Klobex Academic Publishers, Nigeria. BRC 9824/10201

 Journal

 Cowpea Performance Under Interference From Common Weed Associates.

 Smith, M.A.K. And Ayeni, A.O.

 1998

Cowpea performance (dry matter) under weed interference and common weed associates Rothboelia cochinchinensis, Euphorbia heterophylla, Cyperus tuberosus and weed mixture were compared at 1:15 crop-weed ratio in dry and wet season pot experiments. Weed growth and dry weight production were slow during the first 15 days after planting (DAP) but increased sharply after establishment. Wet-season weed growth was slower than dry-season weed growth but established wet-season plants grew better. Cowpea performed better than each weed associate during the first 20 and 25 DAP in the dry wet seasons respectively. However, the crop was considerably less productive than C. tuberosus and weed mixture in the dry season, and the latter in the wet season. Crop and weed productivity were smaller under full-season weed interference in the dry season than in the wet season, and vice versa for weed free crop. In the wet season, crop performance reduced more under shading from E. heterophylla (r = 0.85**) than from R. cochinchinnensis (r= -0.75**), weed mixture (r= 0.58**) and C. tuberosus (r= 0.10). Shading from weed associates reduced crop performance as early as 20 DAP for C. tuberosus and 25 DAP for other weed species. Full-season crop association with R. cochinchinensis and weed mixture caused the greatest reduction in crop performance. Differences in crop and weed productivity were due to soil moisture, growth habit and probably, resource-use efficiency. The implication of weed association with cowpea beyond the first 20-25 DAP and influence on weed species on its productivity are indicated. 

 Klobex Academic Publishers, Nigeria. BRC 9825/10202

 Journal

 Residual Effects Of Selected Herbicides On Seed Germination, Seedling Growth And Survival In Maize (Zea Mays L.).

 Smith, M.A.K.

 1998

: Bioassay tests were carried out to evaluate grain germination and seedling growth responses of maize var. DMR-ESRY in soil collected from Chromolaena odorata regrowth previously treated with varying rates of imazapyr (Arsenal (R)), imazethapyr 2.23% + pendimethalin 30.34% (Pursuit plus (R)) and glyphosate (Roundup(R)) in a tropical rainforest zone of South western Nigeria. Crop responses were assessed after application of Pursuit plus pre-emergence to regrowths and Arsenal and Roundup post-emergence to three-week old regrowths. Soil from untreated plots served as the control germination medium. Grain germination was significantly better in soil from untreated than in those from herbicide-treated plots. Pursuit plus and Arsenal markedly inhibited germination shortly after application but germination increased appreciably and decreased considerably over time respectively in soils from Pursuit plus- and Arsenal-treated plots. Germinated grains from different soils exhibited distinct initial seedling growth responses but these disappeared with time. Observed differences in grain germination were due to herbicide characteristics, application method, persistence and leaching losses. No recropping period is required for maize sowing into C. odorata plots treated with Roundup but Pursuit plus- and arsenal- treated plots require a recropping period of 6 to 9 weeks to prevent crop injury and/or uptake, and possible toxic residues in harvested grains. 

 : Agricultural Research Communication Centre, Sadar Bazar, Post Office Marg, KARNAL-132001, Haryana, India

 Journal

 Influence Of Seed Size On Germination And Seedling Growth In Giant Blue-stem.

 Smith, M.A.K.

 1998

Seed germination (62.5-8.5%) and shoot length (19.8-21.1 cm) were high seven days after germinating light-(LS), medium-(MS) and heavy-(HS) weight seeds of A. tectorum but did not differ significantly with seed size. HS seedlings had significantly longer roots than MS and LS seedling but seed germinability and shoot or root growth were not significantly correlated with seed size. 

 WSSN; ISSN 0794-4950

 Journal

 Some Aspects On The Biology Of Mexican Sunflower (Tithonia Diversifolia).

 Smith, M.A.K. And Anisu, O.O.

 1997

The influence of storage and light on seed germination growth and development pattern of Tithonia diversifolia were studied in the laboratory and screenhouse, respectively. Seeds germinated better in the light than in darkness. Seedling growth was slow during the first five weeks after transplanting but increased rapidly between the 6th and 12th week. Leaf production followed the same trend as seedling growth; a sharp increase in leaf production to a maximum of 273 leaves per plant was obtained after 17 weeks. An average plant produced 7-16 axillary shoots of varying lengths and leaf shapes. Leaf shape varied with number of leaf-lobes and leaf position on the main stem, and ranged from simple, three-lobed and five-lobed to six-lobed leaves. Reproductive growth commenced with the initiation of floral primordia at 10 weeks. Flower production followed an exponential pattern during plant growth and flower-buds matured after 15 weeks. A mature Tithonia plant could produce as many as 42 flowers (capitula). Also, each capitulum produced 26-29 disk seeds and 10-15 ray seeds. It was therefore determined that one plant could produce 1092 to 1218 disk seeds and 420 to 630 ray seeds under favourable growth conditions. Regardless of the plant part, disk florets contained more infertile seeds than fertile seeds but disk florets from both primary and secondary branches did not differ in seed germinability. 

 Institute For Agricultural Research And Faculty Of Agriculture, Samaru, Ahmadu Bello University, Zaria, Nigeria

 Journal

 Characteristics Of Determinate Rhizomes In Speargrass (Imperata Cylindrica) From Three Ecological Zones In Nigeria

 Smith, M.A.K.

 1995

4. Abstract for Publication: Morphological characteristics, pattern of bud distribution and inter-relationships among characteristics of mature determinate rhizomes in speargrass (Imperata cylindrica) (L.) Raeuschel) from locations in the forest/savanna transition (Ibadan), Southern Guinea (Ilora) and Northern Guinea (Bida) savanna agro-ecological zones of Nigeria were studied in the screenhouse. Speargrass form the different zones differed significantly in internode length and number and per cent of visible buds. Per cent visible buds decreased significantly with rhizome length in speargrass from Ibadan (r= -0.76) and Ilora (r= -0.54) but not in speargrass from Bida (r= -0.12). All regions of rhizomes in speargrass from Bida carried visible buds whereas no visible buds were found on both sub-apical regions and the distal sub-apical regions of rhizomes in speargrass from Ibadan and Ilora, respectively. Speargrass rhizomes from different locations widely in the inter-relationships among rhizome characteristics. Observed differences in rhizome characteristics were primarily associated with distinct ecotypic variations. Under favourable conditions, the longer matured speargrass rhizomes at Ibadan would facilitate vegetative growth, spread and persistence than the shorter speargrass rhizomes at Ilora and Bida. In the latter two locations, the higher bud concentration and possibly greater sub-apical bud activity may lead to greater regrowth potential, more rapid colonisation and more aggressive growth of new infestations than in Ibadan where bud concentration is lower and limited to the apical region. Also, there is need to prevent cross dispersal of speargrass rhizomes among zones particularly through farm implements and machinery.