Agricultural Research Laboratories Research Articles

Female Reproductive Potential and 3x by 2x Breeding Approach for Hybrid Seeds Development in Sukali Ndizi Genotype (Musa genome AAB)

Sukali Ndizi is one of the most popular local desert banana cultivars in Uganda. The crop is affected by a number of diseases and pests. Genetic improvement of the crop by hybridization may be hindered by very low seed set and poor seed germination. The main characteristics for assessing the female reproductive potential (seed set, seed quality and embryo germination of hybrid seeds) and 3x by 2x breeding approach were assessed in crosses of eleven different male diploid parents either wild or improved diploids with Sukali Ndizi landrace as the female parent for a period of 5 consecutive years planted in pollination blocks at National Agricultural Research Laboratories Kawanda (NARL). The month of pollination did not show any pattern throughout the pollination period but the crosses showed considerable variability in seed set, seed quality, and seed germination for different male diploids used. The water gravity test which differentiated the extracted seeds as sunken/viable and floating/nonviable seeds showed that a substantial amount of seed was floating and the sunken externally characterized by black hard integuments was only 39% with a range = 24%–60% which contained embryos, of which 22% (range = 0–37%) germinated. The increase in non-viable seed suggested that ovule abortion in Sukali Ndizi which mainly involved embryo and endosperm abortions was the cause of limited seed germination and the paternity of the zygotes was a major factor underlying abortions. Flow cytometric analysis of nuclear DNA content was used to estimate ploidy levels of the progenies with results showing that using 3x by 2x breeding approach differing levels of ploidy were achieved [3x (288), 4x (61), 5x (14) and 2x (2)] signifying the predominance of 3x progenies and the presence of 5x and 4x conforming to the possibility of sexual polyploids. Although pollination of Sukali Ndizi can be done all around the year, the seed set both quantity and quality and germination were very poor, necessitating the development of an efficient regeneration protocol for zygotic embryos at varying maturity stages to increase the recovery of hybrids.

Effect of Different Salt Concentrations on Germination of Forage Pea

As a result of the rapid increase in the world population, the problem of balanced and adequate nutrition has emerged, and at this point, the importance of animal production has increased even more. In this respect, there is a need to increase the cultivation areas of forage crops, as well as the correct management and reclamation of pastures for adequate and balanced nutrition of our existing animals. For this reason, forage pea (Pisum sativum L.), which has high nutritional value and is preferred by animals, is an important forage crop to meet this need. Salinity significantly limits the growth of the plant and causes yield losses. This abiotic stress negatively affects forage peas. In order to reveal the differences in the germination of forage pea varieties at different salt concentrations and the differences in the physical properties of the roots and seedlings, the effect of different salt concentrations on nine different varieties of forage peas was carried out in Bilecik Şeyh Edebali University, Faculty of Agriculture and Natural Sciences, Agricultural Research and Biotechnology Center Laboratories in 2022. In the research, the effects of nine different field types (Ürünlü, Töre, Ateş, Guifredo, Taşkent, Özkaynak, Kurtbey, Uysal and Nany) at one control and eight different salt concentrations (25, 50, 75, 100, 125, 150, 175 and 200 mM) on germination and seedling growth were examined. The experiment was carried out according to Completely Randomized Factorial Designs with 3 replications. In the research; germination speed and power, root dry and fresh weight, root dry and fresh length, seedling dry and fresh weight, seedling dry and fresh length were examined. According to the results obtained, a significant decrease was observed in germination rate, germination strength, root-shoot length and wet-dry weights of forage pea varieties due to increasing salt concentration. It has been determined that Tore field pea variety has the highest germination rate and power. Tore field pea showed 100% germination speed and power up to 150 mM salt concentration. In addition, Töre variety is followed by Ateş variety in all parameters. The varieties with the lowest germination rate and vigour were Guifredo and Uysal. As a result, the growth of forage pea varieties slowed down due to increasing salt concentration.

