Total Storage Root Research Articles

Effect of Vine Harvesting Frequency on Sweetpotato Root Yield Components and Gross Income in Southern Mozambique

Sweetpotato is widely produced by smallholder farmers in Mozambique with average yield of 7.3 t/ha. One of the challenges in sweetpotato production system is inadequate seed during the rainy season resulting in low productivity. The few sweetpotato seed multipliers (Decentralized vine multipliers (DVMs)) resort to several vine harvesting frequency to meet farmers seed requirements at the peak of demand. Repeated vine harvesting contributes to sweetpotato root yield reduction. The objective of the study was to evaluate the effect of vine harvesting frequency on sweetpotato yield components. Three experiments were set up in three farmers’ fields in Vilankulos district inhambane province in Southern Mozambique in the 2021/2022 and 2022/2023 cropping seasons with a sweetpotato variety Esther. The experiments were set up in randomized complete block design with three replications in each farmer’s field. The treatments were no vine harvesting (control), harvesting only once at 8 weeks after planting (WAP), harvesting twice at 8 and 12 WAP, and harvesting three times at 8, 12, and 16 WAP. Total storage root yield, number of roots per plant, root diameter, and root length were measured in each treatment. Results show that storage root yield was significantly higher in control (22.1 t/ha) and harvesting once (17.8 t/ha) compared to harvesting twice (11.8 t/ha) and three times (9 t/ha) (P < 0.05). Additional harvesting from one to two resulted in 33.7% yield decline. Vine harvesting twice resulted in 46.6% storage root yield decline compared to the control treatment. The same observation was noted for the number of roots per plant, where five roots per plant were observed both in no harvesting and harvesting once treatments. A 40% decline in the number of roots per plant was observed when vine harvesting frequency was increased from one to two. No treatment effect was observed on the root diameter. Increasing vine harvesting frequency from one to two or one to three resulted in a 14.7% income loss from sales of both vines and roots. Vine multipliers are recommended to harvest vines for use as planting material only once if they want to benefit from the roots for consumption or commercialization.

Increased cassava growth and yields through improved variety use and fertilizer application in the highlands of South Kivu, Democratic Republic of Congo

Nutrient limitations due to low soil fertility and insufficient fertilizer use widen cassava yield gaps in the Democratic Republic of Congo (DR Congo). This study was undertaken to investigate firstly the effects of variety and combined application of mineral fertilizer and organic (farm yard manure, FYM) inputs on cassava growth and yields, secondly to identify nutrient limitations to cassava production in the highland conditions of South Kivu, and thirdly to evaluate the economic benefits of the use of the improved variety and fertilizer in cassava production. Twenty-one multi-locational trials were conducted on farmers’ fields during two consecutive years. The use of an improved variety resulted in significant increases in both height and stem diameter in both years when fertilizer was applied; without fertilizer, both parameters were higher in the improved variety than in the local variety but only in the second year. Total biomass yield (storage root + stem) was significantly increased by 28% (11.2 t ha−1) through the use of an improved variety with fertilizer in the first year while in the second year, both total biomass and storage root yields were significantly increased by 58% (12.5 t ha−1) and 74% (9.8 t ha−1), respectively without fertilizer. Application of NPK+FYM resulted in significant increases in height and stem diameter over time, independent of the variety; and of total biomass, storage root and stem yields by 38% (11.5 t ha−1), 25% (5.1 t ha−1) and 63% (6.5 t ha−1), respectively relative to the unfertilized treatment. Sole application of mineral fertilizer and omission of macronutrients did not result in significant effects on storage root yields in both years. However, the application of NPK and NPK+ (Ca, Mg, S, Zn) significantly increased stem yield by 51% (6.0 t ha−1) and 56% (6.6 t ha−1), respectively while the omission of N significantly decreased both total biomass and stem yields by 31% (10.4 t ha−1) and 81% (8.0 t ha−1), respectively but only in the first year. Despite the lack of a significant response to applied N, P or K, addition of N and K increases storage root yield by 1.3 t ha−1 and 3.2 t ha−1 respectively (averages for both years). The findings reveal that the positive effects on cassava growth and yields and economic benefits from fertilizer are larger than the one from the choice of variety. Although the importance of combined application of mineral fertilizer and farm yard manure was demonstrated, no evidence of macronutrient limitations to cassava production was proven under the specific conditions of the study sites. A better understanding of the conditions under which positive effects of fertilizer occur can improve targeting and therefore achieve high profitability in cassava production.

