Upland Rice and Dry Season Sorghum Production under Double Cropping Systems in a Tropical Semi-Arid Region

Aims: To investigate the influence of upland rice cultivar and dry season sorghum planting date on crop yield under rainfed double cropping systems as an option to increase cereal production for food security and income generation to farmers.
Study Design: The experimental design was a randomized complete block design with 20 replicates for rice cultivars evaluation the first year (2009). Part of the experimental set up was subsequently used the following year (2010) to evaluate dry season sorghum production as second crop in the system. Treatments were the nine combinations of previous rice cultivars and sorghum transplanting dates replicated four times.
Place and Duration of Study: Experiments were conducted in 2009 and 2010 in a tropical semi-arid area, at Salak in the outskirts of Maroua, the main city of the Far-Northern Region of Cameroon.
Methodology: The three rice cultivars of Brazilian origin tested in this experiment were B22, Primavera and SEBOTA 281.2. They were followed by the local sorghum variety called "Guelendeng’’, sown at three different dates at the onset of dry seasons. Factors evaluated were the paddy yields of rice cultivars and grain yield of dry season sorghum.
Results: The rice cultivars were able to grow and score paddy yields ranging between 2.6 and 5.2tha-1, with a highly significant interaction between years and cultivars (P<0.001). Upland rice grown in the rainy season was followed by the production of 832 to 1819 kg ha-1 of dry season grain sorghum depending on year or preceding rice cultivar. Planting date did not reveal a significant effect on dry season sorghum yield but the latter was significantly determined by preceding rice cultivar P<0.001). Dry season sorghum yield was significantly higher, when the preceding rice cultivar was Primavera the rainiest year (2010), or significantly lower the driest year (2009).
Conclusion: The choice of an upland rice cultivar to be included in double cropping systems with dry season sorghum is important but questions remain concerning the sustainability of the system in relation to moisture and nutrient management. Designing adequate fertilization schemes for cereals in double cropping systems and the availability of relevant short cycle upland rice cultivars to be included as dry season sorghum preceding crop are main challenges to be addressed.