Genetic Diversity in Cowpea (Vigna unguiculata (L.) Walp) under Two Growing Conditions*

This study explores the use of genetic variability for advancing the genetic improvement of Cowpea (Vigna unguiculata (L.) Walp), particularly in response to insect infestation stress. Over a period spanning 2015 to 2017, forty accessions of cowpeas were evaluated to determine their variability under both insecticide spray and no insecticide spray conditions at the Teachings and Research Farms, Federal University of Agriculture, Abeokuta. The experimental design was a randomized complete block design in three replicates. The accessions were evaluated for plant height, leaf length, leaf width, number of days of 50% flowering, number of pods per plant, pod length, number of seeds per plant, 100-seed weight, and seed yield. Data collected were subjected to principal component and single linkage cluster analyses. Principal axis I (PCA1) accounted for 39% and 35% under insecticide spray and no insecticide spray respectively to the total variation in the accessions. Plant height with a factor score of 0.38, leaf length (0.41), number of leaves (0.37), and 100-seed, weight (0.30) was related to PCAI under insecticide spray while leaf width (0.32). Pod length (0.37) and number of seeds/plant (0.38) were significant to PCA1 under no insecticide spray. Notably, accessions such as SAMPEA6, SAMPEA10, IFE-Brown, and IFE-BPE exhibited consistent performance across both conditions, while others displayed condition-specific attributes. For instance, NGB1063, NGB1152, and NGB1093 demonstrated distinct traits under insecticide spray, while NGB1146 and NGB1124 exhibited notable characteristics under no insecticide spray conditions. Therefore, identifying these forty accessions with desirable traits hold promise for future genetic improvement efforts of cowpea cultivation in Nigeria and beyond.

Screen House Assessment of Cowpea [(Vigna unguiculata (L.)] Genotypes for Drought Tolerance Using Selection Indices

Cowpea [Vigna unguiculata (L.)] is one of the most important arid legumes cultivated for pulse and forage production. Drought is one of the most damageable constraints to crop production impacting negatively food security. The potential of cowpea to address food security is well established. However, not much is known about the base index selection method in breeding cowpea for drought tolerance, which is important for yields. Consequently, the present study has been conducted to: 1) evaluate the yield performance of cowpea genotypes under artificial drought and well-watered condition, 2) ranke genotype performance using selection indices, and 3) assess relationship between agronomic traits and yield. The experiment was the 2 watering conditions laid out in a Randomized Complete Block Design (RCBD) with three replications. The experiment was carried out in pots under screen house at the Department of Horticulture at KNUST. The result showed that KPR1-96-73, Simbo, CZ06-4-16, Wilibaly and Agyenkwa were high yielding in well-water condition while Ghana Shoba, Sangaraka, Nketewade, Ghana Shoni and Korobalen were high yielding genotypes in water stress condition. The average yield reduction was 60.6% and 16% for grain and fodder yield respectively. The biplot displays revealed four groups among the genotypes tested which were based on their yielding capacity and drought tolerance. In cluster B high yielding and drought tolerant genotypes were identified, high yielding and drought susceptible have been identified in cluster A, low yielding and drought tolerant in cluster D, and lastly low yielding and drought susceptible in cluster C. Genotypes in cluster B were best due to the fact that it combines high yield and tolerance to drought. They were Ghana Shoni, Nketewade, Sangaraka and Ghana Shoba. These genotypes might be suitably employed in further drought tolerance breeding programs of cowpea. Significant relationships were observed between agronomic trait and yields under drought condition.

