Tuber Initiation Stage Research Articles

Improving Potato Yield Prediction by Combining Cultivar Information and UAV Remote Sensing Data Using Machine Learning

Accurate high-resolution yield maps are essential for identifying spatial yield variability patterns, determining key factors influencing yield variability, and providing site-specific management insights in precision agriculture. Cultivar differences can significantly influence potato (Solanum tuberosum L.) tuber yield prediction using remote sensing technologies. The objective of this study was to improve potato yield prediction using unmanned aerial vehicle (UAV) remote sensing by incorporating cultivar information with machine learning methods. Small plot experiments involving different cultivars and nitrogen (N) rates were conducted in 2018 and 2019. UAV-based multi-spectral images were collected throughout the growing season. Machine learning models, i.e., random forest regression (RFR) and support vector regression (SVR), were used to combine different vegetation indices with cultivar information. It was found that UAV-based spectral data from the early growing season at the tuber initiation stage (late June) were more correlated with potato marketable yield than the spectral data from the later growing season at the tuber maturation stage. However, the best performing vegetation indices and the best timing for potato yield prediction varied with cultivars. The performance of the RFR and SVR models using only remote sensing data was unsatisfactory (R2 = 0.48–0.51 for validation) but was significantly improved when cultivar information was incorporated (R2 = 0.75–0.79 for validation). It is concluded that combining high spatial-resolution UAV images and cultivar information using machine learning algorithms can significantly improve potato yield prediction than methods without using cultivar information. More studies are needed to improve potato yield prediction using more detailed cultivar information, soil and landscape variables, and management information, as well as more advanced machine learning models.

Promotion of potato yield under moderate water deficiency at the seedling stage by modifying sink-source relationship

ABSTRACT Water deficiency is the main bottleneck in potato production in many regions worldwide. The generation of higher tuber yields per unit of water is a key goal for both agronomists and potato growers. In this study, we found that under moderate deficit irrigation (DI; 50% relative water content (RWC)) at the seedling stage of potato growth, the leaf area index (LAI) and dry matter accumulation were lower than control; however, they caught up with and surpassed the control at later developmental stages with a normal water supply, and a higher yield was ultimately achieved. The LAI and total dry weight under severe water stress (35% RWC) also surpassed the control at harvest; however, the final yield remained low, due to the low distribution of dry matter into the tubers. Abscisic acid (ABA) increased under DI conditions at the seedling stage, while gibberellin (GA1 and GA3) levels decreased. Moreover, endogenous ABA increased as plant development proceeded from seedling stage to tuber initiation stage, regardless of water stress. Exogenous ABA application promoted dry matter accumulation and distribution into the tubers. Therefore, it may be that ABA, as a major signaling molecule, mediates water stress to regulate tuber sink capacity at early development period. Through a feedback regulation stronger source capacity was stimulated by sink enhancement mediated by moderate water stress at the seedling stage, reached a higher tuber yield finally by reestablishment of sink-source relationship.

Use of GreenSeeker and CM-100 as manual tools for nitrogen management and yield prediction in irrigated potato (Solanum tuberosum) production

This study evaluated the possibility of the use of GreenSeeker sensor and CM-100 chlorophyll content meter for in-season N and yield prediction in order to promote timely split N application in potato production in Kenya. Four N-fertilization rates; N0 (0), N1 (60), N2 (90) and N3 (130 kg N/ha) were led out in a Randomized Complete Block Design (RCBD) in a Greenhouse for two seasons. The results showed that % N leaf content was significantly affected by N rates. The % N leaf content and potato leaf chlorophyll content decreased as the season continued whereas the Normalized Difference Vegetation Index (NDVI) increased as the season continued. CM-100 values were significantly correlated with % N leaf content at vegetative (r=0.86***) and tuber initiation (r=0.74***) growth stages of the crop whereas the NDVI values were only significantly correlated with % N leaf at tuber initiation (r=0.82***). A significant relationship was found between CM-100 values taken at different potato stages (end of vegetative, tuber initiation, bulking and maturation stages) and tuber yield (r=0.90***, 0.82***, 0.47* and 0.41*). The NDVI values at end of vegetative growth, tuber initiation and maturation of potato were also significantly correlated with tuber yield (r=0.81***, 0.43* and 0.54*), except at bulking stage (r=0.33). For efficient in-season N management and yield prediction, CM-100 and GreenSeeker are recommended at an early stage of the crop. Further research in the different potato growing areas in Kenya to establish the different thresholds at different potato growth stages is recommended.