Genetic Variation of New Purple-Fleshed Sweet Potato (Ipomoea batatas L.) Genotypes in Indonesia by Multivariate Analysis

Purple-fleshed sweet potato (PFSP) is a major staple food and feed material in tropical countries. The pandemic of COVID-19 that encouraged healthy lifestyles worldwide further increases the importance of PFSP. Despite its importance, the investment in research to improve PFSP in Indonesia was left behind. The objective of the research was to estimate the genetic variation and genetic distance of new PFSP genotypes prior to variety release. The research trials were arranged in a randomized block design, with nine new PFSP genotypes from polycrosses breeding as treatments and three check varieties in four growing environments in West Java, i.e., Cilembu, Jatinangor, Maja, and Karangpawitan during one season. Agronomic traits data were analyzed by the multivariate analysis. The principal component analysis (PCA) showed high genetic variation of PFSP in four environments. The eigenvalue ranges from 1.92 to 5.29 in Cilembu which contributed to 80.958% variability, 0.543–6.177 which contributed variability to 92.135% in Jatinangor, 0.824–5.695 in Karangpawitan which contributed to 92.117%, and 0.822–4.797 in Maja which contributed to 86.133%. Storage root length, storage root diameter, number of roots per plant, total root weight per plant, number of marketable/commercial roots, marketable/commercial root weight, number of roots per plot, and total storage root weight have a discriminant value of more than 0.7 in PC 1. Agglomerative hierarchical clustering (AHC) showed a wide distribution obtaining two clusters in Cilembu with euclidean distance 1.92–5.29, Jatinangor 1.72–6.09, Karangpawitan 1.28–6.38, and Maja 2.05–5.09. High genetic variation in the four environments greatly supports to the development of PFSP new varieties.

Genotype by environment interaction effect on some selected traits of orange-fleshed sweet potato (Ipomoea batatas [L].Lam)

In Ethiopia, sweet potato is the 2nd and the most important root crop after Enset [Ensete ventricosum (Welw) Cheesman]. Even though widely cultivated in Ethiopia, the occurrences of wide agro-ecological variability are the key challenge for the selection of high yield and stable orange-fleshed sweet potato genotypes due the high interaction of genotype by environment effect (GEI). Until to date, the research reports on GEI and stability of orange-fleshed sweet potato genotypes under Southwest and West of Ethiopian conditions is very limited. Due to this fact, the study was conducted in main sweet potato growing of Southwest and West of Ethiopia since the 2019-2020 growing seasons. Nine Orange-fleshed sweet potato genotypes were evaluated in four different ecologies in completely randomized block design with three replications. The mainly indicative data and related variables were collected and analyzed by using ANOVA, AMMI, and GGE biplots. The ANOVA for total storage root yield revealed significant difference in the environments, genotypes, and the interactions of both (P < 0.001). The genotypes NASPOT-12 was the mostly performed one over all the rest with total fresh storage root yield of 55.88 ton ha-1 while Kulfo was performed as the lowest. The AMMI1 and AMMI2 biplot analysis revealed that, the genotypes NASPOT-12 was resulted in an above average mean of total fresh storage root yield and the genotype Koka-12, NASPOT-13, NASPOT-12, and Kulfo were far apart from the biplot origin which indicated the genotypes were the more responsive and largely contributed to the interaction component and thus considered as specifically adapted genotypes respectively. The GGE biplot revealed that the total variations of 79% with the PC1 accounted about 55% and the PC2 affect about 24% of variations approximately on the total fresh storage root yield of the tested orange-fleshed sweet potato genotypes. The "which won where" identified the three growing mega environments. In the comparison and ranking of the genotypes by the GGE biplot analyses, the genotype NASPOT-12 was more desirable than the rest genotypes. In the comparison and ranking of the environments by this analysis, the environment Jimma-1 was the most representative followed by Agaro-2 in the total fresh storage root yield of orange-fleshed sweet potato genotypes. Above all the genotype NASPOT-12 was responded well in most of the environments hence, recommended genotype for multipurpose advantage.

Determination of Cassava Leaf Area for Breeding Programs

The evaluation of leaf area provides valuable information for decision-making for the cassava yield trail. The objectives of this study were (1) to determine the relationship between the leaf area and yield of the segregating populations and (2) to investigate the suitable mathematical model for calculating cassava leaf area. The single-row trial for 60 segregating progenies of Kasetsart 50 × CMR38–125–77 was conducted from 2021 to 2022. The trial for eighteen progenies and the Kasetsart 50 and CMR38–125–77 was carried out in 2022. The sampled leaves for each genotype were collected to measure the leaf area. The length (L) and width of the central lobe (W), number of lobes (N), the product of the length and width (L × W; K), and the product of the length and number of lobes (L × N; J) were recorded for developing the mathematical models. The result showed that there were statistically significant correlations between the maximum individual leaf area and the total crop fresh weight and storage root fresh weight. The mathematical model LA = −3.39L + 2.04K + 1.01J − 15.10 is appropriate to estimate the maximum individual leaf area and leaf area index (LAI). This mathematical model also provided the estimated individual maximum leaf area that had the highest correlation with actual biomass at the final harvest as compared to the other three functions. The results showed statistical significance for the estimated LAI and biomass correlation.

