Potato Flower Research Articles

OcBSA: An NGS-based bulk segregant analysis tool for outcross populations

Constructing inbred lines for self-incompatible species and species with long generation times is challenging, making the use of F1 outcross/segregating populations the main strategy for genetic studies of such species. However, there is a lack of dedicated algorithms/tools for rapid quantitative trait locus (QTL) mapping using the F1 populations. To this end, we have designed and developed an algorithm/tool called OcBSA specifically for QTL mapping of F1 populations. OcBSA transforms the four-haplotype inheritance problem from the two heterozygous diploid parents of the F1 population into the two-haplotype inheritance problem common in current genetic studies by removing the two haplotypes from the heterozygous parent that do not contribute to phenotype segregation in the F1 population. Testing of OcBSA on 1800 simulated F1 populations demonstrated its advantages over other currently available tools in terms of sensitivity and accuracy. In addition, the broad applicability of OcBSA was validated by QTL mapping using seven reported F1 populations of apple, pear, peach, citrus, grape, tea, and rice. We also used OcBSA to map the QTL for flower color in a newly constructed F1 population of potato generated in this study. The OcBSA mapping result was verified by the insertion or deletion markers to be consistent with a previously reported locus harboring the ANTHOCYANIN 2 gene, which regulates potato flower color. Taken together, these results highlight the power and broad utility of OcBSA for QTL mapping using F1 populations and thus a great potential for functional gene mining in outcrossing species. For ease of use, we have developed both Windows and Linux versions of OcBSA, which are freely available at: https://gitee.com/Bioinformaticslab/OcBSA.

Effect of anti-ethylene and cytokinin biostimulants on flowering and yield of Sweetpotato (Ipomoea batatas L.)

Breeding is needed to enhance the poor agronomic and qualitative attributes of the majority of sweetpotato cultivars grown in Nigeria. Even though the majority of cultivars don't often flower, the flowers are essential for genetic advancements. This study aimed to assess the effect of anti-ethylene (Silver-thiosulphate) and cytokinin (6-benzyladenine) biostimulants for induction of flowering and yield, to encourage early flowering of delayed sweetpotato genotype, and to ascertain the ideal concentration of growth regulators for sweetpotato flowering induction. A randomized complete block design with three replications was fitted with a 3x3x2 factorial arrangement. The first factor consisted of three different concentrations of two plant growth regulators (PGR): silver thiosulphate (STS) and 6-benzyladenine (BA) (0, 50, and 100 ppm). Three types of sweet potatoes (Umuspo3, Buttermilk, and Tis87) constituted the second factor. After planting, the BA and STS were administered three weeks later. The sweet potato varieties sprayed with STS and BA displayed morphological and physiological challenges, such as stem drooping (Temporal) (Page 1A), which recovered in 24 hours, root swelling, stem splitting, bud and flower production, vine branching, and elongation (Plate 1B). Varieties sprayed with high concentrations of STS (100 ppm) displayed significant morphological and physiological abnormalities, while those sprayed with BA displayed a significant increase in all growth metrics. However, two of the varieties Umuspo3 and Tis87 that were sprayed with STS and BA began buds and set flowers within two weeks after the treatment, whereas the plants that were not sprayed did not flower at all. The results of the interactions showed that the combination of benzyladenine + Umuspo3 at 100% (100T1V1) was superior for yield, whereas the combination of silver thiosulphate + Umuspo3 at 100% (100T2V1) was superior for the total number of flowers/plant. The vegetative growth parameters and the flowering characteristic exhibited a substantial positive connection (P<0.05), however the correlation between the vegetative growth traits and the yield traits was negative. As a result, the higher dosage of BA and STS (100 ppm) that was employed in this experiment is most likely quite near to the ideal concentration for sweet potato flower induction. Despite not being the ideal concentration, sweet potatoes can currently be induced to flower at this level, enabling the start of breeding programs for the crop.

