Grasshopper Incidence and Severity of Damage as Influenced by Cyanogenic Potential in Leaf Tissue of Cassava (Manihot esculenta Crantz)

This study assessed the effect of cyanogenic potential (CNP) in leaf tissue on grasshopper incidence and severity of damage in cassava for the identification of parents with desired complementary traits for crossing. The experiment was conducted at the Foya Wulleh, Njala experimental site in Sierra Leone during 2020 and 2021 cropping seasons in a randomized complete block design with three replications. A total of 30 genotypes comprising 26 breeding lines, two improved and two local genotypes were assessed. Results showed a significant (p < 0.05) linear relationship between leaf CNP and grasshopper infestation (incidence and severity of damage) among cassava genotypes. Findings showed that the higher leaf CNP, the lower the grasshopper infestation in cassava genotypes. About two genotypes (Cooksoon and Cocoa) had low leaf CNP;three genotypes (TR0020, TR0037 and TR0013) CNP had moderately low leaf CNP;eight genotypes (SLICASS 6, TR0029, TR0032, TR0011, TR0012, TR0016-1/17, TR0002 and TR0010) had intermediate leaf CNP;seven (TR0009, TR0015-1/17, TR0036, TR0022-1/17, SLICASS 4, TR0007 and TR0026-1/17) had moderately high leaf CNP;eight (TR0008, TR0019-1/17, TR0006, TR0005, TR0021, TR0021-1/17, TR0022 and TR0024-1/17) had high leaf CNP;and two genotypes (TR0001 and TR0018-1/17) had very high leaf CNP. This suggests the indirect dependence of leaf cyanogenic potential on grasshopper infestation (incidence and severity of damage) in cassava that could be exploited for the genetic improvement of cassava for improved resistance to grasshopper infestation, nutrition and utilization of the crop.

The Influence of Gratering, Fermentation and Variety on the Physio-Chemical Quality of Cassava Starch

The study was conducted to determine the influence of gratering and fermentation parameters on the physicochemical quality of starch obtained from two cassava varieties in Sierra Leone (i.e., SLICASS 11 and SLICASS 6). Fresh cassava roots harvested from the Department of Agricultural Engineering were peeled, washed and grated before fermentation and starch extraction. Fermentation was carried out under separate aerobic and anaerobic conditions for a period of Seven days. Physicochemical analyses were conducted at the Postharvest Food and Bioprocess Engineering Laboratory of the Department of Agricultural and Bio-System Engineering, Njala University to determine the solubility, water absorption capacity and swelling power of starch extracts obtained from various experimental treatments. Fermentation method and duration had significant effects on the solubility, water absorption capacity (WAC) and swelling power (SP) of starch extracts. Maximum solubility and WAC were recorded on the fifth day, for both cassava varieties tested, with apparent significant difference resulting from the two gratering bands (i.e., with 1.5-inch nail hole and 4-inch nail hole sizes, respectively). While swelling power increased consistently with temperature for starch obtained from SLICASS-11 variety, an irregular pattern was observed for SLICASS-6 variety. A multiple correlation analysis proposes a significant and weak correlation between temperature, WAC (+0.150) and swelling power (+0.048). Also multiple correlation analyses suggest a significant correlation between fermentation period, the functional properties of starch extracts obtained from both fermentation methods and cassava varieties (i.e., solubility (−0.226), water absorption capacity (+0.301) and swelling power (+0.329)).

