Number Of Storage Roots Research Articles

Reproductive strategies in the persistence of polymorph clover, an amphicarpic species

Amphicarpic plants produce aerial and subterranean fruits on the same plant. Trifolium polymorphum Poir. is an amphicarpic legume that also reproduces vegetatively by regrowing storage roots. Because of this, resource allocation information for different reproductive strategies is of great interest. In this study, the production of aerial and subterranean seeds and storage roots was evaluated in populations of T. polymorphum. The Pinheiro Machado and Eldorado do Sul populations produced on average the highest (165.50) and lowest (61.87) number of inflorescences per plant, respectively. Total aerial seed production did not differ between populations. Aerial flowers produced more seeds than subterranean flowers. There were positive correlations between number of inflorescences and total aerial seeds (r = 0.73), the number of subterranean legumes and total subterranean seeds (0.94) and between number and weight of storage roots (r = 0.83). Amphicarpy associated with vegetative reproduction is an important strategy for the persistence and increase frequency of T. polymorphum in the natural pastures of the Rio Grande do Sul, where intense grazing and trampling can destroy periodically the aerial part of the plants.

Genome-Wide Identification and Analysis of SUS and AGPase Family Members in Sweet Potato: Response to Excessive Nitrogen Stress during Storage Root Formation.

(1) The development of sweet potato storage roots is impacted by nitrogen (N) levels, with excessive nitrogen often impeding development. Starch synthesis enzymes such as sucrose synthase (SUS) and ADP-glucose pyrophosphorylase (AGPase) are pivotal in this context. Although the effects of excessive nitrogen on the formation of sweet potato storage roots are well documented, the specific responses of IbSUSs and IbAGPases have not been extensively reported on. (2) Pot experiments were conducted using the sweet potato cultivar "Pushu 32" at moderate (MN, 120 kg N ha-1) and excessive nitrogen levels (EN, 240 kg N ha-1). (3) Nine IbSUS and nine IbAGPase genes were categorized into three and two distinct subgroups based on phylogenetic analysis. Excessive nitrogen significantly (p < 0.05) suppressed the expression of IbAGPL1, IbAGPL2, IbAGPL4, IbAGPL5, IbAGPL6, IbAGPS1, and IbAGPS2 in fibrous roots and IbSUS2, IbSUS6, IbSUS7, IbSUS8, IbSUS9, IbAGPL2, and IbAGPL4 in storage roots, and then significantly (p < 0.05) decreased the SUS and AGPase activities and starch content of fibrous root and storage root, ultimately reducing the storage root formation of sweet potato. Excessive nitrogen extremely significantly (p < 0.01) enhanced the expression of IbAGPL3, which was strongly negatively correlated with the number and weight of storage roots per plant. (4) IbAGPL3 may be a key gene in the response to excessive nitrogen stress and modifying starch synthesis in sweet potato.

Castor Meal and Ground Hydrothermalized Phonolite Optimize Sweet Potato Nutrition, Yield, and Quality

To assess the effect of pure castor meal and a mixture of castor meal with ground hydrothermalized phonolite rock (CM+HP mixture) in providing nutrients, particularly N and K, and optimizing yield and quality of sweet potato, a field experiment was conducted using a randomized block design. Treatments were the absence and presence of synthetic N and K fertilizers (ammonium nitrate and KCl) combined with rates of organic fertilizers (1.2 and 2.4 Mg ha−1 of castor meal, 2.25 and 4.5 Mg ha−1 of CM+HP mixture, plus a treatment without organic fertilizers). The CM+HP mixture maintained adequate N and K status in plant leaves. Organic fertilizers increased the number of storage roots per plant and the sweetness of the storage roots, while synthetic fertilizers increased the storage root mean weight. Castor meal combined with synthetic fertilizers improved soil health (increased organic matter and enzyme activity in the soil). The combined application of synthetic fertilizers with 2.4 Mg ha−1 of castor meal or 4.5 Mg ha−1 of CM+HP mixture had the greatest benefit on storage root yield, with an average increase of 128% (10.9 Mg ha−1) on marketable storage root yield, and the nutrient removal compared with the sole application of organic fertilizers.