Scenic perennial plants classification

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Long-distance control of potato storage organ formation by SELF PRUNING 3D and FLOWERING LOCUS T-like 1

Plants program their meristem-associated developmental switches for timely adaptation to a changing environment. Potato (Solanum tuberosum L.) tubers differentiate from specialized belowground branches or stolons through radial expansion of their terminal ends. During this process, the stolon apex and closest axillary buds enter a dormancy state that leads to tuber eyes, which are reactivated the following spring and generate a clonally identical plant. The potato FLOWERING LOCUS T homolog SELF-PRUNING 6A (StSP6A) was previously identified as the major tuber-inducing signal that integrates day-length cues to control the storage switch. However, whether some other long-range signals also act as tuber organogenesis stimuli remains unknown. Here, we show that the florigen SELF PRUNING 3D (StSP3D) and FLOWERING LOCUS T-like 1 (StFTL1) genes are activated by short days, analogously to StSP6A. Overexpression of StSP3D or StFTL1 promotes tuber formation under non-inductive long days, and the tuber-inducing activity of these proteins is graft transmissible. Using the non-tuber-bearing wild species Solanum etuberosum, a natural SP6A null mutant, we show that leaf-expressed SP6A is dispensable for StSP3D long-range activity. StSP3D and StFTL1 mediate secondary activation of StSP6A in stolon tips, leading to amplification of this tuberigen signal. StSP3D and StFTL1 were observed to bind the same protein partners as StSP6A, suggesting that they can also form transcriptionally active complexes. Together, our findings show that additional mobile tuber-inducing signals are regulated by the photoperiodic pathway.

Leaves and stolons transcriptomic analysis provide insight into the role of phytochrome F in potato flowering and tuberization.

Photoperiod plays a critical role in controlling the formation of sexual or vegetative reproductive organs in potato. Although StPHYF-silenced plants overcome day-length limitations to tuberize through a systemic effect on tuberigen StSP6A expression in the stolon, the comprehensive regulatory network of StPHYF remains obscure. Therefore, the present study investigated the transcriptomes of StPHYF-silenced plants and observed that, in addition to known components of the photoperiodic tuberization pathway, florigen StSP3D and other flowering-related genes were activated in StPHYF-silenced plants, exhibiting an early flowering response. Additionally, grafting experiments uncovered the long-distance effect of StPHYF silencing on gene expression in the stolon, including the circadian clock components, flowering-associated MADSs, and tuberization-related regulatory genes. Similar to the AtFT-AtAP1 regulatory module in Arabidopsis, the present study established that the AP1-like StMADS1 functions downstream of the tuberigen activation complex (TAC) and that suppressing StMADS1 inhibits tuberization invitro and delays tuberization invivo. Moreover, the expression of StSP6A was downregulated in StMADS1-silenced plants, implying the expression of StSP6A may be feedback-regulated by StMADS1. Overall, these results reveal that the regulatory network of StPHYF controls flowering and tuberization and targets the crucial tuberization factor StMADS1 through TAC, thereby providing a better understanding of StPHYF-mediated day-length perception during potato reproduction.

Morphological and anatomical characterization of yellow diploid potato flower for effective breeding program

The diploid yellow potato (Solanum tuberosum L. Phureja Group) is an important plant genetic resource. In this study, we report for the first time the characterization of anther development and pollen formation in the cultivar Criolla Colombia. The description of morphological and histological characters of buds and flowers at different developmental stages permitted to identify ten main stages, from the differentiation of the male cells of the sporangium, meiosis, microspores formation and maturation, to the release of mature pollen. In addition, the results provide a graphic guide of the development of the anther, through the sequential and orderly formation of the epidermis, the endothecium, the middle layer and the nutritive layer or tapetum. This microanatomical information will be useful for work focused on androgenesis and identification of gene regulation in floral biology and gamete formation. Therefore, this study determined that to efficiently obtain haploids, flower buds between 5 and 8.9 mm long (stage 6 to 8) should be used, in which tetrads and microspores are in the early uninucleate and binucleate stage.

The StBBX24 protein affects the floral induction and mediates salt tolerance in Solanum tuberosum.

