Cassava Yield Research Articles

Effect of amended soil using different fertilizer applications on phenology of Cassava in Edo State South-South Nigeria

Three experimental fertilization treatments of fertigation (FERT), Nitrogen-Phosphorus-Potassium (NPK), and poultry organic fertilizer (ORG) were applied on a cassava (TMS 30573) cultivation at the rate 300 kg/ha for NPK and ORG, while fertigation was injected at 1.5 litres/minutes. The results were compared with the control and unfertilized field using the same cassava cultivar. The results from the four treatments indicated that the cassava phenological development significantly responded to fertilizer applications. At 183-day after planting (DAP), the plant height under FERT was higher than NPK, OGR and CON by 19.0 cm, 60 cm and 80 cm. Conversely, under ORG, the leaf emergency (le) steady increased to 42 leaves at 183 DAP, whereas NPK reached peak (le) at 161 DAP and dropped to 41 at 183 DAP. Also, under the FERT and CON, le dropped to 38 and 33 leaves at 183 DAP. The rate of leaf death (ld) is significant at P<0.001 under fertigation, NPK and ORG, while insignificant under control treatment. Projected cassava yield per hectare estimated from phenological and morphological development indicated that ORG showed high possibility of producing cassava yield increase of 2.5 tons/hectare over FERT, 3.2 tons/hectare, 4.8 tons/hectare under NPK and CON respectively.

Evaluating cassava best management practices towards low fertility soil in West Java, Indonesia

Marginal land with low fertility is a major problem in cassava cultivation. The purpose of this study was to determine the best combination of fertilization to increase the growth and yield of cassava on an Inceptisols soil. Urea (46% N), SP-36 (36% P2O5), KCl (60% K2O), NPK Phonska (15% N:15% P2O5:15% K2O), Poly4 Sirius (14% K2O:17% CaO:6% MgO: 19% S), and chicken manure were used as a nutrient source into six treatment combinations. The results showed that fertilizer application significantly affected the plant height, stem diameter, leaf number, diameter of tubers, the total number of tubers, number and weight of marketable tubers, and the total weight of tubers per plant. The highest fresh and dry weight of storage roots was achieved in the best management practice involving application of 138 kg N + 36 kg P2O5 + 60 kg K2O + 37 kg Ca + 13 kg Mg + 41 kg S per hectare compared to other treatments where the weight of marketable tubers was also higher. The right combination of fertilizer rates was needed to achieve high yield targets of cassava and depends on the site- specific conditions of soil fertility and nutrient status.

First report of Colletotrichum truncatum causing anthracnose in cassava in Brazil.

Cassava (Manihot esculenta Crantz) presents significant economic importance in Brazil and other developing countries due to its use in human and animal feeding. In 2019, cassava plants sampled in Pará state (Brazil) presented necrotic and irregular leaf spots, characteristic symptoms of cassava anthracnose. About 90% of the plants were symptomatic, and disease severity was higher during months with high temperature and humidity. Fragments of symptomatic tissues were removed from the lesion transition area, surface disinfested (45 s in 70% ethanol, 1 min in 1% NaOCl, and rinsed twice in sterile water), and plated on potato dextrose agar. Cultures were incubated at 25 °C under continuous light for 7 days. Among the obtained isolates, seven presented grey felt-like mycelium with white sectors, reverse greyish, and hyaline, aseptate, smooth-walled, falcate conidia with average size 20.7-30.7 (26.1 ± 2.1) × 2.4-4.8 (3.5 ± 0.5) μm. Phenotypical features were similar to C. truncatum (Damm et al. 2019). The representative isolate UFT/Coll87 was chosen for further assays. The identity of the isolate was determined by maximum likelihood analysis using sequences of actin (ACT, GenBank accession number MT321653), β-tubulin (TUB2, MT856673) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH, MT800857) partial regions. Colletotrichum isolate from cassava nested with C. truncatum isolates in a clade with 100% support, being confidently assigned to this species. Koch's postulates were fulfilled to confirm the pathogenicity of UFT/Coll87. Inoculation was carried out in three cassava plants by spraying a conidial suspension (106 conida mL-1) on unwounded leaves (three leaves per plant). Plants sprayed with sterile water represented negative control. Inoculated plants were kept in a humid chamber for 48 h, 25 °C, and a 12-h photoperiod. The experiment was repeated 2 times. Typical cassava anthracnose symptoms were observed 10 days after inoculation. No symptoms were observed in negative control. The pathogen was reisolated from symptomatic leaves and was phenotypically identical to the original isolate UFT/Coll87, fulfilling Koch's postulates. Colletotrichum fructicola, C. karstii, C. plurivorum, and C. siamense were reported causing cassava anthracnose in China (Liu et al. 2019). In Brazil, C. chrysophilum, C. fructicola, C. siamense and C. theobromicola were reported in association with cassava (Bragança et al. 2016; Oliveira et al. 2018; Machado et al. 2020). To our knowledge, this is the first report of C. truncatum causing cassava anthracnose worldwide. Our finding is important for disease management due to the high host range of C. truncatum. The pathogen can reduce the cassava yield, and the crop may serve as a potential inoculum source since it is commonly cultivated near to other crops that are also infected by C. truncatum.