Canning quality of popular common bean germplasm in Eastern and Central Africa

Common bean (Phaseolus vulgaris L.) genotypes popular in eastern and central Africa were evaluated to determine their suitability for the canning industry. The genotypes were planted at the National Agricultural Research Laboratories (NARL), Kawanda-Uganda in the second rainy seasons (July-September) of 2015, 2016 and off season of 2017 (November- February). Two samples per genotype were evaluated at the canning facilities at Kawanda and Michigan State University (MSU) using a protocol based on home canning. One sample per genotype from the 2017 harvest was evaluated at Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre (AAFC-LRDC) using the industry canning protocol. Data (n=134) was collected on seed moisture content, dry and soaked bean weight, hydration coefficient (HC) and visual quality, including colour retention, appearance, brine clarity, bean splitting and freedom starch/clumps on replicated samples. Additional data on unreplicated samples were collected on 100-seed weight, seed solids for canning, hydration coefficient after soaking (HCS), hydration coefficient after blanching (HCB), drain weight (%), matting, appearance, seed color, texture, and cooking quality traits including hard seed and partially hydrated seed (%) and HC after cooking. Analysis of variance of data from MSU and Kawanda showed significant (P≤0.01) differences among genotypes for the assessed parameters. Majority of the genotypes expressed good soaking ability considering that their HC were above the 1.8 recommended for canning and 28% combined the two mentioned traits with good overall canning quality visual rating. Apart from 26, all other varieties had good HC based on data from Canada. About 24% of genotypes belonging to various market classes consistently combined this trait with good visual quality. The most outstanding genotypes based on these traits included SAB659 (red mottled), MAC44 (red mottled), NABE21 (cream), NABE12C (cream) and VAX5 (cream), KK8 (red mottled), Bihogo (yellow) and VAX4 (black). These genotypes were superior to the white beans: MEXICO 142, Awash1, and Awash Melka, that were considered as high-quality controls. Results indicated that genotypes of diverse backgrounds, with good canning quality traits exist among the currently utilised varieties and breeding lines. This diversity could be exploited for breeding and varietal promotion in the canning industry. Key words: Common bean, canning, hydration coefficient, visual quality, drained weight

Development of information system for tracking breeding traits of improved crops

Plant breeding involves application of a group of systems targeted at transporting collected decent parents’ traits to produce an improved crop in the offspring. Cross-breeding and selection in plant breeding has been able to considerably improve yields as well as pest and disease resistance of crops. Efficiency in crop breeding research programs is contingent upon the aptitude of breeders making it possible to successfully produce, classify, store, track and choose recombinant genetic constitution with a determined number of required traits. It is not easily done with the manual system to store and manage large volumes of data generated in all research institutions. Locating files among tons of data is a tedious and time-consuming process for researchers. The importance of keeping track of research data is becoming vital in agricultural research institutions. A study was conceived in response to the need to improve the storage, tracking and dissemination of research data collected during the breeding of improved crops. It was conducted to develop a system for tracking breeding records, at the National Agricultural Research Laboratories (NARL) in Uganda. This was motivated by the increasing need to develop high yielding yet resilient crop varieties due to the constantly changing climate amid other socio-economic changes like population pressure and loss of soil fertility. Different methods were used to design such systems which included data-flow diagrams (DFDs) and entity relationship diagrams (ERDs). An ERD was used to recognize the data to be apprehended and deposited, and regained in order to accomplish the process of storing and tracking files. As a result, a breeding tracking system was developed as an application tool that can manage the creation and tracking of records. The advanced system supports information sharing between scientists and easy access to the trait information in improved crops. Key words: Data, tracking, plant, breeding.

Decision-making in the purchase of equipment in agricultural research laboratories: a multiple-criteria approach under partial information

Investments in the agricultural sector represented by innovations and new technologies strongly influence the economic growth in developing countries. In this context, purchasing decisions have become more relevant. Multiple-criteria decision-making techniques are well suited for decision-makers (DMs) who are considering the introduction of new technologies. In this paper, a multi-criteria model is built to help a Colombian agricultural research company make decisions on purchasing different laboratory equipment. A compensatory approach based on trade-offs is used to elicit the preferences of a group of DMs. The high number of answers and cognitive effort required from them during the elicitation process led to using an alternative approach based on partial information, called the FITradeoff (The Flexible and Interactive Tradeoff) method. It showed to be the best fit to solve the company’s purchasing problem and allowed its managers to make decisions that consider criteria other than price, taking account of the DMs’ conflicting viewpoints. The proposed model aimed at contributing to the articulation of the end-user knowledge in decision-making in order to ensure effective articulation of actors and strengthening of science, technology and innovation in agriculture.