The transition from vegetative growth to reproductive development is a critical developmental switch in flowering plants to ensure a successful life cycle. However, while the genes controlling flowering are well-known in model plants, they are less well-understood in crops. In this work, we generated potato lines both silenced and overexpressed for the expression of StBBX24, a clock-controlled gene encoding a B-box protein located in the cytosol and nuclear chromatin fraction. We revealed that Solanum tuberosum lines silenced for StBBX24 expression displayed much earlier flowering than wild-type plants. Conversely, plants overexpressing StBBX24 mostly did not produce flower buds other than wild-type plants. In addition, RT-qPCR analyses of transgenic silenced lines revealed substantial modifications in the expression of genes functioning in flowering. Furthermore, S. tuberosum lines silenced for StBBX24 expression displayed susceptibility to high salinity with a lower capacity of the antioxidant system and strongly decreased expression of genes encoding Na+ transporters that mediate salt tolerance, contrary to the plants with StBBX24 overexpression. Altogether, these data reveal that StBBX24 participates in potato flowering repression and is involved in salt stress response.

Transcription factor StABI5-like 1 binding to the FLOWERING LOCUS T homologs promotes early maturity in potato

Potato (Solanum tuberosum L.) maturity involves several important traits, including the onset of tuberization, flowering, leaf senescence, and the length of the plant life cycle. The timing of flowering and tuberization in potato is mediated by seasonal fluctuations in photoperiod and is thought to be separately controlled by the FLOWERING LOCUS T-like (FT-like) genes SELF-PRUNING 3D (StSP3D) and SELF-PRUNING 6A (StSP6A). However, the biological relationship between these morphological transitions that occur almost synchronously remains unknown. Here, we show that StABI5-like 1 (StABL1), a transcription factor central to abscisic acid (ABA) signaling, is a binding partner of StSP3D and StSP6A, forming an alternative florigen activation complex and alternative tuberigen activation complex in a 14-3-3-dependent manner. Overexpression of StABL1 results in the early initiation of flowering and tuberization as well as a short life cycle. Using genome-wide chromatin immunoprecipitation sequencing and RNA-sequencing, we demonstrate that AGAMOUS-like and GA 2-oxidase 1 genes are regulated by StABL1. Phytohormone profiling indicates an altered gibberellic acid (GA) metabolism and that StABL1-overexpressing plants are insensitive to the inhibitory effect of GA with respect to tuberization. Collectively, our results suggest that StABL1 functions with FT-like genes to promote flowering and tuberization and consequently life cycle length in potato, providing insight into the pleiotropic functioning of the FT gene.

Genome-Wide Identification and Expression Analysis of the MADS-Box Gene Family in Sweet Potato [Ipomoea batatas (L.) Lam

MADS-box gene, one of the largest transcription factor families in plants, is a class of transcription factors widely present in eukaryotes. It plays an important role in plant growth and development and participates in the growth and development of flowers and fruits. Sweet potato is the seventh most important food crop in the world. Its tuberous roots, stems, and leaves contain a large number of proteins, lipids, carotenoids, anthocyanins, conjugated phenolic acids, and minerals, which have high edible, forage, and medicinal value, and is also an important energy crop. At present, MADS-box genes in sweet potato have rarely been reported, and there has been no study on the genome-wide identification and classification of MADS-box genes in Ipomoea batatas. This study provided the first comprehensive analysis of sweet potato MADS-box genes. We identified 95 MADS-box genes, analyzed the structure and protein of sweet potato MADS-box genes, and categorized them based on phylogenetic analysis with Arabidopsis MADS-box proteins. Chromosomal localization indicated an unequal number of MADS-box genes in all 14 chromosomes except LG3, with more than 10 MADS-box genes located on chromosomes LG7, LG11, and LG15. The MADS domain and core motifs of the sweet potato MADS-box genes were identified by motif analysis. We identified 19 MADS-box genes with collinear relationships and analyzed duplication events. Cis-acting elements, such as light-responsive, auxin-responsive, drought-inducible, and MeJA-responsive elements, were found in the promoter region of the MADS-box genes in sweet potato, which further indicates the basis of MADS-box gene regulation in response to environmental changes and hormones. RNA-seq suggested that sweet potato MADS-box genes exhibit tissue-specific expression patterns, with 34 genes highly expressed in sweet potato flowers and fruits, and 19 genes highly expressed in the tuberous root, pencil root, or fibrous root. qRT-PCR again validated the expression levels of the 10 genes and found that IbMADS1, IbMADS18, IbMADS19, IbMADS79, and IbMADS90 were highly expressed in the tuberous root or fibrous root, and IbMADS18, IbMADS31, and IbMADS83 were highly expressed in the fruit. In this study, the molecular basis of MADS-box genes of sweet potato was analyzed from various angles. The effects of MADS-box genes on the growth and development of sweet potato were investigated, which may provide a certain theoretical basis for molecular breeding of sweet potato.

