Months After Planting Research Articles

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The objective of this study was to test for appropriate quantity of fertilizer (NPK 12-11-18) required to boost the production of cassava (variety TME 419) in the forest zone of Cameroon. The trial was conducted at the experimental farm of the Institute of Agricultural Research for Development (IRAD) in Mbalmayo. The experimental design was completely randomized block design in three replicates. The treatments were as follows: T0 (Control (No input)); T1 (200 kg.ha-1); T2 (300 kg.ha-1); and T3 (400 kgha-1). The data were analyzed using the IBM SPSS Statistics 20 Software. The results showed that chemical fertilizer improves the growth (number of leaves, plant height, and petiole length) and yield (number of marketable root, yield) of cassava mainly because it enhances soil nutrient availability. Thus, NPK-fertilizer significantly (p<0.001) increased petiole length by 20.71, 27.83, and 31.62% for T1, T2, and T3, respectively at 5 months after planting (MAP). The highest plant height and number of leaves at 4 and 5 MAP was observed with T3 followed by T2 and T1. Similarly, the highest root yield (43.33±10.97 t.ha-1) was observed with treatment T3. Hence, the fertilizer application rate of 400 kgha-1 of NPK 12-11-18 appears most appropriate for intensification of cassava production in the humid forest agro ecological zone of Cameroon. Key words: Cassava, growth, NPK, root yield, soil fertility. &nbsp

Neem leaf and poultry manures soil amendment on growth and yield of Telfairia occidentalis

Telfairia occidentalis is a widely used leafy and seed vegetable in West Africa and adequate soil fertility management is essential for its higher productivity. Field experiments were conducted on neem leaf and poultry manures soil amendment to assess the growth and yields of Telfairia occidentalis between 2013 and 2014 cropping seasons. The experiment was laid out in a randomised complete block design with four replications to include 5 t ha -1 of neem leaf manure (NLM), 5 t ha -1 of poultry manure (PM), 2.5 t ha -1 of neem leaf manure plus 2.5 t ha -1 of poultry manure (NLM+PM) and control. Data collected on vegetative and yield related components were subjected to analysis of variance at p < 0.05 significance level. The results showed that number of leaves, vine length, leaf area and number of branches increased significantly (p < 0.05) in plants treated with NLM, PM and NLM+PM from 2-5 months after planting (MAP) compared to control. At five MAP, NLM+PM significantly (p < 0.05) produced more leaves (52.5; 56.4), longer vines (473.0; 488.4cm), more branches (14.6; 16.3) compared to sole treatment and control. In addition, foliar yield (4.29; 4.94 t ha ‑1 ), number of pods/plant (3.09; 4.11), length of pods (72.80; 81.60cm), number of seeds/pod (87.62; 89.51), seeds yield (61.60; 62.54 t ha -1 ) and pod yield (49.85; 50.15 t ha -1 ) produced were higher in plants treated with combined manures in the two cropping seasons. The applied combined manures (neem leaf and poultry) could be exploited for soil improvement and sustainable yield increase of Telfairia occidentalis production.

Tests of Hexazinone and Tebuthiuron for Control of Exotic Plants in Kauai, Hawaii

