Impact of natural weed infestation on the performance of selected sugarcane varieties in the Southern Guinea Savanna of Nigeria

Experiments were conducted to evaluate the performance of some  sugarcane varieties against natural weed infestation. The trials were laid out in a randomized complete block design with split-plot arrangement andthree replications. The sugarcane varieties were the main plots while the sub-plots consisted of weeding regimes. Recommended cultural and agronomic practices were followed to raise the crops. Data were collected on weed density, weed biomass, sugarcane tiller count and cane yield. Our results revealed that Rottboellia cochinchinensis (Lour.) W.D.Clayton, Panicum maximum Jacq, Imperata cylindrica L., Panicum repens L., Cynodon dactylon L. and Cyperus rotundus L. were the major weed problems of sugarcane in Ilorin. The monthly hoe weeded treatment had significantly higher tiller count which translated to higher cane yield (22.61 to 72.54 t/ha) than other weed control treatments. The reduction in cane yield was between 80.51 and 97.55% depending on duration of weed infestation. Association of weed parameters with cane yield was negative and significant showed that a decrease in weed infestations will result in simultaneous increase in sugarcane yield. Therefore, in selecting  sugarcane variety(s) for breeding programmes, emphasis should be placed on sugarcane growth parameters that negatively and significantly correlated with weed infestation. Key Words: Weeds, sugarcane, plant crop, ratoon, cane yield, tiller coun

Variation in maize tolerance to Striga Lutea (Lour) and influence of Arbuscular Mycorrhizal Fungi

This study was conducted to assess the variation in maize tolerance to Striga lutea and influence of arbuscular mycorrhizal fungi (AMF). Screen house experiment was conducted at the Institute of Agricultural Research and Training, Ibadan while, Farm settlement and Temidire were striga endemic experimental fields in Eruwa. Complete randomized design was used in screen house while, randomized complete block design was adopted on the field with three replications. AMF (Glomus mosseae, G. clarum, G. deserticola and Gigaspora gigantea) in mixtures of soil and root fragments were inoculated at the rate of 25g per plant while, 10.4g of extracted striga seeds were artificially  infested. Uninoculated and uninfested in pots and plots served as control. Four maize genotypes; ILE1- OB, ART-98-SW4-OB, ART-98-SW5-OB and ART-98-SW6-OB were screened for tolerance or susceptibility to S. lutea infestation on disease rating scale of 1 to 9. ART-98-SW5-OB and ART-98-SW6-OB were significantly tolerant (P<0.05) with striga damage rating (SDR) ranging from 1.18-2.48, ART-98-SW4-OB was moderately tolerant with SDR ranging from 3.59-4.57, while ILE-OB was highly susceptible with SDR ranging from 8.61-8.72. Influence of AMF was significant (P<0.05) for growth, yield and striga-related traits with SDR ranging from 1.28- 2.70 and 1.21-2.64 at 8 and 10 weeks after planting respectively.Key words: Maize, mycorrhiza, Striga lutea, tolerance, yiel