The effects of flower removal and earthing up on tuber yield and quality of potato (Solanum tuberosum L.)

A field experiment was conducted in Eastern Tigray, Ethiopia, during the summer season to determine the effects of flower removal and earthing up time on the tuber yield and quality of potato (Solanum tuberosum L.). The experiment comprised three flower removal stages and five earthing up time treatments, which were laid out in a randomized complete block design (RCBD) of a 5x3 factorial arrangement with three replications. Data collected on tuber yield and quality parameters were analyzed using SAS version 9.2. The interaction of flower removal stages and earthing up time treatments affected marketable and unmarketable tuber number and yield, total tuber number and yield, large-sized tuber weight, and number of large-sized tubers. The medium and small-sized tubers were also affected by main treatments but not by their interaction treatments. Similarly, dry matter content was significantly (p<0.05) affected by flower removal alone, but not by earthing up time and its interaction with flower removal. Generally, the highest marketable tuber yield (30.25 t ha-1), large-sized tuber weight (424.9 g), the number of large-sized tubers (5), and total tuber yield (30.96 t ha-1) were recorded in the treatment of potato flower removed at the bud stage and earthed up at 15 days after complete emergence. Therefore, the removal of potato flowers at the bud stage and earthing up at 15 days after complete emergence and common cultivation can be practiced for better tuber yield and quality of potato.

Temperature effect on yield of winter and spring irrigated crops

Extreme weather conditions, such as low and high air temperature changes during the growing season, play a significant role in irrigated crop yield. In this study an iterative chi-square statistical method was used to determine the relationship between air temperature and yield of dominant winter and spring irrigated crops in Shahrekord, Iran. Long term daily weather (1991–2016) and annual crop yield (wheat, barley, potato, alfalfa) data were analyzed and the relationships between low and high crop yield years with maximum and minimum air temperatures was evaluated. Our results indicated that higher temperature during tillering, dormancy breaking and stem elongation (fewer number of days with Tmax ≤ 5 °C and greater number of days with Tmax > 20 °C) and colder temperature in short time before dormancy breaking led to wheat yield loss. Cold weather during germination, seedling growth and tillering (greater number of days with Tmax ≤ 0 °C and excess nights with Tmin ≤ −20 °C) as well as cold temperature during breaking dormancy and kernel dough development (fewer days with Tmax > 25 °C) caused to reduce the barely grain yield. Warmer nights during potato flowering, development of fruit and mid-stage of tuber formation (excess days with Tmin > 10 °C) and cooler days during potato senescence (greater number of days with Tmax ≤ 20 °C) reduced potato tuber yield. Cool weather during emergence of first flower buds and first flowering stages (greater number of days with Tmax ≤ 20 °C) led to forage yield loss of alfalfa. Determination of critical periods when these crops are most sensitive to air temperature extremes provides important information for modifying management practices, such as adjusting planting date in order to reduction the negative effects of temperature extremes on crop yield. This information will also be useful for predicting crop yields in different years.