Selection of Cowpea [(Vigna unguiculata (L.) WALP] Genotypes for Drought Tolerance Using Selection Indices

Cowpea [(Vigna unguiculata (L.)] is one of the most important arid legumes cultivated for pulse and forage production. However, in cowpea, not much is known about the base index selection method in breeding for drought tolerance. Consequently, the present study has been conducted to: 1) evaluate the yield performance of cowpea genotypes under artificial drought and well-watered condition;2) develop a base index using multiple traits for ranking genotype performance. The experiment was a 25 × 2 factorial laid out in a Randomized Complete Block Design (RCBD) with three replications. The experiment was carried out in the screen house at the Department of Horticulture at KNUST. The result showed that KPR1-96-73, Simbo, CZ06-4-16, Wilibaly and Agyenkwa were high yielding in well-water condition while Ghana Shoba, Sangaraka, NKetewade, Ghana-Shoni and Korobalen were high yielding genotypes in water stress condition. The average yield reduction was 60.6% for grain respectively. The biplot displays revealed four groups among the genotypes tested which was based on their yielding capacity and drought tolerance. In cluster B high yielding and drought tolerant genotypes were identified, high yielding and drought susceptible have been identified in cluster A, low yielding and drought tolerant in cluster D, and lastly low yielding and drought susceptible in cluster C. Genotypes in cluster B, were the best due to the fact that it combines high yield and tolerance to drought. They were Ghana Shoni, Nketewade, Sangaraka and Ghana shoba. These genotypes might be suitably employed in further drought tolerance breeding program of cowpea.

Evaluation of Total Seed Protein Content in Eleven Arkansas Cowpea (Vigna unguiculata (L.) Walp.) Lines

Cowpea is cultivated on more than 11 million hectares with a worldwide production of 5.4 million tons of dried seeds. Cowpea is an affordable source of protein, which is used as an alternative to soybean for people who are allergic to soybean protein. The aim of this research was to assess the variability of the total seed protein content in cowpea. Eleven Arkansas breeding lines were used in this study. Field experiment design was a randomized complete block design (RCBD) with 2 blocks, and conducted in three different locations within Arkansas State (Fayetteville, Alma, and Hope) in 2015. A standard chemical protocol was performed involving an analysis of the total nitrogen by combustion using an Elementar Rapid N III instrument to estimate the protein content. The average protein content was 25.4%, and ranged from 23.7% to 27.4% with a standard deviation of 1.9%. The significant effects of genotype, environment (location), and genotype by environment were observed for the total seed protein content in cowpea. The broad sense heritability (H2) for cowpea seed protein was estimated to be 57.8% based on the eleven cowpea genotypes studied. The cowpea lines, “Early Scarlet” and 09-204 had the highest seed protein content with 27.4% and 26.9% dried seed weight, respectively. This study provides valuable information on cowpea protein content for breeders to select and utilize those breeding lines with high seed protein content to develop new high protein cowpea cultivars.

Loss of Certified Maize (<i>Zea mays</i>L.) and Cowpea (<i>Vigna unguiculata</i>(L.) Walp.) Seed Viability during Storage in a Sub-Saharan Region: Analysis of Environmental Factors

The objective of this study was to characterize environment factors involved in loss of seed viability during storage in open granaries. The temperature and relative humidity of the granary as well as the equilibrium moisture content of seeds were determined monthly. Their effects on the loss of viability of maize (Zea mays L.) and cowpea (Vigna unguiculata (L.) Walp.) seeds were examined. The results showed that relative humidity levels > 65% associated with temperatures > 25°C (conditions in the open granary) do not guarantee safe storage of maize lots for a period of 9 to 12 months. Based on these data and the results of seed viability analysis, local environmental conditions in Gandajika (DR-Congo) and seed genetic background are the main factors for the rapid deterioration of seeds during storage. The germination rate correlated negatively with storage duration (-0.94) and temperature (-0.57) while it correlates positively with the relative humidity (0.58) for both lots of maize analyzed. The same trend was observed with the two-cowpea varieties studied (IT82D-889 and Diamant). Similar work using more varieties in other granaries is required to validate key factors involved in seed viability during storage in targeted regions.