Variation in Yellow Root Cassava (Manihot esculentus Crantz) Genotypes and Phenotypic Relationship for Selected Postharvest and Morphological Traits

This study evaluated the variation in yellow root cassava (Manihot esculentus Crantz) genotypes and phenotypic relationship for selected postharvest and morphological traits. The trial was established at the Njala Agricultural Research Centre experimental site, Njala, during 2017/2018 cropping season in a randomized complete block design with three replications. Findings showed that the higher the total carotene content (TCC) in yellow flesh cassava genotypes, the longer the rate of postharvest physiological deterioration (PPD). Genotypes TR-0051-TCC/17 and TR-0012-TCC/17 recorded higher TCC (18.9 µg/g and 13.6 µg/g) and longer rate of PPD (4.29 and 3.14), respectively. Genotypes TR-0051-TCC/17, TR-0016-TCC/17, TR-0028-TCC/17, TR-0012-TCC/17 and TR-0020-TCC/17 had the highest TCC values of 18.9 µg/g, 16.09 µg/g, 14.72 µg/g, 13.6 µg/g and 11.23 µg/g with corresponding higher color chart values of 6, 6, 6, 5, and 6, respectively. This suggests the direct dependence of TCC on the root parenchyma color intensity in yellow flesh cassava genotypes. Findings also show a direct relationship between morphological and postharvest traits in yellow flesh cassava genotypes that could be exploited for the genetic improvement of cassava for increased shelf life, nutrition and related quality traits, as well as conservation and utilization of the crop.

Application of Predictive Model for Efficient Cassava (Manihot esculenta Crantz) Yield in the Face of Climate Variability in Enugu State, Nigeria

Climate variability as occasioned by conditions such as extreme rainfall and temperature, rainfall cessation, and irregular temperatures has considerable impact on crop yield and food security. This study develops a predictive model for cassava yield (Manihot esculenta Crantz) amidst climate variability in rainfed zone of Enugu State, Nigeria. This study utilized data of climate variables and tonnage of cassava yield spanning from 1971 to 2012;as well as information from a questionnaire and focus group discussion from farmers across two seasons in 2023 respectively. Regression analysis was employed to develop the predictive model equation for seasonal climate variability and cassava yield. The rainfall and temperature anomalies, decadal change in trend of cassava yield and opinion of farmers on changes in rainfall season were also computed in the study. The result shows the following relationship between cassava and all the climatic variables: R2 = 0.939;P = 0.00514;Cassava and key climatic variables: R2 = 0.560;P = 0.007. The result implies that seasonal rainfall, temperature, relative humidity, sunshine hours and radiation parameters are key climatic variables in cassava production. This is supported by computed rainfall and temperature anomalies which range from −478.5 to 517.8 mm as well as −1.2˚C to 2.3˚C over the years. The questionnaire and focus group identified that farmers experienced at one time or another, late onset of rain, early onset of rain or rainfall cessation over the years. The farmers are not particularly sure of rainfall and temperature characteristics at any point in time. The implication of the result of this study is that rainfall and temperature parameters determine the farming season and quantity of productivity. Hence, there is urgent need to address the situation through effective and quality weather forecasting network which will help stem food insecurity in the study area and Nigeria at large. The study made recommendations such as a comprehensive early warning system on climate variability incidence which can be communicated to local farmers by agro-meteorological extension officers, research on crops that can grow with little or no rain, planning irrigation scheme, and improving tree planting culture in the study area.

Optimization of the Pretreatment of the Mixture of Cassava Peelings and Pineapple Fibers Using Response Surface Methodology and a Process Simulator for the Bioethanol Production

The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min-1, 5358.1461 J·mol-1, 1383.03691 min-1, 51577.6100 J·mol-1 respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.

Physicochemical Characterisation of Flours from Local Cereals and Powder from Cassava (Manihot esculenta Crantz) Leaves Varieties Cultivated in the Northern-Cameroon in Order to Supplement Infant Flours