High light accelerates potato flowering independently of the FT-like flowering signal StSP3D

Little is known on the environmental control of potato flowering. With recent developments in potato breeding, and the growing interest in true potato seed production, more knowledge on potato flowering is required. This research aims to elucidate the effect of the daily light integral (DLI: the accumulated light throughout a day) on potato flower initiation time and investigate which mechanisms underlie this control. We grew potato plants in climate chambers to compare flower initiation under different DLIs in short and long days. We measured the time until the first appearance of the flower buds and the number of leaves formed before the inflorescence. Furthermore, gene expression changes of the potato flowering time gene StSP3D were measured, and potato plants silenced in StSP3D were used to determine whether DLI mediated flowering time was regulated through StSP3D. Additionally, we determined sucrose and starch concentrations and measured the transcription levels of StTPS1, a gene involved in sugar mediated flowering control. Increasing DLI clearly accelerated flowering in potato. The role of carbohydrates (sucrose and starch) and StTPS1 in DLI-accelerated flowering was inconclusive. Although StSP3D was upregulated under high DLI, transgenic lines silenced in StSP3D also showed accelerated flowering under higher DLIs. We therefore conclude that high DLI accelerates potato flowering and this acceleration happens independently of StSP3D upregulation.

The tuberization signal StSP6A represses flower bud development in potato.

Potato (Solanum tuberosum L.) can reproduce sexually through flowering and asexually through tuberization. While tuberization has been thoroughly studied, little research has been done on potato flowering. Flower bud development in the strictly short-day tuberizing S. tuberosum group Andigena is impaired under short-day conditions. This impaired development may indicate that tuberization negatively influences flowering. Here, we determine how tuberization affects flower bud development. To find out whether the absence of tubers improves flowering, we prevented tuberization by: (i) grafting potato scions onto wild potato rootstocks, which were unable to form tubers; (ii) removing stolons, the underground structures on which tubers form; and (iii) using plants that were silenced in the tuberization signal StSP6A. Additionally, transgenic plants with increased StSP6A expression were used to determine if flower bud development was impaired. The absence of a tuber sink alone did not accelerate flower bud development, nor did it allow more plants to reach anthesis (open flowering stage) or have more open flowers. Interestingly, reducing StSP6A expression improved flower bud development, and increasing expression impaired it. Our results show that flower bud development in potato is repressed by the tuberization signal StSP6A, and not by competition with the underground tuber sink.

Evolutionary History of the Glycoside Hydrolase 3 (GH3) Family Based on the Sequenced Genomes of 48 Plants and Identification of Jasmonic Acid-Related GH3 Proteins in Solanum tuberosum.

Glycoside Hydrolase 3 (GH3) is a phytohormone-responsive family of proteins found in many plant species. These proteins contribute to the biological activity of indolacetic acid (IAA), jasmonic acid (JA), and salicylic acid (SA). They also affect plant growth and developmental processes as well as some types of stress. In this study, GH3 genes were identified in 48 plant species, including algae, mosses, ferns, gymnosperms, and angiosperms. No GH3 representative protein was found in algae, but we identified 4 genes in mosses, 19 in ferns, 7 in gymnosperms, and several in angiosperms. The results showed that GH3 proteins are mainly present in seed plants. Phylogenetic analysis of all GH3 proteins showed three separate clades. Group I was related to JA adenylation, group II was related to IAA adenylation, and group III was separated from group II, but its function was not clear. The structure of the GH3 proteins indicated highly conserved sequences in the plant kingdom. The analysis of JA adenylation in relation to gene expression of GH3 in potato (Solanum tuberosum) showed that StGH3.12 greatly responded to methyl jasmonate (MeJA) treatment. The expression levels of StGH3.1, StGH3.11, and StGH3.12 were higher in the potato flowers, and StGH3.11 expression was also higher in the stolon. Our research revealed the evolution of the GH3 family, which is useful for studying the precise function of GH3 proteins related to JA adenylation in S. tuberosum when the plants are developing and under biotic stress.

