Impact of mulch-based cropping systems using green mulch and residues on the performance of advanced mutant lines of maize (Zea mays (L.)) under infested field with the parasitic weed Striga asiatica (L.) Kuntze in Madagascar.

Abstract In Madagascar, cereal yields remain insufficient due to various biotic and abiotic constraints, including Striga asiatica, a parasitic weed that has contributed to decreased maize yield up to 100%. This work aims to assess the impact of the practice of two cropping systems on the maize crop infested by S. asiatica. PLATA maize seed of the putative tolerant mutant line from the M5 generation after gamma irradiation at 100, 200 and 300 Gy and of the sensitive parent variety were grown in fields naturally infested or artificially inoculated with one pinch of around 3000 ready-to-germinate seeds of S. asiatica. The cropping system (SCV) is a community of plants that is managed by a farm unit to achieve various human goals. The residue of Stylosanthes sp. legumes was used as mulch SCVm and the legume cowpea was planted with the host plant for the intercropping system SCVv. Results have shown that the use of mulch, either residue SCVm or green mulch SCVv, minimizes S. asiatica infestation on maize plants. The SCV reduces significantly the number of emerging Striga plants with an emergence of 1.33 ± 0.36 for SCVm, 4.33 ± 0.27 for SCVv and 15.00 ± 1.08 for the control. Moreover, M5 lines have shown significant differences in plant survival rate of 50.57 ± 1.25% to 80.00 ± 0.91%, versus 13.50 ± 0.47% for the parent variety. Yields of the parent and M5 lines on SCVm are, respectively, 3.46 ± 0.02 t/ha and 4.64 ± 0.01 t/ha, and 2.30 ± 0.04 t/ha and 3.61 ± 0.05 t/ha for SCVv, while that of the control plot remains low, varying from 0.50 ± 0.04 t/ha to 2.29 ± 0.01 t/ha. Cover increases soil humidity and delays the development of S. asiatica and infection of the host plant, thus improving host plant yield. These results demonstrate the benefit of the integrated approach of mutation breeding and cultural practice to ensure more durable crop production under heavy Striga infestation.