Genetic variability and selection criteria of some sesame genotypes for their agronomic traits and seed quality

The identification of genetic variation, mean performance, and selection criteria for twelve sesame genotypes is required for the genetic enhancement of agronomic traits and seed quality. Thus, using a randomized complete block design with three replications, these genotypes were evaluated in a field trial at the Kafr-El-Hamam Agricultural Research Station, Agricultural Research Center, Sharkia Governorate, Egypt, and laboratory experiments at the Seed Technology Research Department, ARC, Giza, Egypt, during the two consecutive seasons of 2018 and 2019. For earliness in flowering, N.A.130 and Shandweel3 were the most promising sesame genotypes, while N.A.114 and RH1F3 had the heaviest weight of seed plant-1 and one or more yield-related traits, and NA114, Shandweel3, and Zahar12 had the best seed quality traits. Furthermore, Shandweel3 and M1A12 had the highest proportion of seed oil, Shandweel3 and Zahar12 had the largest amount of oleic acid, N.A.114 and RH1F3 had the highest content of linoleic acid, and Zahar12 and N.A.114 had the highest proportion of linolenic acid. Seed weight plant-1 can be improved through selecting genotypes having the lengthiest fruiting zone, more branches and capsules, and the high electrical values of seed conductivity, accelerated aging germination as demonstrated by selection criteria. Moreover, the oleic acid proportion had the greatest direct and indirect effect on seed oil content, demonstrating its relevance as sesame oil quality selection criteria.

Heavy Metals and Macronutrients Concentrations in Sewage Sludge Obtained from Decentralized Treatment Facility, Machakos Town, Kenya

With the increase of global population, wastewater treatment facilities face a major challenge of managing the large quantities of sewage sludge produced in urban areas. Due to this challenge many wastewater treatment plants have opted for use of sewage sludge as organic fertilizer to boost agricultural production. In Machakos Decentralized Treatment Facility (DFT), sewage sludge is usually sold to locals as fertilizer to boost crop production within the municipality. However, sewage sludge produced in municipal wastewater treatment plants is known to contain various heavy metals that may limit its usage as agricultural fertilizer. Studies have shown that sewage sludge has been associated with heavy metals which are linked to harmful effects on humans and environmental health. This study investigated the levels of various heavy metals and macronutrients from sewage sludge obtained from Machakos town wastewater treatment plant to test its suitability for use as fertilizer. Sewage sludge samples were obtained from the treatment plant at Mitheu and transported to Nairobi Agricultural Research Laboratory (NARL) for analysis of heavy metals (Cu, Zn, Mn, and Fe) and macronutrients (N, P, Ca, Mg and K). The results for the heavy metals were Zn=171.13±237mg/kg; Fe=17,877±15,700mg/kg; Mn=445.67±213mg/kg and Cu=41.1±16.71mg/kg) while the macronutrients were K=0.17±0.09%, P=1.26±1.75%, N=0.74±0.47%, Ca=0.48±0.72% and Mg=0.10±0.06%. The heavy metal concentrations were below Kenya Bureau of Standards (KEBS) and international permissible limits for sewage sludge application in agriculture and therefore deemed safe. The study concluded that the sewage sludge from Machakos Decentralized Treatment Facility is rich in nutrients and thus a potential fertilizing agent that can be used to boost plant growth in agricultural farms. However, it was noted that not all the wastewater produced in Machakos town gets into the DFT for treatment. Therefore, the study recommended that the county government of Machakos should endeavor to enlarge the small DFT treatment plant to accommodate the large quantities of wastewater generated within the town.

System for Tracking Breeding Traits of Improved Crops

Plant breeding involves application of a collection of techniques aimed at bringing together good parents’ traits to generate a better crop in the progeny. Cross-breeding and selection in plant breeding has been able to considerably improve yields and pest and disease resistance of crops. Efficiency in crop breeding research programs depends upon the ability of breeders and geneticists to effectively and efficiently create, identify, store, track and select recombinant genotypes with a maximum number of desirable traits in the shortest time possible. This was not easily possible with the manual system for storage and management of information lying in large volumes of data generated in all research institutions. Locating files among tons of data is a tedious and time-consuming process for researchers. The need to keep track of research data is significantly becoming important in agricultural research institutions. A study was conceived in response to the need to improve the storage, tracking and dissemination of research data collected during the breeding of improved crops. It was conducted to develop a system for tracking breeding records, at the National Agricultural Research Laboratories (NARL) in Uganda. This was motivated by the increasing need to develop high yielding yet resilient crop varieties due to the constantly changing climate amid other socio-economic changes like population pressure and loss of soil fertility. Different methods were used to design the system which included Dataflow Diagrams (DFDs) and Entity Relationship Diagrams (ERDs). An ERD was used to identify the data to be captured, stored and retrieved in order to support the activities performed in the process of filing and tracking files. As a result, a breeding tracking system was developed in form of an application tool that is able to manage the creation and movement and tracking the originality of files from desk to desk of personnel who work on them. The developed system supports information sharing between scientists as well as easy access to information about good traits in improved crops.