Host-plant location by the Guatemalan potato moth Tecia solanivora is assisted by floral volatiles

Insects locate their host plants using mainly visual and olfactory cues, generally of the exploited plant structure. However, when the resource is difficult to access, it could be beneficial to utilise indirect cues, which indicates the presence of reward (e.g., oviposition site or mate). In the present study, we investigated the host-plant location strategy of the monophagous Guatemalan potato moth Tecia solanivora (Lepidoptera: Gelechiidae). The larva of the moth feed exclusively on potato Solanum spp. (Solanaceae) tubers usually hidden below ground. Using electrophysiological and behavioural tests, we characterised the olfactory cues mediating the attraction of the moth towards their host plant. Odour blends were made to represent different potato structures: tubers, foliage, and flowers. Synthetic blends were created by combining potato-emitted compounds that were antennal active which showed positive dose–response. Attraction to these blends of compounds in relation to the mating status of males and females was tested in dual-choice Y-tube assays. Both males and females, virgin and mated, were attracted to a three-compound blend representing flower odour, while foliage and tuber blends attracted neither sexes. Oviposition bioassays indicated additionally that the floral blend enhances oviposition. We show that potato flower odour might indicate the presence of an oviposition site for the female and possibly an increased mating opportunity for both sexes. Our results provide one of the few examples of the use of floral odour as a reliable indicator of host and probably mating possibility for phytophagous insects exploiting a site spatially separated from the flower.

Bee Community of Commercial Potato Fields in Michigan and Bombus impatiens Visitation to Neonicotinoid-Treated Potato Plants.

We conducted a bee survey in neonicotinoid-treated commercial potato fields using bowl and vane traps in the 2016 growing season. Traps were placed outside the fields, at the field edges, and 10 and 30 m into the fields. We collected 756 bees representing 58 species, with Lasioglossum spp. comprising 73% of all captured bees. We found seven Bombus spp., of which B. impatiens was the only known visitor of potato flowers in our region. The majority of the bees (68%) were collected at the field edges and in the field margins. Blue vane traps caught almost four-times as many bees and collected 30% more species compared to bowl traps. Bee communities did not differ across trap locations but they were different among trap types. We tested B. impatiens visitation to neonicotinoid treated and untreated potato flowers in field enclosures. The amount of time bees spent at flowers and the duration of visits were not significantly different between the two treatments. Our results demonstrate that a diverse assemblage of bees is associated with an agroecosystem dominated by potatoes despite the apparent lack of pollinator resources provided by the crop. We found no difference in B. impatiens foraging behavior on neonicotinoid-treated compared to untreated plants.

Comparative genome-wide phylogenetic and expression analysis of SBP genes from potato (Solanum tuberosum)

Flowering time is a very important phase in transition to reproductive stage of life in higher plants. SQUAMOSA promoter-binding protein (SBP) gene family encodes plant-specific transcription factors that are involved in regulation of several developmental processes, especially flowering. Although SBP-box genes have been identified in different plants, there have been no study indicating the regulatory effect of SBP box in potato flowering. Here, we report for the first time the identification and characterization of SBP-box transcription factors as well as determination of expression level of SBP-box genes in Solanum tuberosum L. an important crop worldwide. Fifteen different SBP-box transcription factor genes were identified in potato genome. They were found to be distributed in nine chromosomes and eight of them included miR156 and miRNA157 target sites. Characterization of amino acid sequences were performed and protein interactions were predicted. In addition, expression levels of five S. tuberosum SBP-box genes were analysed by both in silico and qRT-PCR. All these results provide a better understanding of functional role of SBP-box gene family members in flowering time in potato.

Regulating flower and tuber formation in potato with light spectrum and day length

Solanum tuberosum (potato) can reproduce through tubers and through seeds. Recent developments have enabled hybrid breeding and propagation from seeds in this crop. This makes potato flowering a new focus of research interest. Tuberization and presumably flowering, followed by seed set, are strongly regulated by environmental cues. A well-studied environmental regulator of tuber formation is day length. Photoreceptors are involved in this photoperiodic control of tuberization, suggesting light spectrum may be an important factor for tuberization. However, it is not known how photoreceptors control potato flowering. Here, we aim to elucidate the influence of light spectrum and photoperiod on tuber and flower formation, by growing three potato genotypes in climate chambers with light-emitting diode (LED) lighting and additional far-red and blue LEDs under long and short days. Far-red light accelerated tuber formation up to eleven days and blue light slightly delayed it up to four days. An effect of light spectrum on flowering was not found. Long photoperiods delayed tuber formation compared to short-day conditions in two of the three tested genotypes. Aside from one genotype which only flowered in long-days, no effect of photoperiod on flowering was found.