Evaluation of released sweet potato [Ipomoea batatas (L.) Lam] varieties for yield and yield-related attributes in Semen-Bench district of Bench-Sheko-Zone, South-Western Ethiopia

Sweet potato is a significant root crop that can be used for both food and feed. Bench-Sheko zone mid-altitudes, in general, are among the most important sweet potato growing regions in southwest Ethiopia. During the 2017 and 2018 growing seasons, a study was carried out in the Semen-Bench district of the Bench-sheko zone, southwestern Ethiopia, to investigate the adaptability and performance of improved sweet potato varieties and to identify the best performer variety. A randomized complete block design with three replications was used to compare the performance of five improved (viz., Awassa-83, Beletch, Berkume, Kulfo, Tula) and one Local sweet potato variety. The results of both years and over year combined statistical analysis indicated that the varieties significantly varied in terms of all yield and yield-related traits. As a result, the Awassa-83 variety acquired the greatest values of average root diameter in both the 2017 (11.9 cm) and 2018 (10.1 cm) growing seasons, followed by the Berkume variety. In both 2017 and 2018 growing seasons and over year combined analysis, the highest average storage root length (21.5 cm), marketable storage root yield (29.06 ton/ha), total storage root yield (43.22 ton/ha), and storage root dry weight (42%) was recorded from variety Awassa-83. Variety Beletech and Berkume were found to be statistically similar and the next highest in terms of marketable storage root yield, and total storage root yield; moreover, variety Berkume was found to be the next highest in terms of storage root dry weight in two years combined result. On the other hand, the variety Beletech, which was closely followed by Awassa-83, had the highest average number of roots per plant (8.28) and the greatest number of marketable roots per plant (7.04). Therefore, considering overall traits Awassa-83 was found to be superior in overall performance and can be recommended for production in the study area and related agro-ecologies.

Evaluation of 12 Sweetpotato Clones in Coastal South Carolina for Yield and Insect Resistance Using Organic and Conventional Cultural Practices

The yield and insect resistance of 12 sweetpotato (Ipomoea batatas) clones grown in two different production systems (organic black plastic mulch and conventional bare ground) were evaluated in 2016 and 2017 in coastal South Carolina. Significant differences in total storage root yield, marketable storage root yield, U.S. No. 1 storage root yield, and percent of U.S. No. 1 storage roots in all trials were found, except for percent of U.S. No. 1 storage roots in 2017 for the organic black plastic mulch trial. In the organic black plastic mulch trials, ‘Bonita’ and USDA-04-136 consistently produced high marketable yields, whereas ‘Ruddy’ and USDA-W388 consistently produced the lowest marketable yields. ‘Averre’, ‘Beauregard’, ‘Covington’, and USDA-09-130 exhibited variable performance, with marketable yields among the highest in a single year. For the conventional trials, USDA-04-136 consistently produced high marketable yields, whereas ‘Ruddy’ and USDA-W-388 consistently produced the lowest marketable yields. ‘Averre’, ‘Bonita’, ‘Covington’, and USDA-09-130 exhibited variable performance, with marketable yields among the highest in a single year. For the organic black plastic mulch, significant differences were detected in the percent of uninjured roots and percent white grub (primarily Plectris aliena) damage in 2016 and in wireworm (Elateridae)-cucumber beetle (Diabrotica)-flea beetle (Systena) severity index (WDS severity index) in 2016 and 2017. USDA-04-136 and USDA-W-388 consistently had the lowest WDS severity index, whereas ‘Covington’ consistently had the highest WDS severity index. For the conventional trials, significant differences were found among clones in both years for all insect rating variables, except for percent sweetpotato weevil (Cylas formicarius elegantulus) damage. ‘Ruddy’, USDA-04-136, and USDA-W-388 consistently yielded the highest percent of uninjured roots, whereas ‘Averre’, ‘Bonita’, SC-1149-19, and USDA-09-130 consistently had the lowest percent of uninjured roots. The research reported here for yield and insect resistance under conventional and organic production systems will be useful for producers in the selection of cultivars suitable for growth in South Carolina.

