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.

Influence of Harvest Periods on Cassava (Manihot esculenta Crantz) Agronomic Traits and Physiological Response to Post-Harvest Physiological Deterioration

Cassava (Manihot esculenta Crantz) is the third largest source of calories in tropical countries and the sixth most important food crop in the World. However, the short shelf life of its storage roots after harvest due to a rapid post-harvest physiological deterioration (PPD) makes the roots to be considered as a risky product to market. The objectives of this work were to investigate the influence of two harvest periods on cassava agronomic parameters and their physiological response to PPD. Three cassava cultivars 96/1414, I070593 and LMR were selected for the experiment and harvested at 10 and 12 months after planting (MAP). The response to PPD was assessed during storage at 0, 3, 8 and 15 days after harvest (DAH). Total proteins content, soluble sugars and starch, total polyphenols compounds, polyphenoloxidase and peroxidase activities were recorded during storage. Results showed large variation among the parameters at the two harvest periods across the cultivars. High number of tubers was recorded in all the cultivars at 12 MAP and a significant increase in storage roots length was observed in 96/1414 and LMR from 10 MAP to 12 MAP (25 ± 5.1 to 41.3 ± 5.9 and 22.6 ± 3.3 to 27.9 ± 4.8) respectively. A reduction of about 49% of tubers weight was observed in I070593 from 10 to 12 MAP while an increase of about 36% and 11% were recorded in LMR and 96/1414 respectively. Tubers from I070593 showed less susceptibility to PPD when harvested at 10 MAP compared to those from LMR and 96/1414 where less susceptibility to PPD were recorded at 12 MAP. An increase in soluble sugars content, total proteins content and peroxidase activity subsequently to a decrease in starch content were recorded during storage from 8 to 15 days after harvest especially at 10 MAP in I070593 and at 12 MAP in LMR and 96/1414. High content of total phenolic compounds and less activity of polyphenol oxidase were correlated to PPD susceptibility. This work opens a new insight issue of the consideration of the appropriate harvest time of the cultivars as a tool to better control the onset of postharvest physiological deterioration.

Chemical Constituents from the Stems of Manihot esculenta

Two new compounds,maniesculentins A(1)and B(6),together with four known ones were isolated from the stems of Manihot esculenta Crantz.The structures of the new compounds were elucidated by extensive spectroscopic methods including NMR spectroscopy and mass spectrometry.The two new compounds(1,6)were assayed for antibacterial activity against four tested bacteria lines.

Microscopic Characteristics, Chromatographic Profiles and Inhibition of Peroxidase Activity of the Leaves of <i>Manihot esculenta</i>and <i>Manihot glaziovii</i>, Consumed as Traditional Vegetables

Methanolic extracts from the leaves of Manihot esculenta (Two cultivars) and Manihot glaziovii, consumed as traditional vegetables in DR. Congo was chemically characterized by Thin layer Chromatography and High Performance Liquid Chromatography. In vitro biochemical activities of extracts against Radical Oxidative Species (ROS) production were assessed in cellular models, on enzymes, Myeloperoxidase (MPO) and Horseradish Peroxidase (HRP) involved in inflammation. The microscopic analysis of the powder of leaves showed that each species displays specific and discriminating botanical microscopic features. Varieties of M. esculenta had a chemical fingerprint different from M. glaziovii. The majority of compounds were polyphenols, represented mainly by rutin, kaempferol-3-O-rutinoside, amentoflavone, phenolic acids such as gallic acid. All extracts exhibited high cellular antioxidant activity in the range of 0.1 to 10 μg·mL-1 using lucigenin with neutrophils, but a moderate cellular antioxidant activity ranging between 10 and 100 μg·mL-1 with DCFDA on HL60 monocytes. Extracts from Manihot leaves showed a pronounced inhibitory effect on the production of extracellular ROS, on HRP and myeloperoxidase activity. Cellular antioxidant activities, the inhibitory effect on HRP of extracts from M. glaziovii, M. esculenta cultivar Mwambu were significantly higher, but their inhibitory effect on the activity of MPO was lower than those of M. esculenta cultivar TEM 419. The biological activities of Manihot esculenta and Manihot glaziovii were well correlated to their phytochemicals that could justify their traditional use as vegetables, potential functional foods or nutraceutical resources and medicines.