The aim of the present study was to investigate on the inventory and determination of the nutritional value of cereals flour and cassava leaves powder in order to analyse their use in the production of infant flour. In this paper, a A survey to identify the cereals used in the preparation of infant porridge in the Northern Cameroon was done by using 447 mothers having children between 06 and 59 months from areas (Gbakoungue, Sassa-Mbersi, Sanguere-Ngal and Kotkong-Wouldata) with high rate on malnourished children. Flour was prepared from the most preponderant cereals and Cassava leaves powder from varieties identified by the Regional Centre of Agricultural Research (CRRA) of Wakwa and local population. Flour and powder samples obtained were subjected to chemical composition analysis. Parameters analysed were crude proteins, total carbohydrates, ash, total fats, total phenols, total tannins, total carotenoids, vitamin C or cyanide. Also Iron, calcium and zinc were determined. The results revealed that white maize (62%) was the main cereal used in the preparation of infant porridge followed respectively by red sorghum, white rice and muskwari. Ten cassava varieties were identified: three (03) by CRRA (TME, 96/1/14 and IRAD 4115) and seven (south, gambada, sweet, Benin, six months, M. glaziovii and grouna) by local population. Amongst cereals flour, those from white maize indicated high protein (10.09%), carbohydrates (84.46%) and total fat (7.46%) contents. The powder from 96/14/14 cassava variety showed high amount of iron (11.98 mg/100g), calcium (751.02 g/100g) and low cyanide content (1.21 ppm) amongst all the cassava leaves powder samples. The supplementation of white maize flour by cassava leaves powder from 96/14/14 variety could therefore be recommended for the preparation of infant flours.

Impact of Selected Processing Methods of High-Level Cyanide in Cassava on Optic Neuropathy in Wistar Albino Rats—An Experimental Study

Background: Cassava tuber crop is a staple food rich in carbohydrates and utilized in various forms by millions of Nigerians. The storage root of the cassava contains linamarin, a cyanogenic glycoside that is easily hydrolyzed to release cyanide salt compounds which is toxic to the nervous system especially the optic nerve, sometimes leading to optic neuropathy and visual impairment. Aim: The aim of this study is to find out the impact of selected processing methods of high-level cyanide in cassava on optic neuropathy in Wistar albino rats. Methodology: Twenty-four Wistar albino rats were fed with different concentration and duration of predetermined high-cyanide content cassava root cultivar which was processed using different processing methods adopted by various communities in Rivers State, Nigeria (for human consumption). A control group of 3 Wistar albino rats was fed with normal “Growth Mesh” meals. The pre and post weights of the animals and the fundoscopic optic nerve status of the rats were evaluated after 30 and 60 days. SPSS Version 25 was employed for descriptive and inferential statistical analyses. A p-value of ≤0.05 was considered statistically significant. Results: The Cassava species available in Rivers State have high cyanide content (2336.79 mg CN-/kg dry weight of cassava). There was statistically significant reduction in the cyanide content (p = 0.000) depending on the various common processing methods (into garri for human consumption): 24 hours, 48 hours, fermentation;with and without red palm oil additive. The individual weights as well as the mean weight of the 24 rats in the experimental group increased gradually from the first week to the 9th week with a slight weight reduction on the third and fourth weeks which was not statistically significant (p = 0.092). However, there was a steady increase in the weights of the animals in the control group throughout the 9 weeks. Varying degrees of optic neuropathy occurred, worse with the rats that had 24-hour fermented cassava twice daily for 60 days. The intra and inter group differences in the optic disc changes was statistically significant (p = 0.000). Conclusion: Longer duration of processing cassava roots into garri for human consumption reduces its cyanide content and minimizes the adverse impact on the optic nerve.

In-vitro digestibility,protein digestibility corrected amino acid,and sensory properties of banana-cassava gluten-free pasta with soy protein isolate and egg white protein addition

Soy protein isolate and egg white protein were added to cassava-banana gluten-free pasta and the effects on the nutritional quality,digestibility properties,protein digestibility corrected amino acid(PDCAA),and sensory acceptance of the pasta was observed.Banana-cassava composite flour(75:25)was blended with soy protein isolate or egg white protein at the following rates:0,5,10,and 15 g/100 g flour.Cooked pasta samples were analysed for total phenolic content(TPC),antioxidant activity,amino acid profiles,protein content,starch digestibility,protein digestibility and protein digestibility corrected amino acid score(PDCAAS).Addition of both proteins decreased starch digestibility,increased protein digestibility,improved the balance of the amino acid profile,and PDCAAS whereas only soy protein isolate enhanced the TPC and antioxidant capacity of the banana-cassava pasta.An egg white protein-fortified banana-cassava pasta had better customer acceptance and purchase intent than soy protein isolate inclusion.