Identificación de parásitos gastrointestinales predominantes en bovinos de la Península de Santa Elena

La investigación se realizó en el Centro de Faenamiento Regional del cantón La Libertad, provincia de Santa Elena; el objetivo fue identificar la presencia o ausencia y tipos de parásitos gastrointestinales que se encuentran en los bovinos, para el estudio se utilizó la técnica coproparasitaria de flotación por sacarosa-glucosa y de frotis directo, la toma de muestras fecales se realizó en cincuenta animales post-mortem seleccionando aquellos provenientes de la zona peninsular, se tomó una muestra de heces, se identificó y conservó hasta su posterior análisis en el laboratorio de investigaciones agropecuarias de la Facultad de Ciencias Agrarias de la Universidad Estatal Península de Santa Elena, los resultados obtenidos se procesaron en el paquete estadístico SPSS 21.0. En los resultados se observó principalmente, parásitos gastrointestinales predominando los Nematodos con 87%, Cestodos 9% y quistes de Protozoos 4%; en donde la mayor presencia de los diferentes tipos de parásitos fueron Oesophagostomun spp (Nematodos) con 31%, Moniezia expansa 50% (cestodos) y Balantidium coli (protozoo) con 43%, cabe recalcar que, el método más eficiente en las condiciones para este estudio empleado fue el de la técnica de flotación con sacarosa en el cual se obtuvo un 55% de carga parasitaria en comparación con la de glucosa 35% y con el directo un 10%. Los resultados indican que, de acuerdo con los parámetros establecidos, es necesario realizar un plan sanitario en las diferentes zonas de la Península de Santa Elena para determinar los principales antiparasitarios que se deben utilizar para contrarrestar los nematodos, cestodos y protozoos dentro del tracto digestivo del bovino y poder bajar su presencia en la zona, mejorando el comportamiento productivo de los animales.

Nutritional Composition Analysis of Improved and Released Rice Varieties in Ethiopia

The nutritional composition of ten improved and released rice varieties collected from different research centers in Ethiopia were analysed in Assosa agricultural and nutritional research laboratory. The percent of moisture, ash, crude fat, crude protein, crude fiber, carbohydrate and total energy were 9.78-11.93%, 0.62-1.63%, 1.14-2.57%, 8.41-11.77%, 1.58-3.38%, 74.96-78.03% and 365.35-376.92 kcal (100g)-1 respectively. The analysis of variance shows that the proximate compositions of most rice varieties are significantly different (p < 0.05). Pawe-1 rice variety has good source of protein and total energy. On the other hand, TANA rich in carbohydrate content, Kokit is a good source of fat and SUPARICA-1 rich in crude fiber relative to improved and released rice varieties studied. Therefore, End users can be selecting these rice varieties according to the indicated percent of proximate analysis result and their preference for food formulation, nutrition and other purpose.

Simple Methods to Devitalize Eggs and Larvae ofHeliothis virescensandHelicoverpa zeaunder Laboratory Conditions

Heliothine moths are economically damaging insect pests, significantly affecting world crop production each year. Several species in the subfamily are commonly used in agricultural research laboratories. Research protocols should include methods to ensure that excess individuals are completely devitalized before being discarded, preventing further spread of the pests. Processes such as ultracold temperature freezing, autoclaving, or holding insects under adverse conditions for a long period of time are commonly used devitalization methods. Each method adds significant amounts of time and cost; also increasing competition for space in already crowded laboratories. While these frequently used methods might be necessary for some very resilient species, other species can succumb under less elaborate methods of devitalization. One hour of exposure to undiluted household bleach, brief exposure (>20 seconds) of wetted individuals to microwave radiation, storage in a household freezer for 48 hours, and contact with 70% isopropyl alcohol for 24 hours completely devitalized eggs and L1 larvae of corn earworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (Fab.). These very effective methods might also be applicable for other noctuid species.

English

Fusarium wilt of bananas (Musa species) is caused by Fusarium oxysporum f. sp. cubense (Foc). Foc race 1 in particular affects dessert bananas in Uganda, causing &gt;60% yield loss. This study was conducted to assess the performance of two new apple banana genotypes for bunch yield, resistance to Foc race 1 and consumer acceptability. The new apple banana genotypes (NAMU1 and NAMU2), along with two check cultivars, one susceptible but preferred by consumers (Sukali ndiizi) and the other resistant (Yangambi-KM5), were evaluated at the National Agricultural Research Laboratories in Uganda. Bunch yields of the two new apple bananas were higher than those of check cultivars by &gt;50%. NAMU1 and Yangambi-KM5 showed no symptoms of Foc race 1, whereas NAMU2 showed mild symptoms on its corms. Sukali ndiizi showed severe pseudostem splitting and corm discoloration as the key symptoms of Foc race 1. The consumer acceptability of NAMU1 and NAMU2 was as high as that of Sukali ndiizi, implying that they can be perfect substitutes for the Foc race 1 susceptible Sukali ndiizi.&nbsp; &nbsp; &nbsp; Key words: Dessert banana hybrids, host plant resistance, Panama disease, sensory attributes.