Effect of Different Planting Material on Physiological Parameters and Cassava Mosaic Incidence in Cassava (Manihot esculenta Crantz.)

An investigation was carried out to assess the effect of planting materials on physiological parameters, cassava mosaic incidence and yield of Cassava varieties viz. H-226 and CO.2 at the Department of Vegetable crops, Horticultural College and Research Institute, TNAU, Coimbatore during September 2010 to June 2011. The experiments were laid out in Factorial Randomized Block Design with four treatments and three replications in two varieties. The results revealed that the tissue culture plants were found be the best in virtue of its high leaf area index, net assimilation rate, dry matter content, tuber yield (26.33 t ha-1) and least incidence of cassava mosaic virus. Among the varieties, CO.2 showed less incidence of CMD. The tissue cultured plants may be recommended to farmers to reduce mosaic disease incidence and get maximum yield in cassava.

Effect of Tillage on Agro-morphological Parameters and Yield of Cassava (Manihot esculenta crantz) in Abongoua, East-Central Côte d'Ivoire

The objective of this work is to improve the production and yield of cassava cultivated by tillage. The experiment was conducted in the field for 13 months (June 2019-july 2020) in Abongoua in the department of Bongouanou (East-central Côte d'Ivoire). After the cleaning of a 900 m2 surface of a fallow of more than 5 years, and cleared of all plant debris, soil samples were taken with an auger in the 40 cm surface in each corner and in the center of the experimental plot to constitute the composite sample for laboratory analysis. The trials were conducted in a randomized complete block design with four replicates in which four elementary plots were distributed. Three treatments T1 (tilled soil), T2 (mounded soil) and T3 (ridged soil) compared to a control treatment T0 (no-till soil) were applied in each microplot. The cuttings were directly sown at a rate of 12 cuttings per treatment. The data of the different parameters collected underwent an analysis of variance (ANOVA) performed with SAS software version 9.4 and the means were separated using the Newman and Keuls test at the 5% probability threshold. The results showed an acidic soil with a sandy texture and a good supply of nutrients, particularly major elements, trace elements and clay-humus complex. Good growth and development of agro-morphological parameters as well as yield were obtained with treatments T3 (ridged soil), T2 (mounded soil) and T1 (tilled soil) in decreasing order of importance compared to the control treatment (T0). In conclusion, the study clearly showed that the type of tillage, particularly the ridged tillage technique, improves the agro morphological parameters, productivity and yield of cassava. What we recommend to farmers for a good yield of cassava in the area.