Genetic diversity and a population structure analysis of accessions in the Chinese cowpea [Vigna unguiculata(L.)Walp.]germplasm collection

Cowpea(Vigna imguicuiata) is an important legume crop with diverse uses. The species is presently a minor crop, and evaluation of its genetic diversity has been very limited. In this study, a total of 200 genic and 100 genomic simple sequence repeat(SSR) markers were developed from cowpea unigene and genome sequences, respectively. Among them, 27 genic and 27 genomic SSR markers were polymorphic and were used for assessment of genetic diversity and population structure in 105 selected cowpea accessions. A total of 155 alleles and 2.9 alleles per marker were identified, and the average polymorphic information content(PIC) value was 0.3615. The average PIC of genomic SSRs(0.3996) was higher than that of genic SSRs(0.3235), and most of the polymorphic genomic SSRs were composed of di-and trinucleotide repeats(51.9% and 37.0% of all loci, respectively). The low level of detected genetic diversity may be attributed to a severe genetic bottleneck that occurred during the cowpea domestication process. The accessions were classified by structure and cluster analysis into four subgroups that correlated well with their geographic origins or collection sites. The classification results were also consistent with the results from principal coordinate analysis and can be used as a guide during future germplasm collection and selection of accessions as breeding materials for cultivar improvement. The newly developed genic and genomic SSR markers described in this study will be valuable genomic resources for the assessment of genetic diversity, population structure, evaluation of germplasm accessions, construction of genetic maps, identification of genes of interest,and application of marker-assisted selection in cowpea breeding programs.

A Rapid Method for Measuring Seed Protein Content in Cowpea (<i>Vigna unguiculata</i>(L.) Walp)

Cowpea (Vigna unguiculata (L.) Walp), a legume crop that is grown in the worldwide, provides beneficial proteins for human consumption and animal feeding. In comparison, Rapid N analyzer as traditional method, has been widely used to measure protein content through the percentage of total nitrogen in the seed’s grounded powder. Near-Infrared Reflectance (NIR) has commonly been used to measure protein content in soybean seeds using whole grain without the need of seed grinding, which makes it possible to obtain fast results at a lower cost-per-analysis than the traditional combustion method. The specific objective of this study is to test a rapid method for measuring cowpea seed protein content by the NIR analyzer comparing to the traditional rapid N analyzer. A total of 240 cowpea genotypes were used in this study, including six seed coat colors, black, blackeye, browneye, cream, pinkeye, and red with 40 cowpea genotypes. The results showed that a linear relationship exists between the NIR analyzer and the Rapid N analyzer in the six different color groups. The correlation efficiency (r) between the seed protein contents from NIR and Rapid N was higher for pinkeye seed (r = 0.867), blackeye (0.771), cream (0.729), browneye (0.700), and red (0.623), respectively, but lower for black seeds, indicating that the NIR analyzer can be used to measure protein content for cowpea seeds with the five types of seed coat except black. Overview, the cowpea seed protein content measured from the NIR analyzer showed a little higher seed protein content. A series of regression models with different seed coat color have been built to adjust to protein content of colorful cowpea seeds from the NIR analyzer. But, it is not recommended to use for black color seeds due to a very low correlation efficiency (r) value with 0.184.

Potential of <i>Vigna unguiculata</i>as a Phytoremediation Plant in the Remediation of Zn from Contaminated Soil

Population explosion in the last decades together with global industrialization has caused heavy-metal contamination of air, water and soil, resulting in diverse incurable effects on humans and on the stability of the ecosystem. Non-biodegradable heavy-metals can remain in the ecosystem and the threat associated with their bioaccumulation in food chains represents one of the major environmental and health problems of present day society. Several studies were carried out to understand the ecological effects of the heavy-metal Zn in soil-plant systems. Plants often have a zinc uptake that their systems cannot handle, due to the accumulation of zinc in soils. Of the several Zn toxicity symptoms, fatal are yield reduction, stunted growth, chlorosis, reduced chlorophyll synthesis and chloroplast degradation. Vigna unguiculata is an herbaceous, annual plant in the pea family Fabaceae. In the present study, an experiment was performed to evaluate the Zn phytoextracting ability of V. unguiculata under in vitro condition. We establish that V. unguiculata can uptake a considerable amount of the heavy-metal zinc and this phytoextraction property can be utilized in long run for the cleanup of zinc contaminated soil. To the best of our knowledge, this is the first report of Zn phytoextraction ability of V. unguiculata.

