Tuber Initiation Stage Research Articles

Estimating soil mineral nitrogen from data-sparse field experiments using crop model-guided deep learning approach

Sandy soils are susceptible to excessive nitrogen (N) leaching under intensive crop production which is linked with the soil’s low nutrient holding capacity and high-water infiltration rate. Estimating soil mineral nitrogen (SMN) at the daily time-step is crucial in providing fertilizer recommendations balancing plant nitrogen use efficiency (NUE) and N losses to the environment. Crop models [e.g., Decision Support System for Agrotechnology Transfer (DSSAT)] can simulate SMN trend under varied fertilizer application rates and timings but struggle with accuracy in high-water table conditioned sub-irrigated soil. Alternatively, time-series deep learning (DL) models based on a long short-term memory (LSTM) are promising in understanding nonlinearity among complex variables. Yet, purely data-driven DL models for crops are challenging to develop due to limited field data availability and the excessive costs to collect more field data. Hence, a hybrid model (hybrid-LSTM) was developed by leveraging both the DSSAT and LSTM models to estimate daily SMN primarily using daily weather, applied fertilizer rates-timings, and the SMN sparse observations. This study used the observations from field trials conducted between 2011–2014 in Hastings, FL. The first step was to calibrate the DSSAT-SUBSTOR-Potato model to produce reliable SMN of the topsoil for treatments with varied N applied fertilizer rates split among the pre-planting, emergence, and tuber-initiation stages of the potato. Thereafter, the hybrid-LSTM model was trained on the calibrated DSSAT simulated SMN time-series and fine-tuned its predictions using the observed SMN to improve DSSAT simulated SMN. The hybrid-LSTM model was then tested on both calibrated and uncalibrated DSSAT SMN simulations where it outperformed the DSSAT model (improvement ranged ∼18–30 % on comparing the normalized root mean squared error) in providing reliable estimates of SMN across most of the farms and years. This novel hybrid modeling approach could guide stakeholders and farmers to build sustainable N management with improved crop NUE and yield and help in minimizing environmental losses.

Small soil wetted proportion and emitter flow rate of drip irrigation enhance potato yield by improving soil water and aeration in the sandy loam in arid Northwest China

Creating an ideal soil microclimate through appropriate drip irrigation management practices is crucial for enhancing potato production. Field experiments were conducted during 2021 and 2022 in Wuwei, Gansu Province, Northwest China, with two soil wetted proportion levels (P1: 35 %, and P2: 55 %) and three emitter flow rates (F1: 1.3 L/h, F2: 2.0 L/h, and F3: 3.0 L/h). Results showed that for the same soil wetted proportion, soil water content was reduced in the 0–20 cm soil layer and increased in the 20–40 cm for F1 compared to F2 and F3, with no differences in the 40–60 cm depth. During the tuber initiation and bulking stages, the soil wetted proportion P1 increased soil oxygen saturation by 2.8 % and 0.7 % and reduced CO2 concentration by 26.7 % and 19.2 % in 2021 and 2022, respectively, compared to P2 in the 20–40 cm soil layer. The emitter flow rate F1 exhibited significantly greater soil oxygen (0.7–4.6 %) and lower CO2 concentration (16–46 %) than F2 and F3 in the 0–20 cm. Soil oxygen was significantly higher (0.5–2.1 %) and CO2 concentration was significantly lower (10–39 %) in the 20–40 cm in F1 than in F3. In the 0–40 cm soil layer, both the highest soil oxygen concentration and lowest CO2 concentration were observed for the P1F1 combination. The soil wetted proportion P1 increased average yield by 5.6 % in 2021 and 11.9 % in 2022 compared to P2, while F2 and F3 reduced yield by 2.4 % and 4.6 % in 2021, 4.1 % and 13.8 % in 2022 compared to F1. The soil wetted proportion P2 promoted source growth compared to P1 but limited sink expansion. Source capacity, sink growth, and average tuber growth rates decreased from F1 to F3. Overall, the 35 % soil wetted proportion and 1.3 L/h emitter flow rate are recommended for potato cultivation in sandy loam. This study clarified the importance of coordinating soil water and aeration by drip irrigation management to improve potato tuber production.

