Recent progress in cassava varietal improvement in the Philippines

Abstract

The report covers varietal improvement for the period 1990-1993. Not much progress was made in the 1990/91 season due to the occurence of a super typhoon that damaged standing field trials. In recent years, however, progress in selection was made in terms of high yield and dry matter content and good plant type. The cassava germplasm bank of PRCRTC has currently a total of 270 accessions, includeing 30 varieties introduced through tissue culture from Thailand. From this germplasm a polycross nursery and hybridization block were established to incorporate desirable genes into the local cultivars. Since 1991 about 3659 new genotypes have been evaluated by PRCRTC. From these evaluations and screenings two varieties of CIAT origin were released by the Philippines Seedboard. These were CM4014-3 (PSB Cv-9) named VC-4 and MCol 1684 (PSB Cv-10) named VC-5. CM4014-3 is a cross of CM728-3 x CM681-2 of the 1984 CIAT introduced population. This variety had an average yield of 32.9 t/ha and is recommended throughout the country. It has a medium HCN and high starch content which is good for processing. MCol 1684 is a CIAT clone introduced in 1979. This is the first variety intended for regional release in Mindanao. It has had an average yield of 44.8 t/ha for the last 10 years. This variety has high HCN and medium starch contents and is good for starch processing. Preliminary and General Yield Trials with cassava materials from CIAT/Colombia and the Thai-CIAT program resulted in the identification of outstanding clones that are high yielding, have high dry matter content and good plant type. In the General Yield Trial, about 40% of the Thai-CIAT materials had yields of 30-40 t/ha after 9 months and about 10% had yields of 50-65 t/ha. In the General Yield Trial about 45% of entries from CIAT/Colombia had yields of 20-30 t/ha after 10 months and about 36% produced 30-40 t/ha. This population has also high dry matter content. Germplasm selection focuses also on starch content and plant type aside from resistance to mites and scale insects. Promotional yield trials with the recommended cassava varieties were conducted in farmer's fields and farmers made their own selection of desired varieties. Gradually the distribution system of recommended cassava varieties have gained momentum. Lakan and Golden Yellow, both Philippines Seed board varieties, are already widely used by farmers in Samar, Leyte and northern Mindanao for human food, starch production and feeds. MCol 1684 is planted in almost 2000 ha in Lanao del Sur, specifically for starch processing. The other recommended varieties, VC-1, VC-2 and VC-3, are already in the fields of some farmer cooperators. With the joint effort of the local government and the private sector it is expected that rapid diffusion of recommended cassava varieties will be attained through the establishment of cassava nurseries and demonstration farms in strategic areas where cassava is an important crop.