Plastic Mulch and In-row Spacing Effects on Sweetpotato Yield in Northwest Washington

Sweetpotato (Ipomoea batatas) production in the northern United States is limited due to the perceived barriers of a short growing season and relatively cool summer temperatures, yet recent studies have shown yield in northern regions can be greater than the national average when sweetpotatoes are grown with plastic mulch. A study was conducted in northwest Washington to evaluate the productivity of ‘Covington’ sweetpotato with polyethylene (PE) and soil-biodegradable (BDM) mulches and different in-row spacings (20, 30, and 38 cm) in 2019, and to test accessions resistant to wireworm (Agriotes sp. and Limonius sp.) in 2020. In 2019, slips were shipped from North Carolina, and after 4 days in transit, 60% to 70% died after transplanting in the field. By the end of the season, BDM deterioration reached 11% compared with 0.4% for PE mulch, but there were no differences due to mulch in plant establishment, growth, yield, or the proportion of storage roots damaged by wireworm. Total storage root yield was 22 t⋅ha−1 with PE mulch and 15 t⋅ha−1 with BDM. Percent canopy cover was greatest at 20-cm spacing later in the growing season, likely due to intermingling of vines from adjacent plants, whereas high percent canopy cover at 38-cm spacing was likely due to increased production of secondary vines per plant. Total yield was greatest with 20-cm plant spacing (20.4 t⋅ha−1), intermediate with 30-cm spacing (18.0 t⋅ha−1), and lowest with 38-cm spacing (17.0 t⋅ha−1). In contrast, the greatest number of storage roots per plant was produced with 38-cm plant spacing (3.4). There were more jumbo sweetpotatoes produced with PE mulch (3.4 t⋅ha−1) and with 30-cm spacing (3 t⋅ha−1), and the weight of U.S. No. 2 grade sweetpotatoes was greatest at 20-cm spacing (10.2 t⋅ha−1). Soil temperature was increased by 3 °C under the PE mulch and 2 °C under the BDM compared with bare ground. However, 98% of storage roots were observed to be severely damaged by wireworm in 2019, with more than 10 to 20 holes per storage root. For wireworm-resistant accessions in 2020, 16% of the storage roots were damaged by wireworm, with 1.7 to 4.0 holes per storage root. Total yield of accessions PI 666141 and 04-791 (45.5 t⋅ha−1 on average) was greater than the national average (24.7 t⋅ha−1). Overall, sweetpotatoes appear to be suitable for production in northwest Washington, but low yield in 2019 highlights the importance of healthy slips for successful production. Future research should evaluate cultivars with maximum adaptation to the region, techniques to reduce wireworm damage including genetic resistance, and the economics of producing sweetpotatoes in northern regions.

English

Field studies were conducted to evaluate the effect of various fertilizer placements on nutrient uptake, growth responses, storage root yield and leaf elemental concentration of Whatley/Loretan sweetpotato [Ipomoea batatas (L.) Lam.]. The fertilizer placement treatments comprised broadcast (Br), banded at two different widths (Ba), side dressing (Sd) or applied in various combinations of the above, and an untreated check. Fertilizer rates were 135, 35 and 133 kg.ha-1 each of N, P and K based on soil test. At nine weeks after planting, the fifth fully expanded leaf from the tip of five plants was collected and analyzed for elemental concentration. The plants were harvested 101 days after transplanting and biomass data were collected. Vine yield for all placement treatments was equal to or exceeded that of the full rate broadcast. Yield of US # 1 roots was increased 78 and 72%, respectively, when 2/3 of the fertilizer was banded and tended to increase total storage root yield compared to the same, full or 2/3 the rate broadcast. Leaf N was highest with 1/3 Ba at planting with two side dressings, while leaf P was reduced by all treatments compared to the check. Leaf K was highest with 2/3 the rate Br at planting. Storage root N was lower than foliar N while root K increased with 1/3 Br combined with 1/3 Ba. Root Ca, Mg, Fe and B were not significantly affected by placement. Root Mn was lower than foliar Mn suggesting that sweetpotato distributes more Mn to foliage relative to storage roots. Generally, these results suggest that placement rather than quantity of fertilizer applied enhanced yield and elemental concentration. Key words: Broadcast fertilizer, Ipomoea batatas, banded fertilizer, side-dressing, elemental concentration, storage roots, plant nutrition.