Improving the yield and nutritional quality of cassava (Manihot esculenta Crantz) in the rainforest agro-ecological zone of southeast Nigeria through agronomic biofortification with micronutrients

Cassava (Manihot esculenta Crantz) is an important staple crop, especially for resource-poor populations. Cassava-based diets are rich in calories but grossly deficient in essential mineral elements. A field study in southeastern Nigeria aimed at increasing yields and concentrations of bioavailable mineral elements in a β-carotene cassava variety, UMUCASS 38 (TMS 01/1371), through agronomic biofortification. A randomized complete block design experiment in triplicate, with foliar application of Zn (3.0 kg ha−1 Zn as ZnSO4), I (4.0 kg ha−1 I as KI), Se (0.25 kg ha−1 Se as Na2SeO3) and Zn + Se + I in combination at vegetative, tuber initiation and bulking stages of cassava. Results indicated neither phytotoxicity nor altered physical and chemical soil properties. Application of Zn or Zn + Se + I at the vegetative stage significantly increased cassava tuber yields. More Zn, Se, and I accumulated in fresh and processed cassava tuber products (gari, lafun), especially when Zn + Se + I was applied at tuber initiation stage. The combined application of Zn + Se + I consistently outperformed sole applications indicating a synergistic interaction effect between the three elements. It is concluded that in the Zn-deficient soils of southeast Nigeria, yield of cassava root tubers can be significantly increased by foliar application of Zn-containing fertilizer at the vegetative stage, but for optimal accumulation of elemental Zn, Se, and I, a combined Zn + Se + I fertilizer be applied at the tuber initiation stage.

Nano-zinc oxide foliar application at the tuber initiation stage enhances the starch synthesis and zinc bioaccumulation in potato tubers

Crops cultivated on alkaline soils are normally deficient in micronutrients, therefore among others, zinc deficiency is a widespread problem in Pakistan. By using a novel approach, we have shown that agronomic biofortification of potato tubers can be achieved through application of nano-zinc oxide during the tuber initiation stage. Field experimentation was performed during the potato growing season (2021-2022) with five different concentrations of nano-zinc oxide (0, 25, 50, 100, and 250 mg L-1) applied to 55-d old plants at tuber initiation stage, and after 40 days of spray, potato tubers were harvested for the analysis of various biochemical and agronomic traits and changes in bioavailable concentration of Zn in potato tubers. An increase in growth and yield traits was recorded due to spray of 25 and 50 mg L-1 nano-zinc oxide. Starch fraction in tubers was increased in response to all nano-zinc oxide concentrations. Interestingly, over 50% increase in starch was recorded due to application of 25 mg L-1 nano-zinc oxide, while higher doses up to 250 mg L-1 increased tuber starch by ~34%. Soluble sugars increased progressively up to 250 mg L-1 reaching maximum values than the control. Above all, maximum concentration of Zn in potato tuber was recorded in response to 250 mg L-1 spray of nano-zinc oxide ranging up to 58.2 - 65.5 µg g-1 dry weight. Overall, exogenous application of nano-zinc oxide to potato plants can improve potato tuber quality by enhancing starch contents and contributing to translocation of Zn in potato tubers leading to agronomic biofortification.

Effect of Silicon on Micronutrient Content in New Potato Tubers

Since silicon can improve nutrient uptake in plants, the effect of foliar silicon (sodium metasilicate) application on micronutrient content in early crop potato tuber was investigated. Silicon was applied at dosages of 23.25 g Si∙ha–1 or 46.50 g Si∙ha–1 (0.25 L∙ha–1 or 0.50 L∙ha–1 of Optysil) once at the leaf development stage (BBCH 14–16), or at the tuber initiation stage (BBCH 40–1), and twice, at the leaf development and tuber initiation stages. Potatoes were harvested 75 days after planting (the end of June). Foliar-applied silicon reduced the Fe concentration and increased Cu and Mn concentrations in early crop potato tubers under water deficit conditions but did not affect the Zn, B, or Si concentrations. The dosage and time of silicon application slightly affected the Fe and Cu concentration in the tubers. Under drought conditions, the highest Mn content in the tuber was observed when 46.50 g Si∙ha–1 was applied at the leaf development stage, whereas under periodic water deficits, it was highest with the application of the same silicon dosage at the tuber initiation stage (BBCH 40–41). The Si content in tubers was negatively correlated with the Fe and B content, and positively correlated with the Cu and Mn content.