Cassava yield indicators and total organic carbon in tropical soils under different fertilization treatments

Cassava is a crop of major socioeconomic importance in Brazil because of its versatility and high yield in nutrient-poor soils. Fertilization can improve soil quality and further increase cassava yield. This study aimed to investigate the effects of different fertilizer sources on soil total organic carbon (TOC) and cassava yield indicators. The experiment was conducted on a family farm in Santarém, Brazil, in a randomized block design, with four treatments and five replications. Treatments were as follows: T1, unfertilized soil (control); T2, NPK fertilizer; T3, poultry manure; and T4, cattle manure. The variables analyzed were soil TOC, shoot fresh weight, plant height, marketable stem diameter, marketable root yield, and yield. Data were subjected to analysis of variance, Tukey’s test (p < 0.05), hierarchical clustering, and principal component analysis. Application of organic fertilizers (T3 and T4) increased soil TOC levels. Chemical fertilizer treatment (T2) resulted in the highest shoot fresh weight, yield, and marketable root yield. Marketable stem diameter was positively influenced by T2 and T4. There were no significant treatment effects on plant height. Hierarchical clustering isolated organic fertilizers (T3 and T4) from other treatments. Principal component analysis revealed two principal components, which together explained 87.77% of the total variance. Organic fertilizer application provided the highest TOC accumulation during the experimental period, whereas NPK fertilization was the most effective in increasing cassava yield in the first year of cultivation

Liming and phosphorus fertilization increase cassava root yield without affecting its cooking time

AbstractAcidity and low P availability in tropical soils constrain cassava (Manihot esculenta Crantz) yield. Liming increases soil Ca and P availability, but Ca can increase the storage root cooking time, and its effects vary with soil P availability. The effects of liming and P fertilization on cassava yield and their relationship with storage root cooking need to be better understood. A 2‐yr field experiment was conducted to evaluate the effect of liming at 0, 1.5, 3.1, and 4.8 Mg ha−1 with 0 or 70 kg P ha−1 on plant nutritional status and growth, yield, and cooking of fresh storage roots of the cassava cultivar IAC 576‐70. Foliar concentrations were increased for N, P, and Mg and reduced for Mn and Zn with lime application. Maximum cassava fresh storage root yield (26.4 Mg ha−1) was obtained with an optimal lime rate of 3.0 Mg ha−1 and a base saturation of 50%. Liming promoted a 6.5% increase (1.7 min) in the cooking time of storage roots. Application of P fertilizer increased shoot biomass in acidic soil and the diameter and mean weight of the storage roots in the amended soil. Phosphorus fertilization increased the yield (22% or 4.7 Mg ha−1) and P concentration of the storage roots without changing their P/Ca ratio or cooking time. Liming and P fertilization can be managed to improve cassava storage root yield without affecting storage root cooking.

Cropping Practices and Effects on Soil Nutrient Adequacy Levels and Cassava Yield of Smallholder Farmers in Northern Zambia

Cassava is a staple food and a major source of income for many smallholder farmers. However, its yields are less than 6 t ha−1 compared to a potential yield of 20–25 t ha−1 in Zambia. Understanding cropping practices and constraints in cassava production systems is imperative for sustainable intensification. Therefore, a survey of 40 households each with three fields of cassava at 12, 24, and 36 months after planting (MAP) was conducted. Analyzed soil data, leaf area index (LAI), intercepted photosynthetically active radiation, and management practices from 120 fields were collected and subjected to descriptive statistics. To explain yield differences within the same cassava growth stage group, the data were grouped into low- and high-yield categories using the median, before applying a nonparametric test for one independent sample. Stepwise regressions were performed on each growth stage and the whole dataset to determine factors affecting tuber yield. Cassava intercropping and monocropping systems were the main cropping systems for the 12 and 24–36 MAP, respectively. Cassava yields declined by 209 and 633 kg ha−1 at 12 and 36 MAP due to soil nutrient depletion for each year of cultivation until field abandonment at 8–9 years. Fresh cassava yields ranged from 3.51–8.51, 13.52–25.84, and 16.92–30.98 t ha−1 at 12, 24, and 36 MAP, respectively. For every one unit increment in exchangeable K (cmol (+)/kg soil), cassava yield increased by 435, 268, and 406 kg ha−1 at 12, 24, and 36 MAP, respectively. One unit increment of magnesium (cmol (+)/kg soil) gave the highest yield increase of 525 kg ha−1 at 24 MAP. The low levels of soil organic carbon explained the deficient nitrogen in cassava fields, which limits the LAI growth and consequently reduced intercepted radiation and low yields. The effect of exchangeable K on growth was limited by the moderate availability of Mg and low N, thus the need for balanced fertilizer regimes.