Phenotyping of productivity and resilience in sweetpotato under water stress through UAV‐based multispectral and thermal imagery in Mozambique

AbstractSweetpotato is a crucial crop to guarantee food security in sub‐Saharan Africa, and drought events are considered one of the most critical factors affecting sweetpotato productivity in this region. In this study, airborne imagery based on reflectance (NDVI, CIred‐edge) and canopy temperature minus air temperature (dT) indices was used to characterize sweetpotato genotypes under drought treatments in Mozambique. Two field experiments established in rainy/hot (Trial A) and dry/cool (Trial B) seasons were assessed. In Trial A, 24 genotypes were subjected to early‐ (ESD), mid‐ (MSD) and late‐season (LSD) drought stress treatments and compared against a control. In Trial B, 120 genotypes were subjected to LSD only. The percentage of reduction in vine weight (PRVW) under drought was related primarily to temporal variation of NDVI and CI, regardless of drought treatment and seasons. dT in relation to control (dTAmp) was associated with PRVW in ESD‐Trial A and LSD‐Trial B, whereas under LSD‐Trial A, dTAmp was related to total fresh storage root weight (TRW). During the rainy/hot season, higher TRW reduction was promoted under ESD; however, under LSD, it was possible to identify productive genotypes able to withstand drought stress, highlighting their relevance for drought‐tolerance selection purposes.

The assessment of yield and quality traits of sweet potato (Ipomoea batatas L.) genotypes in middle Black Sea region, Turkey.

Sweet potato (Ipomoea batatas L.) cultivation in Turkey is concentrated in one province situated in Mediterranean region only, which would not fulfill the domestic needs of the country soon. Therefore, cultivation of the crop in other provinces/climatic regions should be initiated to fulfill the domestic needs. The cultivation in other provinces requires thorough assessment of yield and quality traits of target crop. Therefore, yield and quality characteristics of four sweet potato genotypes (i.e., ‘Hatay Kırmızısı’, ‘Hatay Yerlisi’, ‘Havuc’ and ‘Kalem’) were assessed in the current study in Kazova and Niksar counties of Tokat province of the country having middle Black Sea climate in field experiments during 2018 and 2019. The cuttings of the genotypes were planted in Niksar during the second fortnight of April and first week of May in Kazova. The planting density was kept 90 × 45 cm. Data relating to number of storage roots, storage root weight, storage root yield per hill and storage root yield per hectare were recorded. Furthermore, quality traits, including dry matter ratio (%), protein ratio (%) and antioxidant ratio (%) of storage roots were also determined. The highest total storage root yield was recorded for ‘Havuc’ genotype during both years and locations, followed by ‘Hatay Yerlisi’ and ‘Hatay Kırmızısı’ genotypes. Overall, storage root yield (60.06 and 62.40 tons ha-1 during first and second year) recorded for the experiment at Niksar was higher than the storage root yield recorded for Kazova experiment (53.50 and 52.84 tons ha-1 during first and second year, respectively). The highest dry matter was produced by ‘Kalem’ and ‘Hatay Yerlisi’ genotypes during both years and at both locations, followed by ‘Hatay Kırmızısı’ and ‘Havuc’ genotypes. The storage roots of the tested genotypes accumulated higher dry matter at Kazova during both years. The highest protein content was obtained from the ‘Kalem’ genotype, and the protein contents of the ‘Hatay Yerlisi’ and ‘Hatay Kırmızısı’ genotypes were close to the ‘Kalem’ genotype. The results indicated that tested genotypes can successfully be cultivated in middle Black Sea climate. Therefore, production of sweet potato can be initiated in the future to meet the domestic needs for sweet potato in the country.

Identifying Suitable Genotypes for Different Cassava Production Environments—A Modeling Approach

Crop simulation models can be used to identify appropriate genotypes and growing environments for improving cassava yield. The aim of this study was to determine the best genotypes for different cassava production environments using the cropping system model (CSM)–MANIHOT–Cassava. Data from cassava experiments that were conducted from 2009–2011 and 2014–2015 at Khon Kaen, Thailand, were used to evaluate the model. Simulations were then conducted for different scenarios using four cassava genotypes (Kasetsart 50, Rayong 9, Rayong 11, and CMR38–125–77), twelve planting dates (at monthly intervals starting in January and ending in December), and ten locations in Thailand under fully irrigated and rainfed conditions using 30 years of historical weather data. Model evaluation with the experimental data for total biomass and storage root yield indicated that the model classified well for relative productivity among different planting dates. The model indicated that growing cassava under irrigated conditions generally produced higher biomass and storage root yield than under rainfed conditions. The cassava genotype CMR38–125–77 was identified for high biomass, while the genotype Rayong 9 was identified as a good genetic resource for high yield. The December planting date resulted in the highest biomass for all locations, while the February planting date produced the highest storage root yield for almost all locations. The results from this study suggest that the CSM–MANIHOT–Cassava model can assist in determining suitable genotypes for different cassava production environments for Thailand, and that this approach could be applicable to other cassava growing areas.