Non-native plant species have become serious pests in Hawaii’s delicate island ecosystems. It is necessary to control invasive plants. The herbicides hexazinone and tebuthiuron were evaluated for defoliation efficacy to control several major invasive plants and for non-target effects on native plants at Site I in a rainforest at 1200 m elevation and Site II in a mesic area at 640 m elevation on the island of Kauai, Hawaii. The invasive weed species in the sites included daisy fleabane (Erigeron karvinskianus DC.), faya tree (Myrica faya Ait.), strawberry guava (Psidium cattleyanum Sabine), banana passion fruit (Passiflora mollissima Bailey), vaseygrass (Paspalum urvillei Steud.), and highbush blackberry (Rubus argutus Link. 1822). Native plants included ohia lehua (Metrosideros polymorpha Gaudich.), naupaka (Scaevola cerasifolia Labill.), pilo (Hedyotis mannii), hona (Urera glabra (Hook. &amp; Arn.)), aalii (Dodonaea viscosa Jacq.), and amau (Sadleria sp.). The results showed that broadcast applications of hexazinone granules and tebuthiuron pellets were effective on some of those invasive species. Herbicidal tolerance varied among the native species. For example, D. viscosa showed high tolerance to hexazinone. S. cerasifolia was susceptible to hexazinone, but not to tebuthiuron. The inconsistent defoliation of Sadleria sp. occurred among different applications rates of the two herbicides. M. polymorpha, particularly when it was small, could tolerate hexazinone and tebuthiuron. U. glabra was severely injured by the two herbicides. H. mannii was moderately tolerant to hexazinone, but fairly sensitive to tebuthiuron. The invasive loblolly pine (Pinus taeda L.) was highly tolerant to hexazinone, but was very sensitive to tebuthiuron. M. faya was very sensitive to hexazinone, but very tolerant to tebuthiuron. P. cattleyanum was sensitive to both herbicides. Six and nine months after hexazinone and tebuthiuron treatment, respectively, native plants were transplanted into the Sites to observe injury from residual herbicides. Approximately less than 10% mortality was observed for the out-planted native species three months after planting (MAP), indicating that the native species showed less injury in the early period of transplant. The mortality of the three endangered species Kauai hau kuahiwi (Hibiscadelphis distans), Kauai delissea (Delissea rhytidosperma H.Mann) and kawawaenohu (Alsinidendron lynchnoides), however, increased as the MAP increased. Overall, broadcast treatments of hexazinone and tebuthiuron at rates higher than 1 kg active ingredient per hectare would be problematic. The dissipation half-life values of hexazinone and tebuthiuron in the 1-15 cm layer of soils at the two sites were approximately 7 days and greater than 180 days, respectively.

PERTUMBUHAN DAN HASIL PISANG MULI (Musa acuminata L.) DENGAN PEMBERIAN PUPUK ORGANIK GUANO

Banana plants are plants that from the roots to the leaves can be used for human purposes. But the quantity and quality of production is still low, to increase production, it needs special treatment with fertilization. In addition to being a banana producer, Balangan Regency also has the potential for guano fertilizer. The purpose of this study was (i) to find out the growth and yield of muli bananas by guano organic fertilizer (ii) to get the best dose of guano organic fertilizer for optimal growth and yield of muli banana. This research was conducted in Kambiyain Village, Tebing Tinggi District, Balangan Regency, South Kalimantan Province, from March 2018 - May 2019. This experiment used a single randomized block design (RBD), the factor studied was the administration of various doses of guano fertilizer (G) consisting of 4 levels , namely: g1 = 10 tons. ha-1 is equivalent to 3.3 kg. 1, g2 = 15 tons. ha-1 is equivalent to 4.95 kg. 1, g3 = 20 tons. ha-1 is equivalent to 6 , 6 kg. -1, g4 = 25 tons. ha-1 is equivalent to 8.25 kg. -1. Each experimental treatment consisted of 4 combinations and repeated 6 times, so that 24 experimental units were obtained. Where each experimental unit consists of 2 plants so that the whole plant has 48 plants. The results showed the growth of plant height aged 2, 3 and 4 month after planting (MAP); number of leaves aged 4 MAP; stem diameters 2, 3 and 4 showed a response to the growth of muli banana plants against various doses of guano fertilizer on podsolic fields. In generative growth only affects many fruits per comb, while at flowering time, harvest age, bunch length and many combs do not respond to the administration of various doses of guano fertilizer on podsolic fields. The best dose of guano fertilizer was g4 (25 ton.ha-1) for the growth of mauli banana plants on podsolic fields.

Effect of Nano Technology in Combination with Soil Solarization to Control Panama Disease of Banana in Jordan Valley

Soil solarization was applied for a field which was planted with infected banana seedlings. Spreading transparent plastic sheets of 80µ thickness was done from August, 1 until October 12, 2017 at the University Farm in Jordan Valley. Soil solarization was effective in elimination of all phytopathogenic propagules at 30 cm depth. Then clear plastic sheets were removed and the solarized land was planted with healthy banana seedlings cultivar Grand Naine. Banana plantlets were chemically treated as soil drench with Nanoparticle solution of 200 and 400 ppm of Silver Nanoparticles (AgNPs), two fungicides, Revanol and Tachigaren, Sodium Hypochlorite in addition of irrigation of one treatment with treated wastewater. Biological control included three treatments; Endomycorrhiza, Trichoderma as a commercial product (BioHealth) and plant growth promoting rhizo-bacteria. Fresh chicken and sheep manure was added to two treatments. Twelve treatments were distributed randomly in randomized complete block design. Endomycorrhizal inoculation with Glomus mosseae, 200 ppm of AgNPs, Revanol and Tachigaren treatments of banana seedlings were the most effective in completely protecting banana plants from Fusarium wilt during the whole experimental period. Several applications of Trichoderma, wastewater and 400 ppm of AgNPs were effective in maintaining some infected banana seedlings nine months after planting very healthy. Sheep and chicken manure treatments resulted with 60 and 40% disease incidence with Fusarium wilt respectively and 20% of disease incidence in Hypex, PGPR and control treatments. Wastewater, Nanoparticles 200 ppm and endomycorhizal treatments gave the highest ratio of sword sucker development. We recommend soil solarization and use of integrated program to control Panama disease of banana in Jordan.