Role of Tuber Developmental Processes in Response of Potato to High Temperature and Elevated CO2.

Potato is adapted to cool environments, and there is concern that its performance may be diminished considerably due to global warming and more frequent episodes of heat stress. Our objectives were to determine the response of potato plants to elevated CO2 (700 μmol/mol) and high temperature (35/25 °C) at tuber initiation and tuber bulking, and to elucidate effects on sink developmental processes. Potato plants were grown in controlled environments with treatments at: Tuber initiation (TI), during the first two weeks after initiating short-day photoperiods, and Tuber bulking (TB). At TI, and 25 °C, elevated CO2 increased tuber growth rate, while leaves and stems were not affected. Whole-plant dry matter accumulation rate, was inhibited by high temperature about twice as much at TI than at TB. Elevated CO2 partially ameliorated high temperature inhibition of sink organs. At TI, with 25 °C, elevated CO2 primarily affected tuber cell proliferation. In contrast, tuber cell volume and endoreduplication were unaffected. These findings indicate that the TI stage and cell division is particularly responsive to elevated CO2 and high temperature stress, supporting the view that attention should be paid to the timing of high-temperature stress episodes with respect to this stage.

Quantifying Solanum chacoense root morphology responses to limited nitrogen supply using in vitro, hydroponic, and field monolith methods

Solanum chacoense Bitt. (chc) is a short-day adapted wild diploid (2n = 2x = 24) species, relative of the commercial potato S. tuberosum L. (tbr), that has demonstrated higher below-ground biomass when cultivated under limited nitrogen (N) supply, suggesting it possesses greater potential for N recovery by increasing root length density (RLD). The objectives of this study were to compare screening methodologies for evaluating RLD responses of chc genotypes and tbr cultivars under limited N supply for the identification of superior rooting chc genotypes. Seventeen genotypes of chc and three commercial tbr varieties were exposed to 0.5 and 1.0 N rates across three root screening methodologies: in vitro, hydroponic, and field evaluated at tuber initiation and plant maturity stages. Although the development of a reliable high throughput root screening system was unachievable due to differences in environment and root sampling protocols across methodologies, there were significant positive correlations amongst RLD for a majority of methods in both chc and tbr. This suggests that RLD can be utilized for evaluating both Solanum species and genotypes within species and environments. RLD for chc 0048-34 and 0053-7 genotypes were significantly higher than tbr cultivars in all tested methods indicating that chc possesses the potential for increasing N recovery in future breeding with tbr.

Volunteer potato interference and removal timing in sugar beet

AbstractField studies were conducted from 2005 to 2009 in Idaho and Oregon to 1) evaluate the competitive effect of volunteer potato on sugar beet yield (volunteer potato competition experiment), and 2) determine the optimum timing of volunteer potato removal from glyphosate-tolerant sugar beet fields using glyphosate (volunteer potato removal timing experiment). The volunteer potato competition experiment consisted of eight potato densities, including the untreated check: 0, 6,741, 10,092, 13,455, 16,818, 20,184, 26,910, and 40,365 tubers ha−1. The volunteer potato removal experiment consisted of 10 removal timings (including the untreated check) ranging from the 10-cm rosette stage to mid-tuber bulking. There was a linear decrease in sugar beet root and sucrose yield as volunteer potato density increased (P < 0.001) such that with every volunteer potato tuber per square meter, sugar beet root yield decreased by 15% and sucrose yield decreased by 14%. At the highest volunteer potato density (40,365 tubers ha−1), sugar beet root yield was 29,600 kg ha−1 (compared to 73,600 kg ha−1 for the untreated), representing a 60% reduction in sugar beet root yield. In the removal timing study, a one-time application of glyphosate at the 10-cm rosette, hooking, and tuber initiation stages provided 74% to 98% reduction in volunteer potato tuber biomass. Delaying volunteer potato removal beyond the tuber initiation stage reduced sugar beet root and sucrose yield (12% to 20%), resulting in an economic loss of $104 to $161 per hectare. The best potato removal timing that optimizes the trade-off between improved control and potential for sugar beet yield reductions is before or at the tuber initiation stage.

