1. Response of Early and Late Maturing Peanut Cultivars to Sowing Densities and Fungicide Application in Ghana Jesse B. Naab 1, P.V. Vara Prasad 2*, Kenneth J. Boote 2, and James W. Jones 3 1 Savanna Agricultural Research Institute, Wa, Ghana; 2 Agronomy Department; and 3 Department of Agricultural & Biological Engineering, University of Florida, Gainesville FL 32611, USA E-mail: 1 jbnaab@africaonline.com.gh; *Present Address: Agronomy Department, Kansas State University, Manhattan KS 66506, E-mail: vara@ksu.edu Rationale and Objective Peanut or groundnut (Arachis hypogaea L.) is a highly valuable food and forage crop in Ghana. Pod and biomass yields of peanut in Ghana are low (840 kg ha -1 ). It is important to determine yield limiting factors and to develop suitable crop management practices to improve peanut productivity in this region. The objective of our research was to determine the influence of sowing densities and fungicide application on growth, biomass and pod yield of early and late maturing peanut cultivars grown under rain-fed conditions in Northern Ghana. Methods This experiment was conducted at on-station research farm of Savanna Agricultural Research Institute at Wa, Ghana (Latitude, 9.0°N; Longitude, 2.0°W, and Altitude, 390 m above mean sea level). Two peanut cultivars (Chinese, 90-day duration; and Manipintar, 120-day duration) were grown at three sowing densities [low (80,000 ha -1 ), medium (120,000 ha -1 ) and high (200,000 ha -1 )] with and without fungicide application. There were four replications of each treatment in a split-split-plot design, with fungicide in main-plots, cultivars in sub-plots and sowing densities in sub-sub-plots. Peanut cultivars were sown on flat beds in rows 50-cm apart and intra-row spacing of 25-cm (high density), 16-cm (medium density) or 10-cm (high density). At the time of sowing 60 kg P 2 O 5 ha -1 was applied through single super phosphate. Fungicide treated plots were sprayed with tebuconazole (Folicur, 3.6 @ 0.22 kg a.i. ha -1 ) four times at two-week intervals using back-mounted 15-liter knapsack sprayer starting at 21 days after sowing (DAS). Data on leaf area index (LAI), light interception and total biomass was measured at different stages of crop development. Haulm, pod and seed yield were measured at harvest maturity. Conclusions Applications of fungicide (tebuconazole) were effective in controlling leaf spot and improved average peanut haulm yields by 73% and pod yields by 87% as a result of greater leaf area index and light interception. Sowing density of 120,000 plant ha -1 and use of long duration cultivar (such as Manipintar, average pod yield of 1970 kg ha -1 with fungicide application) will be beneficial under rain-fed conditions in Ghana. Results There were no significant higher order interactions between various treatments, therefore, only the main effects are shown (Tables 1 and 2). Leaf spot symptoms were observed in both cultivars and all sowing densities when not treated with fungicide. Applications of fungicide decreased severity of disease (leaf loss), increased LAI, light interception (Table 1) from 65 to 88 DAS, ensuing in higher total dry matter throughout the season and resulting in greater haulm, pod and seed yield at harvest maturity (Table 2). The long duration cultivar Manipintar had significantly greater LAI, light interception at later stages of crop development and yielded better than short duration cultivar Chinese (Tables 1 and 2). The growth and yield was significantly less at lowest (80,000 ha -1 ) sowing density. There was no significant difference between medium (120,000 ha -1 ) and high (200,000 ha -1 ) sowing densities on haulm, pod and seed yield at harvest maturity (Table 2). Treatments Total Dry Matter (kg ha-1) 51 DAS 65 DAS 83 DAS 88 DAS Yield at Harvest Maturity (kg ha -1 ) Haulm Pod Seed Total Fungicide No fungicide Fungicide LSD (0.05) Cultivars Chinese Manipintar LSD (0.05) Densities Low Medium High LSD (0.05) 1019 1806 a 2612 a 2677 a 1087 2645 a 3964 b 4693 b NS 293 357 530 1095 2181 a 2776 a 2665 a 1010 2270 b 3800 b 4705 b NS 293 357 530 842 a 1958 a 3072 3626 1007 a 2191 ab 3446 3711 1310 b 2526 b 3146 3719 292 359 NS NS 1732 a 953 a 583 a 2685 a 2993 b 1784 b 1272 b 4777 b 265 163 130 343 1553 a 1237 a 843 a 2791 a 3172 b 1500 b 1012 b 4672 b 265 164 130 343 2149 a 1231 a 845 a 3381 a 2389 ab 1367 ab 892 ab 3756 ab 2549 b 1508 b 1045 b 4057 b 324 200 159 420 Table 2. Main effects of fungicide, cultivar and sowing densities on total biomass at different days after sowing (DAS) and haulm, pod and seed and total yield at harvest maturity. Acknowledgements We thank Peanut Collaborative Research Support Program of United States Agency for International Development for financial assistance. We thank all farmers and researchers who participated in this project. Symptoms of Leaf spot Fungicide Treatments Leaf Area Index 41 DAS 51 DAS 65 DAS 83 DAS 88 DAS Light Interception (%) 65 DAS 83 DAS 88 DAS Fungicide No fungicide Fungicide LSD (0.05) Cultivars Chinese Manipintar LSD (0.05) Densities Low Medium High LSD (0.05) 1.2 2.0 2.0 a 2.8 a 2.7 a 1.2 2.2 2.5 b 3.6 b 3.2 b NS NS 0.2 0.3 0.2 1.4 2.2 2.3 3.1 2.5 a 1.0 2.0 2.2 3.3 3.4 b NS NS NS NS 0.2 1.0 a 1.8 a 2.0 a 3.0 a 2.9 1.2 a 2.1 a 2.2 a 3.2 ab 2.9 1.4 b 2.5 b 2.6 b 3.4 b 3.0 0.2 0.4 0.3 0.3 NS 73 a 83 a 80 a 78 b 89 b 86 b 6 2 2 77 85 a 79 a 74 88 b 88 b NS 2 2 73 85 a 83 75 86 ab 83 78 88 b 84 NS 2 NS Table 1. Main effects of fungicide, cultivar and sowing densities on leaf area index and light interception at different days after sowing (DAS). NS = non-significant; numbers followed by different letters within the treatments are significantly different. No Fungicide