A homeodomain-leucine zipper I transcription factor, MeHDZ14,regulates internode elongation and leaf rolling in cassava(Manihot esculenta Crantz)

Drought stress impairs plant growth and other physiological functions. MeHDZ14, a homeodomainleucine zipper I transcription factor, is strongly induced by drought stress in various cassava cultivars.However, the role of MeHDZ14 in cassava growth regulation has remained unclear. Here we report that MeHDZ14 affected plant height, such that a dwarf phenotype and altered internode elongation were observed in transgenic cassava lines. MeHDZ14 was found to negatively regulate the biosynthesis of lignin. Its overexpression resulted in abaxially rolled leaves. The morphogenesis of leaf epidermal cells was inhibited by overexpression of MeHDZ14, with decreased auxin and gibberellin and increased cytokinin contents. MeHDZ14 was found to regulate many drought-responsive genes, including genes involved in cell wall synthesis and expansion. MeHDZ14 bound to the promoter of caffeic acid 3-Omethyltransferase 1(MeCOMT1), acting as a transcriptional repressor of genes involved in cell wall development. MeHDZ14 appears to act as a negative regulator of internode elongation and epidermal cell morphogenesis during cassava leaf development.

Cassava Me RS40 is required for the regulation of plant salt tolerance

Soil salinity affects the expression of serine/arginine-rich(SR) genes and isoforms by alternative splicing, which in turn regulates the adaptation of plants to stress.We previously identified the cassava spliceosomal component 35 like(SCL) and SR subfamilies, belonging to the SR protein family, which are extensively involved in responses to abiotic stresses.However, the post-transcriptional regulatory mechanism of cassava arginine/serine-rich(RS) subfamily in response to salt stress remains to be explored.In the current study, we identified 37 genes of the RS subfamily from 11 plant species and systematically investigated the transcript levels of the RS40 and RS31 genes under diverse abiotic stress conditions.Subsequently, an analysis of the conserved protein domains revealed that plant RS subfamily genes were likely to preserve their conserved molecular functions and played critical functional roles in responses to abiotic stresses.Importantly, we found that overexpression of MeRS40 in Arabidopsis enhanced salt tolerance by maintaining reactive oxygen species homeostasis and up-regulating the salt-responsive genes.However,overexpression of MeRS40 gene in cassava reduced salt tolerance due to the depression of its endogenous gene expression by negative autoregulation of its own pre-mRNA.Moreover, the MeRS40 protein interacted with MeU1-70Ks(MeU1-70Ka and MeU1-70Kb) in vivo and in vitro, respectively.Therefore, our findings highlight the critical role of cassava SR proteins in responses to salt stress in plants.

Down-regulation of MeMYB2 leads to anthocyanin accumulation and increases chilling tolerance in cassava(Manihot esculenta Crantz)

Chilling-induced accumulation of reactive oxygen species(ROS) is harmful to plants,which usually produce anthocyanins to scavenge ROS as protection from chilling stress.As a tropical crop,cassava is hypersensitive to chilling,but the biochemical basis of this hypersensitivity remains unclear.We previously generated Me MYB2-RNAi transgenic cassava with increased chilling tolerance.Here we report that Me MYB2-RNAi transgenic cassava accumulated less ROS but more cyanidin-3-O-glucoside than the wild type under early chilling stress.Under this stress,the anthocyanin biosynthesis pathway was more active in Me MYB2-RNAi lines than in the wild type,and several genes involved in the pathway,including Me TT8,were up-regulated by Me MYB2-RNAi in the transgenic cassava.Me MYB2 bound to the Me TT8 promoter and blocked its expression under both normal and chilling conditions,thereby inhibiting anthocyanin accumulation.Me TT8 was shown to bind to the promoter of Dihydroflavonol 4-reductase(Me DFR-2)and increased Me DFR-2 expression.Me MYB2 appears to act as an inhibitor of chilling-induced anthocyanin accumulation during the rapid response of cassava to chilling stress.