Yield performance and anthocyanin content of several purple-fleshed sweet potato clones grown in two locations in East Nusa Tenggara, Indonesia

Abstract. Arsa IGBA, Mau YS, Ndiwa ASS, Gandut YRY, Ishaq LF, Mahayasa INW. 2024. Yield performance and anthocyanin content of several purple-fleshed sweet potato clones grown in two locations in East Nusa Tenggara, Indonesia. Biodiversitas 25: 2276-2289. Several promising purple-fleshed sweet potato hybrid clones were identified to have high yield potential and, thus, can be evaluated for other superior traits and later be further processed for varietal registration and release. This study aimed to determine the tuber yield performance and anthocyanin content of several purple-fleshed sweet potato clones across two locations and to identify the best clones based on mean performance and stability. The study was conducted in the farmer's field in two different altitudes in West Timor, i.e., Mata Air Village, Kupang District (86 masl) and Netpala Village, Timor Tengah Selatan (TTS) District (1,090 masl) from April to September 2023. Six purple-fleshed sweet potato clones/varieties were assigned as treatment. The experiment was laid out in a complete block design in each location, and each treatment consisted of three replicates. Observed data included fresh storage root yield, number of storage roots per plant, storage root length, storage root tuber diameter, and tuber anthocyanin content. Observed data from the two trial locations were subjected to a combined ANOVA, cluster analysis, Principal Component Analysis (PCA), and GGE biplot analysis. The results showed that the genotype-by-location interaction effect was significant in all studied traits. Meanwhile, location or genotype significantly affected all traits except for the location, which did not significantly affect the anthocyanin content. The storage root yield ranged from ~19.95 t ha-1 to ~49.33 t ha-1, while the anthocyanin content ranged from ~28,64 mg/100 g to ~157,65 mg/100 g. The ranks of the tested genotypes based on the mean performance and stability are Undana UJ 7&gt;Undana UJ 1&gt;JPV-1&gt;Antin 3&gt;Undana UJ 6&gt;Undana UJ 3 for storage root yield and JPV-1&gt;Antin 3&gt;Undana UJ 7&gt;Undana UJ 6&gt;Undana UJ 3&gt;Undana UJ 1 for anthocyanin content.

Effect of potassium fertilization on storage root number, yield, and appearance quality of sweet potato (Ipomoea batatas L.).

Increasing storage root number is a pivotal approach to enhance both storage root (SR) yield and appearance quality of sweet potato. Here, 2-year field experiments were conducted to investigate the effect of 0 (K0), 120 (K1), 240 (K2), and 360 (K3) kg ha-1 potassium fertilizer (K2O) on lignin metabolism, root growth, storage root yield, and uniformity. The results demonstrated that potassium (K) application led to a decrease in the activities of key enzymes involved in lignin biosynthesis, including phenylalanine deaminase (PAL), 4-coumarate coenzyme A ligase (4-CL), cinnamic acid dehydrogenase (CAD), polyphenol oxidase (PPO), and peroxidase (POD). This resulted in a significant reduction in lignin and G-type lignin contents in potential SRs compared to K0 treatment within 10-30 days after planting (DAP). BJ553 exhibited a significant decrease in PAL activity, as well as lignin and G-type contents at 10 DAP, whereas YS25 showed delayed effects until 20 DAP. However, the number and distribution of secondary xylem conduits as well as the mid-column diameter area in roots were increased in K2 treatment. Interestingly, K2 treatment exhibited significantly larger potential SR diameter than other treatments at 15, 20, and 25 DAP. At harvest, K2 treatment increased the SR number, the single SR weight, and overall yield greatly compared with K0 treatment, with an average increase of 19.12%, 16.54%, and 16.92% respectively. The increase of SR number in BJ553 was higher than that of YS25. Furthermore, K2 treatment exhibited the lowest coefficient of variation for both SR length and diameter, indicating a higher yield of middle-sized SRs. In general, appropriate potassium application could effectively suppress lignin biosynthesis, leading to a reduction in the degree of pericycle lignification in potential SRs. This promotes an increase in the number of storage roots and ultimately enhances both yield and appearance quality of sweet potato. The effect of potassium fertilizer on lignin metabolism in BJ553 roots was earlier and resulted in a greater increase in the SR number compared to YS25.

Multivariate analysis of yield and quality traits in sweet potato genotypes (Ipomoea batatas L.)