Molecular Characterization of Type II Transposable Elements in Cowpea [<i>Vigna unguiculata</i>(L.) Walp]

Previous genetic studies in cowpea [Vigna unguiculata (L.) Walp] have shown that an active bipartite transposable element (TE) is responsible for a range of mutant phenotypes of its leaf, stem and flower. Since type II TEs have not been characterized at the molecular level in cowpea, this study was initiated to survey the presence of type II TEs in the cowpea genome. Type II TEs: Enhancer/Suppressor-mutator (En/Spm) and Miniature Inverted-repeat Transposable Elements (MITEs) were isolated and characterized. The sequence identity between the EnSpm TE clones was 46% at the nucleotide level (NL) and 30% at the amino acid level (AL) while that of MITEs was 71% at NL and 63% at AL. These cowpea En/Spm TEs were 80% homologous with En/Spm elements of other crops at NL and 46% at AL. The MITEs were 96% similar at NL and 18% homologous at AL. DNA gel blot analysis confirmed the presence of the En/Spm TEs in cowpea. RT-PCR (reverse transcriptase polymerase chain reaction) analysis showed that the VuEnSpm-3 and the MITE clone, VuPIF-1 were actively transcribed in wild type and mutant cowpea tissues. Overall, our data show that multiple, divergent lineages of En/Spm and MITEs are present in the cowpea genome, some of which are actively transcribed. Our findings also offer new molecular resource to further investigate the genetic determinants underlying previously described mutant cowpea phenotypes.

Influence of phosphorus on the performance of cowpea (Vigna unguiculata (L) Walp.) varieties in the Sudan savanna of Nigeria

Savanna regions of Nigeria are deficient in nitrogen and phosphorus, which retard the growth and yield of crops. Therefore, a study was conducted in the wet season of 2006 at the Dry Land Teaching and Research Farm of Usmanu Danfodiyo University, Sokoto to evaluate the effect of phosphorus on the growth and yield of two cowpea varieties sourced from Republic of Niger. Treatment consisted of four (4) rates of phosphorus (0, 20, 40, 60 kg.ha–1) factorialy combined with (2) varieties of cowpea (kvx303096G and TN5-78) and laid out in a randomized complete block design (RCBD) replicated three (3) times. Results showed significant response to applied P on pods per plant, grain and stover yield and 100-seed weight with highest response to the application of 60 kg.P.ha–1. From this study it can be concluded that KVX303096G and TN5-78 could both be sown under Sokoto condition to obtain reasonable yield of about 1 t.ha–1 of grain and 1.6 t.ha–1 of stover. Irrespective of the varieties, application of 60 kg P2O5 ha–1 could be recommended for higher yield of cowpea (1.4 t.ha–1) relative to 0 kg.P.ha–1 that yielded 1.0 t.ha–1.

Bioactive profile of borno brown Vigna unguiculata grains as influenced by pre-harvest synthetic chemicals