Determination of Suitable Deficit Irrigation Stage in Potato Production

Water deficiency is the major limiting factor for potato yield promotion. Increasing tuber yield and decreasing consumption of water at the same time are a challenge in development of new potato cultivar. Deficit irrigation is regarded as one of the promising approaches to solve this problem, however no practical technique has been proposed in potato production as yet. By setting different deficient irrigation regimes and investigating potato growth and water use efficiency, we found that only application of deficit irrigation at the seedling stage could achieve the goal of increasing water use efficiency and maintaining marketable tuber yield at the same time. Almost half of the normal full irrigation doubled promotion effects on water efficiency and yield, especially the marketable tuber yield. This may be mainly attributed to establishment of a strong root system, including longer root length and larger root surface area under water deficit at the seedling stage. Based on such a root system at the early development stage, leaf area index and dry matter accumulation were optimized at the later developmental stages. Thus, maintaining water deficit at the seedling stage with enough water supplied at the tuber initiation and bulking stages should be practiced in potato production in water limited areas.

Yield Response of Determinate Chipping Potato to Artificial Defoliation.

The relationship between canopy defoliation by insects and yield loss in potato (Solanum tuberosum L.) has been extensively researched. However, detailed analysis of varieties with different properties and examination of methods of defoliation are still lacking. Absence of research results has led many producers to use a very conservative economic threshold (ET) of 10% defoliation in the management of insect defoliators. A series of leaf removal experiments was conducted on a determinate chipping variety of potato at different plant stages. In 2002, the highest levels of defoliation induced upon the plant canopy were 50, 30, and 75% for tuber initiation, full bloom, and plant maturity stages, respectively. In 2003, defoliation levels were increased to 70, 80, and 90% for tuber initiation, full bloom, and plant maturity, respectively. Total yield was unaffected, and no significant changes in market sized yield, or number of marketable tubers were observed at any growth stage in either year. Because the determinate variety showed remarkable ability to recover from substantial defoliation, two different methods of defoliation: hand cut (cutting the edge of leaves with scissors while avoiding the midrib) and hole punching (hole-punching leaf tissue [15.08-mm diameter] while avoiding midrib) were tested. Although total yield was unaffected, marketable yield and small potato yield were reduced, Thus, although defoliation methods must be considered, a 10% defoliation ET is exceedingly conservative and an ET of 60% for all stages of determinate chipping potato could be adopted by growers.

Plant growth promoting rhizobacteria alleviates drought stress in potato in response to suppressive oxidative stress and antioxidant enzymes activities