Production of Corn (Zea mays) Starch and Cassava (Manihot esculenta) Starch and Their Application as Yogurt Stabilizer

The present study evaluated the stabilizing effect of starch produced from corns and cassava on the stability of cow milk yogurt. A sample of both corn and cassava starch was selected and used in the yogurt making as stabilizers. The yogurt samples have been analyzed for their WHC, syneresis and protein content. The yogurt with no added starch has found to have very low WHC and high syneresis compared to other samples. The yogurt made with the addition of corn starch as a stabilizer was highly accepted than the yogurt with cassava starch and the yogurt without starch. The findings from this study provide an alternative to add the value of local corns and cassava.

Genetic Structure and Diversity Study of Cassava (Manihot esculenta) Germplasm for African Cassava Mosaic Disease and Fresh Storage Root Yield

A better understanding of population structure and genetic diversity among cassava germplasm for African cassava mosaic disease and fresh root yield traits is useful for cassava improvement programme. Phenotype-based selection for these traits is cumbersome due to phenotypic plasticity and difficulty in screening of phenotypic-induced variations. This study assessed quantitative trait loci (QTL) regions associated with African cassava mosaic disease (ACMD) and fresh storage root yield (FSRY) in 131 cassava (Manihot esculenta) genotypes using a genome-wide association study (GWAS). The single nucleotide polymorphism (SNP) loci and associated candidate genes, when validated, would be a valuable resource for marker-assisted selection in the breeding process for development of new cassava genotypes with improved resistance to ACMD and desirable high root yield. Population structure analysis using 12,500 SNPs differentiated the 131 genotypes into five distinct sub-groups (K = 5). Marker-trait association (MTA) analysis using the generalized linear model identified two QTL regions significant for ACMD and three for FSRY. This study demonstrated that DArTseq markers are useful genomic resources for genome-wide association studies of ACMD and FSRY traits in cassava for the acceleration of varietal development and release.

Ethnobotanical Knowledge of Local Cassava Varieties and Characteristics Desired by Farmers in Sierra Leone

It has been observed that farmers adopt only a small number of the “improved” cultivars. A nationwide germplasm collection exercise in February 2018 provided the opportunity to collect indigenous technical knowledge (ITK) of the diversity of cassava varieties in terms of: their morphology, growth characteristics, uses (of tubers and leaves) and desirable characteristics. The objective is to see to what extent the objectives of the plant breeders are consistent with what farmers’ value. We performed 405 structured and semi-structured interviews with informants who were selected based on “purposive household sampling”. We found a considerable turn-over in cassava varieties, just over a third (45) have been in cultivation for at least 40 years, however, since the end of the civil war an additional 25 varieties are cultivated, while others varieties seem to have disappeared. One major issue with estimating turnover of varieties is whether the same variety might have several local names, and conversely the same name may be applied to different cultivars. Farmers overwhelmingly use ITK to select and preserve cassava germplasm for future use. Farmers have a clear preference for: sweet taste, high yield, early maturity and easy cooking and preferentially adopt cultivars that have those qualities. Cassava is primarily a human food eaten boiled or fried, some are processed into fufu and gari, and uses as livestock feed and medicine are reported but at low levels. The information produced during this study could help plant breeders choose selection criteria that will ensure their efforts are adopted and sustainable, the importance of preserving the genetic resources of local cultivars is also highlighted.