Improving sweet potato traits and genotype selection based on specific traits of interest is crucial to motivate farmers and rural households to enhance their livelihoods by increasing income and improving nutritional intake. This research offers a thorough analysis of genotype selection guidelines considering multiple traits of sweet potatoes, including vine length (VL), average root length (ARL), average root diameter (ARD), marketable storage root number (MRN), marketable storage root yield (MRY), non-marketable root number (NMRN), non-marketable root weight (NMRW), dry weight of root (DW), beta-carotene content (BC), vitamin C content (VC), starch content (ST), total sugar content (TS), total soluble solid (TSS), and titratable acidity (ACD). The findings showed that the genotype Moz1.15 achieved the highest MRY at 46.46 t/ha, H5.ej.10 displayed the top BC level at 48.94 mg/100 g, and Moz1.9 had the highest VC (23.89 mg/100 g). Furthermore, there was a significant positive correlation between VL and DW, TSS, ST, TS, and VC. Additionally, ARL, ARD, and MRN showed significant positive correlations with MRY. The principal component analysis (PCA) biplot further confirmed how traits were connected with each other. There were four separate clusters of genotypes found, each having its specific significant trait representation. The distance between these clusters ranged from 21.79 to 54.13, while within each cluster, the distances varied from 0 to 17.45. The factor analysis using the multi-trait genotype-ideotype distance index (MGIDI) showed that sweet potato traits played a substantial role in three distinct factors during both growing seasons (2020-21 and 2021-22). This allowed for the selection of genotypes capable of achieving favorable genetic gains ranging from 1.86% to 75.4%, alongside a broad-sense heritability (h2b) spanning from 64.9% to 99.8%. Through the application of the MGIDI index, a number of potential genotypes were identified, among which BARI Mistialu-12 and H9.7.12 stood out as consistently chosen across both years. These promising genotypes exhibited high performance while displaying their strengths and weaknesses in terms of their contributions to the identified factors. This thorough research offers valuable insights into the complex relationship between different traits in sweet potatoes and how genotype selection based on a multi-trait index can significantly assist in shaping upcoming breeding and cultivation strategies.

Genome-Wide Analysis of Sweet Potato Ammonium Transporter (AMT): Influence on Nitrogen Utilization, Storage Root Development and Yield.

Ammonium, as a major inorganic source of nitrogen (N) for sweet potato N utilization and growth, is specifically transported by ammonium transporters (AMTs). However, the activities of AMT family members in sweet potatoes have not been analyzed. In the present study, the sweet potato cultivar 'Pushu 32', which is planted in a large area in China, was used in field experiments at the Agricultural Base of Hainan University (20°06' N, 110°33' E) in 2021, and Sanya Nanfan Research Institute of Hainan University (18°30' N, 109°60' E) in 2022. Four N levels were tested: 0, 60, 120, and 180 kg ha-1. The results are as follows. Twelve IbAMT genes were identified in the sweet potato genome, which were classified into three distinct subgroups based on phylogeny; the same subgroup genes had similar properties and structures. IbAMT1.3 and IbAMT1.5 were mostly expressed in the storage roots under N deficiency. Compared with the NN and HN groups, IbAMT1.3 and IbAMT1.5 expressions, N content in storage roots, N uptake efficiency at the canopy closure, N fertilization contribution rates, number of storage roots per plant, storage root weight, and yield were all increased in the MN group. Furthermore, there was a significant positive correlation between the expressions of IbAMT1.3 and IbAMT1.5 with N content in the storage roots of sweet potato. In a word, IbAMT1.3 and IbAMT1.5 may regulate N utilization, affect the development of the storage root. and determine the yield of sweet potato. The results provide valuable insights into the AMT gene family's role in the use of N and effects on storage root development and yield in sweet potatoes.