Maintenance of plant physiological functions under drought stress is normally considered a positive feature as it indicates sustained plant health and growth. This study was conducted to investigate whether plant growth-promoting rhizobacteria (PGPR) Bacillus subtilis HAS31 has potential to maintain potato growth and yield under drought stress. We analyzed trends of chlorophyll concentration, photosynthesis process, relative water content, osmolytes, antioxidants enzymes and oxidative stress, relative growth rate, tuber and aboveground biomass production in two potato varieties, Santae (drought-tolerant) and PRI-Red (drought-sensitive). Plants of both genotypes were treated with 100 g of HAS31 inoculant at 10 days after germination and exposed to different soil relative water contents (SRWC), including 80 ± 5% (well watered), 60 ± 5% (moderate stress) and 40 ± 5% SRWC (severe stress) for 7 days at tuber initiation stage (30 days after germination). The drought stress reduced plant relative growth rate, biomass production, leaf area, number of leaves and tubers, tuber weight, and final yield. The drought-stressed plants showed decline in chlorophyll contents, membrane stability, leaf relative water contents and photosynthetic rate. Under drought stress, enzymatic activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD), contents of total soluble sugars, soluble proteins and proline increased. The application of PGPR reduced the impact of drought and maintained higher growth and physio-chemical traits of the plants. The plants with PGPR application showed higher relative growth rate, dry matter production, leaf area, number of tubers, tuber weight and yield as compared to plants without PGPR. The PGPR-HAS31 treated plants maintained higher photosynthetic process, contents of chlorophyll, soluble proteins, total soluble sugars, and enzymatic activities of CAT, POD and SOD as compared to plants without PGPR. The results of the study suggest that plant growth regulators have ability to sustain growth and yield of potato under drought stress by maintaining physiological functions of the plants.

Nitrogen Fertilization Effects on the Composition of Foliar Amino Acids of Russet Burbank Potato

Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is an important pest of potato crops. Potato foliar amino acids play essential roles in CPB growth. In this study, amino acids were classified into four groups according to their different roles in promoting CPB growth. Then, nitrogen (N) rate effects on the concentrations of amino acid groups were investigated under field conditions. Experiments were carried out with five N rates of 0, 60, 120, 180, and 240 kg N ha−1 in a randomized complete block design. Twenty leaves were collected at 40, 54, 68, and 82 days after planting (DAP) for amino acids analysis. Results showed that N rate had no significant effect on concentrations of each amino acid group at 40 DAP. However, their concentrations linearly increased as N rate increased at 54, 68, and 82 DAP, suggesting that higher N rates could potentially favor CPB growth after potato enters tuber initiation stage.

Foliar application of glycinebetaine regulates soluble sugars and modulates physiological adaptations in sweet potato (Ipomoea batatas) under water deficit.

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 (11.75g plant-1) with 50mM GlyBet application was retained in a similar pattern to cv. Japanese Yellow (12.25g 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.

Split application improving sweetpotato yield by enhancing photosynthetic and sink capacity under reduced nitrogen condition

Injudicious nitrogen (N) fertilizer application has increased the risk of environmental pollution and decreased sweetpotato yield as well as farm profits in China. Appropriate N fertilizer management is beneficial for improving growth, and yield attributes of field crops. Field experiments were conducted to determine the effects of application methods [three N treatments-conventional basal application 100 kg N ha−1 as control (100:0) and two treatments which received a total of 80 kg N ha−1 applied either 100% at basal application (80:0), 50% at basal application and 50% at tuber initiation stage (35 days after transplanting, 40:40)] on the sweetpotato growth and yield formation for the first time during growing season 2015 and 2016. Two sweetpotato cultivars, Xushu 22 (XS22) and Shangshu 19 (SS19), were used in three N treatments. Although a reduced N rate decreased initiation biomass accumulated, splitting N relatively delayed late-season leaf senescence as indicated by the increased chlorophyll content, LAD, NAR and biomass accumulated during the intermediate and final growth phases compared to conventional basal application of 100 kg N ha-1. Compared to 100:0, sweetpotato yields were significantly lowered by the reduced applications of 80:0 (relative yield of 95.3% for XS22 and 94.3% for SS19, respectively) but were significantly increased by the split applications of 40:40 (relative yield of 117.2% and 118.9% for XS22 and SS19, respectively). The improved yield by split N was due to both enhanced canopy photosynthetic capacity with higher biomass products and increased sink with greater tuberous root numbers, higher biomass partition ratio to storage root and larger storage root weight. This indicates that split application of N was more beneficial in terms of better growth, balanced sink–source ratio and higher storage root yield under reduced N condition. Outcomes of this research will help producers schedule fertilization to maximize yield and nutrition use efficiency.

