Assessment of weeds of cassava and farmers management practices in Nigeria

Open Access JournalLa concurrence des mauvaises herbes est un obstacle à la rentabilité de la production du manioc. La connaissance des espèces de mauvaises herbes qui affectent négativement la productivité du manioc est essentielle pour une gestion efficace. Une étude a été conduite entre mai et juin 2014 et 2015 pour évaluer les mauvaises herbes dans 200 exploitations agricoles de manioc, dans trois zones agroécologiques au Nigeria. L’Analyse des Correspondances Détendancées (ACD) a permis d’identifier quatre groupes distincts illustrant la variation des espèces de mauvaises herbes parmi les zones agroécologiques. Le pH du sol et la teneur en limon, la durée des jachères, la méthode de culture et la méthode de gestion des mauvaises herbes ont contribué à la variation de la composition des espèces. L’évaluation par les agriculteurs et sur le terrain ont identifié Euphorbia heterophylla, Imperata cylindrica, Aspilia africana, Panicum maximum, Chromolaena odorata, Commelina benghalensis, Digitaria horizontalis, et Rottboellia cochinchinensis comme principales mauvaises herbes du manioc. La gestion de ces mauvaises herbes par les paysans varie à travers les zones, suggérant ainsi que les stratégies de gestion de ces mauvaises herbes devraient être axées sur les zones écologiques. Dans la zone forestière humide, le désherbage à la houe (51,2%) et à la machette (43,0%) étaient les principales méthodes de contrôle. L’utilisation d’herbicides était élevée dans le sud de la savane guinéenne et modérée dans la savane dérivée. L’éducation afin d’accroitre la connaissance des agriculteurs sur la problématique des mauvaises herbes et l’amélioration de leur choix à la fois sur les herbicides appropriés et leur utilisation sans risque est essentielle pour une gestion efficace des mauvaises herbes dans la culture du manioc. Competition from weeds is an obstacle to profitable cassava production. Knowledge of weed species negatively affecting productivity is essential for effective management. A field evaluation of weeds and management practices was conducted between May and June in 2014 and 2015 in 200 cassava farms in three agroecologies in Nigeria. Detrended Correspondence Analysis identified four distinct clusters depicting variation in weed species composition among the agroecologies. Soil pH and silt content, fallow length, cultivation method, and weed management method contributed to the variation in species composition. Farmers and field evaluations identified Euphorbia heterophylla, Imperata cylindrica, Aspilia africana, Panicum maximum, Chromolaena odorata, Commelina benghalensis, Digitaria horizontalis, and Rottboellia cochinchinensis as major problem weeds in cassava. Farmers’ management of these weeds varied across zones, suggesting that weed management strategies in cassava should be focused on ecological zones. In the Humid forest, hoe-weeding (51.2%) and slashing (43.0%) with machetes were the predominant methods of control. Herbicide use was high in the Southern Guinea Savanna and medium to high in the Derived Savanna (26.3-42.2%). Education to increase farmers’ knowledge of the problematic of weeds and to improve both their choice of appropriate herbicides and their safe use is critical to effective and efficient weed management in cassava

Effects of synthetic hormone substitutes and genotypes on rooting and mini tuber production of vines cuttings obtained from white yam (Dioscorea rotundata, Poir)

Open Access JournalThis study was designed to evaluate the effects of some root - promoting substances on rooting andmini tuber formation using vine cuttings obtained from two genotypes (TDr 335 and TDr 93 - 49) of whiteyam (D. rotundata). The ashes were obtained from rice straw, bamboo, Gliricidia sepium, dry leaves ofAzardiracta indica (neem), and 1% indolebutyric acid (IBA). These were powdered on the nodal woundsof vine cuttings before they were planted in planting media (carbonized rice husk). The plant asheswere mixed at 1, 3 and 5 g each in 100 ml of water. Coconut water was also diluted at 1, 5 and 10 ml in100 ml of water while pyroligneous acid (PA) was diluted (1 ml each in 500, 1000, 2000 and 3000 ml in5000 ml of water). Both dilutions were used to treat vine cuttings before planting in cups filled withcarbonized rice husk. The vine cuttings were sampled for rooting percentage, number of roots, rootlength and mini tuber initiation 21 days after treatment (DAT). The number and weight of tubersobtained from IBA and wood ash treated vines were not significantly different. The rice straw ash, IBAand neem leaves powder treated vines produced greater rooting percentage (above 70%) than percentrooting obtained from vines treated with other plant ashes. Rice straw ash (5% concentration) had thehighest rooting percentage (80%) relative to other plants ash concentrations. Higher rooting percentagewas obtained in coconut water diluted at 1 and 5% than 10 and 100% dilutions. Rooting percentagesfrom vine cuttings treated with pyroligneous acid (PA) dilutions were not better than control(unteeated). The rooting percentages obtained from vines treated with different concentrations of plantsashes, root - promoting substances and control in this study were not significantly different (P = 0.05),except in vine cuttings treated with 5 g rice straw ash in 100 ml of water. Higher values of rootingpercentage, number of roots, root length and mini tubers were obtained from genotype TDr 93 - 49compared with values recorded from vine cuttings obtained from the genotype TDr 335