Quantitative Analysis of Source-Sink Relationships in Two Potato Varieties under Different Nitrogen Application Rates

Nitrogen is an essential nutrient for plant growth. However, the excessive use of nitrogen fertilizers not only increases production cost, but also has negative a impact on the environment. The purpose of this study was to quantify the source-sink characteristics and length of each growth stage in two potato varieties under different nitrogen application rates. This clarifies the source-sink coordination characteristics of the nitrogen-efficient variety and the source-sink coordination mechanisms of high nitrogen use efficiency (NUE). Field experiments were conducted in 2019, 2020, and 2021 using a split-plot design, with a nitrogen application rate of (0; 150 kg·ha−1; 300 kg·ha−1) as the main plot and variety (J, nitrogen-efficient variety Jizhang 12; Y, nitrogen-inefficient variety Youjia 70) as the subplot. The results showed that the yield and NUE of Jizhang 12 at 300 kg·ha−1 were, on average, 90.73% and 75.15% higher than those of Youjia 70, respectively. The NUE and nitrogen utilization efficiency of Jizhang 12 increased on average, with decreasing N application at 68.66% and 24.53%, which were higher than those of Youjia 70 at 62.89% and 10.86%. Quantitative analysis of the source and sink showed that the Jizhang 12 had a higher source and sink capacity of 23.45 g and 51.85 g, respectively, and the maximum source and sink activity was on average 0.28 g·plant−1·d−1 and 1.47 g·plant−1·d−1 higher, and the growth period of the source and sink was on average 24 days and 7 days longer, respectively. On the basis of these results, the nitrogen-efficient varieties had a higher yield base and a smaller reduction in NUE with reduced N application. In terms of source-sink growth, N-efficient varieties lasted longer at the seedling and tuber initiation stages, when potatoes grew above ground and source organs grew for longer periods, providing a solid foundation for later sink growth, as evidenced by their higher source-sink activity, capacity, and growth time than N-inefficient varieties.

StOFP20 regulates tuber shape and interacts with TONNEAU1 Recruiting Motif proteins in potato

The OVATE family proteins (OFPs) are plant-specific proteins that modulate diverse aspects of plant growth and development. In tomato, OFP20 has been shown to interact with TONNEAU1 Recruiting Motif (TRM) proteins to regulate fruit shape. In this study, we demonstrated that mutation of StOFP20 caused a shift from round to oval shaped tuber in a diploid accession C151, supporting the role of StOFP20 in controlling tuber shape. Its expression reached a maximum in the tuber initiation stage and then decreased as the tuber develops. To help elucidate the mechanism of StOFP20 regulating tuber shape, 27 TONNEAU1 Recruiting Motif (TRM) proteins were identified and 23 of them were successfully amplified in C151. A yeast two-hybrid assay identified three TRM proteins interacting with StOFP20, which was confirmed by the firefly luciferase complementation in tobacco leaves. The OVATE domain was indispensable for the interactions, while necessity of the M10 motif in TRM proteins varied among interactions between StOFP20 and the three TRMs. In summary, both StOFP20 and SlOFP20 directed interactions with TRM proteins, but the interactants were not completely consistent, implying that they exert regulatory roles through partially overlapping mechanisms.

