Crop emergence and canopy cover are important physiological traits for potato (Solanum tuberosum L.) cultivar evaluation and nutrients management. They play important roles in variety screening, field management and yield prediction. Traditional manual assessment of these traits is not only laborious but often subjective. In this study, semi-automated image analysis software was developed to estimate crop emergence from high-resolution RGB ortho-images captured from an unmanned aerial vehicle (UAV). Potato plant objects were extracted from bare soil using Excess Green Index and Otsu thresholding methods. Six morphological features were calculated from the images to be variables of a Random Forest classifier for estimating the number of potato plants at emergence stage. The outputs were then used to estimate crop emergence in three field experiments that were designed to investigate the effects of cultivars, levels of potassium (K) fertiliser input, and new compound fertilisers on potato growth. The results indicated that RGB UAV image analysis can accurately estimate potato crop emergence rate in comparison to manual assessment, with correlation coefficient ( $$ r^{2} $$ ) of 0.96 and provide an efficient tool to evaluate emergence uniformity. The proposed UAV image analysis method is a promising tool for use as a high throughput phenotyping method for assessing potato crop development at emergence stage. It can also facilitate future studies on optimizing fertiliser management and improving emergence consistency.

Continuous potato cropping systems cause yield reduction, soil-borne disease aggravation, and soil degradation, but crop rotation can alleviate these negative effects. However, there are limited studies on the relationships between microbial community and other soil biochemical properties of continuous potato cropping at both pre-planting and harvest in North China. A 4-year study was conducted to explore the effects of different rotation system on soil biochemical properties, microbial community at pre-planting and harvest, and potato yield, tuber number and black scurf incidence at harvest in 2020 and 2021, which included 4 treatments vis. potato-potato-potato-potato (PC), potato-oat-faba bean-potato (PR), oat-faba bean-potato-oat (O), and faba bean-potato-oat-faba bean (B). The results showed that soil biochemical properties and microbial community among all treatments showed no significant difference at pre-planting after a long cold winter generally. At harvest, PC reduced tuber yield and number and significantly increased black scurf incidence relative to potato rotation systems. PC also reduced soil enzyme activities, the content of soil nutrients, and fungal community diversity, and increased bacterial community diversity compared with the other treatments, insignificantly when compared with PR. Relative abundance of microorganisms related to the degradation of organic residues, soil nitrogen cycling, and disease suppression, such as the genera Devosia, Aeromicrobium, Paraphoma, and Papiliotrema, were significantly higher in O or B than in PC and PR, while microorganisms related to disease infection such as the genera Pseudomonas, Colletotrichum, Plectosphaerella, Fusarium, and Verticillium exhibited increased in PC and PR. Principal Coordinates Analysis (PCoA) showed that there were significant differences in the microbial community structure of PC and PR at harvest compared with that of O and B. Redundancy analysis (RDA) revealed that soil available potassium (AK), acid phosphatase (ACP), available phosphorus (AP), sucrase (SUC) and pH were the dominant factors that significantly affected bacterial and fungal community structure. Partial least squares structural equation model indicated rotation system had significant negative effect on fungal community. It was concluded that growing oat or faba bean after potato can increase soil beneficial microorganisms and maintain the ecosystem healthy, thus reducing the incidence of tuber black scurf and increasing potato yield.

Late blight, caused by Phytophthora infestans (P. infestans), is a devastating disease in potato worldwide. Our previous study revealed that the Solanum andigena genotype 03112-233 is resistant to P. infestans isolate 90128, but susceptible to the super race isolate, CN152. In this study, we confirmed by diagnostic resistance gene enrichment sequencing (dRenSeq) that the resistance of 03112-233 toward 90128 is most likely based on a distinct new R gene(s). To gain an insight into the mechanism that governs resistance or susceptibility in 03112-223, comparative transcriptomic profiling analysis based on RNAseq was initiated. Changes in transcription at two time points (24 h and 72 h) after inoculation with isolates 90128 or CN152 were analyzed. A total of 8,881 and 7,209 genes were differentially expressed in response to 90128 and CN152, respectively, and 1,083 differentially expressed genes (DEGs) were common to both time points and isolates. A substantial number of genes were differentially expressed in an isolate-specific manner with 3,837 genes showing induction or suppression following infection with 90128 and 2,165 genes induced or suppressed after colonization by CN152. Hierarchical clustering analysis suggested that isolates with different virulence profiles can induce different defense responses at different time points. Further analysis revealed that the compatible interaction caused higher induction of susceptibility genes such as SWEET compared with the incompatible interaction. The salicylic acid, jasmonic acid, and abscisic acid mediated signaling pathways were involved in the response against both isolates, while ethylene and brassinosteroids mediated defense pathways were suppressed. Our results provide a valuable resource for understanding the interactions between P. infestans and potato.