A Combined Nutrient/Biocontrol Agent Mixture Improve Cassava Tuber Yield and Cassava Mosaic Disease

Cassava (Manihot esculenta Crantz) is an important tropical root crop and a major dietary energy source for more than 500 million people. The major production constraints in cassava are the occurrence of nutrient deficiency and cassava mosaic disease (CMD). Hence to increase the cassava yield, it is critical to develop a technology to overcome the problems associated with nutrient deficiencies and CMD. Series of field experiments were conducted to evaluate and validate a new mixture containing biocontrol agent and nutrients on different genotypes and locations. The result indicated that foliar spray of combined nutrient/biocontrol agent mixture at 21 d interval from one to five-month after planting (MAP) had significantly decreased the incidence of nutrient deficiency symptom and CMD incidence resulting in an increased tuber yield. There were significant differences among the cassava genotypes for CMD reaction and foliar spray of combined nutrient/biocontrol agent mixture at 21 d interval from 1 to 5 MAP. The genotype H226 had lower CMD incidence and higher tuber yield. The multilocation trial indicated that foliar spray of combined nutrient/biocontrol agent mixture at 21 d interval from 1 to 5 MAP significantly improved the tuber yield (24%) and decreased the CMD incidence (65%) than unsprayed control. Metabolomic study indicates that foliar spray of combined nutrient/biocontrol agent mixture has altered lipid biosynthesis and metabolism, as evidenced by increased accumulation of octadecatrienoic acid (2.28-fold) trilinolein (126.3-fold) in combined nutrient/biocontrol agent mixture sprayed plants over unsprayed control. Overall, it is evident that foliar spray of combined nutrient/biocontrol agent mixture from 1 to 5 MAP has decreased CMD incidence and increased the tuber yield.

CO-INTEGRATION AND ERROR CORRECTION MODELING OF AGRICULTURAL OUTPUT: THE CASE OF CASSAVA IN ONDO STATE, NIGERIA

Cassava is an important food crop in Nigeria providing households food security and income. Cassava production has received government and stakeholders’ intervention dating back to the 1970s. Nevertheless, increased and sustainable production of the crop is under threat by exogenous factors of climate change and variability. This study investigates this concern by assessing the effects of climate change on cassava output in Ondo state, Nigerian using Co-integration and Error-Correction Modelling (ECM). Time series (1971-2010) data were sourced from the Central Bank of Nigeria (CBN), National Bureau of Statistics (NBS) Abuja, Nigerian Meteorological Agency Oshodi, Lagos. The results of the Augmented Dickey-Fuller (ADF) test revealed that all variables (cassava yield and climate variables; rainfall, temperature, and relative humidity) all have unit root problems (non-stationary) but become stationary after the first difference 1(1). The results confirmed a long-run equilibrium relationship between all identified variables as the absolute values of the variables are greater than their critical values at a 5% level of significance for both trace statistics and maximal-eigen values. The ECM result shows that rainfall exerts a positive effect, while temperature and relative humidity exert negative effects on cassava production. This indicates the sensitivity of cassava to climate change in the study area. Thus, increased and sustained production of cassava for household’s food security income would be attainable by designing programmes and policies geared toward reducing the effect of climate change. Keywords: Co-integration, Error-Correction Modeling, Cassava Output, Climate Variability, Nigeria.

