Performance of farmer-preferred maize varieties intercropped with beans in the semi-arid regions of kenya
Recurrent droughts are often associated with maize crop failures and therefore food insecurity especially in semi-arid areas of Kenya. To cope with drought, farmers are advised to adopt drought tolerant maize varieties and maize-legume intercropping as a diversification strategy. As such, a study was conducted in Machakos, Mwea and Waruhiu in 2008 short rains and 2009 long rains to determine the performance of maize varieties currently grown in the semiarid regions and their compatibility with a commonly grown bean variety Katumani bean 1, KB 1. Sixteen maize varieties sold by seed stockists in the semi-arid regions were evaluated. The maize varieties comprised two composites, Katumani and KCB, and fourteen hybrids which included the DHO series (DHO 1, DHO 2, DHO 4), the Five series (H513, H515, H516), H614D, Duma 43, DK 8031, the Pannar series (Pannar 4M, Pannar 67, Panner 77 and Pannar 7M) and pioneer hybrid (PHB 3253). The maize varieties were grown either as sole crops.or as intercrops with KB 1. The experiments were laid out in a randomized complete block design with a split plot arrangement and replicated three times. Maize variety was assigned to the main plot while the maize-bean intercrop system was assigned to the sub plot. Data collected included maize plant height at 57 days after emergence (DAE), bean plant height at 43 DAE, bean nodulation, plant shoot biomass, plant stand count, lodging percentage, DAE to 50% flowering and maturity of maize, maize and bean yield and yield components. Land equivalent ratio (LER) and Monetary Advantage (MA) indices were calculated to evaluate ecological and economic productivity of intercropping. In 2008 short rains the component crops were severely affected by drought at Machakos before any data could be obtained while the beans component dried up at seedling stage at Mwea and Waruhiu. During 2009 short rains in Machakos, the maize component dried at the flowering stage but its shoot biomass data was collected. Results showed that performance of maize was not significantly affected by the bean component in a maize/bean intercrop system. Maize flowered and matured significantly earlier in Mwea (60.3 and 108.1 DAE respectively) than in Waruhiu (75.:r-and 118.5 DAE respectively). KCB and Katumani composites took significantly shorter time (88 DAE) to mature than the rest of the varieties. Among the DHO series,DHO 1 and DHO 2 took significantly shorter time to mature (average 101.6 DAE) than DBO 4 which took 122 DAE. The Five series took an average of 120.9 DAE to mature while the Pannar series took an average of 117.2 DAE to mature. DK 8031, Duma 43 and PHB 3253 took 112, 114.4 and 117.2 DAE respectively to mature. H614D took significantly the longest duration of 131.5 DAE to mature. Maize varieties differed significantly in grain yield and yield components. Significant differences in grain yield were noted in 2009 long rains with Duma 43 giving the highest grain yield of 2.9 t ha-1 while H614D gave the least grain yield of 1.33 t ha-1 • Variety PHB 3253 which was among the high yielding varieties had significantly more number of kernel-rows per cob. Harvest index was .inversely related to time taken to physiological maturity. Thus, the early maturing varieties were more efficient in growth resourc~ allocation to the grain. The late maturing varieties had low harvest indices. Varieties KCB, Katumani, DHO 1 and DHO 2, which had high harvest indices, manifested high lodging percentages. Performance of beans was significantly affected by the maize component in the intercrop system and bean yields were depressed by 51.5% to 58.9%. The declined bean seed yields are also associated with reduced pods per plant and number of seeds per pod by the intercrop beans as opposed to the sole crop beans. However, according to LER and monetary advantage indices, intercropping was ecologically and economically superior to sole cropping. The results indicate that varieties KCB, Katumani, DHO 1 and DHO 2 may be suitable for the semi-arid regions because they flower significantly early. Since several researchers have cited early withdrawals of rainfall especially at flowering stage, these early maturing varieties can therefore escape-drought if planted early in the growing season.