矮壮素浸种对木薯苗期生长的影响

为改进木薯种茎的矮壮素浸种技术,设置不浸种、不同浓度矮壮素(0、50 mg/L、100 mg/L、200 mg/L、300 mg/L)浸种、不同浸种时长(6 h、12 h),研究其对袋栽木薯幼苗根、茎、叶的生长及土壤酶活性的影响。结果表明,与不浸种比较,100~200 mg/L浸种6 h和12 h显著增粗茎径;200 mg/L浸种6 h、50 mg/L浸种12 h均显著提高总根长,并增粗细根根径。其中,总根长增幅分别达22.69%~31.33%、27.38%~36.86%,细根根径增幅分别达10.53%~20.29%、17.11%~20.29%;100~200 mg/L浸种6 h和50~100 mg/L浸种12 h显著提高茎叶干重和膨大根干重;50~200 mg/L浸种6 h显著提高细根干重32.77%~76.76%,50~100 mg/L浸种12 h显著提高细根干重25.54%~71.83%;100~200 mg/L浸种6 h和50~100 mg/L浸种12 h显著提高薯干淀粉含量;100~200 mg/L浸种6 h和50~100 mg/L浸种12 h有效提高土壤脲酶活性,100~200 mg/L浸种6 h和12 h均提高土壤酸性磷酸酶活性。50~200 mg/L矮壮素溶液浸泡木薯种茎6 h,能较好促进木薯苗的根、茎、叶生长,并提高土壤的脲酶和酸性磷酸酶活性。

木薯NHX基因家族鉴定及特征分析

【目的】鉴定木薯NHX基因家族成员并分析特征,为研究木薯耐盐新种质和挖掘木薯抗逆特性基因具有重要意义。【方法】基于全基因组水平上对木薯NHX基因家族进行鉴定,对其系统进化树、蛋白理化性质、保守结构、保守基序、共线性、蛋白互作等进行分析。【结果】在木薯中共鉴定到9条MeNHX基因(MeNHX1~MeNHX9),分为3个亚族,且不均匀地分布在7条染色体上,其中,染色体Chr03和Chr15中均包含2条MeNHX基因,染色体Chr01、Chr08、Chr09、Chr10和Chr17均只有1条MeNHX基因。MeNHX蛋白有520~1 157个氨基酸,其相对分子质量为58.09~128.21 kDa,理论等电点为5.63~9.11;为两性蛋白,不稳定系数为34.60~41.34;为疏水性蛋白,其GRAVY为0.094~0.595。9条MeNHX基因均含有典型的Na^(+)/H^(+)保守结构域,木薯NHX存在多个共线性区块,进化压力Ka/Ks值均小于1,主要受纯化选择作用;含有光响应、生物胁迫及非生物胁迫作用相关元件MeNHX基因同多条离子通道基因存在蛋白互作关系。【结论】MeNHX基因在木薯受到光、生物胁迫和非生物胁迫时参与生长发育过程,以适应其环境变化。

木薯FER基因家族的全基因组鉴定和表达分析

植物铁蛋白(Ferritin, FER)既能存储铁,又能响应各种非生物胁迫。该研究基于全基因组水平对木薯(Manihot esculenta)的FER基因家族进行分析,结果表明,从木薯中共鉴定到4个FER基因,根据系统发育树将木薯FER基因划分为2支,所有成员均包含Euk_Ferritin的功能结构域并位于叶绿体内。木薯FERs基因位于LG7~LG10染色体上;基因共线性分析表明,共有3对潜在的复制基因对,无串联重复事件;Ka/Ks值表明,MeFER同源基因经过了纯化选择;该家族含有响应激素和胁迫诱导的顺式作用元件;q RT-PCR分析表明,MeFER基因的表达具有组织特异性,MeFER4基因响应多种胁迫,且在干旱胁迫下响应最为显著。该研究为木薯FER基因家族的功能研究奠定了基础。

