Influence of weed control options on growth and yield of cassava in Eastern zone of Tanzania.
| dc.contributor.author | Leonard, Joseph Adonia | |
| dc.date.accessioned | 2022-10-13T09:44:52Z | |
| dc.date.available | 2022-10-13T09:44:52Z | |
| dc.date.issued | 2022 | |
| dc.description | Masters Dissertation | en_US |
| dc.description.abstract | Cassava (Manihot esculenta Crantz) is an important crop in sub-Saharan Africa as it has been used as staple food by most of tropical Africans, it is averaged to be used as food on over 24 countries in Tropical Africa. Despite of the importance of cassava as food and cash crop in Tanzania, its production is affected by several factors, weed being one of those and it has been estimated that weed reduce cassava yields by almost fifty percent. In the Eastern zone of Tanzania, adoption of the best integrated weed control options on cassava production has not been clearly done, thus farmers still face challenges in terms of efficiency, timeliness and effectiveness in weed control as they mostly relay on a single weed control option. Also, weed control cost has been very high leading to inappropriate weed control as it has been estimated that the annual cost of weed control been almost $ 4.3 billion in Africa. This study aimed at developing the best integrated weed control combination for improved cassava productivity. Specifically, the study sought to: (1) to identify common weeds found in the selected cassava farms in Eastern zone of Tanzania, (2) to determine the effect of tillage, pre-emergence and post-emergence weed control options on weed growth, cassava yield and soil quality and (3) to conduct cost benefit analysis of the selected weed control options in cassava farms. The first chapter contain general introduction, the second, third and fourth in the dissertation comprise manuscripts in the form of publishable papers which cover the first, second and third specific objectives while chapter five covers general conclusion and recommendations. The effects of different weed control treatment combinations were studied during the 2019/2020 planting season at Ilonga village, Kilosa district and Kiimbwanindi village, Mkuranga district. For the first objective, a study was carried out from November 2019 to April 2020 in which a field survey was done to identify common weeds found in cassava fields in two sites. A total of 24 random 1 m × 1 m quadrat were placed in each cassava field whereby all weed species found in each quadrat were identified to a species level. During weed identification, weed density, uniformity and frequency were calculated according to Thomas methodology and used to determine relative abundance. The effect of different weed control treatment combinations on weed growth and cassava yield, soil quality and cassava profitability were studied for the objectives two and three, respectively. Till only and till + Ridge, pre-emergence herbicides (Primagram Gold a.i 290 g/L S-metolachlor + 370 g/L atrazine and Oxfen a.i Oxyfluorfen 24% EC), post emergence herbicides (Force up a.i 480 g/L of Glyphosate-Isopropylamine salt and back pack weeder with modified tines) were tested on Cassava variety Kiroba in a factorial experiment arranged in a randomized complete block design (RCBD) replicated three times. Data on the number of days for the weed reemergence, cassava plant height and cassava stem girth at five months after planting, cassava fresh root weight, cassava biomass and cassava dry matter content were collected. Also, a random composite soil samples were collected from each field at a depth of 0-30 cm before land preparation and after harvesting, and analyzed in the laboratory to determine the soil pH, total N, P, K, Ca and Mg nutrients content. Data obtained were subjected to analysis of variance (ANOVA) at P≤0.05 using R statistical package version 3.5.2. The treatment means were compared using Tukey’s honestly significance test at alpha 5% for objective two. For the objective three, data collected were all variable costs for the inputs applied on each weed control treatment combination, costs of cassava harvesting and the price of cassava per kilogram, and data were subjected to benefit-cost ratio analysis. Results revealed that, there were 22 weeds species belonging to 16 families identified in the cassava fields, whereby out of those species, 14 were broad leaved weeds, 6 grassy weeds, 1 sedged weed and 1 mushroom belonging to 10 perennial and 12 annual weediv plants. During weed identification, Cyperus rotundus and Echinochloa colona were the most abundantly weed species while Dactyloctenium aegyptium, Portulaca oleracea, Agaricus sp and Bidens pilosa were the least abundant weed species at both sites. Results showed, a combination of tillage practices and pre-emergence herbicides application (S- metolachlor + atrazine at 3.0 lts a.i/ha and Oxyfluorfen at 3.0 lts a.i/ha) increased number of days weeds took to emerge in both sites. Also, the correlation analysis showed a non- significant positive relationship, r = 0.389, p > 0.05 and r = 0.055, p > 0.05 between cassava stem height and cassava fresh root weight, and cassava stem girth and cassava fresh root weight, respectively at Kiimbwanindi site and highly significant strong positive relationship, r = 0.925, p < 0.001 and r = 0.781, p < 0.05 between cassava stem height and cassava fresh root weight, and cassava stem girth and cassava fresh root weight, respectively at Ilonga site. Combination of weed control treatments significantly affected cassava fresh root weight and biomass, (p = 0.019 and p = 0.026, respectively) at Kiimbwanindi while at Ilonga, combination of weed control treatments did not significantly affected the cassava fresh root weight, (p = 0.514) and cassava biomass (p = 0.732). Further findings indicated that, the selected weed control treatment combinations had not significantly affected soil pH, amount of total N, P, K, Ca and Mg nutrients at Ilonga and Kiimbwanindi sites. The highest profit at Kiimbwanindi site was recorded on till × Oxfen × Force up and till × Primagram × Force up treatment combinations which had the benefit cost ratio of 2.39 and 2.04, respectively while at Ilonga site, only Till and Rigde × Oxfen × Force up treatment combination had the benefit cost ratio of 2.31 and high cassava root yield of 25.58 t ha -1 . We conclude that, perennial weeds Cyperus rotundus, Echinochloa colona, Trichodesma zeylanicum, Reissantia sp, Mucuna pruriens and Commelina benghalensis were the most and abundant occurred weed species due to their ability to adapt into various soil typesv and their ability to reproduce as compared to other weeds. The combination of till + ridges, application of pre-emergence herbicide (S-metolachlor + atrazine) and post emergence herbicides (glyphosate) provided favorable environment for cassava growth and root formation as compared to other treatment combinations. Also, these results proved that, proper use of weed control methods have had minimum effects on the soil quality while having positive impacts on the cassava performance. However, its recommended that, for the positive nutrient balance in cassava production, it is important to apply fertilizers that contain high N and K nutrients because cassava responds effectively on these nutrients. Also, good farm preparation, the use of Oxyfluorfen 24% EC herbicides as pre-emergence herbicide and 480 g/L of Glyphosate-Isopropylamine salt as post emergence weed control treatments should be encouraged in cassava production as they lead to maximum profit. For maximum cassava productivity, proper tillage and ridging before cassava planting, use of pre-emergence herbicide made of S-metolachlor and atrazine and proper use of glyphosate as post emergence herbicide could highly help keeping cassava farms free from weed for a longer period of time as compared to other treatment combinations. Also, more research is recommended on a regular basis to identify possible weed population shifts for improved control measures needed. | en_US |
| dc.identifier.uri | http://www.suaire.sua.ac.tz/handle/123456789/4659 | |
| dc.language.iso | en | en_US |
| dc.publisher | Sokoine University of Agriculture. | en_US |
| dc.subject | weed control | en_US |
| dc.subject | Cassava | en_US |
| dc.subject | Tanzania | en_US |
| dc.subject | Cassava Production | en_US |
| dc.title | Influence of weed control options on growth and yield of cassava in Eastern zone of Tanzania. | en_US |
| dc.type | Thesis | en_US |
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