Genetic variability and divergence analysis in cassava (Manihot esculenta Crantz) accessions for storage root yield and other agronomic characters

Understanding the character of genetic variability and diversity is crucial to enhancing selection efficiency in plant breeding programs. This study aimed to estimate the magnitude of genetic variability and diversity among 64 accessions based on quantifiable characteristics to provide valuable information for breeding programs and conservation. The 64 accessions were evaluated in the two locations using an 8x8 lattice design. Analysis of variance showed a significant difference among the tested accessions for the characters studied, indicating the presence of variability and the possibility of character selection and improvement. The highest genotypic coefficient of variation revealed for the aboveground biomass, storage root yield, and storage root number indicates that the possibility of selection of those characters might be effective for their improvement. High heritability along with high genetic advance as a percent of the mean was observed for number of storage roots, length of storage roots, storage root yield, aboveground biomass, and harvest index, suggesting the existence of additive gene effects. The first three principal components explained 49 % of the total variation, with PC I accounting for 22.5 %, PC II for 15.6 %, and PC III for 10.9 % of the total variation. The 64 accessions were grouped into five clusters, and the number of accessions in each cluster was varied from 3 in cluster V to 31 in cluster II. The maximum inter-cluster diversity was found between IV and V (82.60), while cluster V (6.12) had the highest intra-cluster diversity. Accessions G8, G16, G40, G43, G46, G53, and G57 have been identified as the best candidates for the breeding program in terms of storage root yield. The various analyses performed in the present study confirmed the presence of wide variability & diversity among accessions, which could be used to develop cassava cultivars with optimal storage root yield through effective selection.

Morphoagronomic characterization and reproductive versatility in polymorph clover

Trifolium polymorphum Poir. is a legume of natural pastures that combines amphicarpy with vegetative reproduction, but with little morphoagronomic information in populations of southern Brazil. In this study, plant height and diameter, number of primary stolons, dry matter, number of inflorescences, number of flowers per inflorescence, number of flowers with legume with seeds, number of flowers without legume or with legume without seeds, seed production, number and dry weight of storage roots were evaluated in populations of T. polymorphum. Little variation was observed for most characteristics, including low dry matter and aerial seed production. There were positive correlations between plant height and dry matter (r = 0.44), plant diameter and dry matter (r = 0.43), number of inflorescences and number of flowers per plant (r = 0.98) and number of inflorescences and seed production (r = 0.84). T. polymorphum presented low dry matter yield, however, the reproductive versatility of the species with the amphicarpic condition combined with vegetative propagation are mechanisms that allow the species to increase its frequency and contribution in natural pastures.

Impact of paclobutrazol on storage root number and yield of sweet potato (Ipomoea batatas L.)

Increasing storage root number is an important way to improve the yield of sweet potato. Here, two-year field experiments were conducted to study the effect of 0 (CK), 10, 20 and 30 mg kg−1 paclobutrazol (PBZ) on the phytohormones and lignin biosynthesis, and root growth and yield of sweet potato. The current study found that PBZ10 decreased the concentration of phytohormones gibberellin 3 (GA3), indole acetic acid (IAA) and abscisic acid (ABA) in the subterranean stem, whereas increased the concentration of zeatin riboside (ZR) and methyl jasmonate (MeJA), resulting in lower root length, volume and tip number at 3 and 5 days after planting (DAP). At 5 DAP, PBZ10 decreased GA3, MeJA and ABA concentration in adventitious root, and increased IAA and ZR concentrations, resulting in increased root length, volume, tip number and surface area at 10 DAP. By 5–30 DAP, PBZ10 decreased the concentration of GA3 and ABA in potential storage roots and increased the concentration of IAA, ZR and MeJA, thus increasing root number. At 10–20 DAP, PBZ10 decreased the lignin concentration in the potential storage root along with the expression of IbEXP1 and the enzymatic activities of phenylalanine ammonialyase, 4-coumaric acid CoA ligase and peroxidase, which are involved in the regulation of lignin biosynthesis, resulting in increased potential storage root diameter; interestingly, the opposite pattern was observed by 25–30 DAP. Then, PBZ10 increased the SR number at 40 DAP, and the yield of sweet potato at harvest time, and no PBZ was detected in SRs of PBZ10. But excessive concentration of PBZ is unfavorable to root development and led to a decrease of yield. These results indicated that a moderate PBZ (10 mg kg−1) application could reasonably regulate phytohormones and lignin biosynthesis, then increase storage root number and yield of sweet potato.