Nutritional Value and Sensory Quality of New Potatoes in Response to Silicon Application

Since silicon regulates plant physiological and biochemical processes, it was hypothesized that foliar silicon application could contribute to improving the quality of new potatoes. This paper analyzes the effect of silicon (sodium silicate) on the nutritional value and sensory quality of new potatoes. Silicon was applied at the dose of 23.25 g Si·ha−1 or 46.50 g Si·ha−1 once at the leaf development stage (BBCH 14–16) or at the tuber initiation stage (BBCH 40–41) and twice, at the leaf development and tuber initiation stages. Potatoes were harvested 75 days after planting (the end of June). Silicon had no effect on the dry matter, total sugars and monosaccharides, protein, L-ascorbic acid or nitrate content in new potato tubers, but it increased the starch content under water deficit conditions. The most starch was accumulated by tubers following the application of 46.50 g Si·ha−1 at the leaf development stage (BBCH 14–16). Silicon did not affect the color of tuber flesh after cooking.

Effect of Foliar Silicon Application on Nutrient Content in Early Crop Potato Tubers

As some trace elements can enhance plant nutrient uptake and assimilation, it was hypothesized that foliar silicon application could enhance nutrient content in early-crop potato tubers. The effect of dosage (23.25 g Si∙ha−1 or 46.50 g Si∙ha−1) and time (the leaf development stage—BBCH 14–16, tuber initiation stage—BBCH 40–41, at both the leaf development stage and tuber initiation stage) of the silicon application on the nutrient contents in early crop potato tubers was investigated. Silicon had no effect on the potassium (K), phosphorus (P), calcium (Ca), or magnesium (Mg) contents in potato tubers, but it reduced sodium (Na) accumulation, especially under water deficit conditions during tuber bulking. This resulted in a reduction in the mass ratios of Na+/Ca2+ and Na+/Mg2+ in tubers. Silicon dosage significantly affected the Na accumulation by potato tubers only in the warm and very dry growing season. Under drought stress, silicon at 46.50 g Si∙ha–1 reduced the Na content in potato tubers more than at 23.25 g Si∙ha−1. Under periodic water deficits, the time of silicon application affected the Na accumulation by potato tubers more than the silicon dosage. The Na content in tubers was the highest with two silicon applications. Although silicon reduced the Na accumulation, the ratio of the sum of univalent cations to the sum of bivalent cations (K+ + Na+)/(Ca2+ + Mg2+) in tubers was at the same level, both in cultivations with and without silicon.

Possibility of increasing early crop potato yield with foliar application of silicon

This paper analyses the effect of dosage (0.25 dm3 ha–1 or 0.50 dm3 ha–1) and time (the leaf development stage – BBCH 14–16, tuber initiation stage – BBCH 40–41, at both the leaf development stage and tuber initiation stage) of silicon-based stimulant Optysil application (200 g SiO2 and 24 g Fe in 1 dm3) on early potato yield and yield components. Optysil resulted in an increase in tuber number and tuber weight per plant. As a result, under periodic water deficits during tuber bulking, Optysil increased marketable tuber (with a diameter above 30 mm) yield by an average of 6.90 t ha–1 (50%) and under drought conditions during the potato growth period by 0.70 t ha–1 (8.6%). Under periodic water deficits during tuber bulking, the marketable tuber number per plant and marketable yield were greatest after applying 0.50 dm3 ha–1 of Optysil in the tuber initiation stage (BBCH 40–41). Under drought conditions, the most practical were two Optysil applications at 0.25 dm3 ha–1. The Optysil application improved the market value of the early potato yield by increasing the share of medium-sized tubers (with a diameter of 41–50 mm).

Modelling and Evaluation of Potato Water Production Functions in a Cold and Arid Environment