White Gold: Cassava as an Industrial Base

A great number of production sectors in Africa that make use of maize, rice and wheat starches have carried out several experiments on cassava (Manihot esculenta) flour and starch, and found them to be potentially valuable substitutes. The benefits ranged from being a human staple food, constituent of animal feeds, and raw material in food processing, textile, pharmaceutical, detergent, alcohol and plastic industries to production of confectioneries like bread, spaghetti and chinchin. The vast availability of this “white gold” in most African countries can be explored in order to fully maximize its potential as an industrial base for interested entrepreneurs.

High-Yielding and Carotenoid-Rich Clones Identification among Thirty-One Cassava Clones with Colored Flesh

Cassava is the second most important food crop produced and consumed in Côte d’Ivoire, after yam. White-fleshed varieties, which are low in total carotenoids, are widespread, while coloured-fleshed varieties (yellow to orange), carotenoid-rich, are rare. However, the consumption of carotenoid-rich cassava varieties could help to alleviate health problems related to vitamin A deficiency. This study aims to identify high agronomic performance, carotenoid-rich and versatile cassava varieties among 31 clones introduced from IITA. They were compared to three controls, Bocou2, Yacé and Bonou2, according to agronomic and technological parameters. Results found that out of the 31 clones, six (I082425, I084157, I084563, I085894, I083774 and I070520) were more productive than the control Bocou2 (46.01 ± 14.88 t·ha-1);the clone I083774 had the highest yield (55.88 ± 6.16 t·ha-1). Twenty-one clones had dry matter contents, ranging from 37% to 41%, significantly similar to Yacé control (42.70%). Thirteen clones had highest total carotenoid contents than the control Bocou2. Clones I084157 and I082425 recorded the highest total carotenoid contents with 17.57 ± 1.92 and 18.39 ± 1.19 μg·g-1 respectively. Overall 31 tested clones were fibrous to varying degrees while 27 clones had mild or neutral post-cooking flavours and 17 clones had poor cooking. The clone I084157 is the best compromise of agronomic and technological desired traits.

Cassava Flour: Quantification of Cyanide Content

Cassava flours are obtained from the roots of Manihot esculenta Crantz and daily fairly consumed by the Brazilian population considering it comes to hum food, and also inserted into food baskets, besides to present low cost and easy access, in addition to being plant easily cultivated by the population. However, the food obtained with cassava may contain hydrocyanic acid, in the form of cyanogenic glycoside when those meals are not cooked properly. The oral toxicity can range 30 - 210 mg/kg body, the average daily consumption per capita in larger rural areas than in urban areas for cassava flour 19.1 g against 4.7 g, respectively. Brazil’s North and Northeast have higher consumption of cassava flour, associated with family monthly monetary income, making this region more vulnerable to poisoning. The objective of this study was to quantify cyanogenic glycosides present in some types of Brazilian cassava foods by means of spectrophotometric technique (reading at a wavelength of 530 nm). For quantitative determination of cyanide content, linamarase hydrolysis was used. The amount of cyanide was determined, and results were: artisan toasted cassava flour: 15 mg/500g, sweet cassava starch: 32.5 mg/500g, artisan dried cassava flour: 37.5 mg/500g, “bijuzada” cassava flour: 60 mg/500g, industrialized, toasted cassava flour: 115 mg/500g, industrialized, raw cassava flour: 140 mg/500g, and wet cassava flour: 225 mg/500g. Considering the chronic ingestion of cyanide present in these foods, they can cause public health problems.