Cultivation of Cassava (Manihot Esculentus C.) With Selected Legumes for Growth, Yield and Economic Advantages as Climate Change Mitigations

Cassava (Manihot esculentus Crantz.) is a monoecious perennial shrub that is extensively cultivated as an annual crop in tropical and subtr++=opical regions for its edible, starchy, tuberous roots. It is ideal for intercropping with short-duration crops, which are often harvested before the cassava canopy closes. Thus, intercropping cassava, especially with legumes, is an important way for poor farmers to provide additional crop yield during the early growth stage. Moreover, the incorporation of legumes into cassava-based cropping systems may offer one of the most feasible ways of enhancing protein intake and nutritional security of farming households. Accordingly, a 1-year field study on cassava intercropped with three legumes (haricot bean, mung bean, and soybean) in southern Ethiopia was conducted to determine the effect of intercropping on the growth, yield, and economic advantage of the cassava. The experiment was laid out in a randomized complete block design (RCBD) with three replications. The results revealed that there were significant (P&lt;0.05) differences for cassava plant height, leaf number, stem width, number of storage roots per plant, storage root weight, dry matter, and root yield due to cassava legume intercropping. Cassava- haricot bean intercropping increased root yield by 28% as compared to cassava-mung bean (21%), and cassava-soybean (18 %), respectively. And it can improve land-use efficiency by 31% as compared to cassava-soybean and cassava-mung bean intercropping. The partial budget analysis also revealed that cassava planted with haricot bean gave the highest economic benefit of 199,250 Birr ha-1. Further researches on relative planting time of legumes with cassava and soil fertility variation under sole cassava and intercropping systems are important for improving productivity of growers under the study area.

Cytokinin application improving growth, sugar content, polyphenol and flavonoid content in Yacon tuberous roots

Yacon is a tuberous crop that accumulates sugar in large quantities and has many valuable secondary compounds in medicine such as phenolic compounds and flavonoids. The objective of this study was to increase the size and content of sugars, polyphenols and flavonoids during the early growth of tubers. Therefore, early tuber stimulation and tuber size are important as they determine yield over time. Cell restructuring along with growth expansion as well as control of tuber reserves also takes place. This study investigated anatomy structure changes, fresh weight, dry weight, respiratory intensity and sugar content in different Yacon root types. A spray of N-benzyl adenine (BA) (0–25 ppm) is applied in the initial stage. Determining agronomic, physiological, and, biochemical indicators after 4 weeks of treatment, the sugar content of tubers determines the yield of tubers after 16 weeks of treatment. The results showed that Yacon crops at the stages of 5 to 9 weeks develop fibrous roots, thin fibrous roots and pre-tuberous roots at week 13, intermediate storage roots at week 17 and mature storage roots at week 17. BA 20 ppm application on Yacon crop week 13 increased the number of storage roots, fresh weight, dry weight tuber diameter, total sugar content, fructan content, total phenolic and flavonoid remarkably compared to controls, but reducing sugar content is lower than treating BA at 15 ppm. BA 20 ppm application on Yacon crop week 13 increased the parameters of sugar growth and accumulation, tuber yeild on a plant increased 2 times, dry weight increased 1.65 times, sugar content, total sugar 1.12 times, reducing sugar 3.01 times, fructan 1.36 times, total phenolic and flavonoid 1.36 and 1.26 times after 25 weeks of treatment.

Influence of Planting Density on Sweet Potato Storage Root Formation by Regulating Carbohydrate and Lignin Metabolism.

An appropriate planting density could realize the maximum yield potential of crops, but the mechanism of sweet potato storage root formation in response to planting density is still rarely investigated. Four planting densities, namely D15, D20, D25, and D30, were set for 2-year and two-site field experiments to investigate the carbohydrate and lignin metabolism in potential storage roots and its relationship with the storage root number, yield, and commercial characteristics at the harvest period. The results showed that an appropriate planting density (D20 treatment) stimulated cambium cell differentiation, which increased carbohydrate accumulation and inhibited lignin biosynthesis in potential storage roots. At canopy closure, the D20 treatment produced more storage roots, particularly developing ones. It increased the yield by 10.18-19.73% compared with the control D25 treatment and improved the commercial features by decreasing the storage root length/diameter ratio and increasing the storage root weight uniformity. This study provides a theoretical basis for the high-value production of sweet potato.

