Explore the vast range of titles available.

Nitrogen (N), phosphorus (P), and potassium (K) fertilization is widely used to enhance crop productivity. However, the synergistic effects of combined N, P, and K application on sweetpotato yield and nutrient use efficiency are not fully understood. To address this knowledge gap, a field experiment was conducted with five treatments: control (CK), no N (-N), no P (-P), no K (-K), and full NPK application (NPK). We systematically analyzed storage root yield, yield components, and nutrient accumulation characteristics. Additionally, fertilizer use efficiency and soil nutrient balance were evaluated. The NPK treatment significantly increased storage root yield by 34.8–53.1% compared with single nutrient deficiency treatments. The greatest yield reduction was observed under -P conditions, associated with low soil available P and a disordered N and K allocation ratio (5.10–14.40%). Phosphorus application resulted in high agronomic efficiency (187.79 kg kg −1 P 2 O 5 ) but low recovery efficiency (0.05–0.25 kg kg −1 P 2 O 5 ), whereas -N and -K treatments led to soil P surplus (50.25–63.06 kg ha −1 ). A logistic model revealed that NPK treatment increased the maximum and average nutrient accumulation rates compared with deficient treatments. Pearson correlation analysis showed significant positive relationships between yield and yield components, as well as nutrient accumulation in storage roots and whole plants. Random forest regression identified P accumulation in storage roots as the most important predictor of yield. In conclusion, combined NPK fertilization enhances both storage root yield and nutrient use efficiency, with targeted P management playing a critical role in achieving high-yield and high-efficiency sweetpotato production.

Drought tolerance in higher plants can result in enhanced productivity, especially in case of carbohydrate storage root crop. Sweet potato has been reported as a drought-tolerant crop, while it is very sensitive to water shortage in the root initiation of cutting propagation and tuber initiation stages. In the present study, we aimed to alleviate the drought-tolerant abilities in sweet potato cv. Tainung 57 (drought-sensitive cultivar) using foliar glycine betaine (GlyBet) application as compared with drought-tolerant cultivar (cv. Japanese Yellow). Leaf osmotic potential in GlyBet applied plants under mild- (25.5% soil water content; SWC) and severe-water deficit (15.5% SWC) stresses was maintained through the accumulation of total soluble sugars as a major osmotic adjustment, thus stabilizing the photosynthetic pigments, chlorophyll fluorescence, net photosynthetic rate, and retaining the overall growth performances, i.e., shoot height, number, and length of leaves. In the harvesting process, storage root weight in water deficit stressed sweet potato cv. Tainung 57 (11.75 g plant−1) with 50 mM GlyBet application was retained in a similar pattern to cv. Japanese Yellow (12.25 g plant−1). In the present investigation, exogenous foliar GlyBet application strongly alleviated water deficit stress via sugar enrichment to control cellular osmotic potential, retain high photosynthetic abilities and maintain the yield of storage root yield. In summary, the regulation on total soluble sugar enrichment in water deficit–stressed sweet potato using GlyBet foliar application may play an important role in maintaining the controlled osmotic potential of leaves, thereby retaining the photosynthetic abilities, overall growth characters and increasing the yield of storage roots.

This study aimed to characterize sweetpotato genetic resources based on shoot traits to promote compact plant type. Subsequently, the relationship between shoot traits and storage root yield was studied under short-period cultivation. Thirty-five sweetpotato genotypes were cultivated for two years in Miyazaki, Japan. Shoot traits at the intermediate phase (50 days after transplanting, DAT) and root and shoot traits at the time of harvesting (approximately 100 DAT) were investigated. There were significant correlations in all the traits over the two years ( P  < 0.01), and the two-year average data were subjected to clustering and principal component analysis (PCA). The 35 genotypes were divided into three groups, where Group II consisted of six genotypes with compact plant type. PCA revealed that PC1, which explained 43.3% of the total variation, was closely related to shoot traits associated with canopy morphology. The stem length/plant height ratio was considered equivalent to the PC1 score. PC2, explaining 21.4% of the total variation, was strongly associated with shoot dry matter weight (DMW). Subsequently, ‘Kyushu No.199’ and ‘Kyukei 281’ were identified as compact and vigorous shoot genotypes. According to correlation analyses, compact plant type not have any adverse effect on storage root yield under short-period cultivation. Among the Group II compact genotypes, there was considerable variation in the root DMWs; ‘Kyushu No.199’ had a relatively high root DMW and root/shoot DMW ratio, and it was identified as a promising compact shoot genotype. This study provides valuable knowledge for promoting plant type-based breeding programs. Graphical Abstract