Multiplex PCR for Identification and Detection of Cassava Mosaic Begomoviruses in Togo

Cassava mosaic disease (CMD) caused by Cassava Mosaic Begomoviruses (CMBs) is one of the most devastating crop diseases and a major constraint for cassava production. In order to ensure surveillance for epidemic prevention, low-cost diagnostic tools are appropriate for large-scale testing of cassava viruses. Multiplex PCR diagnosis is one approach that can reduce diagnostic costs and delays. A multiplex PCR approach was developed for simultaneous detection of African cassava mosaic virus (ACMV), East African Cassava Mosaic Virus and East African cassava mosaic Cameroon virus (EACMV/CM) in Togo CMD-infected cassava leaves. Three primers pairs were used to target their respective viruses in a single tube PCR. Multiplex PCR detected ACMV, EACMV and EACMV/CM in plant DNA extracts prepared from cassava leaves infected with CMB. The primers amplified 783 bp specific to ACMV, 650 bp specific to EACMV and 560 bp specific to EACMCV/CM in both uniplex and multiplex formats. Multiplex PCR is an excellent tool for the effective control of cassava diseases. .

Thermo-Mechanical Properties Study of Stabilized Soil Bricks to Sugar Cane Molasses and Cassava Starch Binders

The current study deals Swith thermo-mechanical properties of stabilized soil small bricks with the help of organic binders of sugar cane molasses and cassava starch. Different formulations of soil concrete have been suggested after the geotechnical characterization of samples of soil was taken. From these, it arises that the studied soil is the most plastically clay (of type A3) according to GTR classification. Samples made of small bricks and measured out at 4%, 6% and 8% of binders (molasses, starch or molasses + starch) have been warmed up to different temperatures (100°C, 150°C, 200°C and 250°C) for the rising of the thermic behavior under different conditions and submitted to crushing testings for the estimation of characteristic resistances to the compression. According to the mechanical behavior, we note an improvement of resistances for small bricks measured 4%, 6% and 8%, of molasses respectively of 32.44%, 32.06% and 23.43% against the value of reference for small bricks without molasses. In the same way, the binder (molasses + starch) also reveals an improvement of resistance to the compression of 13.27%, 26.17% and 26.17%. On the contrary, the stabilization with the starch binder did not bring a significative improvement. According to the thermic influence, the heating at 100°C of stabilized small bricks at 4%, 6% and 8% of molasses, reveals a significative improvement of resistances. Moreover, the stabilization with the starch reveals on the contrary a good behavior for heatings at 150°C and 250°C. In short, for the binder (molasses + starch), it is the heating at 200°C that shows some improvements of remarkable resistances. Different analyses of realized statistics also show the effectivity of obtained results. For all realized formulations, the measuring out at 6% of binders (molasses, or molasses + starch) seems as optimal in front of the best thermo-mechanical revealed properties.

Cassava Groundnut Intercropping: A Sustainable Land Management Practice for Increasing Crop Productivity and Organic Carbon Stock on Smallholder Farms

Cassava-groundnut intercropping is not a common practice among smallholder farmers in Sierra Leone even though both crops are well suited for intercropping. On-farm trials were conducted in three locations (Bai Largor, Bassah, and Njala Kanima) in the Moyamba district during the 2021 cropping season to investigate the efficacy of cassava-groundnut intercropping for increasing crop productivity and soil organic carbon stock on smallholder farms in the Moyamba district, Southern Sierra Leone. The experimental design was a randomized complete block design in three replications with treatments of sole groundnut, sole cassava and cassava-groundnut intercropping. Data on the yield and yield components of cassava and groundnut were analysed using the PROC MIXED procedure of SAS 9.4 and means were compared using the standard error of difference (SED). The above-ground biomass, number of roots per plant, and fresh root yield of cassava were not significantly (p > 0.05) affected by the cassava-based cropping system. Averaged across locations, intercropping cassava with groundnut decreased the above-ground biomass, the number of roots per plant, and fresh root yield of cassava by 17%, 11%, and 17%, respectively. The above-ground biomass, number of pods per plant and fresh pod yield of groundnut were significantly (p 1), the highest net revenue and benefit-cost ratio. The benefit-cost ratio was also favourable for the sole cassava (BCR > 1) but not favourable for the sole groundnut (BCR < 1). Averaged across locations, intercropping cassava with groundnut increased the benefit-cost ratio by 121% and 13% when compared to the sole groundnut and sole cassava. In the event of a 40% yield loss for the cassava and groundnut, the benefit-cost ratio was favourable (1.12) only for the cassava groundnut intercropping system. The net soil organic carbon stock was favourable only for the cassava-groundnut intercrop. Averaged across locations, the net soil organic carbon for the cassava-groundnut intercropping increased by 3.4% when compared to the baseline within one cropping cycle of the cassava (12 months). The results confirm that cassava-groundnut intercropping is a sustainable land management practice that could enhance crop productivity and soil organic carbon stock on smallholder farms.

