Evaluation of yield performance of different highland sorghum landraces grown in a lowland area

Abstract

Sorghum (Sorghum bicolor (L.) Moench) is one of the cash and staple food crops in SubSaharan-Africa, where it ranks fifth most cultivated cereal crop on the continent and third most important cereal in Uganda. Its productivity and yield per unit area in Uganda, however, are still low due to poor yielding local varieties, declining number of native varieties as well as biotic and abiotic stresses. This study investigated the agronomic and yield performance of highland sorghum landraces when grown in a lowland area. Fifty-five highland sorghum landraces were randomly collected from different farmers in Southwestern highlands of Uganda and grown together with checks (existing lowland varieties) in an Alpha Lattice Incomplete Block Experimental Design at MUARIK for comparison. Data were collected on agronomic parameters which included plant height, number of leaves, leaf length, leaf width, leaf area, leaf area index, number of days to 50% flowering and number of days to physiological maturity. Data were also collected on yield traits that included number of panicles per unit area, Panicle length and width, 100-seed weight, yield per m2 and grain yield per hectare. Analysis of variance revealed significant differences in plant height, number of leaves, leaf length, leaf width, leaf area, leaf area index, number of days to 50% flowering and number of days to physiological maturity among the highland sorghum landraces and the checks. Similarly, results showed marked differences in number of panicles per unit area, panicle length and width, 100-seed weight, yield per m2 and grain yield per hectare among the sorghum landraces. When compared with the checks, several highland sorghum landraces that performed better in leaf number, leaf area and leaf area index also performed well in grain yield per square meter and per hectare indicating a positive relationship between vegetative growth vigor and grain yield. Grain yield was highest in sorghum landraces SWUSC20-18 (5.29 tons/ha), SWUSC20-09 (5.09 tons/ha), SWUSC20-22 (4.99 tons/ha), SWUSC20-21 (4.74 tons/ha), SWUSC20-13 (4.42 tons/ha) and SWUSC20-23 (4.25 tons/ha), which performed better than the high yielding check ECO25 (4.16 tons/ha), and lowest in highland sorghum landraces SWUSC20-47 (1.33 tons/ha), SWUSC20-41 (1.85 tons/ha), SWUSC20-50 (1.88 tons/ha), SWUSC20-29 (1.94 tons/ha), SWUSC20-38 (2.12 tons/ha) and SWUSC20-49 (2.17 tons/ha). Over 33 (70%) of the highland sorghum landraces studied produced intermediate grain yields ranging between 2.2 – 4.2 tons/ha. It was intriguing to note that a number of highland sorghum landraces when grown a lowland area (foreign environment) performed better than the established improved lowland sorghum varieties in many parameters including grain yield. The cause of this phenomenon requires further investigation.