Background: Optimized nitrogen (N) application and planting density can enhance sweet potato yield. However, the agronomic mechanisms underlying their effects on photosynthetic efficiency and carbohydrate metabolism in sweet potato remain unclear. Methods: To address this, a two-year field experiment was conducted using a split-plot design with two varieties (YS-25 and GX-14), three N levels (60, 90, and 120 kg/ha; designated N60, N90, and N120, respectively), and three planting densities (D1–D3: 50,000, 62,500, and 83,333 plants/ha). Each treatment was replicated three times. Results: The results showed that the N60D2 treatment (60 kg/ha N; 62,500 plants/ha) optimized canopy light distribution by significantly increasing IPAR, light transmission rate, and extinction coefficient (K). This treatment enhanced individual plant photosynthetic capacity (higher photosynthetic rate: Pn, Ci, Gs, and Tr) and light energy use efficiency (Fv/Fm, Y(II), ETR, and qP), and promoted carbohydrate metabolism (sucrose, starch, fructose, and glucose) by increasing enzyme activities (Rubisco, SuSy, SPS, NI, SSS, and AGPase) in functional leaves and roots. These effects improved source–sink coordination, ultimately increasing storage root yield by 63.27–95.47% compared with the control plants (N120D1). Correlation analysis revealed that single-plant root weight and medium-sized root count were important yield determinants for both varieties. Conclusions: These results indicate that reducing nitrogen fertilizer combined with dense planting shapes a reasonable canopy structure for light distribution at the population level and optimizes light and carbon use efficiency at the individual plant level, thereby improving storage root yield and commercial characteristics of sweet potato.

Sweetpotato is grown throughout the year in Mozambique but drought affects storage root yield and biomass productivity. The objectives of this research were to estimate the impact of genotype × environment interactions (G × E) in sweetpotato and select genotypes based on drought indices such as geometric mean, percent yield reduction, drought sensitivity index and harvest index. A total of 58 clones were evaluated during the dry season of 2006, 2008 and 2009. Two treatments were applied for this multi-year trial: full irrigation and without irrigation at the middle of root initiation growth stage. The field layout was a randomized complete block design with three replications. ‘Jonathan’, ‘Resisto’ and ‘Tanzania’ were the check cultivars in each treatment. Storage root and vine yields were recorded at harvest in the trials. Harvest index was computed from the yield data. The analysis of variance, regression and the additive main effects multiplicative interaction (AMMI) analyses, plus phenotypic coefficient of variation and ecovalence were used for dissecting the G × E and assessing the stability of each clone. Treatment, genotype × treatment and genotype × year (G × Y) interactions had highest contributions to the variation in storage root yield observed among clones. The stability of harvest index was significantly correlated with the absolute AMMI’s IPCA1 and IPCA2 values for storage root yield. Cultivar performance varied within treatments. Four clones had significantly higher storage root yield (t ha⁻¹) than ‘Tanzania’, the best check cultivar under drought. In conclusion, storage root yield (t ha⁻¹) was negatively affected by drought and G × Y interaction. Harvest index stability and the geometric mean may be key to identify clones with storage root yield stability and high storage root yield under both treatments. At least two environments should be used at early breeding stages to consider harvest index in the early breeding cycle.

The white-fleshed sweetpotato (WFSP) remains vital to household food security in Ethiopia, where its adoption is limited by vulnerability to sweetpotato virus disease (SPVD) and low dry matter content (DMC). We assessed 10 WFSP genotypes (nine advanced lines and the standard check ‘Awassa‑83’) across six environments (Halaba, Arbaminch, Werer; 2024 – 2025 main seasons) using a randomised complete block design with three replications. The analysis of variance was computed, and the results detected significant genotypic differences (p < 0.05) for storage root yield, DMC, and SPVD response. Genotype G2 (Ininda‑1‑20) achieved the highest mean yield (28.1 t/ha), a 32.3% advantage over the check, high DMC (~33%), and low SPVD severity (mean ≈1.5). The notable G × E interaction was observed for all traits recorded, including SPVD, vine length (VL), number of roots per plant (NRPP), above-ground fresh biomass weight (AGFW), storage root yield, and DMC, with variable magnitudes such as SPVD=21.3%, VL=6.7 %, storage root yield=8.9%, NRPP=8.7%, AGFW=3.2%, and DMC=7.6%. This demonstrates that the tested genotypes are sensitive to G × E interaction, warranting further stability analysis. GGE biplots (mean versus stability and the ‘which‑won‑where’ approach) indicated that G2 combined superior performance with acceptable stability across environments. Most genotypes scored less than 3.0 for SPVD, indicating resistance/or tolerance under the test conditions. We recommend on‑farm participatory trials for G2 towards potential release in similar agro‑ecologies. The results highlight the feasibility of selecting WFSP genotypes that simultaneously meet productivity, quality (DMC), and SPVD resistance requirements in Ethiopia’s diverse environments.