This study was conducted at the Yimin Irrigation Experiment Station, Minle County, Zhangye City, Gansu Province, from April to October in 2019 and 2020. The relationship between water consumption and yield of potato at different stages of fertility under deficit-regulated irrigation was analyzed in a field trial study over two growing seasons. The results showed that the average annual water consumption in the tuber bulking stage was the largest, reaching 185.35~239.52 mm, followed by the average annual water consumption in the tuber initiation stage and starch accumulation stage, which were 100.02~132.30 mm and 82.48~112.36 mm, respectively, and the average annual water consumption in the seedling stage was the least, at 49.32~69.81 mm. Simultaneously, the average annual yield of potatoes in the treatment of WD1 was the highest, reaching 47,766.96 kg·hm−2, followed by CK, which was 43,707.6 kg·hm−2, and the yield of WD6 was the smallest in the treatment of moderate water deficit during tuber initiation, which was only 35,721.25 kg·hm−2. Combining the four moisture production function models of Jensen, Minhas, Blank and Stewart, the Jensen and Stewart models were identified as suitable for the potato moisture production function in a cold and arid environment. The water production function model was used to investigate the relationship between water consumption and yield in each growth period of potato, and to provide a theoretical basis for the optimization of the irrigation system under deficit-regulating irrigation conditions for potato in this irrigation area.

Observed and modeled response of water yam (Dioscorea alata L.) to nitrogen supply: Consequences for nitrogen fertilizer management in the humid tropics

Yam (Dioscorea spp.) is an important source of food for millions of people throughout the tropics. Yam yields are constrained by several factors such as low soil fertility and a poor response of the crop to nutrient supply. Here we present an experimental and modeling study performed to test the hypothesis that N leaching in the humid tropics is a key factor that explains the poor response of water yam (Dioscorea alata L.) to N fertilization. A field experiment was carried out to assess the impact of three levels of N supply (50, 125 and 200 kg N ha−1) on crop growth and soil N availability. The N fertilizer was split into two equal doses (i.e., 50%/50% split ratio), one applied just before emergence and the other a month after tuber initiation, which corresponds to the current management used by farmers. The CropSyst-Yam model was adapted to include a new soil-crop N component describing the effects of limiting N conditions on yam growth, and then to test different N fertilizer managements. The experimental results indicated that all variables linked to the soil-crop system were affected by the increase in N supply (soil N availability, crop biomass, leaf area and N uptake), and the model well described these impacts. Nitrogen leaching throughout the field experiment represented about one third of the total N supplied by each treatment. Observed and predicted data revealed that N leaching reduced yam growth under the N50 and N125 treatments by reducing soil N availability near the tuber initiation stage. This effect was not observed under the N200 treatment. Model results showed that N leaching and its negative impact near tuber initiation in N50 and N125 could be diminished by advancing the second N application by two or three weeks, and by using a split ratio of 70%/30%. Model results also indicated that this fertilizer strategy would even be suitable during very rainy growing seasons.

Predicting Phenology of Four Major Hemipteran Pests to Enhance Integrated Pest Management Programs in Potatoes in the Lower Columbia Basin.

The potato crop (Solanum tuberosum L.) is affected by various hemipteran insect pests including Circulifer tenellus Baker, Lygus spp., Myzus persicae Sulzer, and Macrosiphum euphorbiae Thomas. These pests can cause direct foliage damage or vector plant pathogens, and consequently reduce potato yield. Gaining insights into which factors have the greatest impact on seasonal population growth of insect pests is key for improving integrated pest management strategies. Moreover, abiotic and biotic cues such as temperature and crop growth stage can strongly influence insect population growth. Hence, the seasonal population dynamics of C. tenellus, Lygus spp., M. persicae, and M. euphorbiae, and temperature, were monitored weekly throughout potato growing seasons in commercial fields located in the lower Columbia Basin (USA). Using a multi-year dataset, we developed phenology models of each pest based on the accumulated degree days (DD) and potato days (PD). Temperature-mediated population growth models suggest that C. tenellus and Lygus spp. are the first of the pests to colonize the potato crop fields, with 90% of cumulative catch by 2,823 and 1,776 DD, respectively. In contrast, M. persicae and M. euphorbiae populations increased more gradually over the course of the season, with 90% cumulative catch by 5,590 and 5,047 DD, respectively. PD-mediated population growth models suggest that 50% of the populations of C. tenellus, Lygus spp., and M. persicae can be collected at potato tuber growth stage, while 50% of the M. euphorbiae population at tuber initiation stage. The results presented here will help in improving hemipteran potato pests' management.

