: Forages. Eds. L 't Mannetje and R M Jones. pp. 64–65. Pudoc-DOC. Wageningen, the Netherlands.
Turner N C 1986 Crop water deficits: A decade of progress. Adv. in Agron. 39, 1–51.
Turner N C 1997 Further progress in crop water relations. Adv. In Agron. 58, 293–338.
Utrillas M J and Alegre 1997 Impact of water stress on leaf anatomy and ultrastructure in Cynodon dactylon (L.) Pers. under natural conditions. Int. J. Plant Sci. 158, 313–324.
Utrillas M J, Alegre L and Simon E 1995 Seasonal changes in production and nutrient content of Cynodon dactylon (L.) Pers. subjected to water deficits. Plant Soil 175, 153–157.
Volaire F and Thomas H 1995 Effects of drought on water relations, mineral uptake, water-soluble carbohydrate accumulation and survival of two contrasting poulations of Cocksfoot (Dactilys glomerata L.). Ann. Bot. 75, 513–524.
Wilson J R and Ludlow M M 1983a Time trends for change in osmotic adjustment and water relations of leaves of Cenchrus ciliaris during and after water stress. Aust. J. Plant Physiol. 10, 15–24.
Wilson J R and Ludlow M M 1983b Time trends of solute accumulation and the influence of potassium fertilizer on osmotic adjustment of water-stressed leaves of three tropical grasses. Aust. J. Plant Physiol. 10, 523–537.
Wilson J R, Ludlow M M, Fisher M J and Schulze E D 1980 Adaptation to water stress of the leaf water relations of four tropical forage species. Aust. J. Plant Physiol. 7, 207–220.
Winkel T, Payne W, Renno J F 2001 Ontogeny modifies the effects of water stress on stomatal control, leaf area duration and biomass partitioning of Pennisetum glaucum. New Phytologist 149: 71–82.
Wright G C, Smith R C G and Morgan J M 1983 Differences between two grain sorghum genotypes in adaptation to drought stress. III. Physiological responses. Aust. J. Agric. Res. 34, 637–651.
Zar J H 1984 Biostatistical analysis. 2nd ed. Prentice-Hall International, Inc. New Jersey, USA. 718 pp.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Guenni, O., Baruch, Z. & Marín, D. Responses to drought of five Brachiaria species. II. Water relations and leaf gas exchange. Plant and Soil 258, 249–260 (2004). https://doi.org/10.1023/B:PLSO.0000016555.53797.58
Issue Date:
DOI: https://doi.org/10.1023/B:PLSO.0000016555.53797.58