This study investigated the impact of pre-harvest synthetic chemical treatments on the post-harvest bioactive contents,pasting,colour,and thermal properties of borno brown V.unguiculata(L.)Walp grains.Seeds of borno brown V.unguiculata(L.)Walp was planted on an already ploughed,harrowed and ridged plot of land with a portion cultivated as organic and another non-organic.After 90 days,mature grains were harvested and analyzed using standard procedures.Results showed that a total of 44.33 g bioactive compounds/100g grain was present in the organic borno brown V.unguiculata grains whereas,20.56 g bioactive compounds/100g grain was present in the non-organic(control).The identified bioactive compounds in the organic grains included[heneicosane(4.50g/100g grain)];[12-Methyl-E,E-2,13-octadecadien-1-ol(4.09/100g grain)];[3-(2-Hydroxy-6-methylphenyl)-4(3H)-quinazolinone(7.40 g/100g grain)];[Methaqualone(9.08 g/100g grain)].The non-organic contained[heneicosane(4.07g/100g grain)];[3-(2-Hydroxy-6-methylphenyl)-4(3H)-quinazolinone(5.09 g/100g grain)];[Methaqualone(10.61 g/100g grain)].Flavonoids,alkaloids,total phenolic,2,2-diphenyl-1-picryl-hydrazl(DPPH)and ferric ion reducing antioxidant power(FRAP)contents of the organic grains were 19 mgRE/100g,3.40 mg/100g,1550 mgGAE/100g,2840μmolTEAC/100g,and 20.08 mmol Fe^(2+)/100g,respectively.The non-organic grains had flavonoids(11.31 mgRE/100g),alkaloids(1.86 mg/100g),total phenolic(1110 mgGAE/100g),DPPH(1779μmolTEAC/100g)and FRAP(12.24 mmol Fe^(2+)/100g).The peak viscosity of 111.52 RVU,final viscosity(141.25 RVU)and pasting temperature(82.01℃)were obtained for the organic grains while non-organic had peak viscosity of 93.10RVU,final viscosity(95.20 RVU)and pasting temperature(80.10℃).The colour parameters L^(*),a^(*),b^(*)and ΔE were 73.10,0.68,14.47 and 12.98 for the organic and 84.25,0.30,21.10,and 0.00,respectively for non-organic grains.The thermal property showed enthalpy(ΔH)and peak temperature(T_(p))of 3.12 J/g and 78.25℃ for organic,and 2.14 J/g and 76.28℃ for non-organic grains,respectively.Phenolic compounds profile showed that organic grains were richer in epicatechin,gallic acid,ferulic acid,chlorogenic acid,4-hydroxy benzoic acid,and catechin.Organic grains showed significant(p<0.05)superiority in bioactive compounds,phytochemicals,and antioxidants over non-organic grains.Good pasting properties of the organic grains showed that it could function as a food thickener.Organic borno brown V.unguiculata grains are rich in health-promoting compounds and could,therefore,be used as an ingredient in the development of functional foods.

豇豆(Vigna unguiculata)VQ蛋白家族基因的序列与进化分析

VQ蛋白是一类植物特有的转录调控辅助因子,主要与WRKY蛋白互作,参与诸多生物学功能。尽管一些植物VQ家族基因已经被鉴定,但在豇豆中有关VQ家族基因的研究未见报道。本研究利用生物信息学手段从豇豆中鉴定出37个VuVQ基因,并详细分析这些基因的序列、微共线性、表达谱与进化关系。染色体与共线性分析表明,豇豆VuVQ基因定位在11条染色体上,基因扩增主要由片段重复产生,其中4对重复基因所在区段共线性程度高。序列分析结果显示:豇豆VuVQ基因结构有3种类型,绝大多数无内含子;豇豆VQ蛋白均包含VQ结构域,同时这些VQ保守基序数目和顺序变异较高。进化研究揭示豇豆VQ蛋白存在6大类群,这些类群均起源于陆生植物。选择压力检测表示,豇豆的8对VuVQ基因均受严格的负选择。表达分析表明了豇豆VQ基因具有多样化的表达模式,这意味着VQ蛋白参与多种生物学过程。本研究结果为豇豆VQ基因的功能解析提供线索。

Phytochemical Composition and Insecticidal Property of Native Plants against the Cowpea Weevil Callosobruchus maculatus Fab. (Coleoptera: Bruchidae) for Natural Preservation of Cowpea Seeds