Characterisation of Phaseolus coccineus interspecific germplasm accessions for disease resistance, grain market class and yield attributes

Sister species of the common bean (Phaseolus vulgaris L.) are an attractive genetic resource to broaden the genetic base of this crop, especially for adaptation to extreme environments. The runner bean (Phaseolus coccineus) in particular, has been shown to contribute to disease resistance and tolerance to low soil fertility, and has been used to introduce these traits into the common bean. The objective of this study was to identify germplasm with agronomic traits suitable for cultivation from an interspecific population (Phaseolus coccineus G35346 x P. vulgaris; SER 16) of 186 bush lines. The lines, coded ALB and one yield check, CAL96, were field evaluated for three rain seasons; 2011a (March-June), 2011b (September-November) and 2012 (March-June) at the National Agricultural Research Laboratories (NARL)-Kawanda, Uganda. Artificial inoculum of bean common mosaic virus (BCMV) was applied to the field experiment in 2011a. The morphological (seed type and growth habit) and agronomic attributes (plant vigour, days to physiological maturity; DPM and days to 50% flowering; DF), reaction to occurring diseases and yield performance were monitored. The lines including root rot resistant and susceptible checks; MLB-49-89A, RWR 719 and CAL 96, were also subjected to inoculum of two major root rot pathogens; Fusarium solani f.sp. phaseoli (isolate FSP3) and Pythium ultimum (isolate MS61) under screen house conditions to select for root rot resistance. Results indicated significant differences (P&lt;0.05) among the interspecific lines for the parameters measured. Days to flowering and to DPM ranged from 31-39 and 81-86, respectively. Field disease pressure was generally low, but in general, 50% of the lines had yield above the mean; while 8% maintained above average yield in all seasons. The superior lines included; ALB169 (mean yield 2,564 kg ha-1), ALB214 (mean yield 2,125 kg ha-1), ALB196 (mean yield 2,084 kg ha-1), ALB5 (2,062 kg ha-1), ALB152 (2,016 kg ha-1), and ALB179 (2011 kg ha-1), compared to the check CAL96 (1,607 kg ha-1). These lines, except ALB169 and ALB179, were resistant root rot. More lines expressed resistance to Fusarium than to Pythium root rot, with 21.5% showing resistance to both root rot isolates. Over 91% of the lines were small or medium seeded (&lt; 35.0 g per 100 seeds), with red monochrome seed pattern; characteristics that are important for farmer acceptance. Key words: Fusarium, Phaseolus coccineus, Phaseolus vulgaris, root rot

Impact of crop rotation sequences on potato in fields inoculated with bacterial wilt caused by Ralstonia solanacearum

The potato industry in Kenya is threatened by bacterial wilt because most production areas are infested with the wilt-causing Ralstonia solanacearum and over 50% yield losses have been reported. Continuous cultivation causes soil physical and biological constrains that greatly affect the crop performance and increase proliferation of the bacterium. Rotation with non-host or suppressant plant species could contribute to considerable reduction of bacterial wilt in the subsequent potato crops. This study tested the effect of different crop sequences on R. solanacearum population in the soil, wilting incidence and yield of potato. Two season field experiments were conducted at two sites (Egerton University, Njoro and National Agricultural Research Laboratories (NARL), Kabete) with 17 different crop sequences. Rotations involving brassica and legumes with potato gave a higher emergence percentage compared to the other sequences. The bacterial population was significantly influenced by the different environments from the first season to the third season; F (1, 102) =53.2, P<0.001, F (1, 102) =12.5, P< 0.001 and F (1, 102) =236.8, P<0.001 respectively. There was a significant effect F(16,119)=7.063, P<0.001 of the crop rotation sequences on the wilting incidence of potato. Pre cropping potato with spring onion and barley resulted to a significantly lower wilting incidence compared to all the other crop rotation sequences with a mean of 8.3% across sites. The results showed that Potato-Lablab-Potato and Cabbage-Lablab had the highest yield with 19.9 and of 19.7 tons/ha in the one crop rotations and pre crops to potato respectively. A Genotype x Environmental means versus IPCA scores showed that the yield due to barley-spring onion, spring onion-barley and wheat-spring onion as pre crops were more stable in both locations compared to the other cropping sequences. The study indicates that rotations involving spring onion with the locally grown cereals such as barley and wheat can be utilized in curbing bacterial wilt. Rotations involving lablab and cabbage may also be used to increase the yield of potato in bacterial wilt infested fields. These crops should be used in rotations involving more seasons so as to achieve better effects. Key words: Bacterial wilt, crop rotation, potato yield, Ralstonia solanacearum, wilting incidence.