Identifying Suitable Genotypes for Different Cassava Production Environments—A Modeling Approach

Crop simulation models can be used to identify appropriate genotypes and growing environments for improving cassava yield. The aim of this study was to determine the best genotypes for different cassava production environments using the cropping system model (CSM)–MANIHOT–Cassava. Data from cassava experiments that were conducted from 2009–2011 and 2014–2015 at Khon Kaen, Thailand, were used to evaluate the model. Simulations were then conducted for different scenarios using four cassava genotypes (Kasetsart 50, Rayong 9, Rayong 11, and CMR38–125–77), twelve planting dates (at monthly intervals starting in January and ending in December), and ten locations in Thailand under fully irrigated and rainfed conditions using 30 years of historical weather data. Model evaluation with the experimental data for total biomass and storage root yield indicated that the model classified well for relative productivity among different planting dates. The model indicated that growing cassava under irrigated conditions generally produced higher biomass and storage root yield than under rainfed conditions. The cassava genotype CMR38–125–77 was identified for high biomass, while the genotype Rayong 9 was identified as a good genetic resource for high yield. The December planting date resulted in the highest biomass for all locations, while the February planting date produced the highest storage root yield for almost all locations. The results from this study suggest that the CSM–MANIHOT–Cassava model can assist in determining suitable genotypes for different cassava production environments for Thailand, and that this approach could be applicable to other cassava growing areas.

The effect of tillage depth and micro-fertilizer addition on the growth and production of cassava (Manihot esculenta Crantz) planted in early dry season

The climate change from the dry season to the rainy season, causes cassava to rot a lot when harvested, this research was conducted in the early dry season by practicing two tillage depths to handle the excessive water around the rooting area, and by addition of micro-fertilizer. This study aimed to determine the cassava growth and yield when planted at the early dry season, combined with tillage depth and micro-fertilizer addition. This research was conducted in South Lampung Regency, Lampung Province, Indonesia. The cutting stems of cassava were planted in the early dry season (May) and harvested in April 2020. The tillage depth consisted of two depths: shallow tillage, above hardpan layer (30 cm), and deep tillage, including hardpan layer (60 cm). Micro-fertilizers were applied with two dosages: without fertilizer (0 kg ha−1) and with fertilizer (40 kg ha−1). Those treatments were arranged factorially (2x2) in Strip Plot Design with three replications. The result showed that deep tillage caused the rotten tubers only 15 tubers compared with the shallow tillage which was 39 tubers. The treatment of micro-fertilizer (40 kg ha−1) on the contrary increased the rotten tubers up to 35 tubers. In general, deep tillage could increase the dry weight of tubers, and micro-fertilizers could increase the fresh weight of tubers.

Effect of Weed Control Methods and Canopy Characteristics on Weed Biomass, Yield and Yield Components of Two Contrasting Cassava Varieties in the Rainforest Zone of Nigeria

Weed infestation is one of the reasons why the average cassava yield is low in Nigeria. This study was conducted in 2010 at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife to evaluate the impact of different cassava canopy structures on (i) weed biomass and (ii) yield and its components. The treatments consist of hand-weeded, herbicidal treatment, and unweeded checks in the main plot. The sub-plots constituted the cassava cultivars (TMS 30572 and TME 1) laid out in a randomized complete block with a split-plot arrangement in three replications. TMS 30572 reduced weed biomass by 59% when compared to TME 1 in the unweeded plot. However, there was no significant difference in the weed biomass between the hand-weeded and herbicide-treated where TMS 30572 and TME 1 were cultivated. Root dry matter of TMS 30572 was higher by 72% when compared to TME 1 in the untreated field. However, there was no significant difference between the yield of TMS 30572 and TME 1 in both hand-weeded and herbicide-treated plots. In conclusion, TME 30572 is recommended for cultivation in regions with similar agroecological patterns coupled with Integrated Weed Management (IWM) especially, when planting TME 1 to obtain optimum yield. Keywords: Weed biomass, TMS 30572, TME 1, Yield, and Integrated Weed Management. DOI: 10.7176/JNSR/12-14-05 Publication date: July 31 st 2021

Improved genotypes and fertilizers, not fallow duration, increase cassava yields without compromising arbuscular mycorrhizal fungus richness or diversity