Effects of nitrogen fertilizer reduction management on photosynthesis and chlorophyll fluorescence characteristics of sweetpotato

Crop productivity depends on photosynthetic source capacity. Appropriate nitrogen (N) fertilizer management is beneficial for improving growth, photosynthetic capacity and thereby increasing crops yield. A two-year pot experiment was conducted with four N treatments, i.e., conventional basal application 100 kg N·hm-2 as control (FP), a total of 80 kg N·hm-2 applied either 100% at basal application (JS), 100% at tuber initiation stage (35 d after transplant, KS), 50% at basal application and 50% at tuber initiation stage (35 d after transplant, FS), to examine the effects of reduced nitrogen fertilizer combined with application methods on the photosynthesis and chlorophyll fluorescence characteristics of sweetpotato (Ipomoea batatas) during summer 2016 and 2017. The results showed that the conventional basal application of a reduced N rate decreased photosynthesis of sweetpotato during the final growth phases compared to conventional application, dressing application relatively delayed late-season leaf senescence as indicated by the increased net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci) and chlorophyll (Chl a+b) content during tuber expansion period. Split application of N fertilizer had noticeably higher Pn, gs, Ci and Chl a+b than other treatments. Furthermore, split application of N fertilizer had a significantly higher photochemical efficiency of photosystem 2 (Fv/Fm), quantum yield of electron transport (ΦPS2), and photochemical quenching co-efficient (qP), but lower initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ) during tuber expansion period. The improved photosynthesis by split N was due to both increased Fv/Fm with higher electron transfer rate and reduced thermal dissipation of light energy in the tuber expansion period. Results were consistent between two sweetpotato cultivars across years. The results indicated that one-time fertilization at basal or tuber initiation stage were not conducive to sweetpotato leaf photosynthesis. The split N application was more beneficial in terms of delaying late-season leaf senescence, extending leaf function period, enhancing photosynthesis and biomass production under reduced N application rate, which would be beneficial for sweetpotato yield.

Assessment of Yield and Yield Components of Starch Potato Cultivars (Solanum tuberosum L.) Under Nitrogen Deficiency and Drought Stress Conditions

Water and nitrogen (N) management is a key factor in starch potato (Solanum tuberosum L.) production to ensure good yield and quality. Due to its shallow root system, potato is sensitive to drought and N uptake is limited to the upper soil layer resulting in leaching of nitrate. Efficient utilization of N and water can be optimized by adaptation of the cropping system and by selection of improved genotypes. A 2-year pot experiment with 14 modern starch and 3 table potato cultivars was conducted under controlled conditions in a rain-out shelter in order to investigate genotype-dependent responses to N deficiency and drought stress with regard to yield and yield components. Plants were grown at two N levels and a short-term drought-stress period during the sensitive tuber initiation stage was applied. Starch yield under control condition reached an average of 80.2 g plant−1, which was reduced under drought stress by 18% at sufficient N supply and by 23% at N deficiency. Sufficient N fertilization improved the water use efficiency under both continuous water supply and drought stress. N limitation increased the N use efficiency (NUE) at continuous watering, while NUE was not affected by drought stress at sufficient N supply but decreased under N deficiency. Genotype and drought as well as genotype and N level interactions were significant for all investigated traits, i.e. tuber yield (fresh and dry matter), starch and NKjeldahl contents, starch yield and water consumption.

COMBINED ANALYSIS OF RADARSAT-2 SAR AND SENTINEL-2 OPTICAL DATA FOR IMPROVED MONITORING OF TUBER INITIATION STAGE OF POTATO