Comparative Assessment of Yield Performance of Neglected Cocoyam (Colocasia esculeta (L.) Schott) Parts as Planting Materials in the South Western Nigeria

Hitherto, there is scarcity of information on the usefulness of neglected small corms and cormels of cocoyam in the South West Nigeria. A 9 (nine) months trial was conducted to compare the growth and yield performance of different types of cocoyam planting materials with treatment consisting of T1; sprouted small cocoyam cormels, T2, trimmed out lower parts of harvested cocoyam corm and T3; moderate sized corm of 50-100g (control) arranged in a Randomised Complete Block Design (RCBD) with three replicates. Data on the number of leaves and plant height was taking at 4 week interval for 24 weeks while data on number and weight of harvested cormels was taking at 9 months after planting (MAP). The data collected were subjected to a univariate General Linear Model (GLM) two ways Analysis of Variance (ANOVA) using IBM SPSS software statistical package 21. Significance mean differences were separated using Duncan Multiple Range Test (DMRT) at 0.05 level of significance. The result showed that the highest mean number of leaves and plant height was obtained from treatment T1 (10.22) and T2 (92.83) respectively at 24 weeks after planting (WAP). While both treatment T1 and T3 collectively had the highest number of consumable cormels (54.0) in which treatment T3 weighed the highest (3.202 kg). There was no significant difference (P&gt;0.05) in both the number of leaves produced and plant height among the different cocoyam planting materials utilised at 24 (WAP). Similarly, there was no significant difference (P&gt;0.05) in the number and weight of cormels produced by the different treatments at 9 months after planting (MAP). The study therefore concluded that both sprouted small cocoyam cormels, trimmed out corms during planting compared favourably with moderate sized corm of weight 50-100g commonly used as planting material in term of yield potential and therefore recommended to be schedule for demonstration to cocoyam farmers in the study area for adoption.

Whitefly resistance in African cassava genotypes

Whitefly ( Bemisia tabaci ), a major pest and vector of viruses in cassava, is the greatest current threat to cassava production in sub-Saharan Africa (SSA). Research efforts have focused on management of the two viral diseases: cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), and have ignored the whitefly vector that is driving the spread of the viruses, causing CMD and CBSD in SSA. The objective of this study was to evaluate cassava genotypes for resistance to B. tabaci based on field infestation and damage in Uganda. The study was carried out in four sites with diverse agro-ecologies including: Namulonge, Kasese, Ngetta and Serere during 2015 and 2016.Whitefly nymph abundance and feeding damage were assessed on each test genotype from 3 to 6 months after planting (MAP). In 2015, the highest broad sense heritability estimates were 39% (4 MAP) and 53% (5 MAP) for whitefly nymph abundance and feeding damage, respectively. In 2016, broad sense heritability estimates were 23% (3 MAP) and 41% (4 MAP) for whitefly nymph abundance and feeding damage, respectively.Analysis of variance of whitefly nymph abundance showed a significant (P< 0.05) location × genotype × season interactions at 3, 4, 5 and 6 MAP. There were also significant (P< 0.05) location × genotype × season interactions at 3 and 4 MAP for whitefly feeding damage. Ten genotypes showed good levels of resistance to whitefly infestation and feeding damage including: UG120202, UG120174, NASE13, UG120160, UG120286, UG120293, UG130075, CSI-142, CS1-144 and UG130085. These genotypes may serve as parental materials for breeding programmes for whitefly and viral disease control. Key words: Bemisia tabac i, cassava brown streak disease, cassava mosaic disease

Genotype x Harvest Cycles Interaction in Sugarcane on the South Coast of Pernambuco