Arbuscular mycorrhizal fungi (AMF) are ubiquitous in agroecosystems, but their role in mediatingagricultural yield remains contested. Field experiments testing effects of realistic agronomic practices ofintensification on AM fungus composition and yields are scarce, especially in the low-input systems ofsub-Saharan Africa. A large, full-factorial field experiment was conducted in South-Kivu (DR Congo),testing effects of fallow duration (6 vs. 12 months), genotype (landrace vs. improved), and fertilizermanagement (control vs. five combinations omitting N, P, K, and/or secondary macro- andmicronutrients) on yields of cassava, an important staple crop strongly colonized by AMF. Furthermore,we used DNA-metabarcoding to evaluate effects of these agronomic practices on the AM fungalcommunities on the roots. The shorter fallow duration strongly increased diversity and richness of AMF,but this did not correspond with increased yields. Cassava yield was mainly determined by genotype,being largest for the improved genotype, which coincided with a significantly higher sum of AM fungalsequences. Effects of fertilizer or genotype on community composition were minor to absent. We foundno evidence that increased AMF richness and diversity enhanced cassava yields. In contrast, the use ofthe improved genotype and mineral fertilizers strongly benefitted yields, without compromising richnessor diversity of AMF. Cassava-AMF associations in this work appear robust to fertilizer amendments andmodern genotype improvement.

The Phosphate Inhibition Paradigm: Host and Fungal Genotypes Determine Arbuscular Mycorrhizal Fungal Colonization and Responsiveness to Inoculation in Cassava With Increasing Phosphorus Supply.

A vast majority of terrestrial plants are dependent on arbuscular mycorrhizal fungi (AMF) for their nutrient acquisition. AMF act as an extension of the root system helping phosphate uptake. In agriculture, harnessing the symbiosis can potentially increase plant growth. Application of the AMF Rhizophagus irregularis has been demonstrated to increase the yields of various crops. However, there is a paradigm that AMF colonization of roots, as well as the plant benefits afforded by inoculation with AMF, decreases with increasing phosphorus (P) supply in the soil. The paradigm suggests that when fertilized with sufficient P, inoculation of crops would not be beneficial. However, the majority of experiments demonstrating the paradigm were conducted in sterile conditions without a background AMF or soil microbial community. Interestingly, intraspecific variation in R. irregularis can greatly alter the yield of cassava even at a full application of the recommended P dose. Cassava is a globally important crop, feeding 800 million people worldwide, and a crop that is highly dependent on AMF for P uptake. In this study, field trials were conducted at three locations in Kenya and Tanzania using different AMF and cassava varieties under different P fertilization levels to test if the paradigm occurs in tropical field conditions. We found that AMF colonization and inoculation responsiveness of cassava does not always decrease with an increased P supply as expected by the paradigm. The obtained results demonstrate that maximizing the inoculation responsiveness of cassava is not necessarily only in conditions of low P availability, but that this is dependent on cassava and fungal genotypes. Thus, the modeling of plant symbiosis with AMF under different P levels in nature should be considered with caution.

Is cassava yield affected by inverting tillage, chiseling or additional compaction of no-till sandy-loam soil?

Defining a suitable soil tillage option that provides adequate soil physical conditions for optimum cassava (Manihot esculenta Crantz) productivity has not been adequately researched in southern Brazil. This study aimed to evaluate, in an Argissolo Vermelho-Amarelo Distrófico (Acrisol or Hapludalf), three tillage methods – conventional (inverting) tillage, chiseling, and long-term no-tillage (without and with, additional soil compaction), as affecting soil hydro-physical properties and cassava yield, in southern Brazil. Undisturbed and disturbed soil samples were collected from row and interrow [...]

Improvement of Intercropping Performance Assessment in a System with Difference of Crops’ Cycle Durations: Calculation Methods for Rice-cassava Association

Crop performance evaluation in intercropping involving booth crops with different cropping cycle durations is still a concern for agronomic research while farmers already adopted this agro-system in spite of yield decreasing of one of the component. Agronomic trial involving rice-cassava intercropping with different densities of cassava planting was undertaken in western Côte d'Ivoire to determine most reliable parameters for performance index calculation comparing the conventional to new proposed methods. In a Fisher design, number of root/plant, cassava yield, cassava yield/2 rice cycles, 1000 rice grain weight, and rice grain yield were collected for exploring their reliability on global yield determination. Area Time Equivalent Ratio (ATER) and Crop Performance Ratio Time corrected were calculated as conventional method of performance index assessment while, average yield of cassava for two cycle of rice (ATER1) and the mean for both cropping cycles of rice (ATER2) were proposed as new methods. Except the variation of yield in single cropping, no significant effect of cassava planting density was recorded in global production and ATER value overlapped the threshold value of 1 in some extend. Only calculated yield were reliable for global production pointing out ATER1 as the most consistent method for rice-cassava intercropping performance determination. Rice grain yield and half of cassava yield calculated on basis of two rice cropping cycle were revealed as the most reliable parameters for ATER calculation highlighting such method viability for intercropping performance assessment when involving two crops with different cycle durations.