Resistance Levels to Root Rot and Angular Leaf Spot Diseases in Selected High Iron Bean Genotypes

Common bean production is constrained by different diseases the major ones being, Angular Leaf Spot (ALS), bean root rot, anthracnose, Common Bright Bacteria (CBB), Bean Common Cosaic Virus (BCMV) and Bean Common Mosaic Necrotic Virus, (BCMNV). The aim of this study was to identify new and better sources of broad resistance to both bean ALS and Root Rot diseases among nutritional bean varieties. Fifty seven varieties were planted in the screen house of CIAT Africa based at Kawanda Agricultural Research Laboratories Institute (KARL). Virulent inocula actually used at CIAT were used to test these genotypes. Different varieties were resistant to specific isolates but interestingly, only ACC 714 contained broad resistance to both Andean and MesoAmerican isolates of bean Angular Leaf Spot as well as Fusarium root rot and Pythium root rot at mean, median and mode basis. Since different nutritional bean varieties have varying levels of resistance to different pathogens, it may be possible to pyramid these resistance genes into appropriate background so as to provide durable resistance in biofortified bean genotypes higher in iron and zinc content.

Application of Response Surface Methodology for Determining Optimal Factors in Maximization of Maize Grain Yield and Total Microbial Count in Long Term Agricultural Experiment, Kenya

The Agriculture sector is the main stay of the Kenyan economic development contributing over 70% of the Gross Domestic Product (GDP). The sector is faced with numerous challenges leading to frequent and recurrent food shortages. Declining maize grain yield is one among the major challenges that call for urgent interventions to address the looming food crisis in the country. Maize play a big role in the Kenyan food security and in most case lack of the same is taken to mean food insecurity. It is due the importance attached to the crop that a Long Term Agricultural Experiments (LTAE) was set up specifically to research on the Maize grain yield. Many paper published on the LTAE in the country are only single factors analysis and lack the application of Response Surface Methodology (RSM) approaches in solving challenges facing the low and declining maize grain yield (y1), total microbe population (y2) a crucial component of Soil Organic Matter (SOM) and their optimization. The focus of this paper therefore is the application of RSM in maize grain yield and total microbial population optimization. Specifically, the paper determined the most significant factors for maize grain yield and total microbial population (bacteria, fungi, actinomycetes, rhizobia), (screening phase of the paper), constructed of an efficient and appropriate experimental design for evaluating the optimal settings of maize yield and total microbial population count and determined univariate optimal settings for maize grain yield and total microbial population. The primary data was summarized from LTAE in National Agricultural Research Laboratories (NARL) in Kabete under the Kenya Agriculture and Livestock Research Organization (KALRO) and secondary data imputed for experimental points falling outside the set field experimental design points. Two treatment factors were identified as the most significant treatment factors (Farm Yard Manure (FYM) and Nitrogen and Phosphorus (NP)) at their low levels and Circumscribed Central Composite Design (CCCD) with two star points as the most efficient design. CCCD passed most optimal criteria of DAET. Univariately, optimal setting for maize grain yield was realized at 3.8x103 kg/ha and that of the total microbial population at 3.6x106 count. The study confirmed that it was possible to optimize the input treatment factor that lead to the optimization of both maize grain yield and maintaining maximal total microbial population count at its optimal levels.