Aims: To quantify the magnitude of the genotype x harvest cycle interaction (GxC) of sugarcane during three harvest cycles and to select superior clones for cultivation on the Coast of the Southern Forest of Pernambuco.&#x0D; Study Design: The experiment was conducted in a randomized complete block design.&#x0D; Place and Duration of Study: Evaluated during the 2011/2012, 2012/2013 and 2013/2014 harvest years in the agricultural area of the Cucaú Plant, located in the Municipality of Rio Formoso (8°39' 49" S and 35º09'31" W, altitude of 5 m), Microregion of the Southern Forest of Pernambuco.&#x0D; Methodology: 11 genotypes Republic of Brazil of the RB 2004 series and three RB cultivars were evaluated. Each plot was represented by five grooves of 8.0 m in length, spaced in 1.0 m, totaling 40 m². The crops were harvested 15 months after planting (MAP) for the first crop cycle and 12 MAP during the two subsequent cycles were evaluated tons of sugarcane per hectare (TCH), tons of pol per hectare (TPH) and total recoverable sugar (ATR). The variance analyses, the Scott and Knott clustering test, the estimative of the simple and complex parts of the G x C interaction and the Pearson correlation coefficient were processed in the Genes program.&#x0D; Results: The genotypes showed a significant reduction of TCH from the first to the second cycle and that only the genotype UFRPE11 showed a significant decrease for the third. The genotypes UFRPE10, UFRPE6, UFRPE11, UFRPE7, UFRPE2, UFRPE9 and UFRPE1 exceeded all commercial varieties in TPH. It was observed for the variable ATR that there were no significant differences between the genotypes in the third cycle. The simple fraction of the interaction G x C were predominant between cycles C1 and C2 for TCH (67.91%) and TPH (69.35%), while for ATR (56.42%) the complex fraction was predominant. For the pair C2 x C3, the simple fraction of the interaction G x C predominated only in the TCH (62.85%) and TPH (62.41%) variables, but was not significant for the variable ATR. It is worth mentioning that the C1 x C3 cycle pair presented predominantly complex type interactions for all variables TCH (50.42%), TPH (52.20%) and ATR (59.66%).&#x0D; Conclusion: The simple fraction of the genotype x harvest cycles (G x C) interaction provides genetic gain for yield of sugarcane and sugar in selection in subsequent pairs of harvest cycles, year by year. The complex fraction of G x C interaction reduces the predictability of genetic gain, making it difficult to select new cultivars. Local selection favors expressive genetic gain in a few selection cycles. However, it does not favor the selection of genotypes with high adaptability and phenotypic stability, requiring tests in several environments. The UFRPE06 and UFRPE10 clones can be selected to continue the selection cycles for the southern coastal conditions of the Mata de Pernambuco.

Effect of Paclobutrazol Application Field on Seed Rhizome Quality of Ginger during Storability

Maintaining the availability of high quality of seed on-time is one of the major problems in the production of large white ginger seed rhizomes (LWG). LWG seeds cannot be stored for a long period of time because it is easily wrinkled and sprouted during the storage. This study aimed to understand the effect of PBZ treatment time and concentration on the quality of LWG seeds during the storage. This study used a randomized square experimental design with three replications. The main plot is the time of application of paclobutrazol: 1) 4 months after planting (MAP) and 2) 5 MAP, and as subplots are five levels of PBZ concentration : 0, 100, 200, 300 and 4 00 ppm. The results showed the treatment of PBZ 400 ppm at 4 and 5 MAP was the best concentration in increasing the shelf life of LWG seeds: growth speed (4.8% / etmal ), seedling height (60.38 cm) and dry weight of seedlings (1.51 g) after stored for 4 months compared with no PBZ treatment.

Varietal response of cassava root yield components and root necrosis from cassava Brown streak disease to time of harvesting in Uganda