About 80% of cowpea seeds are lost along with 30% of their weight after six months of unprotected storage due to attacks by Callosobruchus maculatus. This study aimed at evaluating the effect of applying bioinsecticides on the biological parameters of C. maculatus to reduce its damage to cowpea stocks. Four treatments including an untreated control and three doses of powdery extracts of C. nigricans, Z. zanthoxyloides and H. suaveolens, were compared in a Fischer block with four completely randomized repetitions. One hundred undamaged cowpea seeds were mixed with doses of each extract in Petri dishes and then fed as food substrates to ten pairs of C. maculatus for eight days. The extracts of H. suaveolens, C. nigricans and Z. zanthoxyloides all contain active ingredients including polyphenols, flavonoids, anthocyanins and alkaloids, etc. The extract of Z. zanthoxyloides was found to be more active on adults (100.00% mortality) followed by C. nigricans (98.75% mortality) and H. suaveolens (97.50% mortality) at 80 mg/g. Fecundity per female decreased significantly in the treated batches of 13.82 eggs for H. suaveolens at 10.12 eggs for C. nigricans at a dose of 80 mg/g. Germination rate of seeds was statistically raised to 100% at 60 and 80 mg/g by C. nigricans powder and lowered to 83.00% at 20 mg/g by Z. zanthoxyloides extracts. The application of Z. zanthoxyloides extract would be a less expensive alternative for the sustainable management of C. maculatus in cowpea stocks.

辽宁豇豆主要病虫害及绿色防控技术

豇豆营养丰富,有较好的保健功效,在我国是一种很受欢迎的蔬菜。但豇豆在生产中具有生长周期短、病虫害发生重、用药频次高等特点,使其农药残留超标情况常位于蔬菜品种前列。豇豆病虫害防治不当制约着豇豆产业的绿色发展。为切实做好豇豆农药残留突出问题攻坚治理,该文基于对辽宁豇豆生产环节的跟踪评价,介绍了辽宁地区豇豆主要病虫害种类及其危害症状,并从绿色防控角度提出针对性措施与建议,为辽宁豇豆安全生产提供参考。

施氮水平对普通大蓟马繁殖及子代性比的影响

为了评价施氮(N)水平对普通大蓟马(Megalurothrips usitatus)繁殖及其性比的影响,采用盆栽法种植豇豆(Vigna unguiculata),分别按低N(0 kg·hm^(-2))、中N(160 kg·hm^(-2))和高N(320 kg·hm^(-2))水平于苗前土施尿素,用叶盘法在室内单头饲喂已交配的1日龄雌虫,以嫩豇豆荚饲养其子代,观察亲代雌虫的繁殖与存活状况、子代的数量与性别。结果显示:与低N和中N处理相比,高N显著延长亲代雌虫的存活天数和产卵期,缩短产卵前期,提高产卵量和日产卵量。低N、中N和高N处理的子代雄性比分别为0.70、0.59和0.45,彼此之间差异显著。子代雌虫数量随施N水平的提高而增加,高N处理的子代成虫数显著大于低N和中N。施N对子代存活率没有影响。以上结果表明,施N水平能影响普通大蓟马的生长繁殖和性比,偏施N肥有利于普通大蓟马的繁殖,促使子代性比偏雌。

豇豆品种在盐胁迫下叶片叶绿素荧光特性聚类分析

以50个豇豆品种为试验材料,设置ck、NaCl、EBR与EBR+NaCl组等4个处理,于7 d后测量叶片叶绿素荧光参数,研究各处理下豇豆幼苗的叶片荧光特性。主成分分析表明,Y(Ⅱ)、Fv/Fm和Y(NO)可以代表豇豆的13个荧光参数。聚类分析结果显示,50个豇豆品种聚为Ⅰ类、Ⅱ类、Ⅲ类,Ⅰ类有46个品种,Ⅱ类有2个品种,Ⅲ类有2个品种;其中Ⅱ类的668绿条和豇豆WJ-60的Y(Ⅱ)与Fv/Fm值最高,Y(NO)值最低,表明光合作用效率高,光损伤程度低,是较为理想的豇豆品种;而Ⅲ类的青条和花荣的Y(Ⅱ)与Fv/Fm值最低,Y(NO)值最高,表明光合作用效率低,光损伤程度高。同时EBR对豇豆叶绿素荧光特性有影响,因品种不同而存在差异。