Evaluation of the Most Significant Treatment Factors for Maize Grain Yields and Total Microbial Count in Long Term Agricultural Experiment (LTAE), Kenya

Agriculture and its related economic activities form the main livelihood for Kenya population. The sector faces numerous challenges that have led to food insecurity in the country. Maize production plays a significant role in the country’ economic development contributing significantly to the national overall Gross Domestic Product (GDP). Declining maize grain yield is one of the major challenges that require interventions to avert the looming food crisis. To address the challenge various Long Term Agricultural Experiments (LTAE) and studies on soil fertility maintainance options have been developed. However, such studies have explored only single factors at a time with limited application of robust statistical application. Statistical procedures could offer best set of few treatment factors that explain the maize grain yields in LTAEs in Kenya and beyond. The focus of this paper was the application of robust statistical methods in obtaining set of minimum treatment factors that could be used in the determination maize grain yield in LTAE. Specifically, the paper sought to describe the trend in maize grain yield over the experimental period, characterize the input factors for maize grain yield and to determine the most significant treatment factors for maize grain yield and total microbial population count (bacteria, fungi, actinomycetes, rhizobia). The primary data was summarized from LTAE in National Agricultural Research Laboratories (NARL), Kabete under the Kenya Agriculture and Livestock Research Organization (KALRO) and secondary data imputed for experimental points falling outside the set field experimental design points. Two treatment factors were isolated (Farm Yard Manure (FYM) and Nitrogen and Phosphorus (NP)) at their low factor levels as the most significant treatment factor in maximizing the maize grain yield and total microbial population count. It was possible to select a minimum set of treatment factors in LTAE that are critical in predicting the maize grain yield.

人工模拟降水条件下旱作农田土壤“Birch效应”及其响应机制

PDF HTML阅读 XML下载 导出引用 引用提醒 人工模拟降水条件下旱作农田土壤“Birch效应”及其响应机制 DOI: 10.5846/stxb201403120428 作者: 作者单位: 西北大学,西北大学,西北大学,中国科学院水利部水土保持研究所,ARS Northern Plains Agricultural Research Laboratory 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31270484,41171033);教育部科技重点项目(209123);西北大学研究生自主创新项目(YZZ13006) Response of soil "Birch Effect" to simulated rainfalls in dry croplands Author: Affiliation: Northwest university,Northwest university,Northwest university,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:降水事件引起干土复湿刺激土壤CO2脉冲释放的现象被称为"Birch效应",其作用机制可能是降水刺激土壤"底物供给"增加或引起土壤"微生物胁迫"所致。为深入了解土壤"Birch效应"对降水格局改变的响应过程及内在机制,在冬小麦拔节期和夏闲期分别进行了不同降水量(1-32 mm)人工模拟降水实验,系统观测了降水后0-72 h土壤呼吸及土壤碳组分变化特征,结果表明:土壤呼吸随降水量的增大而增强,1-16 mm降水土壤呼吸峰值出现在降水后4 h,而32 mm降水土壤呼吸峰值出现时间滞后了4 h。与较小降水量相比,较大的降水量能增加土壤呼吸但会推迟土壤呼吸峰值出现时间。土壤呼吸速率峰值(SR-P)与降水量(P)呈幂相关(拔节期:SR-P=0.97P0.09, R2=0.5, P < 0.05;夏闲期:SR-P=1.07P0.09, R2=0.98, P < 0.01)。降水后72 h累积CO2释放量(CO2-P)与降水量呈线性相关(拔节期:CO2-P=0.03P+5.99, R2=0.58, P < 0.05;夏闲期:CO2-P=0.11P+6.04, R2=0.86, P < 0.01)。土壤呼吸温度敏感性系数和降水量之间存在二次曲线关系(拔节期:Q10=-0.007P2+0.2P+0.7, R2=0.32P < 0.05;夏闲期:Q10=-0.01P2+0.3P+0.2, R2=0.86, P < 0.01)。逐步回归分析表明,冬小麦拔节期所有降水量处理土壤呼吸与土壤微生物量碳相关性均达到显著水平(P < 0.05),指示土壤"Birch效应"是由"微生物胁迫"所致。而在夏闲期,当降水量小于8 mm时土壤呼吸与微生物量碳相关性显著,即以微生物胁迫机制占主导;8 mm降水处理下土壤呼吸与氯仿熏蒸-K2SO4提取态有机碳相关性达到极显著水平,指示则为两种机制共同起作用,而当降水量大于16 mm时,土壤呼吸主要与可提取态有机碳显著相关,"Birch"效应转为以底物供给机制占主导。与夏闲期相比,冬小麦拔节期作物生长会削弱"Birch效应",并改变其响应机制。 Abstract:In the dry cropping lands, soil rewetting due to precipitation can stimulate soil CO2 efflux pulses, which is called the "Birch Effect". Two types of responding mechanisms:"Substrate supply" and "Microbial stress", were proposed to explain the soil "Birch effect". To elucidate how precipitation change affects the "Birch effect "and its responding mechanism, we conducted precipitation simulation experiments in a winter wheat field to measure the short-term response of precipitation levels(1-32 mm) on soil respiration from 0 to 72 h at the jointing stage and during the summer fallow period on the Loess Plateau. The results showed that soil respiration peaked at 4 h with 1 to 16 mm of precipitation, but the peak was delayed by another 4 h at 32 mm precipitation. Higher precipitation delayed, but increased soil respiration compared to lower precipitation. The peak value for the soil respiration rate(SR-P) increased exponentially with increased precipitation(P)(jointing:SR-P=0.97P0.09, R2=0.5, P < 0.05, fallow:SR-P=1.07P0.09, R2=0.98, P < 0.01). Cumulative soil respiration after 72 h(CO2-P) increased linearly with the precipitation level(jointing:CO2-P=0.03P+5.99, R2=0.58, P < 0.05; fallow:CO2-P=0.11P+6.04, R2=0.86, P < 0.01). The temperature sensitivity of soil respiration(Q10) was correlated binomially with the precipitation level(jointing:Q10=-0.007P2+0.2P+0.7, R2=0.32, P < 0.05; fallow:Q10=-0.01P2+0.3P+0.2, R2=0.86, P < 0.01). Stepwise correlation analysis between soil carbon fractions and soil respiration rate showed that soil respiration rate was significantly correlated with soil microbial biomass C at the jointing stage for all precipitation levels, indicating that a "microbial stress" mechanism dominated the "Birch effect" during growing season. However, during summer fallow period, soil respiration rate was significantly correlated with microbial biomass C, which suggested "microbial stress", when the precipitation amount was lower than 8 mm, but correlated with chloroform-fumigated extracted C, which suggested that both mechanisms were operating when precipitation amount was equal to 8 mm. However, soil respiration was significantly correlated with K2SO4-extracted soil C when precipitation amount was equal to or higher than 16 mm, indicating a shift to the "Substrate supply" mechanism. Compared with that during the summer fallow period, the soil "Birch effect" was weaker and its responding mechanism had changed at the wheat jointing stage due to root respiration and shading effects. 参考文献 相似文献 引证文献