Cassava brown streak disease (CBSD) is the most important biotic constraint threatening cassava (Manihot esculenta Crantz) production in eastern and southern Africa, and the food and income security of millions of rural farmers. With no tangible solution in view, farmers cope with the disease by harvesting the crop early, a practice that also leads to yield losses owing to small root size. This study evaluated CBSD root necrosis (RN), the total fresh root yield (TFRY), percentage marketable fresh root yield (PMFRY) and dry matter content (DMC) of six cassava varieties (MM, 2006/90, MM, 2006/123, MM, 2006/128, MM, 2006/130, MM 96/4271, and TME14) at different times of harvesting after the recommended 12 months after planting (MAP). Trials were planted during April 2012 at Sendusu and Serere located in the Wakiso and Serere districts of Uganda, respectively. The two sites are distinct in climatic, soil and CBSD disease pressure conditions. A split-plot design was used with cassava varieties as the main plots and times of harvesting (12, 16, 20 and 24 MAP) as sub-plots. Highly significant differences (P ≤ 0.001) were detected between sites (S), varieties (V) and time of harvesting (T) for TFRY, PMFRY and RN, whereas only V effects were highly significant (P ≤ 0.001) for DMC. The V × S interactions were highly significant for TFRY, PMFRY and RN, while the V × T interactions were highly significant for PMFRY and significant (P ≤ 0.01) for TFRY and DMC. The PMFRY decreased by about 14–27% as the plants remained in the field after 12 MAP. There was a great difference among clones, depending on location. Variety MM 2006/128 performed the best, with virtually no root damage even at 24 MAP at both sites. The mean CBSD root necrosis severity score among the varieties at each site increased from 2.6 (at 12 MAP) to 3.1 (at 24 MAP) at Sendusu, and from 1.9 (at 12 MAP) to 2.4 (at 24 MAP) at Serere. However, for MM2006/128 which was the best performing variety, the root necrosis score remained about 1.0 at Sendusu and about 1.3 at Serere. Time of harvesting had no significant effect on DMC. This study showed it is possible to breed new cassava varieties that combine tolerance to CBSD with long periods of in-ground storability. Genotype and environment had a profound effect on all the traits analysed, suggesting that genotypes should be selected for specific environments and harvest times. The results indicate that some of the clones (MM, 2006/128, MM, 2006/123 and MM, 2006/130) investigated in this study will be useful in the fight against CBSD in the region especially for the mid-altitude areas, which have recently been seriously affected by the virus disease.

THE INFLUENCE OF INITIAL IRRIGATION ON THE GROWTH OF TWO HYBRIDS OF EUCALYPTUS

In order to maximize the productivity of forest species, techniques such as irrigation have been used. The objective of this study was to evaluate the water use efficiency and the influence of the irrigation located in the growth of the hybrids of eucalyptus Grancam and Urograndis at 65 months. The study was carried out in the experimental area of the State University of Mato Grosso do Sul (UEMS), in Aquidauana (state of Mato Grosso do Sul, Brazil). The experimental design was randomized blocks with subdivided plots. The treatments used in the plots were two irrigation systems (microsprinkler and drip) and one control treatment with no irrigation (dryland), and in the subplots, the two hybrids of eucalyptus: Grancam (Eucalyptus grandis x Eucalyptus camaldulensis) and Urograndis (Eucalyptus urophylla x Eucalyptus grandis), submitted to irrigation up to the 53° month after planting (MAP). The results were submitted to the analysis of variance and the Tukey test for means comparisons at 5% of probability. The use of irrigation in eucalyptus influences the productivity, providing increased wood volume, height of plants and diameter at breast height (DBH). The hybrid Grancam showed greater increase in height, and Urograndis increased in DBH. The higher efficiency of water use for the volumetric production of wood was observed in drip irrigation for the hybrid Grancam. The hybrid Urograndis is more efficient in the use of water for the volumetric production of wood regardless of the treatment.

Increasing Growth Rate and Production of Bioactive Compounds Curcuminoid and Xanthorrhizol in Javanese Turmeric (Curcuma xanthorrhiza Roxb.) Rhizomes with Biso Zyme Application

The bioactive compounds from Javanese turmeric (Curcuma xanthorrhiza Roxb.), curcuminoid and xanthorrhizol, have been used to treat human diseases. This research aims to study the Javanese turmeric growth, its curcuminoid and xanthorrhizol content using Biso Zyme with different concentration and interval spraying. Biso Zyme is is conjugated enzyme concentrate (CEC) produced by yeast extracts that can be applied to the plant to increase and improve plant yields. The treatments were arranged in a randomized block factorial design with three replications. The concentrations of Biso Zyme were 0.0, 0.1, and 0.05 %, with monthly spraying intervals at 1, 2, 3, 4 and 5 months after planting (MAP). The results showed that the highest leaf area index was 2.71 cm2g-1 followed by leaf area ratio which was 66.47 cm2.g-1 with 0.1% Biso Zyme application. Relative growth rate was 0.048 g.day-1while net assimilation rate was 0.00092 g.cm-2.day-1 without Biso Zyme application. The highest fresh and dry weight was those treated with 0.05% Biso Zyme applied at 4 to 5 MAP, i.e., 444.44 g and 68.72 g, respectively. The highest curcuminoid and xanthorrhizol contents were 0.435% and 1.505%, respectively, with 0.05% Biso Zyme spraying interval at 4 to 5 MAP, and 0.1% Biso Zyme with sprayed at 1 to 5 MAP. Thin layer chromatography (TLC) analysis detected standard curcuminoid at Rf 0.23 and xanthorrhizol at Rf 0.66 with dichloromethane:chloroform eluents. Keywords: curcuminoid, Javanese turmeric, Leaf Area Index, organic fertilizer, xanthorrhizol

