Biomass production of three cultivars of Cenchrus purpureus grown on sandy vertisol soil at Naibonat, West Timor-Indonesia

Three cultivars of Cenchrus purpureus (cvs. Cipelang, Biograss, and Mott) grown on Sandy Vertisol Soil at Naibonat, West Timor-Indonesia were evaluated for their biomass production (leaf, leaf sheath, and stem) and some agronomic characters (plant height, stem diameter, leaf length, and leaf width). Plants were planted in rows of 1 m x 1 m at 6 m length in a Block Randomized arrangement and replicated four times. Plants were established in October 2021 by watering using sprinklers during the dry season (just to keep the soil moist enough to still encourage growth) and under rainfall during the wet season (rainfall data presented). Harvests were conducted in 2022 (wet and dry season). No chemical fertilizer was applied, however, 3 kgs of manure were applied in each planting hole, and the soil surface of the plot was evenly covered by dry leaves of bamboo collected from nearby the plot. Data collected were then subjected to Analysis of Variance using the SPSS program and means were compared using the List Significant Difference (LSD) test. Biomass production was significantly different between cv Mott compared with Cipelang and Biograss, however, there was no significant difference recorded between Cipelang and Biograss at each harvest as well as for one-year total biomass production.


Introduction
The introduction of improved grasses into the region of East Nusa Tenggara, especially in the lowland with watering facilities (especially bore water and pumps) and into the highland areas (with or without watering facilities) has shown increasing areas of cultivation such as from species of Cenchrus purpureus (syn.Pennisetumpurpureum) cultivars (Cipelang, Biograss, Mott, etc.), Megathyrsus maximus (syn.Panicum maximum) cultivars (Gatton, Hamil and Mombasa), and Tripsacum laxum in providing reasonable forage biomass for cattle feeding in the wet and dry seasons.The current technique of irradiation tends to increase the variation of the cultivars selected for various superior traits with certain objectives, such as higher protein content [1,2], and lower fiber content, even with a particular ability to survive in different agroecological conditions such as drought tolerance [3], or to induce useful morphological variation [4].The three grass cultivars mentioned above should be measured for their biomass production to obtain information on their capacity to provide forage for cattle feeding in the region especially when grown on a similar soil condition (sandy vertisol) and treatments.

Material and Method
Rainfall during the experiment can be seen in the following table [5].The plot of the experiment was established in October 2021 and measurement was conducted for biomass production and some agronomic parameters (plant height, stem diameter, leaf length, leaf width, leaf sheath length, and number of nodes).Plants were planted in rows (6 m length) with planting distance of 1m x 1 m within and between rows 4 replications.Stem cuttings of every cultivar were planted in prepared holes 20 cm x 20 cm x 40 cm filled with 3 kgs of manure into each hole, while no chemical fertilizer was applied.Each hole was planted with 3 stem cuttings (with 3 nodes) watered during the dry seasons and relayed on rainfall during the rainy seasons.
Data collected include plant height, stem diameter, leaf length, leaf production, leaf sheath production, and stem production.Data collected were then subjected to statistical analysis by using the SPSS software which was further tested by LSD for the differences between the means.
Selected samples of the three kinds of grass were taken to measure the N total content to give pictures of their quality (protein content by multiplying N x 6.25) at the former BPTP NTT laboratory in Naibonat-Kupang District East Nusa Tenggara.

Plant height and stem diameter
Plant height was highest in Biograss (326 cm), followed by Cipelang (288 cm), and the lowest was in Mott Grass (170 cm), respectively.Plant diameter was highest in BioGrass (2.4 cm), followed by Cipelang (2.1 cm), and the lowest was in Mott Grass (1.65 cm).Plant height in the three types of grass tested was higher than those measured by Jabessa et al [6] which ranged between 126 cm -233.5 cm.The difference might be directed to the difference in time of harvest and soil fertility conditions.
Biomass production was highest in Mott with no significant difference between Cipelang and Biograss.However, at harvest 2 to 4 in general, Mott has the lowest biomass production compared with both the others while no difference was observed between the latter two.Harvest 4 has higher biomass production than others may be related to the increase of tillers and rainfall achieved (Table 1).If converted to yield of biomass per ha/year Biograss had higher total biomass (340.26tons/ha/yr) compared to that of Husni et al (319.15tons/ha/year) [1] but this may be attributed to that in this experiment planting was conducted in October 2021 and harvest was started in January 2022.

Forage N content
The protein content of the three grass cultivars harvested 90 days after planting (taken at the first harvest) which was obtained by multiplying the total N content x 6.25 were as follows: Biograss protein content of 10.94, Mott protein content of 12.9% and the lowest was in Cipelang of 9.18%.The higher protein content in Mott may be related to the lower proportion of stem in total biomass (Table 1).The protein content of Biograss harvest at 90 days should be sufficient for the standard need of protein by cattle, and also higher in Mott cultivar, but the lowest in Cipelang.The protein content of Biograss was lower than that of Husni et al., 2012 (14.49%) [1] which may be due to the different climate, soil, and harvest time.Husni et al., [1] however, did not provide the days at harvest but only stated that it was before the plant flowering.Therefore, further experiments may be needed to determine the best time for harvest to obtain the best protein content and biomass production of the grasses.

Carrying capacity potential
The grass may be given by itself but also can be mixed with legumes to increase the quality of the diet given to the animals.The proportion and grass would be the best when mixed at 60% grass and 40% legume forage.Roughly the total biomass production (when mixed at 60% grass and 40% legume) [8] may be able to support 45 head of bulls in Cipelang, 52 bulls in BioGrass, and 39 bulls in Mott.

Conclusion
All three types of grass (Cipelang, Mott, and Biograss) may be recommended for producing forage biomass in the current soil and climate conditions.However, further experiments are needed to determine better harvesting time in terms of obtaining optimum forage quality such as protein content and biomass production.

Table 1 .
Rainfall and climate data during the experiment in 2022 [5] Biograss, and Mott) were used in the experiment.Cipelang and Mott were obtained from the former Research Station in West Timor (The East Nusa Tenggara Assessment Institute for Agricultural Technologies -BPTP NTT -Department of Agriculture), while Biograss was obtained from the former Central Research Institute for Livestock Production -Department of Agriculture in Bogor).