Abstract. Tuber initiation and tuber bulking stages are critical part of various phenological phases for potato production. Tuber initiation covers the period from the formation of spherical rhizome ends, the flowering and the start of tuber bulking. In general, the tuberization spans from 3 to 5 weeks after emergence and ends with the row closer i.e. canopies in adjacent rows touch each other across the furrow. Hence, this rapid growth seeks critical agronomic management practices such as irrigation and fertilization. It majorly influences the growth of stems, foliar area, dry weight and number of tubers particularly at the phase of tuber initiation. During these phenological stages, potato crops are susceptible to the infestation of late blight diseases caused by Phytophthora infestans and largely affects the potato production. Thus identifying the crop risk using remote sensing approaches can provide an efficient potato growth monitoring framework. In the context of monitoring crop dynamics, quad-pol Synthetic Aperture Radar (SAR) data has proven to be effective due to its sensitivity towards dielectric and geometric properties. In addition to SAR data, optical remote sensing data derived vegetation information can provide an improved insight into crop growth when combined with SAR data. In this research, quad-pol RADARSAT-2 and Sentinel-2 optical data are analyzed to monitor potato tuberization phase over Bardhaman district in the state ofWest Bengal, which is one of the major potato growing regions in India. The proposed approach uses polarimetric parameters such as backscatter intensities, ratio (HH/VV, VH/VV, linear depolarization ratio), and co-pol correlation (ρHH–VV) along with the vegetation indices derived from the Sentinel-2 data for understanding the spatio-temporal dynamics. The initial results show a promising accuracy in monitoring the dynamics of potato tuberization. Integration of such earth observation (EO) data, in conjunction with in-situ field measurements, might significantly enhance the current capabilities for crop monitoring.

Optimizing yield and economic returns of rain-fed potato (Solanum tuberosum L.) through water conservation under potato-legume intercropping systems

Even though potato (Solanum tuberosum L.)-based intercropping systems are widely practised in developing countries, only a few studies have focused on legumes as the companion intercrops. This study was conducted to assess the effect of incorporating legumes into the potato production system on ground cover, soil moisture content (SMC), tuber and legume yield, potato equivalent yield (PEY), gross and net income and benefit: cost ratio (BCR). The treatments comprised of pure potato stand (PS), potato-dolichos (Lablab purpureus L.) (PD), potato-garden pea (Pisum sativum L.) (PG) and potato-bean (Phaseolus vulgaris L.) (PB). Results indicated a significantly higher (69%) ground cover at tuber initiation stage in PD compared to 66% in PG and PB and 56% in PS. Similarly, the highest SMC values were recorded at tuber initiation stage: 230, 207, 201 and 188 mm m−1 in PD, PG, PB and PS, respectively. Fresh tuber yield was highest in PS (36 t ha−1) and PD (35 t ha−1) and lowest in PG (29 t ha−1). PEY was higher under intercropping than monocropping systems. Potato-dolichos was the most profitable intercropping system with a net income of US$ 9174 ha−1 and a BCR of 5.7 compared to PS (US$ 7436 ha−1) with a BCR of 5.1. The study showed that dolichos is a promising legume crop that could be integrated into potato cropping systems to improve CWP without compromising the tuber yield.

Overexpression of StNF-YB3.1 reduces photosynthetic capacity and tuber production, and promotes ABA-mediated stomatal closure in potato (Solanum tuberosum L.)

Nuclear factor Y (NF-Y) is one of the most ubiquitous transcription factors (TFs), comprising NF-YA, NF-YB and NF-YC subunits, and has been identified and reported in various aspects of development for plants and animals. In this work, StNF-YB3.1, a putative potato NF-YB subunit encoding gene, was isolated from Solanum tuberosum by rapid amplification of cDNA ends (RACE). Overexpression of StNF-YB3.1 in potato (cv. Atlantic) resulted in accelerated onset of flowering, and significant increase in leaf chlorophyll content in field trials. However, transgenic potato plants overexpressing StNF-YB3.1 (OEYB3.1) showed significant decreases in photosynthetic rate and stomatal conductance both at tuber initiation and bulking stages. OEYB3.1 lines were associated with significantly fewer tuber numbers and yield reduction. Guard cell size and stomatal density were not changed in OEYB3.1 plants, whereas ABA-mediated stomatal closure was accelerated compared to that of wild type plants because of the up-regulation of genes for ABA signaling, such as StCPK10-like, StSnRK2.6/OST1-like, StSnRK2.7-like and StSLAC1-like. We speculate that the acceleration of stomatal closure was a possible reason for the significantly decreased stomatal conductance and photosynthetic rate.