Effect of Vermicompost Amendment on Nutritional Status of Sandy Loam Soil, Growth Performance, and Yield of Pineapple (Ananas comosus var. MD2) under Field Conditions

Vermicompost is the product of composting or breaking down organic matter through the use of earthworms. It is rich in essential plant nutrients, and has the ability to enhance the condition and increase the quality of the soil. In the present study, a field trial was conducted from January 2015 until March 2016 to elucidate the effects of vermicompost application (compared to supplementation with chemical fertilizer and no fertilizer) on the sandy loam soil and plant nutrients of pineapple (Ananas comosus var. MD2). The morphophysiology and yield performance of MD2 pineapple grown with vermicompost in the field were also evaluated. In this study, vermicompost was applied onto the sandy loam soils during transplanting, followed by a second application at seven MAP (months after planting) at the rate of 10 t ha−1. On the other hand, the chemical fertilizer was applied based on the normal conventional cultivation practice. The soil and D-leaf samples at six MAP (S1) and during the red bud stage (S2; 10 MAP) were used to determine the soil and plant nutrient contents. The morphology of the plants was evaluated every month, and the fruits that were produced were subjected to quality analysis. Data analysis revealed that soil pH was increased after a second supplementation of vermicompost and contained significantly higher total N (0.15%) in the soils compared to the control (0.07%). There was no significant difference between plants supplied with chemical fertilizer and vermicompost in terms of plant height, number of leaves, or the length and width of D-leaves. However, different fertilization treatments were found to affect the yield and physical characteristics of the resulting fruits. Plants supplied with chemical fertilizer produced the highest fruit yield (136.97 t ha−1) with the largest fruit size, followed by vermicompost (121.39 t ha−1) and the control (94.93 t ha−1). However, fruits supplied with vermicompost were observed to have the smallest crowns. Taken together, these results indicated that the use of vermicompost produced pineapple plants with excellent growth performance, comparable to that obtained when chemical fertilizer was used. Also, based on the cost analysis conducted, it was shown that the total cost (fertilizer and labor) for plants grown with vermicompost was lower than plants grown with chemical fertilizer. However, the usage of vermicompost as the single source of nutrients is not suggested for this type of soil and field conditions, but can be used as a supplement to maintain the soil quality and ensure agricultural sustainability.

Cassava response to the integrated use of manure and NPK fertilizer in Zambia

Cassava is Africa's second most important food source in terms of calories consumed per capita. However, farmers use little or no fertilizer on cassava and scant information is available regarding the cassava yield response to mineral and organic fertilizer inputs in Zambia. This study was undertaken to determine the response of cassava to the integrated use of organic and inorganic nutrient sources in two contrasting agroecological zones of Zambia; Mansa located in Zone III and Kabangwe located in Zone II. The treatments consisted of a factorial combination of four NPK rates (unfertilized control, 50N-11P-41.5K, 100N-22P-83K, and 150N-33P-124.5K kg/ha) with four rates of chicken manure (0, 1.4, 2.8, and 4.2 t/ha). The treatments were laid out in a randomized complete block design with three replications. Cassava height, stem girth, canopy diameter, leaf area index, and chlorophyll index were monitored over time and roots were harvested at 12 months after planting (MAP). Growth parameters and yield varied significantly (p < 0.01) both with NPK, manure application, and their interaction effects at 12 MAP. The combined application of 4.2 t/ha of chicken manure and 100N-22P-83 K kg/ha of mineral fertilizer resulted in the highest yields of 35.2 t/ha at Kabangwe. But, the highest average yield of 34.4 t/ha was recorded with the application of 2.8 t/ha manure and 100N-22P-83 K kg/ha mineral fertilizer at Mansa. This increased treatment yield by 24 and 29% over the sole NPK fertilizer application at Mansa and Kabangwe sites, respectively. Harvest index (HI) was higher when 2.8 t/ha chicken manure was applied in combination with 50N-11P-41.5K kg/ha at Kabangwe. But, the highest HI at Mansa site was achieved with the combination of 2.8 t/ha manure and 100N-22P-83 K kg/ha. This combination also resulted in the highest agronomic efficiency of N, P and K at both sites. It is concluded that cassava productivity and nutrient use efficiency can be improved through the integrated use of NPK and manure in Zambia.