Effects of Non-Conventional Substrate and NPK Fertilizer on Cassava Plantlets Acclimatization for Plant Material Production

The adaptation of cassava plantlets to natural conditions remains the main obstacle in the process of free virus plantlets production. In this study, cassava plantlets acclimatization was assessed by pre-acclimatization, height of acclimated plantlets, substrate, and nutrient watering solution. The results revealed that pre-acclimatization gave a high survival rate (61.9%) whereas the direct tunnel acclimatization was conducted to low rate (27.31%) of plantlets. Furthermore, the height of plantlets influenced significantly (p < 0.05) their survival rate with best survival rate observed on plantlet height from 1 cm to 5 cm. There was no significant difference between the substrates used and watering solutions. However, the Sawdust substrate gave a high survival rate (46.67%) and better phylogenesis (1.8) in the variety RB 89509. Likewise, plantlets treated with NPK nutrient watering solutions (20-10-10) had a better survival rate (48.57%), better phylogenesis (2.125) with the variety RB 89509 and better growth in height (1.18 cm) with the variety BF92/0267. These findings constitute a database for the establishment of the technical itinerary for the acclimatization of cassava plantlets.

发酵条件对木薯嫩梢腌制蔬菜营养品质和风味的影响

目的探究发酵条件对木薯(Manihot esculenta Crantz)嫩梢腌制蔬菜(pickled vegetables with cassava tender shoots,PVCT)营养品质和风味影响。方法分别采用模糊数学感官综合评价法、电感耦合等离子体发射光谱法、高效液相色谱法和顶空固相微萃取-气相色谱-质谱法对不同原料配比和发酵时间条件下的PVCT感官评分、元素、有机酸和挥发性成分进行分析。结果木薯嫩梢、橄榄酱、食盐水浓度配比为100:15:2(m:m:c)时,感官评分最高,且有较高的K、Mg和P元素含量(分别为1126.74、206.00、276.88 mg/100 g,DW)和适中的Ca、Zn和Mn等元素(分别为503.41、11.06、12.84 mg/100 g,DW)。发酵腌制10 d后脂肪含量达到最低值,为1.78 g/100 g,蛋白质含量在腌制的第15 d到达最高值,为28.34 g/100 g。亚硝酸盐含量在发酵10 d后趋于稳定,约为0.97 mg/kg;PVCT经炒制后氰化物含量符合国家安全标准,约为0.0595 mg/kg;单宁含量对PVCT风味影响较小,且在发酵30 d后含量降至最低,为1.75 g单宁酸/100 g。乳酸(含量最高为33.96 mg/g)为主要有机酸成分,挥发性物质在第10 d开始显著富集,第15 d后丰度逐渐下降,其中烃类物质(含量最高为83.76%)在PVCT中最丰富。结论不同原料配比和不同发酵时间会显著影响PVCT品质,发酵会造成矿物质元素不同程度的流失,而有机酸和挥发性风味的富集并不是发酵越久越好,其主要集中在发酵的10~15 d,因此,木薯嫩梢发酵菜的腌制应综合考虑原料的配比和发酵时间,研究可为木薯叶食品化利用提供新方向和参考。

二斑叶螨抗性木薯木质素合成途径基因表达特性研究

木质素是作物防御有害生物的重要理化屏障,但其在木薯抗虫性中的作用机制尚不明确。为了探讨木质素合成途径基因在木薯抗二斑叶螨中的作用,以抗螨木薯品种C1115、缅甸(Myanmar)、SC9和感螨木薯品种SC205、面包(Bread)、BRA900为材料,采用实时荧光定量PCR分析二斑叶螨取食上述木薯品种不同时间后(0、1、4 d)木质素合成途径基因(PAL、4CL、C4H、HCT、CSE、COMT、CCoAOMT、F5H、CCR、CAD)在不同品种间的表达量差异。结果表明,与螨害前相比,抗、感螨木薯品种中C4H、HCT、CSE、F5H、CAD的表达量虽总体上有所提高,但并不是都能够达到显著差异水平,并且相同螨害时间内,这5个基因的表达量在抗、感木薯品种间整体上也未表现出显著差异。与之相反,PAL、4CL、CCoAOMT、CCR这4个基因的表达量在抗螨木薯品种中显著提高,在感螨木薯品种中显著降低或无显著差异,并且在相同的螨害时间内,抗螨木薯品种中这4个基因的表达量普遍高于感螨木薯品种,尤其以螨害4 d后表达量表现出显著差异,进一步相关性分析发现,这4个基因表达量的提高与木薯抗螨性显著正相关。根据上述结果可以推测,螨害后木质素合成途径基因PAL、4CL、CCoAOMT、CCR表达量的高低可能与木薯品种的抗螨性水平有关。