Nutritional status, yield components, and yield of cassava as influenced by phenological stages and water regimes

Water deficiency affects several important processes for the plants and, although cassava crop is known to have genotypes well adapted to drought, studies about the characteristics that may indicate tolerance or sensitivity to this abiotic stress are scarce for this crop. The objective of this research was to evaluate the nutritional responses and productive components in cassava plants, in different development stages and under different soil water tensions. The experiment was laid out following completely randomized design, composed by three growth stages, 90 to 180, 180 to 270 and 270 to 360 days after planting (DAP), and three soil water tensions (−10, −40 and − 70 kPa), with five replicates. The plants were mainly affected from 90 to 180 DAP, by soil tensions (−40 and −70 kPa), showing decreases in K and Fe levels and increases in P, Mg and Zn levels. The yield components were also affected by water deficit in this stage, with decreases in the shoot dry matter mass (61.7%), of the tuberous roots (80.4%) and of the stake (43.9%). The imposition of severe water deficit caused 100% of reduction in the diameter and length of the commercial root, in the peel thickness and in the pulp diameter. And yield was drastically affected by soil tensions −40 and −70 kPa in the third and fifth growth stages.

What is the impact of rural bank credit access on the technical efficiency of smallholder cassava farmers in Ghana? An endogenous switching regression analysis

This paper assesses the impact of access to credit from rural and community banks (RCBs) on the technical efficiency of smallholder cassava farmers in Ghana. The study employed the stochastic frontier, and endogenous switching regression models to estimate the technical efficiency, and the impact of RCB credit access, respectively, on a randomly selected sample of 300 smallholder cassava farmers in the Fanteakwa District of Ghana. Results suggest that cassava farmers in the District are 70.5 percent technically efficient implying that cassava yield levels could be increased further by 29.5 percent without changing the current levels of inputs. The results further reveal that the gender of the household head, access to extension services, membership in farmer organizations, and proximity to the bank are the major factors that positively influence farmers to access credit from RCBs. On average, farmers who accessed credit from RCBs have significantly higher technical efficiencies than farmers who did not access, suggesting that access to credit from RCBs positively impacts the technical efficiency of smallholder cassava farmers.

GROWTH AND YIELD INDICES OF CASSAVA (MANIHOT UTILISSIMA) AND SOIL PHYSICO-CHEMICAL PROPERTIES AS AFFECTED BY DIFFERENT TRADITIONAL TILLAGE PRACTICES IN A HUMID ENVIRONMENT

The study was conducted to assess the effects of traditional tillage practices namely No-till, Ridge-till and Mound-till, on cassava growth parameters and soil physico-chemical properties. It was a factorial experiment laid out in a randomised complete block design replicated 3-times. The factors were the 3-tillage methods and cassava plant as a test crop. Data collected on soil properties include the particle size distribution, soil bulk density, soil water content, hydraulic conductivity, soil pH, soil organic carbon, total nitrogen, available phosphorus and exchangeable bases, while data collected on plant growth and yield indices include; plant height, stem girth, number of leaves, number of tubers, tuber length and weight of tubers. The data were collected at 2, 4, 6, 8, 10 and 12 months but cumulated at 12 months after planting. The data were subjected to analysis of variance and relationship between cassava tuber yield and some soil properties measured. Results of the study showed that there was no significant difference between Ridge and Mound-till. The Ridge-till and Mound-till systems significantly influenced plant height, stem girth, number of leaves, tuber weight and total yield of cassava than No-till system, hence were recommended of increased yield of cassava in the study area.