Effect of Different Chemical Treatments on Seedling Emergence Growth of Frozen Cassava

The rooting and growth of frozen cassava under different chemical treatments were studied.The result has demonstrated that disinfection effect could increase rooting rate and seedling emergence rate of cassava seed stem and decrease the rate of mildew.The sportak treatment could generate better effect(rooting rate and seedling emergence rate were 63%,the mildew rate of stem was 28%).Among different rooting reagents,Genwang+lime treatment generated better effect on rooting rate and emergence rate of frozen cassava than these of other groups and control group.It was concluded from the effects of different rooting reagents on growth of seed stem that Genwang+lime treatment could promote elongation and growth of cassava significantly(the mean plant height of experimental groups inceased 8.58 cm compared with that of control group) while paclobutrazol+lime generated the best effect on crassation of stem(the stem diameter of experimental group increased 0.4 cm compared with that of control group).

Study on Pathogeny Identification and Biological Characteristics of Anthracnose in Cassava

[Objective] The research aimed to isolate and identify the anthracnose pathogen of Cassava and study its biological charcteristics.[Method] Two isolates of anthracnose （CCGHN01 and CCGHN03） in Cassava were isolated from the diseased leaves collected from Hainan of China.They were identified through the morphological observation of conidia and ITS sequence analysis.And the morphological characteristics were studied.[Result] The morphological observation of conidia and ITS sequence analysis indicated that the two isolates were Colletotrichum gloeosporioides.The morphological characteristics study results showed that optimum medium for the growth of two strains was PSA,the optimum temperatures were 26 ℃ and 30 ℃ respectively,the optimum pH was 8.0,the optimum light conditions were alternative light and dark and complete darkness respectively.For the conidia germination of two strains,the optimum temperatures were 28 ℃ and 30 ℃ respectively and the lethal temperature was 55 ℃ remaining 10 min.[Conclusion] The research laid the foundation for further control of anthracnose in Cassava.

Effects of Different Intercropping Modes on Growth, Yields and Economic Benefit of Cassava and Peanut in Symbiotic Period

[Objective] This study was conducted to investigate effects of different intercropping modes on growth, yields and economic benefit of cassava and peanut in symbiotic period. [Method] With sole cropping of cassava （M1） and sole cropping of peanut （M2） as control groups, effects of intercropping of cassava with 1 row, 2 rows and 3 rows of peanut （M3, M4 and M5）on crop growth, yields and economic benefit were studied. [Result] Intercropping affected both growth and yields of cassava and peanut. Growth competition existed between cassava and peanut, and plant heights of cassava and peanut changed similarly. In late stages of intercropping, treatments M1, M2 and M5 showed higher plant heights under no nitrogen application, while treatment M3 and M4 exhibited higher plant heights under nitrogen application; intercropping improved leaf temperature, but no obvious law could be observed among different intercropping treatments; and intercropping improved total dry matter amount, which was the highest in M5 in root expanding stage and on the 30th day of the expanding stage, and the highest in M4 on the 60th day of the expanding stage. Intercropping reduced the yield of single plant, but improved the economic benefit of red upland soil; and under no nitrogen application and nitrogen application, cassava yields decreased by 25.35% and 14.55%, respectively, peanut yields decreased by 28.76% and 52.60%, respectively, while economic benefit increased by 72.90% and 56.82%, respectively. [Conclusion] Compared with sole cropping, interplanting cassava with 1 row, 2 rows or 3 rows of peanut could all improve economic benefit, and the economic benefit increased with number of rows of interplanted peanut increasing.