木薯种子休眠特性及破除方法研究

木薯(Manihot esculenta Crantz)作为全球重要的粮食作物和生物能源作物,杂交育种是木薯种质改良和品种选育的重要手段之一。然而,由于木薯存在种子萌发困难等一系列问题,极大限制了新品种的选育。本研究以新收获的华南124号母本自然结实种子为材料,通过一系列室内试验,对木薯种子休眠特性及休眠破除方法进行研究,结果表明:(1)解剖学和扫描电镜发现,木薯种子呈卵圆形,由种皮、胚乳和胚组成;其中,种子外表皮整体光滑,由外至内依次为表皮层、海绵组织层和栅栏组织,且栅栏层细胞排列较为致密。(2)种阜和种皮虽减缓木薯种子本身吸水速率,但种阜不是诱导其休眠的原因,而种皮的机械阻碍作用或抑制物的存在是诱导种子休眠的主要原因,从而判断木薯种子休眠类型为生理休眠。(3)采用砂纸打磨发芽口、去种皮和砂纸打磨发芽口+冷热循环2次处理均可有效破除种子休眠,显著提高种子萌发率;其中,砂纸打磨发芽口效果最佳,可使萌发率由2%提高至88%,处理后萌发速率最快。(4)35℃是木薯种子萌发的最佳温度,其萌发率和萌发指数分别达88%和36.6。本研究从木薯种子结构、种子休眠特性及其有效破除方法等方面为生产实践提供科学依据,也为木薯杂交后代优良性状得以表达提供理论参考。

木薯高、低粉品种贮藏根生长关键期的生理生化特性比较

通过研究木薯Manihot esculenta高粉和低粉品种贮藏根在发育关键期(形成–膨大期)主要生理生化性质的差异及其动态变化,为木薯栽培管理和育种改良提供理论基础。对高粉木薯品种‘辐选01’(FX01)和‘Kasetsart 50’(KU50)以及低粉品种‘华南124’(SC124)和‘9I’于种植后120、130、140、151和165 d五个时期分别取贮藏根样品,测定淀粉、可溶性糖、脱落酸(ABA)、保护酶、活性氧(ROS)、丙二醛(MDA)等生理生化指标并分析变化规律。结果表明,可溶性糖含量在贮藏根皮层中始终高于淀粉储藏区;高粉品种中总可溶性糖含量在贮藏根膨大期快速增加,且表现出较高的抗氧化酶活性和较低的ROS及MDA含量;ABA含量呈现出高粉品种比低粉品种低的趋势。木薯低粉和高粉品种中可溶性糖的分布与其转运后合成淀粉的规律相一致,高粉品种中淀粉的积累速率始终高于低粉品种,其较高的抗氧化酶活性和较低的ROS及MDA含量有利于木薯贮藏根中淀粉的积累。