我国豇豆中农药最大残留限量和检测标准新进展

通过对《食品安全国家标准食品中农药最大残留限量》(GB 2763—2021)和《食品安全国家标准食品中2,4-滴丁酸钠盐等112种农药最大残留限量》(GB 2763.1—2022)中涉及豇豆的农药最大残留限量值、相关检测方法等信息的归纳分析,梳理出目前涉及豇豆的农药限量标准共有131项,其中104项农药残留参数有配套的检测方法41个。截至2023年6月,我国豇豆中已批准登记的农药产品有188种,包含有效成分39种。针对当前豇豆农药残留限量标准未完全覆盖已登记有效成分、相关配套的检测方法不全等问题,建议探索制定豇豆中农药残留高通量检测方法,尽快补充完善已登记农药有效成分的限量值,为提高豇豆质量安全水平提供更有力支撑。

盐碱胁迫对闽南饲用(印度)豇豆种子萌发及幼苗生长的影响

利用0.4%、0.8%、1.2%、1.6%、2.0%、2.4%浓度的Na_(2)SO_(4)、NaCl和NaHCO_(3)在闽南饲用(印度)豇豆种子的萌发阶段进行胁迫处理,以蒸馏水处理作为对照,分析闽南饲用(印度)豇豆种子的发芽率、发芽指数、平均发芽时间,以及闽南饲用(印度)豇豆幼苗的活力指数、胚根长和胚芽长的变化规律,研究盐碱胁迫对闽南饲用(印度)豇豆种子萌发及幼苗生长的影响。结果表明:Na_(2)SO_(4)和NaCl处理后的豇豆种子萌发及幼苗生长指标均随盐溶液浓度的增大而呈下降趋势;相比于对照,0.4%浓度的Na_(2)SO_(4)和NaCl溶液处理后种子的发芽率、发芽势、发芽指数的差异不显著,在盐溶液浓度为0.8%~2.4%时,种子萌发及幼苗生长指标差异极显著;NaHCO_(3)处理下闽南饲用(印度)豇豆种子的发芽率、发芽势、发芽指数、活力指数、胚根胚芽长随着碱溶液浓度的增大呈现出先增后降的趋势,在NaHCO_(3)浓度为0.4%时,活力指数、胚根胚芽长与对照差异极显著。根据盐浓度与发芽率间的显著相关性建立线性回归方程,得出闽南饲用(印度)豇豆种子对Na_(2)SO_(4)、NaCl、NaHCO_(3)耐盐适宜浓度分别为0.79%、0.68%和0.61%,半致死浓度分别为1.38%、1.23%和1.28%,极限浓度分别为2.32%、2.12%和2.35%。

Plants Extracts and a Mycoinsecticide in Cowpea Yield Improvement in Guinean Savanah and Sahelian Savanah Agro-Ecological Zones of Cameroun

Cowpea yield improvement is done by adding agricultural inputs. The use of natural substances as pesticides is being encouraged to fight against cowpea field pests. The pesticidal potentials of Azadirachta indica and Boswellia dalzielii water extracts, Metarhizium anisopliae, alone and in combination with plant extracts, and a commercial synthetic pesticide (Decis®) were tested in field on two varieties of cowpeas, Vigna unguiculata in two agroecological zones (Guinean Savanah and Sahelian Savanah) of Cameroon. The field trials were carried out in a full randomized block design including nine treatments and a control. Four replications were made concerning the different treatments and control. At the flowering stage, the cowpea field was sprayed three times with different pesticidal formulations at the interval of five days. The number of ramifications per plant, and that of pods per block and seed yield were determined. The pesticide formulations considerably (p ®). Bafia variety treated with the combination of M. anisopliae and A. indica recorded the highest ramification rate (37.03 ± 1.59) in Maroua (Sahelian Savanah). The same variety also produced more important pods number (90.50 ± 16.66) in Ngaoundere (Guinean Savanah) with the binary combination of two plants used in this experiment. The highest seed yield (44.23 ± 2.31) was recorded in Ngaoundere with B125 variety treated with the combination of the three pesticidal formulations separately (A. indica, B. dalzielii, M. anisopliae). The plant products used in this work, M. anisopliae and their mixtures could supersede the synthetic pesticides considering environmental issue in cowpea crop protection. Then, such formulations would not only improve crop productivity but also preserve environment from the pollution due to the use of synthetic residual chemicals.