Preliminary study on the adaptation of wild Guinea grass (Panicum maximum) to different agro-climatic regions in Hambanthota District

Abstract

Guinea grass (Panicum maximum Jacq.) was introduced to Sri Lanka in the 1820s for forage and has become naturalised in most ecological zones, ecosystems and habitats. This is generally called “Wild Guinea Grass” and has become common and valuable forage especially in the Southern area.  Two main varieties are found: a coarse, broad leaved, hairy, stemmy, robust grass up to 3 meters high, known locally as Guinea-“A” and a finer, narrower leaved, leafy grass with smaller culms of 1-2 meters known as Guinea-“B”. Naturally, it now overruns road and railway sides, natural forests, crop plantations, natural grasslands and scrubland at low and mid elevations. Therefore, the objectives of this study were to compare the morphological and proximate properties of wild Guinea grass grown in Katuwana (IL_1b) and Sooriyawewa (DL₅) respectively intermediate and drought regions in Hambanthota District where   it was used as sole cattle feed especially during drought periods.

Random samples of Guinea grass were collected from three representative places of each from Katuwana and Sooriyawewa areas. Morphological parameters such as plant height, number of tillers, number of reproductive tillers, leaf width, leaf length, stem diameter, panicle length, panicle width, spikelet width (from base) and, root depth were investigated  in the field itself. Proximate analysis was done for both post and pre blooming stages of P. maximum.

It was revealed that height of P. maximum plants in Sooriyawewa area (231.33^a ±16.0cm) were shorter than (P>0.05) that of Katuwana area (172.3^b ± 17.5cm), may be attributed with the prolonged drought stress. Similarly, as water stress enhanced the tillering habit, numbers of tillers and reproductive tillers per plant were (27.67^a ± 4.04 and 8.33 ^a ± 2.52 respectively) greater in (P>0.05) Sooriyawewa area as compared with Katuwana (7.333^b ± 1.155 and 1.667^b ± 0.577 respectively).

When compared the inflorescence characters panicle length showed significantly higher value for Katuwana area (65.00^a ± 12.00cm) as compared to Sooriyawewa (42.00^b ± 5.00cm) while the panicle length and spikelet width (from base) were also slightly higher in Katuwana area. Dry matter (DM) content of Guinea samples was slightly higher in Sooriyawewa in both pre and post blooming stages. Furthermore, in crude protein (CP) content was also slightly higher in pre blooming stage in drought area (10.094% ± 0.624) than intermediate climate (8.54% ± 2.50) but it is opposite in post blooming stage as 5.429% ± 0.839 in drought area and 6.52% ± 1.75 in  intermediate climatic area.

The results revealed that drought stress could effect on phenotypical characters of wild Guinea grass therefore, yield could be affected but not the quality by means of dry matter and crude protein contents. However, further investigations should be carried out to find out whether those characters are genetically heritable or not.