能源作物资源现状与发展前景

能源作物是生物质能源发展的基础环节,本文就国内外能源作物研究现状与前景进行综合述评。分析了能源作物的基本概念和分类,明确了适合中国国情的能源作物概念,归纳了当前淀粉与糖料作物、油脂作物和木质纤维素作物三类能源作物研究与应用现状。重点介绍了当前几种受国内外重视的新型能源作物甜高粱(Sorghum bicolor)、木薯(Manihot esculenta)、柳枝稷(Panicum virgatum)、芒属植物(Miscanthusspp.)和柳属植物(Salixspp.)的发展现状和前景。从土地的承载能力和对环境的影响方面分析了中国发展发展能源作物的存在的问题与前景,明确提出,中国要坚持利用边际性土地、与生态恢复相结合发展能源作物的原则。指出中国能源作物种类筛选及品种改良至关重要,选择目标上应重视高光效、多年生、以收获营养器官为收获对象和高度抗逆等特征,以期形成具有地区适应性且收获季节多样化的系列能源作物种类与品种。

木薯害虫普查及其安全性评估

为适应中国木薯产业的可持续发展需要,于2008～2009年间对木薯害虫、害螨在中国华南地区的分布、危害进行普查,并对2种国家检疫性毁灭性害虫、害螨进行了风险评估和5种主要害虫、害螨对木薯产业及本地生态经济的影响进行了分析。结果表明,海南、广西、广东共查获木薯害虫、害螨36种,其中害虫33种,害螨3种,并在国内首次发现木薯单爪螨和螺旋粉虱危害木薯,朱砂叶螨、蔗根锯天牛、白蛴螬在国内木薯种植区大面积严重发生与危害;木薯单爪螨、螺旋粉虱对木薯均属于高度危险有害生物;目前,木薯害虫、害螨已成为中国热区木薯产业能否可持续发展的重要限制因子之一,对木薯产业及本地生态经济的潜在影响与威胁十分严重。

前期干旱锻炼对木薯根系内源激素及可溶性糖含量的影响

干旱胁迫前,对木薯进行前期干旱锻炼,胁迫期间测定干旱锻炼和未干旱锻炼木薯根系中内源激素(ABA、IAA、GA、ZR)及可溶性糖(葡萄糖、果糖、蔗糖)含量,根据其含量变化阐明前期干旱锻炼对木薯激素调节和渗透调节的影响。实验结果表明,经前期干旱锻炼的木薯再次受水分胁迫时,抗旱品种SC124和KU50根系中内源ABA在短时期内大量积累,其积累速率与积累量均高于对照(未干旱锻炼);而体内与植物生长发育相关激素IAA、GA和ZR的变化与对照相比在短时间内含量急剧下降,下降幅度增大。内源激素的变化结果说明前期的干旱锻炼改变了木薯再次受胁迫时内源激素的响应速度,提升了其响应程度,使植物在生理、生化等各方面发生相应变化,以提高自身的抗旱力,从而减轻干旱造成的伤害。不抗旱品种SC8的根系激素变化趋势不同于其他品种,变化幅度也明显小于抗旱品种,进一步说明了激素调节对木薯适应干旱的重要性。干旱锻炼的木薯根系中葡萄糖、果糖、蔗糖含量在不同的干旱胁迫时期(除少数几个时间点外)均高于未干旱锻炼情况,前期干旱锻炼增加了可溶性糖的积累,提高了植株的抗旱性能。本研究为深入研究木薯的抗逆性和人为提高木薯抗旱性能提供理论基础。

大豆、木薯播期对间作大豆产量和主要农艺性状的影响

于2010和2011年采用桂春8号春大豆新品种,在木薯间作大豆模式下,研究播期对大豆产量和主要农艺性状的影响。结果表明:大豆播期固定时,木薯不同播期对大豆产量和主要农艺性状均没有产生显著影响;大豆木薯同期播种时,随着播期的推迟,大豆生育期缩短,株高增加,茎秆变细,分枝数、单株荚数和粒数减少,脂肪含量无明显变化,4月5日播种时,大豆产量和蛋白质含量极显著低于其它处理。综合分析,大豆和木薯在3月25日之前播种的大豆产量、主要农艺性状及间作体系综合效益较好。

木薯的组织培养和基因转化

木薯是重要的热带作物之一， 其块根富含淀粉， 是热带、亚热带地区近５ 亿人粮食的主要来源。简单介绍近年来运用生物技术改良木薯的研究进展。