MSc

The present study entitled “Performance evaluation of turf grass species in the humid tropics” was carried out at the Department of Pomology and Floriculture, College of Horticulture, Vellanikkara from January 2012 to August 2013. The objective was to evaluate the performance of turf grass species with respect to growth, establishment rate and tolerance to biotic and abiotic stresses in order to introduce new grass species for the tropical lawns.
Ten turf grass species, viz., Cynodon dactylon, Stenotaphrum secundatum, Zoysia japonica, Paspalum notatum, Eragrostis curvula, Cynodon dactylon 419, Poa pratensis, Lolium perenne, Agrostis palustris, Dichondra micrantha were selected for the study. The first four species were local and the remaining six were imported from the USA. Three species, viz., Poa pratensis, Lolium perenne and Agrostis palustris did not establish and hence further studies were carried out on the remaining seven.
Besides the studies in the open field condition, their tolerance to shade and air pollution were also evaluated. The experiment was laid out in CRD for shade tolerance studies and RBD for open field condition with three replications. Various vegetative and qualitative characters were recorded and data were statistically analysed.
The maximum duration for total coverage of the area was recorded by Paspalum notatum (189 days) and the minimum by Eragrostis curvula (100 days). There were significant differences for plant height and shoot length in shade and open field conditions. Leaf length, leaf width, leaf texture, leaf colour and arrangement of unfurled leaves were recorded and were used for categorizing the species. Based on leaf width, plants were categorized into fine, coarse and medium coarse textured. Leaf colour was categorized as light, medium and dark green. According to arrangement of unfurled leaves, they were classified as rolled and folded.
Root characters were recorded in terms of number, length and root shoot ratio. Growth habit was recorded as spreading and upright. Response of different turf grass species to mowing was recorded in terms of time taken for first mowing, relative mowing height, weight of biomass removed at first mowing, recuperative ability, frequency of mowing and mowing tolerance. The maximum duration for first mowing was recorded by Dichondra micrantha (174.7 days) and the minimum by Eragrostis curvula (57.7 days). The later showed the highest value (3330.7g) for biomass and the minimum (30.0 g) was by Zoysia japonica.
Relative mowing height in open field condition was recorded as low in Cynodon dactylon 419 and Zoysia Japonica, medium for Dichondra micrantha and Cynodon dactylon and high in Paspalum notatum, Eragrostis curvula and Stenotaphrum. Recuperative ability was poor in Dichondra micrantha, Paspalum notatum and Eragrostis curvula and high in Cynodon dactylon 419 and Cynodon dactylon.
Mowing frequency was less in Dichondra micrantha, Cynodon dactylon 419, Zoysia japonica and Stenotaphum secundatum. It was more in Paspalum notatum, Eragrostis curvula. Mowing tolerance was low in Dichondra micrantha, Paspalum notatum and Eragrostis curvula whereas it was high in Cynodon dactylon 419, Cynodon dactylon, Zoysia japonica. Response to mowing followed the same pattern under various shade levels also.
Air Pollution Tolerance Index of Dichondra micrantha was the highest (24.8) and the lowest value (8.35) was observed for Cynodon dactylon. Turf grass species were categorized into sensitive (value ≤ 14), intermediate (15-19), medium tolerant (20-24) and tolerant (>24). All the species, except Dichondra micrantha, was sensitive to air pollution.
Major pests observed were, leaf eating caterpillars (army worm) in Paspalum notatum and Eragrostis curvula and termites in Dichondra micrantha, Zoysia japonica, Cynodon dactylon 419, Eragrostis curvula, and Paspalum notatum. Rats were another problem in turf area. No serious disease was observed except the gray leaf disease, caused by Pyriculari grisea which was found in Stenotaphrum secundatum.Weeds affected the turf growth seriously, both under shade and in open field conditions. The important weeds were Alloteropsis cimicina, Ageratum conyzoides, Lindernia crustacean, Cyperus iria, Cyperus rotandus , Digitaria bicornis, Synedrella nodiflora, Mimosa pudica and Desmodium triflorum.
Among the turf grass species evaluated under open field condition Cynodon dactylon 419, Cyndon dactylon, Zoysia japonica, Stenotaphrum secundatum and Paspalum notatum were suitable for lawn under humid tropical condition. Eragrostis curvula, though not suitable as a turf grass, can be grown in pots and also as an edge plant. Among the turf grass species evaluated under various shade levels (0%, 25% and 50%) Dichondra micrantha, Zoysia Japonica and Paspalum notatum performed better under 25 per cent and zero per cent shade levels and Stenotaphrum secundatum at the shade levels tried.