Mervyn M. Ludlow

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Introduced African grasses are invading the grasslands of the Venezuelan savannas and displacing the native grasses. This work, which is part of a program to understand the reasons for the success of the African grasses, specifically investigates whether introduced and native grasses differ in some photosynthetic characteristics. The responses to photon(More)
Molecular markers [random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP)] were used to determine the frequency of DNA polymorphism in grain sorghum (Sorghum bicolor (L.) Moench). Twenty-nine oligonucleotide primers were employed for RAPDs, generating a total of 262 DNA fragments, of which 145 were polymorphic in at(More)
The water relations characteristics of three grass species (Panicum maximum var. trichoglume, Cenchrus ciliaris, Heteropogon contortus), and a legume (Macroptilium atropurpureum) grown in the field were measured using both a modified pressure/volume technique with pressure bomb measurements on single leaves and a dewpoint hygrometry technique applied to(More)
Damage to primary photosynthetic reactions by drought, excess light and heat in leaves of Macroptilium atropurpureum Dc. cv. Siratro was assessed by measurements of chlorophyll fluorescence emission kinetics at 77 K (-196°C). Paraheliotropic leaf movement protected waterstressed Siratro leaves from damage by excess light (photoinhibition), by heat, and by(More)
Two perennial tussock grasses of savannas were compared in a glasshouse study to determine why they differed in their ability to withstand frequent, heavy grazing; Cenchrus ciliaris is tolerant and Themeda triandra is intolerant of heavy grazing. Frequent defoliation at weekly intervals for six weeks reduced shoot biomass production over a subsequent 42 day(More)
The effect of temperatures between 15 and 50°C on the light utilization efficiency of leaf net photosynthesis was studied in two C4 grasses and two C3 legumes. In the legumes, light utilization efficiency (μ mol of CO2 fixed per μ Einstein of incident photosynthetic quantum flux) declined linearly with temperature between 15 and 45°C. On the other hand, it(More)
The coupling of HPLC with UV detection and on-line NMR spectroscopy and mass spectrometry combined with a dedicated interface for the collection of the chromatographic eluent for subsequent Fourier transform (FT) IR has been investigated using a number of polymer additives as model compounds. Size-exclusion chromatography was performed using deuterated(More)
Water stress is one of the major constraints to the grain yield of sorghum in tropical and sub-tropical areas of the world. Osmotic adjustment has been widely proposed as a plant attribute that confers adaptation to water stress. The inheritance of osmotic adjustment to water stress was investigated in a series of generations derived from the three possible(More)
At constant cladode temperature the stomatal resistance of O. inermis increased when the cladode-air vapor pressure difference was increased and stomatal resistance decreased when the cladode-air vapor pressure difference was lowered. Net CO2 fixation in the dark was very responsive to these humidity dependent changes in stomatal resistance. Net CO2(More)