PENGEMBANGAN TEKNIK RATUN PADA BUDIDAYA BEBERAPA GENOTIP SORGUM LOKAL (Sorghum bicolor (L.) Moench) SUMATERA UTARA

The development of sorghum (Sorghum bicolor (L.) in North Sumatra holds dual potential as a food source and an energy resource, yet the interest of farmers in cultivating it is declining. This indicates the presence of problems that need to be identified and addressed so that the potential of local North Sumatran sorghum can be redeveloped and provide optimal benefits. Special attention is required to overcome cultivation constraints, increase economic attractiveness, and utilize sorghum's potential as a renewable energy source
This research aims to: 1) Obtain the characterization of the growing environment of several local sorghums in North Sumatra, 2) Obtain sorghum cultivation techniques through the development of ratooning in an effort to increase the growth and production of local sorghum genotypes, 3) Obtain North Sumatran local sorghum genotypes that are responsive to ratooning techniques, and 4) Obtain information on the production potential of local sorghum genotypes obtained through ratooning cultivation techniques.
The research was conducted in three stages, namely: 1) Analysis of the environmental characteristics of local sorghum growth in North Sumatra (carried out at the Soil Laboratory of PT. Socfindo, Agrotechnology Laboratory of the University of Muhammadiyah North Sumatra). 2) Cultivation of several local sorghum genotypes using the Ratoon Technique (carried out at the Experimental Farm of the University of Muhammadiyah North Sumatra). Analysis of the production potential of the first planting, first ratoon, second ratoon, and third ratoon (carried out at the Experimental Farm of the University of Muhammadiyah North Sumatra).
A survey of sorghum growing locations identified nine local sorghum genotypes spread across Langkat, Karo, Deli Serdang, and Serdang Bedagai Regencies, North Sumatra, indicating significant variation in growing environments. These genotypes are adaptable to a wide range of altitudes, from 6 to 1,200 meters above sea level. However, climate analysis revealed that high rainfall (>1,200 mm/year) is the main limiting factor for location suitability. In terms of soil, the dominant soil orders in local sorghum growing locations are Ultisols and Andisols, characterized by acidic pH and low nitrogen and phosphorus availability. Although potassium content varies, the potential for increasing sorghum production in these locations can be achieved through appropriate soil management strategies, including pH correction, balanced fertilization, and the utilization of phosphate-solubilizing microorganism populations, which vary across locations.
This study also identified several local sorghum genotypes that showed varying responses to the ratoon system. The Numbu variety (G5) was the best performing genotype, consistently showing the highest yield among all genotypes, with production reaching 2722.22 in the second ratoon. The results showed a correlation between high carbohydrate content (above 62%) and high production (more than 2700 g per plot), indicating good physiological efficiency. In addition, Numbu had a good balance between quality and yield, with the highest protein content of 12.69% under ratoon-free conditions. The Beringin (G3) and Selotong (G1) genotypes showed moderate tolerance to the ratoon system, especially up to two prunings. The Pertumbuh (G2) and Pengajahan (G4) genotypes were less suitable for the repeated ratoon system, as they experienced a downward trend in yield.