Principal Component Analysis and Clustering of Cassava Germplasm based on N and K Efficiency

The present study was undertaken at ICAR-CTCRI, Sreekaryam to identify and group N and K efficient genotypes from a pool of released varieties, pre-breeding lines and elite landraces of cassava during 2021-2022. Thirty genotypes of cassava were evaluated for their diversity based on N and K efficiency along with some of its contributing plant characters using statistical tools like principal component analysis, and dendrogram clustering. The variation existing among the selected genotypes was observed through PCA, where the first six principal components accounted for nearly 81% of the total variability. Characters like tuber yield, plant height, stem girth, tuber length and tuber girth contributed to the greater variability among the genotypes. The dendrogram analysis classified the genotypes into six clusters based on the 18 parameters contributing to nutrient use efficiency. The proportion of the variance accounted by these clusters came up to the extent of 50% displaying the association of the genotypes with similar characters in these clusters. These analyses helped to realize the wide range of variability existing among the selected genotypes for the 18 characters studied. A simple correlation was also worked out between N and K use efficiency with root traits, which revealed that characters such as weight of storage roots, number of storage roots, and number of basal roots showed a positive correlation with both N and K use efficiency in cassava.

Magnesium chelatase subunit D is not only required for chlorophyll biosynthesis and photosynthesis, but also affecting starch accumulation in Manihot esculenta Crantz

BackgroundMagnesium chelatase plays an important role in photosynthesis, but only a few subunits have been functionally characterized in cassava.ResultsHerein, MeChlD was successfully cloned and characterized. MeChlD encodes a magnesium chelatase subunit D, which has ATPase and vWA conservative domains. MeChlD was highly expressed in the leaves. Subcellular localization suggested that MeChlD:GFP was a chloroplast-localized protein. Furthermore, the yeast two-hybrid system and BiFC analysis indicated that MeChlD interacts with MeChlM and MePrxQ, respectively. VIGS-induce silencing of MeChlD resulted in significantly decreased chlorophyll content and reduction the expression of photosynthesis-related nuclear genes. Furthermore, the storage root numbers, fresh weight and the total starch content in cassava storage roots of VIGS-MeChlD plants was significantly reduced.ConclusionTaken together, MeChlD located at the chloroplast is not only required for chlorophyll biosynthesis and photosynthesis, but also affecting the starch accumulation in cassava. This study expands our understanding of the biological functions of ChlD proteins.

Effect of Leaf Harvest Intensity and Frequency on Sweet Potato Weevil (Cylas puncticollis) Infestation, Yield and Quality Traits of Sweet potatoes (Ipomoea batatas L.)

Objective: The present study assessed Cylas puncticollis (C. puncticollis) infestation, foliage, and root yields of sweet potatoes as influenced by the leaf harvest intensity and frequency in the inland valley swamp (IVS) and upland soils of Njala. Methods: The trial involved 2 varieties namely Kabia and Gbanie; 4 levels of foliage harvests: 0, 30, 60 and 90 days after planting; and 4 levels of leaf harvest intensities: 0, 25, 50 and 100%. The treatments were established in a randomized complete block design and replicated 3 times. The parameters that were investigated included the severity of C. puncticollis infestation on vines and storage roots, fresh foliage yield, storage root yields and other related traits (fresh storage root length, width and numbers). Results: Our findings showed that there were significant differences in foliage and root yields, as well as related traits among different leaf harvest frequency intensities. The 25 and 50% harvest plots produced optimum fresh foliage and storage root yields and other related traits of the crop. C. puncticollis infestation in sweet potatoes cultivated during the dry season in the IVS ecology was more severe than that in those grown in the upland during the wet season. The ecology and time of cultivation of sweet potatoes influence infestation by C. puncticollis on vines and roots more than the combined effects of putative varieties, leaf harvest intensity and frequency. Conclusion: Improved agronomic management practices support optimization of fresh leaf and root yields of sweet potatoes. These can be exploited and chosen to achieve optimum productivity and quality of the crop for both the fresh foliage and storage root consumers.