Cassava is a crucial starchy root crop cultivated worldwide in tropical and subtropical areas. Efforts have been made to improve its desirable characteristics to increase food and nutritional quality. However, the adoption of new cassava varieties can be influenced by their yield performance, which can be affected by cassava mosaic disease (CMD). The present study evaluated selected cassava genotypes' performance across two years at the advanced breeding stage. Using a randomized complete block design with two replications, 16 genotypes, a yellow root variety (TMS07/0593) and a white root (TMS30572) as checks were evaluated for yield, yield-related traits and response to CMD. There were highly significant (P < 0.001) variations among the cassava genotypes for yield-related traits, but no genetic variation was reported for fresh and dry root yields. The effect of season and genotypes × season interaction on all traits was significant only for harvest index and percentage of survival plants, respectively. Only genotype UIC-17-2428 and the two national check varieties (TMS07/0593 and TMS30572) did not resist CMD completely. At harvest, genotype UIC-17-2031 had the highest fresh root yield (39.0 t/ha), dry root yield (10.5 t/ha), and harvest index (0.63). Genotype UIC-17-58 had the highest dry matter content (37.2%) at harvesting, followed by UIC-17-46 (36.4%) while genotype UIC-17-583 had the lowest value (22.8%). The genotypes evaluated have promising premium agronomic traits. To assess their stability, genotypes with outstanding dry root yield must be evaluated across multiple environments.  

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.

Emphasis on sustainable cassava production is increasing, with aims to increase the net income of cassava farmers in an ecologically friendly way. This study examined the optimization of soil fertilizer management at two research locations (Nampong and Seungsang) in northeastern Thailand. The experiment was conducted as a randomized complete block design with five replications. Eight different fertilizer management protocols consisted of (1) no fertilizer application (control), (2) the recommended dosage of chemical fertilizer (RDCF), (3) 3.12 t ha−1 of chicken manure (CM), (4) 937.5 L ha−1 of swine manure extract (SME), (5) CM + SME, (6) ½ RDCF + ½ CM, (7) ½ RDCF + ½ SME, and (8) CM + PGPR (stake soaking with PGPR solution). At the Nampong site, the application of CM + PGPR has the most potential for increasing the cassava yield in terms of the fresh tuber yield when compared with no fertilizer and RDCF applications. At the Seungsang site, the application of CM gave the high fresh tuber yield, without significant differences from RDCF applications. Furthermore, compared to the RDCF treatment, both soil fertilizer management protocols produced positive marginal rate of return values, showing clear potential for contributing to sustainable cassava production.

The goal of yam bean improvement in Africa is to develop superior high yielding and high dry matter cultivars that are preferred for adoption. In this study, the estimates of variance components, heritability and response to selection were studied in F3 yam bean families selected from interspecies crosses targeting improvement of storage root dry matter and associated traits. Breeding populations were generated using North Carolina II (NC II) mating design involving high dry matter P. tuberosus chuin cultivar, low dry matter P. ahipa and the high yielding P. erosus yam beans. The progenies were advanced through selfing from F1 to F2 population and then exposed to selection at 10% selection intensity to obtain 83 high dry matter lines. The selected lines were evaluated in an F3 trial using a randomized complete block design (RCBD) with three replications at the National Crops Resources Research Institute (NaCRRI) Namulonge, in Central Uganda. The results revealed significant (P < 0.001) genetic variation for storage root dry matter (RDM), storage root fresh yield (RFY), storage root dry yield (RDY), vine yield (VNY), fresh biomass yield (FBY), harvest index (HI), starch (STA) and protein (PRO) content. High genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were obtained for VNY, RDY, FBY, RFY, RDM and STA. Narrow sense heritability was higher than 0.5 and response to selection was 15.5 to 33.1 for RDM, RFY, RDY, VNY, FBY and STA, indicating rapid genetic progress is achievable and early generation selection would be effective to improve these traits. Significant (P < 0.01) positive genetic correlations were observed between RDM, RDY, RFY, VNY, FBY and STA ranging from 0.422 to 0.963 implying that simultaneous improvement of these traits is possible in the current yam bean populations.