Effectiveness of Imazapyr-Resistant and Selected Striga-Tolerant Maize (Zea Mays L.) Varieties on Striga Hermonthica Control and Yield of Maize in Western Kenya

Abstract

Witch weed (Striga hermonthica) is a hemi-parasitic weed that causes severe maize yield losses globally and in western Kenya. A study was conducted to determine the effectiveness of herbicide coated Imazapyr Resistant (IR) hybrids, selected Striga-tolerant and Local maize varieties on Striga management and yield of maize in western Kenya. The study also determined the cost-benefit analysis of IR maize compared to Local landraces in western Kenya. The study was conducted in two Striga-infested sites, Rangwe (Homa Bay County) and Kenya Agricultural and Livestock Research Organization (KALRO), Alupe (Busia County) during the 2018/2019 cropping seasons. The varieties evaluated comprised of two IR coated hybrids (H528IR, FRC425IR), two Striga tolerant open pollinated varieties (KSTP94, GAF4), five commercial susceptible hybrids (DK8031, H513, DUMA43, DH04, HARAKA 101) and one local landrace. The experiment was laid in a randomized complete block design (RCBD) with three replications for two seasons. Data was collected on days to 1st Striga shoot appearance, Striga shoot emergence counts, Striga damage severity rating, Striga plants flowering at maize physiological maturity, maize plant height (cm), grain yield (t ha-1), maize yield components (kernels per cob, 1000-seed weight (g), and grain yield loss. Data collected were subjected to analysis of variance using Statistical Analysis System software (version 9.0) and treatment means separated using Tukey’s HSD test at P≤0.05. Results indicated significant differences (P≤0.05) of varieties in response to Striga infestation. Striga count, Striga plant rating and significantly reduced (P≤0.05) in the IR treated hybrids as compared to the susceptible genotypes. IR maize varieties (H528IR, FRC425IR) delayed the emergence of Striga shoots by 20 days compared to the commercial susceptible varieties. Additionally, IR coated genotypes reduced striga shoot emergence by 79.5%, reduced Striga damage severity by 68.1% compared to susceptible varieties in both sites. In conclusion finding from this study showed that IR hybrids has potential to manage Striga and improve maize yield by 57% from 1.152 t ha-1 (Local) to 2.37 t ha-1 (H528IR) in western Kenya. Further, the coated hybrids performed well economical with a MRR of 3.3, enabling farmers to earn an extra income of Ksh29, 950 by adopting IR technology. This study recommends the adoption of Imazapyr coated varieties in Striga prone areas of western Kenya in order to improve grain yield that will ultimately contribute to improved food and nutrition security, household incomes and poverty alleviation in western Kenya.