Seasonal variation in photosynthesis performance of cassava at two different growth stages under irrigated and rain-fed conditions in a tropical savanna climate

Seasonal variations in photosynthesis of cassava cv. Rayong 9 (RY9) under irrigated and rain-fed conditions were evaluated at the age of three and six months after planting (MAP). Photosynthetic light-response (PN/I) curves revealed that cassava leaves attained the highest maximum net photosynthetic rates (PNmax) in the rainy season, followed by the hot one, while the lowest PNmax was found in the cool season. Photosynthetic potential of the 3-month-old plants was mostly higher than that of the 6-month-old plants, and the seasonal variation in photosynthetic capacity was also more apparent in the younger plants. PN/I curves were used to predict daily net photosynthetic rate (PN) for each season based on daily average solar radiation data. The predicted PN were considerably lower than the PNmax values. This indicated that solar radiation is a limiting factor for photosynthesis, particularly in the rainy season. The data provided basic information for breeding cassava genotypes with enhanced photosynthesis during the period of unfavorable environment. Furthermore, the data are potentially useful in modeling photosynthesis and crop growth as affected by environmental factors.

Genome-wide association mapping and genomic prediction for CBSD resistance in Manihot esculenta

Cassava (Manihot esculenta Crantz) is an important security crop that faces severe yield loses due to cassava brown streak disease (CBSD). Motivated by the slow progress of conventional breeding, genetic improvement of cassava is undergoing rapid change due to the implementation of quantitative trait loci mapping, Genome-wide association mapping (GWAS), and genomic selection (GS). In this study, two breeding panels were genotyped for SNP markers using genotyping by sequencing and phenotyped for foliar and CBSD root symptoms at five locations in Uganda. Our GWAS study found two regions associated to CBSD, one on chromosome 4 which co-localizes with a Manihot glaziovii introgression segment and one on chromosome 11, which contains a cluster of nucleotide-binding site-leucine-rich repeat (NBS-LRR) genes. We evaluated the potential of GS to improve CBSD resistance by assessing the accuracy of seven prediction models. Predictive accuracy values varied between CBSD foliar severity traits at 3 months after planting (MAP) (0.27–0.32), 6 MAP (0.40–0.42) and root severity (0.31–0.42). For all traits, Random Forest and reproducing kernel Hilbert spaces regression showed the highest predictive accuracies. Our results provide an insight into the genetics of CBSD resistance to guide CBSD marker-assisted breeding and highlight the potential of GS to improve cassava breeding.

Modelling of Root Age Influence on Compressive Strength Properties of Cassava Root

The influence of root age and moisture content on compressive strength properties of an improved (TMS 30572) and a local (TME 7) cassava cultivar were investigated. Roots harvested at 12, 15 and 18 months after planting (MAP) were used to determine stress at peak, energy to break and Young’s modulus of the roots at moisture contents of 50 %, 55 %, 60 %, 65 % and 70 % (w.b.). Mean stress at peak, energy to break and Young’s modulus of TMS 30572 ranged from 0.61 – 0.88 N.mm-2, 0.89 – 1.13 N.m and 0.92 – 0.84 N.mm-2; 4.80 – 6.67 N.mm-2, 5.99 – 9.21 N.m and 4.55 – 5.11 N.mm-2; and 4.81 – 9.28 N.mm-2, 5.27 – 5.77 N.m and 5.68 – 8.84 N.mm-2at 12, 15 and 18 MAP, respectively. Corresponding values for TME 7 ranged from 0.41 – 1.06 N.mm-2, 0.95 – 1.15 N.m and 1.07 – 1.30 N.mm-2; 3.23 – 8.18 N.mm-2, 5.70 – 8.37 N.m, 5.56 – 8.04 N.mm-2; and 3.22 – 6.96 N.mm-2, 4.25 – 5.58 N.m and 6.69 – 8.38 N.mm-2, respectively. Second-order polynomials described the behaviours of the roots. Root age, and not moisture content, influenced the strength of TME 7 roots, while none of the parameters studied influenced toughness and stiffness (p&gt;0.05). Neither age nor moisture content significantly affected the toughness and stiffness of the roots of the two varieties