Effect of Drying Methods on the Steroidal Alkaloid Content of Potato Peels, Shoots and Berries.

The present study has found that dried potato samples yielded significantly higher levels of steroidal alkaloids such as α-solanine and α-chaconine than the corresponding fresh samples, as determined by the UPLC-MS/MS technique. Among the drying techniques used, air drying had the highest effect on steroidal alkaloid contents, followed by freeze drying and vacuum oven drying. There was no significant difference between the freeze dried and vacuum oven dried samples in their α-chaconine contents. However, freeze dried potato shoots and berries had significantly higher α-solanine contents (825 µg/g dry weight (DW) in shoots and 2453 µg/g DW in berries) than the vacuum oven dried ones (325 µg/g dry weight (DW) in shoots and 2080 µg/g DW in berries). The kinetics of steroidal alkaloid contents of potato shoots during air drying were monitored over a period of 21 days. Both α-solanine and α-chaconine content increased to their maximum values, 875 µg/g DW and 3385 µg/g DW, respectively, after 7 days of drying. The steroidal alkaloid contents of the shoots decreased significantly at day 9, and then remained unchanged until day 21. In line with the potato shoots, air dried potato tuber peels also had higher steroidal alkaloid content than the freeze dried and vacuum oven dried samples. However, a significant decrease of steroidal alkaloid content was observed in air dried potato berries, possibly due to degradation during slicing of the whole berries prior to air drying. Remarkable variation in steroidal alkaloid contents among different tissue types of potato plants was observed with the potato flowers having the highest content.

Effects of fertilizer application on water consumption characteristics and yield of potato cultured under ridge-furrow and whole filed plastic mulching in rain-fed area.

Chemical fertilizer reduction and organic manure substitution are the useful methods to increase potato water-and nutrient use efficiency, which is cultured under ridge-furrow and whole soil surface mulched by plastic film in semiarid rain-fed area. A 4-year field experiment was carried out from 2011 to 2014 with three treatments: 1) traditional chemical fertilizer application (F), 2) chemical nitrogen fertilizer reduced by 25% and dressing at flowering stage (DF), and 3) chemical nitrogen fertilizer reduced by 50% and organic manure substitution (OF). The soil moisture and potato yield were investigated, and seasonal water consumption, water use efficiency (WUE) were calculated to study the regulations of different nutrient management methods on potato water use process, as well as its effects on potato tuber yield and WUE. The results showed that soil water storage in potato flowering stage was the highest under DF treatment, but there were no significant difference among these three treatments. The depth of soil water depletion in DF and OF showed an increasing trend at post-flowering stage. Potato water consumption decreased significantly at pre-flowering stage, but increased by 36.2%, 23.2%, 24.8% and 19.0% respectively at post-flowering stage in 2011-2014 under DF treatment, as compared with those under F treatment. OF treatment increased potato water consumption by 20.7% and 16.3% than that under F treatment at post-flowering stage from 2011 to 2012, respectively, but exerted no significant effect at pre-flowering stage. Compared with F, DF increased potato tuber yield averagely by 2595.1 kg·hm-2 from 2012 to 2014 and significantly increased the WUE by 14.4% and 6.3% in 2013 and 2014, respectively; OF significantly increased potato tuber yield averagely by 2945 kg·hm-2 tuber yield in 4 experimental years and WUE was significantly higher than that under F from 2012 to 2014. It was indicated that both DF and OF could regulate water consumption between pre-flowering and post-flowering stages, and increase potato tuber yield and WUE. OF showed more significant effects than DF on the increment of tuber yield and WUE.