Substâncias húmicas: efeito no crescimento e na produtividade de plantas de batata

ABSTRACT The results from humic substances (HS) application in varied crops and conditions are controversial, and the experiments with the potato crop in Brazil are scarce. The objective of this study was to evaluate the effects of HS doses on the growth and yield of two potato cultivars. Four doses of HS were tested: 0, 5.05, 10.10, and 15.15 L ha-1, applied in the planting furrows of cvs. Agata and BRS F63 Camila, in Guarapuava-PR, in the 2015 and 2016 crop seasons, between October and February. The experiment was carried out using a randomized complete block design, in a factorial scheme (crop season x dose x cultivar), with four replications. Plant samplings were performed at tuber initiation, flowering, tuber bulking, and plant maturation growth stages. After shoot senescence, the total and commercial tuber yields were evaluated. Cultivars responded similarly to HS application, with no significant interaction between HS and cultivars, for most assessed variables. At tuber initiation, there was a negative linear effect of HS doses on leaf area index, number of formed tubers, and tuber and total plant dry weight. In the other evaluations, the effect of HS application was not observed regarding the assessed variables. Likewise, no effects were detected on the number and fresh weight of tubers in total and commercial yields. We concluded that HS application affected both cultivars similarly, hampering initial plant growth and not increasing potato yield.

Drought tolerance assessment of potato (Solanum tuberosum L.) genotypes at different growth stages, based on morphological and physiological traits

The objective of this study was to determine drought tolerance of diverse potato (Solanum tuberosum L.) genotypes. The physiological and morphological responses of eight potato genotypes were assessed under well-irrigated (Wi) and deficit irrigation (Di) conditions across four different growth stages, namely, the Vegetative (VG), Tuber Initiation (TI), Tuber Bulking (TB) and maturity (MAT) stages, using an 8 × 4 × 2 factorial treatment structure with three replications. Data were collected on morphological traits such as Plant Height (PH), the Number of Leaves (NL), Tuber Yield (TY) and Total Above-Ground biomass (TAG), as well as the physiological traits such as stomatal conductance (gs), Transpiration rate (Tr), the rate of photosynthesis (A), Water Productivity (WP), Chlorophyll Content Index (CCI) and Relative Water Content (RWC). A significant (p < 0.05) genotype x water condition x growth stage effects were observed for A, Tr, WP, RWC, CCI, PH, NL, TY and TAG, which indicated the varied responses of the genotypes to the water conditions across the growth stages. This is useful when recommending the growth-stage specific and drought tolerant potato genotypes for production. Correlation analysis revealed significant and negative association between gs and WP with TY (r = −0.81; r = −0.77) at the VG stage, positive association between PH, Tr, A and WP with TY (r = 0.92; r = 0.65; r = 0.95; r = 0.88) at the TI stage.CCI positively correlated with TY (r = 0.71) at the MAT stage, and a negative association was observed between TAG with TY (r = −0.85) at the MAT stage, under Di conditions. Principal component bi-plot identified that the all-rounder genotypes that are resistant to drought in all stages include the Challenger, Sifra and Tyson. These genotypes are recommended for cultivation in water-restricted environments.

Potato (Solanum tuberosum L.) Growth in Response to Foliar Silicon Application

As silicon induces abiotic stress tolerance in crop plants, it was hypothesized that foliar silicon application could improve potato growth in an early crop culture. The effect of dosage (0.25 dm3·ha−1 or 0.50 dm3·ha−1) and time (the leaf development stage, BBCH 14–16, tuber initiation stage, BBCH 40–41, or both the leaf development stage and tuber initiation stage) of application of the silicon-based biostimulant Optysil (200 g SiO2 and 24 g Fe in 1 dm3) on potato growth was investigated. Optysil caused an increase in plant height and above-ground plant biomass, enlarged leaf area and decreased leaf weight ratio (LWR), and, as a result, increased tuber number and tuber weight per plant. The effect of Optysil depended on a water deficit during potato growth. The average tuber weight per plant in the cultivation treated with Optysil was higher by 23% under periodic water deficits during potato growth, and by 13% under drought conditions, than in the cultivation without the biostimulant. Dosage of Optysil had a significant effect on above-ground plant biomass and leaf area in the warm and arid growing season. Under drought stress, Optysil at 0.50 dm3·ha−1 stimulated potato growth more than at 0.25 dm3·ha−1. Under periodic water deficits during potato growth, the time of Optysil application affected potato growth more than the biostimulant dosage. The plants produced greater above-ground biomass and had a larger leaf area with two Optysil applications; one in the initial plant growth period (BBCH 14–16), and a repeated treatment in the tuber initiation stage (BBCH 40–41). The tuber weight per plant was positively correlated with the plant height, above-ground plant biomass, leaf area, and LWR.

