EVALUATION OF NEWLY RECOMMENDED SWEET POTATO VARIETIES UNDER COCONUT BY NELSIE MODINA FERNANDEZ
This study was conducted to evaluate the growth and yield performance of different sweet potato varieties grown under coconut, and to determine which variety of sweet potato would perform best under coconut. Among the agronomic characteristics measured, only herbage yield differed significantly among sweet potato varieties and was lowest in PSB-Sp 16. Based on ocular observation, this might be attributed to smaller stem produced by this variety. On the other hand, the yield, yield components as well as harvest index of five sweet potato varieties differed significantly. It was found that PSB-Sp 15 performed better under coconut since this variety produced more and heavier weight of marketable roots which led to higher total root yield and harvest index. Results showed that all sweet potato varieties did not compensate the cost of production and thus, were unprofitable. This was due to the very low root yield probably due to soil activity-related problems. INTRODUCTION
Sweet potato (ipomoea batatas L.) plays a major role in the national economy and the country’s effort to attain self-sufficiency in food. Is one of the world’s most important food crops as cheap source of energy. In the Philippines, sweet potato has gained popular attention as an important source of food, feed and raw materials for industrial products (Sanico, 1980). Through processing, sweet potato storage roots can be converted into flour and starch which can be used in many food and non-food industries. Villanueva (1979) also mentioned that sweet potato is a good source of alcohol. He noted that a ton of fresh sweet potato roots yielded about 125 liters of alcohol which is twice as much as that extracted from sugarcane. Sweet potato roots are rich in vitamins and minerals. Sufficient amount of calcium, iron, phosphorous, and other nutrient elements are present in various plant parts making them a good vegetable and forage materials. Yoshii and Garcia (1982) stated that the combined sweet potato roots and shoot tips are even much richer in protein than rice and corn that can possibly meet the protein requirements for many people. Sweet potato also possesses some pharmacological and therapeutic properties that can help individuals suffering from high blood pressure, marasmus and mental retardation, xerophthalmia and anemia (Villareal, 1975). In comparison with other crops like rice, sweet potato can produce more yield per hectare with fewer inputs and lesser management, depending on the varieties used. Thus, this is an important factor to consider in the country with rising population and limited area of production. The national average yield of sweet potato (5 tons/ ha) is very low compared with that in other countries (PCARR, 1083). This low yield may be increased substantially with the use of proper cultural management practices and high yielding varieties. Therefore, varietal selection is necessary to taken into consideration. The Philippine Seed Board recommends new sweet potato varieties which produce higher yield compared to other varieties. There were already several studies conducted by which newly recommended sweet potato varieties are being used. It is observed that these varieties of sweet potato thrive under wide range of environment and produce higher yield. Thus, this is an important factor to consider in selecting sweet potato varieties as an intercrop to coconut. In the Eastern Visayas region, particularly in Leyte, intercropping sweet potato under coconut has long been practiced by farmers due to their limited land holdings, consequently increasing the productivity of the area. Sweet potato grown under coconut produces lower yield compared to those planted in the open field due to shading effects. Shading could adversely affect the photosynthetic process consequently affecting the performance and yield of sweet potato grown under...
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