The Application of Nitrogen Source in Regulating Lignin Biosynthesis, Storage Root Development and Yield of Sweet Potato

The understanding of the effects of nitrogen sources on lignin synthesis in sweet potato during storage root formation is limited. In this study, we investigated the effects of different nitrogen source on sweet potato storage root formation and development, as well as lignin synthesis in potential storage roots. The sweet potato cultivars Shangshu 19 and Jixu 23 were used in field experiments in 2019 and 2020. Three treatments were tested: (a) no nitrogen fertilizer application (control); (b) 60 kg hm−2 ammonium nitrogen; and (c) 60 kg hm−2 amide nitrogen. The results indicate that during sweet potato storage root formation, ammonium nitrogen significantly enhanced root activity compared to that of the control. The ammonium nitrogen treatment promoted IbEXP1 and inhibited Ibkn1 and Ibkn2 expression during the early stages of storage root formation, then increased gibberellic acid and decreased zeatin riboside content, enhanced phenylalanine ammonia lyase and peroxidase activities, and promoted lignin synthesis in potential storage roots. The opposite effects of ammonium nitrogen treatment on gene expression, hormone contents, and enzyme activity were observed in the late stages of storage root formation. Relative to the control, the ammonium nitrogen treatment significantly increased the number of storage roots during canopy closure. The ammonium nitrogen treatment produced the highest storage root yield and number of storage roots per plant. These results indicated that the ammonium nitrogen can inhibit root lignin synthesis, then promote storage root formation and increase the yield of sweet potato.

Evaluation and Selection of Elite Cassava Varieties for Storage Root Yield in the Transition and Guinea Savannah Ecologies of Ghana

This study was carried out to identify and select local and improved cassava varieties suitable for cultivation in the transition and Guinea savannah agroecology of Ghana against climate change. Two agroecologies; transition and Guinea savannah ecologies were considered for the study. Four cassava growing communities were chosen in the transition zone whilst three cassava growing communities were chosen for the Guinea savannah ecology. The cassava varieties representing the treatments were arranged in a randomized complete block design with three replications at each location. A total of 13 cassava varieties were used for the study. Cassava cuttings measuring 20-25 cm were planted using a spacing of 1m × 1m. Harvesting was done at 12 months after planting to assess storage root yield of the cassava varieties at the different locations. Analysis of variance indicated significant (P≤ 0.05) varietal differences among the local varieties for root yield (11.25 - 29.27 t/ha), harvest index (0.46 – 0.75), storage root number per plant (2 - 8 roots/plant) and mean storage root weight (307.0 - 972.4 g) in Transition zone. However, there were no significant varietal differences between the improved varieties for root yield. The best performing improved varieties in the transition zone were Bankyehemaa (28.06 t/ha), Eskamaye (27.76 t/ha) and Nkabom (26.99 t/ha) whilst Filindiakong (22.65 t/ha) and Nyerikobga (31.17 t/ha) were identified to be suitable for the Guinea savannah ecology. Therefore, these cassava varieties can be cultivated to mitigate the effects of climate change on cassava and ensure food security.

Response Mechanism of Endogenous Hormones of Potential Storage Root to Phosphorus and Its Relationship With Yield and Appearance Quality of Sweetpotato.

Field and pot experiments were conducted to explore the response mechanism of endogenous hormones of potential storage root to phosphorus and its relationship with yield and appearance quality of sweetpotato using five different rates of phosphorus addition. Application of adequate amounts of phosphorus (P2 treatment, 112 kg of P2O5 ha–1 in field experiment or 0.04 g of P2O5 kg–1 in pot experiment) improved the yield and the appearance quality of sweetpotato when compared to the control treatment. This observation can be attributed to the fact that P2 treatment significantly increased the expression of Ibkn1 and APRT genes and the concentration of ZR from 20 to 40 days after planting, but the results were the opposite at 10 days after planting. In addition, an increase in the expression of SRD1, NIT4, IbMADS1, and OPR3 and the concentrations of IAA and JA from day 10 to day 40 after planting were observed. Furthermore, the expression of GA3oX4 and the concentration of GA3 decreased significantly from 20 to 30 days of planting and significantly increased after 40 days of planting. Moreover, a significant decrease in the expression of AAO and concentration of ABA was observed from 10 to 30 days after planting, and a significant increase was observed after 40 days of planting. The results show that P2 treatment promoted root development, particularly significantly increased the number of roots and potential storage roots. P2 treatment significantly increased the diameter, weight, and number of storage roots at 40 days after planting. Finally, proper phosphorus application (112 kg of P2O5 ha–1) increased the yield (enhanced from 18.99 to 25.93%) by increasing the number of storage roots per plant and improving the appearance quality by increasing the length/diameter ratio and uniformity of storage root weight.

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.