Performance of the CSM–MANIHOT–Cassava model for simulating planting date response of cassava genotypes

Selecting the appropriate genotypes for particular planting dates may help increase cassava productivity. The CSM–MANIHOT–Cassava model is a new tool to support decision making for crop management. However, it is important to explore the potential of a model prior to any application. The objective of this study was to evaluate the CSM–MANIHOT–Cassava model in simulating the performance of cassava genotypes for different planting dates. An experiment with four cassava genotypes and eight planting dates was conducted on the experimental farm of the Faculty of Agriculture at Khon Kaen University, Thailand, under optimum conditions. The data for soil and weather conditions, crop management, and crop traits were recorded. The cultivar parameters were determined using experimental data for three planting dates, while the remaining five planting dates were used for model evaluation. A scenario analysis for different planting dates using historical weather data from 2003 to 2018 was also conducted. The calibration results showed a good agreement between simulated and observed phenology and crop traits. Model evaluation based on the d-index showed a good agreement between simulated and observed total crop, stem, and storage root dry weights with values above 0.8 for almost all four genotypes and five planting dates. The model provided acceptable outputs for final total crop dry matter and storage root yield. The results from both the scenario analysis with the CSM–MANIHOT–Cassava model and the actual experiment classified Kasetsart 50 and CMR38–125–77 as one out of the top two genotypes based on final total crop biomass, demonstrating the potential of the model to help identify promising cassava genotypes.

­­­­­­­Growth, Yield and Yield Components of Anchote (Coccinia Abyssinica L.) in Response to Farmyard Manure and Phosphorus Fertilizer Rates at Masha, South Western Ethiopia

Anchote (Coccinia abyssinica L.) is an important household food security crop especially in the western and southwestern parts of Ethiopia. Despite its nutritional, socio-cultural and socio-economic importance, is constrained by different factors, among which low and imbalanced nutrient supply in the soil, therefore, the yielding ability and performance of this under-utilized crop has not been studied under various phosphorus (P) and farm yard manure (FYM) levels. Thus, a field experiment was conducted to determine the effect of P and FYM on the growth, yield and yield components of anchote at Masha, Southwest Ethiopia in 2019. The treatments consisted of four levels of FYM (0, 5, 10, and 15 t FYM ha-1) and five levels of P (0, 24, 48, 72 and 96 kg P2O5 ha-1). The experiment was laid out in Randomized Complete Block Design in 4×5 factorial arrangements and replicated three times. Different growth, yield and yield related traits were collected and statistically analyzed using SAS version 9.3 software. The result detected that the traits were affected by the combine application of phosphorus and FYM except day of 50% emergency, harvesting index, and unmarketable storage root yield. Highest average vine length (3.89 cm) and vine internode length (12.45cm) was recorded with 0 kg P2O5 + 15 t FYM ha-1 whereas, highest vine branch numbers (4.0), vine internodes number ( 43.87) , average total storage root yield (63.60 t ha-1), average storage root diameter (8.53cm), average storage root length (10.24 cm), average marketable storage root yield (63.3tha -1) and average total dry biomass yield (1.65kg plant-1) were recorded in response of 96 kg P2O5 ha-1 with 15t FYM ha-1. In general, results of this study indicated that combined application of the P and FYM fertilizer has a promising positive effect on yield and yield components of anchote. Hence, application of 96 P2O5 kg ha-1 and 15 tha-1 FYM considered as better for anchote production at Masha, Southwestern Ethiopia. However, since the data is obtained from only one season, it will be worth repeating the experiment under field condition, across different seasons and locations to draw sound conclusions and recommendations.