Ambient and Elevated Ozone (O3) impacts on Potato Genotypes (Solanum tuberosum.L) over a high altitude Western Ghats location in Southern India

<div><p><em>Globally, next to CO<sub>2</sub> and Methane, raising levels of <strong>tropospheric ozone (O<sub>3</sub>), acts as a secondary pollutant and green house gas </strong>which is a silent threat as well as one of the biggest challenges for the decrease in agricultural production. The diurnal and seasonal variation characteristics of ambient ozone (O<sub>3</sub>) and its precursor NOx was investigated by their continuous measurements at ISRO-Climate Change Observatory situated in a high altitude Western Ghats location of Ooty. The impact of ambient O<sub>3</sub> on the growth and yield characteristics of various potato genotypes were assessed by the calculated higher ozone exposure indices <strong>AOT40 and SUM60 </strong>than critical levels by showing<strong> “latent injury“ </strong>in the form of yield reduction (4.56 - 25.5 %) in potato genotypes. The impact of three elevated O<sub>3 </sub>levels (100, 150 and 200 ppb for 4 hd<sup>-1</sup>) on ten potato genotypes was done by fumigation under controlled open–top chamber during its critical stage namely the tuber initiation stage resulted that Kufri Surya proved to be moderately resistant by recording the highest yield.</em></p></div>

Fertilizer nitrogen uptake efficiencies for potato as influenced by application timing

Estimation of N uptake efficiency of fertilizer applications at different growth stages of crop plants is critical to develop management recommendations that enhance fertilizer use by minimizing N losses. In this study, the N-fertilizer uptake efficiency (FNUE) of two chipping potato (Solanum tuberosum L.) varieties (‘Atlantic’ and ‘FL1867’) under three typical fertilizer application timings was investigated. All treatments received a total of 225 kg ha−1 of N throughout the season, split into three applications of 75 kg ha−1 as ammonium nitrate (NH4NO3) applied at pre-plant, plant emergence and tuber initiation. FNUE at each application timing was evaluated by the substitution of conventional N-fertilizer by isotope labeled ammonium nitrate (15NH 4 15 NO3). Total tuber yield was similar between the two varieties at 48.8 and 37.5 Mg ha−1 in 2013 and 2014, respectively. Likewise, the overall FNUE was also similar at 45 % across both varieties and years. FNUE was 11 % for the pre-plant application, while 62 % for the applications at emergence and tuber initiation stages. Since a small fraction of the N applied at pre-plant was recovered in the plant, N fertilizer application closer to the potato planting may increase the FNUE.

Genome-wide survey of Aux/IAA gene family members in potato (Solanum tuberosum): Identification, expression analysis, and evaluation of their roles in tuber development

The Auxin/indole-3-acetic acid (Aux/IAA) genes encode short-lived nuclear proteins that are known to be involved in the primary cellular responses to auxin. To date, systematic analysis of the Aux/IAA genes in potato (Solanum tuberosum) has not been conducted. In this study, a total of 26 potato Aux/IAA genes were identified (designated from StIAA1 to StIAA26), and the distribution of four conserved domains shared by the StIAAs were analyzed based on multiple sequence alignment and a motif-based sequence analysis. A phylogenetic analysis of the Aux/IAA gene families of potato and Arabidopsis was also conducted. In order to assess the roles of StIAA genes in tuber development, the results of RNA-seq studies were reformatted to analyze the expression patterns of StIAA genes, and then verified by quantitative real-time PCR. A large number of StIAA genes (12 genes) were highly expressed in stolon organs and in during the tuber initiation and expansion developmental stages, and most of these genes were responsive to indoleacetic acid treatment. Our results suggested that StIAA genes were involved in the process of tuber development and provided insights into functional roles of potato Aux/IAA genes.