In vitro mutagenesis creates distinct morphological variants in cassava (Manihot esculenta Crantz.): A characterisation study

The present investigation was conducted to evaluate the variability created due to induction of in vitro mutagenesis in cassava. The calli and somatic embryos from the leaf explants of superior cassava genotypes Sree Jaya and CC1 established in Murashigue and Schoog (MS) media supplemented with 8 mg L -1 picloram were subjected to treatment with Ethyl Methyl Sulphonate (EMS), 0.6-1.2 per cent at 0.1 per cent interval. Forty-four plants survived out of sixty-eight regenerated plants kept for hardening under pad and fan greenhouse followed by rain shelter. Irrespective of the dosage field evaluation of these plants showed variations in morphological traits with respect to their respective controls at 3, 6 and 9 months after planting (MAP). These plants can be clonally propagated and the genetics of the observed variations in quantitative traits of these plants can be validated under different conditions.

Characterization of Irradiation Induced Mutants of Cassava (Manihot esculenta Crantz) Generated from Jame-jame and Adira-4 Genotypes at M1V2 Generation

Cassava (Manihot esculenta Crantz., Euphorbiaceae) is an important dietary carbohydrate source for approximately 800 million people in the tropics. It is a potential crop for food, feed, and industry. Cassava breeding through conventional approaches are hampered with some limitations which resulted in a low number of superior varieties. The objective of this research was to generate several mutant lines with higher yield and starch content. This research intended to identify the second generation (M1V2) Jame-jame and Adira-4 variant cassava mutants from gamma ray irradiation. Jame-jame is a local genotype from Halmahera (local high yielding genotype, sweet, and potential) and Adira-4 is an Indonesia national variety of cassava. Mutant diversity appears on the plant height, plant branching, and plant tubers that harvested at 10 months after planting (MAP). Our results showed the positive correlation between plant height, first branching height, tuber weight, number of roots, and number of economic roots. Based on tuber weight and number of economic tuber there were 9 potential mutants (putative). Based on the stability test, there were 6 potential stable mutants (putative) by first branching height, tuber weight, total number of tubers, and total number of economies tuber, namely: V5D1-(2), V5D1-2(2), V5D1-3(2), V5D1-4(3), V5D2-2(2), and V5D2-6(2). Keywords: local genotype, M1V2, storage root, characters, stability.

English

Sweet potato (Ipomoea batatas [L.] Lam) is an important root crop in Malawi and Sub-Saharan Africa where micronutrient deficiency is an eminent health problem. Using 15 sweet potato genotypes grown in a randomized complete block design at Bvumbwe Research Station, a study was undertaken to determine the extent of variability of selected micronutrients in the genotypes as influenced by storage root age and peeling. Analysis of variance (ANOVA) showed significant (p&le; 0.01) variability among genotypes for dry mater, &beta;-carotene, ascorbic acid levels and reduction of &beta;-carotene due to peeling across all ages. Significant (p &le; 0.05) variations in zinc, iron and copper were also observed among all genotypes. Peeling reduced &beta;-carotene, ascorbic acid levels, iron, zinc and copper content while late harvesting resulted in low iron, zinc and copper. Therefore, 5 months after planting (MAP) and 4 MAP are recommended for high levels of &beta;-carotene and ascorbic acid and iron, zinc and copper, respectively. Ten genotypes exhibited acceptable levels of dry mater of &ge;30%. Zondeni (10.9 mg/100 g, WW) and Babache (23.84 mg/100 g, WW) had highest levels of &beta;-carotene and ascorbic acid, respectively. Mzungu displayed the highest levels of Iron (0.67 mg/100 g, DW) and zinc (0.63 mg/100 g, DW) while Yoyera (0.61 mg/100 g, DW) had the highest levels of copper. Variations of various traits entail potential to breed for higher levels of micronutrients. Key words: Sweet potato, genotypes, &beta;-carotene, ascorbic acid, iron, zinc, copper, peeling, storage root age.