Sprouting and yield of yam (Diocorea spp.) minisetts in relation to sett size, soil moisture and agroecology

Seed tuber production of Dioscorea rotundata using the minisett technique was tested on-farm and on-station in different agro-ecological zones in Nigeria. A lower sprouting rate of minisetts was observed in the southern Guinea savanna than in the tropical forest zone. Sprouting and tuber yield in direct field planting of minisetts was strongly influenced by variety of D. rotundata, but D. alata was less affected by sett size. An increase in minisett size in some varieties of D. rotundata would enhance their sprouting potential

Effect of photoperiod on the development of inflorescences in white Guinea yam (Dioscorea rotundata)

In experiments in 2001 to 2003, 50-day-old plants of four varieties of white Guinea yam (D. rotundata) were exposed to 10 h (short-day) day length for 15 days, 14 h for 30 days or constant 24 h, with natural day length as the control. Under natural day length the male varieties flowered earlier than the female. Short day-length delayed and reduced the intensity of development of inflorescences, but the response to the 14 h and 24 h treatments differed between the varieties

Effect of day length on the development of tubers in yams (Dioscorea spp.)

Sixty-day-old plants of white Guinea yam (Dioscorea rotundata), water yam (D. alata) and yellow Guinea yam (D. cayenensis) were exposed to 10 h day lengths (short days) for 15 and 30 days. Short-day treatment applied at the early growth stage of yams promoted the enlargment of tubers, but the responses varied among species and cultivars. The photoperiodic sensitivities of D. rotundata and D. alata were lower than for D. cayenensis. Early-maturing cultivars were lower in photoperiodic sensitivity than the late ones. Short day length is a major factor in the enlargement and maturation of yam tubers. It appears that day length treatments could be used to distinguish between early-and late-maturing cultivars of yams

Influence of exogenous gibberellins inhibitors on tuber sprouting in yam

To induce sprouting two gibberellin inhibitors, uniconazole-P (UP) and prohexadione-calcium (PC), were applied to foliage of white Guinea yam (Dioscorea rotundata) and water yam (D. alata) 30 days before harvest or to tubers at harvest. The tuber sprouting period was shortened by about 35 days in D. alata TDa 95/00328 in response to UP and PC, and TDa 92-2 in response to PC, but not in others through foliage treatment. Sprouting of tubers was promoted in D. rotundata TDr 99-12 and D. alata TDa 99/00049 and TDa 291 when they were soaked in UP or PC, but the others had a limited response at harvest. Sprouting of TDa 99/00049 tubers started 70 days earlier and the periods of sprouting were 35 to 42 days shorter in response to the UP and PC. Foliar application was more effective in promoting tuber sprouting than tuber soaking at harvest in TDa 92-2 and TDr 93-31, and the reverse was true for TDr 99-12 and TDa 291. The responses of yam varieties to UP and PC seem to vary depending on the stage of dormancy in their tubers

Induction of sprouting in dormant yam (Dioscorea spp.) tubers with inhibitors of gibberellins

A reliable means to induce sprouting in dormant seed tubers of yams (Dioscorea species) is required to enhance flexibility in planting date and rate of propagation of the crop. Experiments were conducted to assess the potential of two gibberellin inhibitors, Uniconazole-P and Prohexadione-calcium, to induce sprouting in tubers from three varieties of D. rotundata and four of D. alata.Uniconazole-P and Prohexadione-calcium shortened the period of dormancy in tubers of some varieties. In others, they either had no effect or extended dormancy. The varietal responses were also influenced by whether the tubers were treated at harvest (before shoot senescence) or four weeks after harvest by which time shoots had senesced fully. Tubers stored in darkness at a constant temperature of 30◦ C sprouted earlier but lost weight faster than did those stored under natural daylight and ambient temperature. The apparent slow action of Uniconazole-P and Prohexadione-calcium, and their variable effectiveness in relation to variety, would limit their usefulness in seed or breeding programmes, or in determining treatment timing and the best storage environment for the tubers after treatment

The ABC of weed management in cassava production in Nigeria: a training manual

This guide is in response to demands from cassava stakeholders on the Cassava Matters WhatsApp group and the Knowledge Attitude and Practices study (KAPs) that was conducted by the IITA-led Cassava Weed Management Project. This easy-to-read reference manual for farmers will help them to cultivate cassava better and increase their productivity. The three dimensions of weed control: cultural, mechanical, and chemical are captured and illustrated in a logical and simplified manner. Our aim is that farmers and other extension service actors reading this guide will be properly informed about critical aspects of cassava cultivation, and will be able to pass on this information to others. This material primarily belongs to the IITA Cassava Weed Management Project that is funded by the Bill & Melinda Gates Foundation. The mention of specific companies or products of manufacturers, whether or not these have been registered, does not imply that these have been endorsed or recommended by the IITA Cassava Weed Management Project in preference to others of a similar nature that are not mentioned. We encourage the use, reproduction, and dissemination of materials in this information product. Except where otherwise indicated, materials may be copied, downloaded, and printed for private study, research and teaching purposes, or for use in non-commercial products or services, provided that appropriate acknowledgment of the IITA Cassava Weed Management Project as the source and copyright holder is given