Fruit Fly (Diptera: Tephritidae) Host Status and Relative Infestation of Selected Mango Cultivars in Three Agro Ecological Zones in Uganda

ABSTRACTDespite their economic importance, there is paucity of knowledge on fruit fly host status in Uganda. Therefore, this study set out to profile the host range of the main fruit fly pests and determine the susceptibility of selected fruits and mango cultivars across three main mango agro ecological zones, which included: Western Medium High Altitude Farmlands (WMHF), Lake Victoria Crescent (LVC), and the Northern Moist Farmlands (NMF) in Uganda. A wide range of fruits was sampled across the three zones. These were incubated at the National Agricultural Research Laboratories following standard protocols. Emerging fruit fly species were identified using standard keys and counted. Among the sampled fruits, 633 (35.0%) individual fruits from 15 plant families were positive for fruit fly infestation. Bactrocera invadens dominated (76.3%) of the positive samples, while infestation by native species, such as Ceratitis capitata and Ceratitis cosyra, was negligible. Annonaceae, Solanaceae, Rutaceae, and Anacardiaceae plant families recorded significantly more host species, while the number of pest fruit flies (species richness) per plant species followed a similar trend: Solanaceae > Rutaceae > Anacardiaceae. There was significant (P < 0.0001) variability in infestation among mango fruit cultivars, both within and across zones. When all zones were pooled together, Tommy Atkins and Kent, and Keitt, Kate, and Biire were the least and most infested, respectively. In conclusion, fruit flies have a diverse range of commercial and non-commercial hosts in Uganda. Strategies for fruit fly pest eradication in the country should ensure elimination or management of alternative fruit hosts and integration of tolerant mango cultivars in fruit development programs.

Application of indicators and quality index as a tool for critical analysis and continuous improvement of laboratories accredited against ISO/IEC 17025

In this work, a model for developing indicators and quality index was developed and applied, meaning to evaluate laboratories which have implemented the quality management system in accordance with the ISO/IEC 17025 requirements. Firstly, the chosen analysis tool (such as “brainstorming” and PDCA) to create a development of indicator and quality index model is discussed. This model was applied at the National Agricultural Research Laboratory of Sao Paulo—Laboratorio Nacional Agropecuario do estado de Sao Paulo (Lanagro-SP). As a result, a set of indicators was developed and applied which were grouped to obtain an indicator of unique quality for ten different laboratory units evaluated. This proved to be an essential tool for critical analysis and continual improvement of the quality management system in laboratories exercising the ISO/IEC 17025.