Potato (Solanum tuberosum L.) is one of the three most important food crops worldwide; however, it is strongly affected by drought stress. The precise molecular mechanisms of drought stress response in potato are not very well understood. The diploid potato genotype P3-198 has been verified to be highly resistant to drought stress. Here, a time-course experiment was performed to identify drought resistance response genes in P3-198 under polyethylene glycol (PEG)-induced stress using RNA-sequencing. A total of 1665 differentially expressed genes (DEGs) were specifically identified, and based on gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the transcription factor activity, protein kinase activity, and the plant hormone signal transduction process were significantly enriched. Annotation revealed that these DEGs mainly encode transcription factors, protein kinases, and proteins related to redox regulation, carbohydrate metabolism, and osmotic adjustment. In particular, genes encoding abscisic acid (ABA)-dependent signaling molecules were significantly differentially expressed, which revealed the important roles of the ABA-dependent signaling pathway in the early response of P3-198 to drought stress. Quantitative real-time PCR experimental verification confirmed the differential expression of genes in the drought resistance signaling pathway. Our results provide valuable information for understanding potato drought-resistance mechanisms, and also enrich the gene resources available for drought-resistant potato breeding.

Since 1950, more than 620 potato cultivars have been released from Chinese breeding programs, some of which have similar genetic background and phenotype. In this study, 16 parental cultivars widely used in breeding were used to screen 138 simple sequence repeat (SSR) markers. Out of 138 SSR markers, 20 were polymorphic that were used to analyze the genetic diversity of 217 potato cultivars grown in China. In total, 249 alleles were detected with these 20 markers and 244 of them (97.99%) showed polymorphism. The number of alleles ranged from 7 to 22 with an average of 12.45 alleles per primer and polymorphic information content (PIC) ranged from 0.64–0.93 with an average of 0.83. Fragment sizes varied from 80 to 380 bp. Based on PIC values and the clarity of PCR amplification bands, 11 SSR markers were selected and able to differentiate all of the 217 cultivars. The estimated similarity using these polymorphic SSR markers between the cultivars ranged from 0.63 to 0.99, indicating a narrow genetic base. Fingerprinting and genetic diversity analysis in this study provides useful information for the protection of intellectual property, as well as the exploration and utilization of these potato cultivars. Desde 1950, se han liberado más de 620 variedades de papa de los programas chinos de mejoramiento, algunos de los cuales tienen antecedentes genéticos y fenotipo similares. En este estudio, se usaron 16 variedades parentales utilizadas ampliamente en mejoramiento, para hacer un estudio de 138 marcadores de repeticiones simples de secuencia (SSR). De los 138 marcadores SSR, 20 fueron polimórficos que fueron usados para analizar la diversidad genética de 217 variedades de papa cultivadas en China. En total, se detectaron 249 alelos con estos 20 marcadores y 244 de ellos (97.99%) mostraron polimorfismo. El número de alelos tuvo un rango de 7–22 con un promedio de 12.45 alelos por iniciador, y el contenido de la información polimórfica (PIC) varió de 0.64–0.93 con un promedio de 0.83. Los tamaños de los fragmentos variaron de 80–380 pb. Con base en los valores PIC y la claridad de las bandas de amplificación, se seleccionaron 11 marcadores SSR y fue posible diferenciar a la totalidad de las 217 variedades. La similitud estimada usando estos marcadores polimórficos SSR entre las variedades varió de 0.63 a 0.99, indicando una base genética angosta. Los análisis de huellas y diversidad genética en este estudio proporcionan información útil para la protección de propiedad intelectual, así como para la exploración y utilización de estas variedades de papa.