Evaluating drought tolerance of potato genotypes at different growth stages using yield performance and tuber quality traits

Selection of drought-tolerance (Solanum tuberosum L.) genotypes is essential to enhance tuber yield and quality for food and processing. The aim of the study was to evaluate effect of water deficit on tuber yield, quality and drought-tolerance of selected potato genotypes at different growth stages. Tuber quality of eight potato genotypes were evaluated under well-watered (Ww) and water-deficit (Wd) conditions at four different growth stages, namely, vegetative (VG), tuber initiation (TI), tuber bulking (TB) and maturity (MAT) stages using an 8 × 4 × 2 factorial treatment with three replications. Data was collected on morphological traits such as tuber yield (TY), number of tubers (NT), tuber size distribution (TSD) and dry matter content (DMC). Significant (p < 0.05) genotype x water condition x growth stage effect were observed for TY, NT, TSD and DMC, indicating varied responses of genotypes to water conditions across growth stages. Correlation analysis shown significant and positive associations among medium tubers and yield (r = 0.76; p = 0.05), between large tubers and number of tuber (r = 0.42; p = 0.05) at VG stage, DMC and yield (r = 0.79; p = 0.010) at TI stage and highly significant negatively correlated with NT (r = -0.94; p = 0.001) at TB stage. Mondial and Sifra produced high percentage of medium (35-55 mm) and large tubers (>55 mm) across all growth stages. Genotypes Bikini, Mondial, Sababa and Sifra were identified as drought tolerance genotypes due to high yield observed under water deficit conditions.

Genomic regions associated with physiological, biochemical and yield-related responses under water deficit in diploid potato at the tuber initiation stage revealed by GWAS.

Water deficit, which is increasing with climate change, is a serious threat to agricultural sustainability worldwide. Dissection of the genetic architecture of water deficit responses is highly desirable for developing water-deficit tolerant potato cultivars and enhancing the resilience of existing cultivars. This study examined genetic variation in response to water deficit in a panel of diploid potato and identified the QTL governing this trait via a genome-wide association study (GWAS). A panel of 104 diploid potato accessions were evaluated under both well-watered and water deficit treatments at tuber initiation stage. Drought stress index (DTI) was calculated to assess tolerance of the diploid potato genotypes to water deficit. The GWAS was conducted using a matrix of 47K single nucleotide polymorphisms (SNP), recently available for this population. We are reporting 38 QTL, seven for well-watered conditions, twenty-two for water deficit conditions and nine for DTI which explain between 12.6% and 44.1% of the phenotypic variance. A set of 6 QTL were found to be associated with more than one variable. Marker WDP-9.21 was found associated with tuber fresh weigh under WD and gene annotation analysis revealed co-localization with the Glucan/water dikinase (GWD) gene. Of the nine QTL detected from DTI on chromosomes 2,3,5,8,10 and 12, three candidate genes with a feasible role in water deficit response were identified. The findings of this study can be used in marker-assisted selection (MAS) for water- deficit tolerance breeding in potato.