English

This study was done to determine the mid-parent heterosis, the general (GCA) and specific (SCA) combining abilities of storage root yield, sweet potato virus resistance (SPVD), flesh color and vine weight of candidate sweet potato clones. Sixteen selected genotypes from two gene pools were crossed in an 8B&times;8A cross having 64 families. Trials were conducted with 1,896 offsprings and 16 parents during two seasons at the National Crops Resources Research Institute in Uganda (NaCRRI) using a Westcott design (only checks were replicated). Significant differences in performance were noted among families for all traits in both seasons (P &le; 0.001). Magabali&times;NK259L and Resisto&times;Naspot 7 were the best crosses for improving total storage root while Naspot 5&times;Naspot 7 stood out as the best cross for flesh color. The ratio of general combining ability to specific combining ability (GCA/SCA) for storage root, flesh color and SPVD ranged from 0.55 to 0.79, implying that additive gene effects were more important than non-additive gene effects for these traits.&nbsp; For vine weight, non-additive gene effects tended to be predominant.&nbsp; A susceptible parent Magabali and a moderately susceptible parent Naspot 1 had the most resistant progenies. This suggests that SPVD resistant alleles could be homozygous recessive, which may be confirmed in further studies. Correlation studies between traits were almost all significant except for flesh color and storage root yield. There was a positive and significant correlation (P &le; 0.001) between flesh color and SPVD resistance, with orange roots being the most resistant to SPVD. This important finding can help breeders to come up with orange-fleshed sweet potatoes that are highly resistant to virus diseases. Key words: Sweet potato combining ability, heterosis, genetic effect, storage root, sweet potato virus resistance (SVDP), flesh color, vine weight. &nbsp

META-ANALYSES OF SWEETPOTATO (IPOMOEA BATATAS L. LAM) STABILITY PERFORMANCE IN DIFFERENT AGROECOLOGIES OF THE TIGRAY REGION, ETHIOPIA

The study aimed at evaluating the influence of environment on sweetpotato stability and identifying superior genotype(s) with high yield stability in the farmers’ field conditions. Six sweetpotato genotypes were evaluated for two years in ‘meher’ season (July- December), 2014 and 2016; four of the six genotypes were assessed for three years in the ‘meher’ season, 2012, 2014, and 2016. Planting was done in three replications in RCBD in three unique agro-ecologies: Endayesus-dry highland, Fachagama-dry lowland, Rarhe-moist lowland. Genotypes genetic merits were predicted using BLUP. The AMMI and GGE were used to test the genotypes stability. The ANOVA for AMMI model showed high significant difference (P0.01) for genotypes, environments, seasons, and the interactions. Environment (41.67%) and the genotype main effect (35.71%) contributed largely to the cumulative variance for three years testing of four genotypes and two years testing of six genotypes, respectively. Berkume (42.44 t/ha), Tulla (33.92 t/ha) and Kulfo (33.67 t/ha) were superior for total storage root tuber yield (TTRY).Both the AMMI and GGE biplot predicted Tulla and Kulfo as ideal genotypes with dynamic stability; Berkume with static stability to Rarhe. The environment main effect had significant influence in determining how genotypes expressed their genetic potentials and stability as shown by the AMMI model and GGE biplot. The AMMI model partitioned the studied agro-ecologies of the Tigray region into two mega sweetpotato growing environments; the dry high/lowland in one environment and the moist lowland in another, completely different, but with high potentials for sweetpotato production.

Adaptability and Evaluation of Improved Orange Fleshed Sweet Potato (&amp;lt;i&amp;gt;Ipomoea batatas L. &amp;lt;/i&amp;gt;) Varieties in the Mid Altitude of Guji Zone, Southern Ethiopia

"Oromia Agricultural Research Institute, Bore Agricultural Research Center, Bore, Ethiopia Low yields and yield instability due to the use of old land races were limiting sweet potato production by resource-poor farmers in the zone. The Experiment was conducted at Bore Agricultural Research Center during 2018 and 2019 summer cropping season at Adola sub station and on-farm with the objective of identifying the cultivars, which could have wide or specific adaptations, and to select and recommend adaptable, frost and disease tolerant and high yielding orange type sweet potato cultivars for midlands of Guji Zone. To this effect four (Kaboli, Naspot 12, Naspot 13, Kaboli and local) improved orange varieties of sweet potato, <i>Ipomoea batatas</i> L., based on their yield and disease resistance performance were tested in RCBD with three replications with the spacing of 100cm*30cm between rows and plants, respectively. A widely cultivated variety (Local) was included as check. The combined analysis of variance across locations showed significant variation among genotypes and locations interaction for the number of roots, root weight, marketable yield, unmarketable yield and total storage root yield (t/ha). Based on this, the maximum mean value of root number per plot (21.33, 36.66 and 21.33) was recorded from Naspot-13, Naspot-12 and Naspot-13 variety at Dufa, Boke and Gobicha sites, respectively. However the minimum (16.00, 19.33 and 16.00) mean value of root number was recorded from Local Variety across locations. The maximum fresh root weight (670.33g and 444g) was recorded for Kabode and NASPOT-13 Variety over locations. On the other hand, the lowest fresh root weight (447.33, 437.33g and 296.33g) was recorded by Kaboli variety at all locations. The highest mean value of total root yield (65.09 t ha^-1 and 59.88 t ha^-1) was recorded by Naspot-13 at Dufa and Gobicha locations in 2018 and 2019 cropping seasons. While Naspot-12 gave maximum (55.16 t ha^-1) total root yield at Boke location. However Kaboli gave the least (43.09, 27.19 and 37.69 t ha^-1) total root yield over locations and years. Therefore Naspot 13 and Naspot-12 sweet potato varieties were more adaptable, disease tolerant and high yielder and should be promoted to farmers of the study areas for optimum production. "

Growth rates and yields of cassava at different planting dates in a tropical savanna climate

ABSTRACT: Details on growth and yield for cassava planted on different dates are useful for determining suitable genotypes for particular growing seasons. Our aim was to study growth and yield of cassava planted on different dates. Four cassava genotypes (Kasetsart 50, Rayong 9, Rayong 11 and CMR38-125-77) were evaluated using a randomized complete block design (RCBD) with four replications in six growing periods (20 Apr, 25 May, 30 June, 5 Oct, 10 Nov and 15 Dec 2015-2016) at Khon Kaen, Thailand. Soil properties were determined prior to planting, and crop traits and weather data were recorded. The six planting dates had a statistically significant effect on all crop traits. Low temperatures and solar radiation related to low biomass accumulation rates and short periods of linear phases for total crop and storage root dry weights with the 30 June planting date. CMR38-125-77 is likely to be a good genotype with respect to total crop and storage root dry weights at final harvest for almost all growing dates, except for the 20 Apr. Leaf area index (LAI) at 120, 240 and 300 days after planting (DAP), specific leaf area (SLA) at 120 DAP, storage root growth rate (SRGR) during 300-360 DAP and leaf growth rate (LGR) during 60-120 and 300-360 DAP were the components for the physiological determinants of total crop and storage root dry weight. The relationship between these physiological traits and storage root could be useful for cassava breeding.

LEAF PERFORMANCES OF CASSAVA GENOTYPES IN DIFFERENT SEASONS AND ITS RELATIONSHIP WITH BIOMASS

Information on leaf performances in different growing seasons of cassava could help achieve the recommendation regarding suitable cassava genotypes for particular planting date and a new plant type to improve cassava productivity. The objective of this study was to investigate leaf growth habit and biomass of the four cassava genotypes grown under irrigated condition in different growing seasons. The four cassava genotypes, i.e., Kasetsart 50, Rayong 9, Rayong 11 and CMR38-125-77 were grown at 30 June 2015 and 20 May 2016 and 3 November 2016 at Khon Kaen University, Thailand. A Randomised Complete Block Design (RCBD) with four replications was used for each planting date. Data recorded were leaf life, fallen leaf ratio, leaf area index (LAI), leaf area duration (LAD), storage root dry weight, total crop dry weight, harvest index (HI) and daily weather data. The results indicated that greater values of leaf life during 180 days after planting (DAP), LAD during 180-270 DAP, and LAI at 270 DAP appeared to associate with higher temperature. A combination of LAI at 180 DAP, leaf life during 90 and 180 DAP and fallen leaf ratio for 90 and 180 DAP was related to total biomass, while storage root dry weight was associated with a combination of LAI at 180 and 270 DAP and fallen leaf ratio for 90 and 180 DAP. CMR38-125-77 produced high total biomass and storage root dry weight at 270 DAP with possessing high LAI at 180 DAP.

Extended Utilization of Constraint-Based Metabolic Model in a Long-Growing Crop

The constraint-based rMeCBM-KU50 model of cassava storage root growth was analyzed to evaluate its sensitivity, with respect to reaction flux distribution and storage root growth rate, to changes in model inputted data and constraints, including sucrose uptake rate-related data—photosynthetic rate, total leaf area, total photosynthetic rate, storage root dry weight, and biomass function-related data. These mainly varied within ±90% of the model default values, although exceptions were made for the carbohydrate (−90% to 8%) and starch (−90% to 9%) contents. The results indicated that the predicted storage root growth rate was highly affected by specific sucrose uptake rates through the total photosynthetic rate and storage root dry weight variations; whereas the carbon flux distribution, direction and partitioning inclusive, was more sensitive to the variation in biomass content, particularly the carbohydrate content. This study showed that the specific sucrose uptake rate based on the total photosynthetic rate, storage root dry weight, and carbohydrate content were critical to the constraint-based metabolic modeling and deepened our understanding of the input–output relationship—specifically regarding the rMeCBM-KU50 model—providing a valuable platform for the modeling of plant metabolic systems, especially long-growing crops.