The Effect Irrigation Scheduling and Potassium Fertilization on Water Consumption of Potato (Solanum tuberosum L.) Under Modern Irrigation Systems

A field experiment was conducted in Yusufiya sub-district - Mahmudiya township/Baghdad governorate in silty loam texture soil during the spring season of 2020. The experiment included three treatments with three replicates, as the Randomized Complete Block Design (RCBD) was used according to the arrangement of the split design block. The treatments are in the irrigation system, which included surface drip irrigation (T1) and sprinkler irrigation (T2). Secondly, the Irrigation levels including the irrigation using 0.70 Pan Evaporation Fraction PEF (I1), irrigation using 1.00 PEF (I2), and irrigation using 1.30 PEF (I3). Coupled with, Potassium fertilization treatments that include (0.0 kg k ha-1 (K1), 150 kg k ha-1 (K2) and 300 kg k ha-1 (K3)). The results showed that the actual seasonal water consumption reached its peak at irrigation level I1, which reached 390.03 and 256.41 mm for the sprinkler and drip irrigation systems, respectively. However, the actual seasonal water consumption at irrigation level I2 was 373.92 and 255.63, and it was 353.82 and T255.15 mm at irrigation level I3 for the sprinkler and drip irrigation systems, respectively. The lowest values of the crop coefficient at the tuber maturity stage using the sprinkler irrigation system were 0.49, 0.46, and 0.44, and at the vegetative growth stage using the surface drip irrigation system by 0.37, 0.32, and 0.38 for irrigation levels I1, I2, and I3, respectively. Even though the greatest values were in the tuber Initiation and bulking stages, as they reached 0.86, 0.66, and 0.79 using the sprinkler irrigation system, while they reached 0.49, 0.54, and 0.51 using the surface drip irrigation system for I1, I2, and I3 levels, respectively. The highest water productivity for treatment I3K3 was 15.70 and 27.20 kg m-3 of sprinkler and surface drip irrigation systems, respectively. In contrast, the lowest water productivity was 8.73 and 17.72 kg m-3 for treatment I1K1 of sprinkler and surface drip irrigation systems, respectively. Whereas, the highest value of crop water use efficiency was 11.70 and 17.58 kg m-3 for I3K3 treatment of sprinkler and surface drip irrigation systems, respectively. Although, the lowest value of crop water use efficiency was 6.71 and 11.49 kg m-3 for I1K1 treatment of sprinkler and surface drip irrigation systems, respectively. Lastly, the highest yield was 44.87 Mg ha-1 at treatment T1I3K3.

‘Atlantic’ and ‘Dakota Pearl’ chipping potato responses to glyphosate and dicamba simulated drift

AbstractField trials were conducted to determine the effects of glyphosate and/or dicamba simulated drift rates on chipping potatoes (Solanum tuberosum L.) ‘Atlantic’ and ‘Dakota Pearl.’ Sublethal herbicide rates were applied at the tuber initiation stage and consisted of dicamba at 99 g ae ha−1 or glyphosate at 197 g ae ha−1 applied alone or the combinations of dicamba at 20 or 99 g ae ha−1 and glyphosate at 40 or 197 g ae ha−1, respectively. At 7 days after treatment (DAT), the high spray combination of glyphosate plus dicamba resulted in the greatest plant damage (28%). Plant injury from plants treated with the low combination of glyphosate plus dicamba did not differ from the nontreated control. At 21 DAT, visible injury increased to 40% for plants treated with the high combination of glyphosate plus dicamba. Total yield suggested that dicamba and glyphosate caused similar yield reductions as plants that received glyphosate at 197 g ha−1 or dicamba at 99 g ha−1 had lower total yields compared to the nontreated and plants that received the combination of glyphosate (197 g ha−1) and dicamba (99 g ha−1) had lower total yields compared to plants that received either herbicide alone. However, ‘Dakota Pearl’ plants were more sensitive to glyphosate at 197 g ha−1 than were ‘Atlantic’ plants, causing the interaction for most tuber grades. Tuber specific gravity was lower for plants that received glyphosate at 197 g ha−1, dicamba at 99 g ha−1, or this combination, but this reduction would not prevent chip processing. Results reinforce the need for diligence when applying these herbicides in proximity to a susceptible crop, such as chipping potatoes, and the need to thoroughly clean sprayers before application to a sensitive crop.