Tuber Bulking Stage Research Articles

Shortcutting Photorespiration Protects Potato Photosynthesis and Tuber Yield Against Heatwave Stress.

Over two growing seasons, a chloroplast localized synthetic glycolate metabolic pathway expressed in potato, enhanced tuber biomass. We confirmed that this yield benefit did not come at the cost of tuber quality. In 2022, after two early season natural heatwaves, we observed enhanced daily carbon assimilation rates and increased photosynthetic capacity, with transformed plants having up to 23% higher Vcmax and 13% higher Jmax during tuber bulking stages, indicating that transformed plants were better able to withstand growing season heatwaves than untransformed controls. The increases in photosynthetic capacity and potato tuber mass after early season heatwaves were greater than in seasons without heatwaves and present the AP3 pathway as a promising avenue for yield increases in the face of forecast increased intensity and duration of heatwave events as a result of global warming.

Caracteres morfológicos que contribuem para o aumento da produtividade de cultivares de batata no Brasil

ABSTRACT A previous study revealed that modern potato cultivars used in Brazil have higher commercial tuber yield than old cultivars. The objective of the present study was to clarify which morphological characters influence the yield gain of modern cultivars. Two field experiments were performed in Brazil: in Guarapuava-PR and Brasilia-DF. The treatments consisted of six cultivars, classified according to origin and year of release: Bintje (European, 1910), Baronesa (Brazilian, 1955), Monalisa (European, 1982), Agata (European, 1990), Catucha (Brazilian, 1995) and BRS Clara (Brazilian, 2010). These were the main cultivars used in southern Brazil in the last 65 years and represent 100 years of breeding. A randomized complete block design with six treatments and four replications was used. The following plant morphological characters were evaluated at four growth stages (the beginning of plant development, the beginning of tuberization, maximum shoot growth and tuber bulking stages): leaf area index, specific leaf area, number of main stems, initiated and bulked tubers. At 15 days after emergence, modern cultivars have higher leaf area index and bulked tubers compared to older cultivars. Also, a larger number of mainstems and smaller specific leaf area were observed in modern cultivars. A high leaf area index at the beginning of the growing development combined with a large number of bulked tubers contributed to the increase of the yield potential of modern cultivars.

Technological Quality of Potato Tubers: Effect of Potassium Fertilization and Application Time

The effect of potassium fertilization and time of application on yield and tuber quality of potato (Solanum tuberosum L., cv. Agria) was studied in Bekaa region in Lebanon. Potassium was applied in one split at tuber initiation (T1) and at tuber bulking (T2) in four different rates: K0 (0 kg/ha), K1 (100 kg/ha), K2 (200 kg/ha) and K3 (300 kg/ha). Results showed that aerial dry matter decreased and tuber dry matter increased during the growing period. The dry matter accumulation was dependent on potassium fertilization. Potassium concentration gradually decreased in leaves and increased in tubers during the growing period, while the most potassium treatment (K3) has accumulated at harvest, higher potassium concentrations in leaves and tubers, with more emphasis to application time T2 with respect to T1. Moreover, potassium has accelerated significantly (p<0.05) tuber dry matter accumulation. This was revealed by growth rate and harvest index values that were significantly higher (p<0.05) in K3 treatment with comparison to other treatments. Results also showed that fresh tuber yields increased with potassium fertilization and were more pronounced with T2 application whereas K3 had significantly (p<0.05) the highest value of 62.9 t/ha (K3). Yield augmentation was primarily due to an increase in tuber size in the larger (> 60 mm) and the medium (35 – 60 mm) grades. In addition, results showed that tuber dry matter content and specific gravity were statistically dependent on potassium fertilization and application time (p<0.05). The highest potassium treatment K3, regardless of application time, gave the best tuber quality of industrial potato by having the highest dry matter and the lowest reducing sugar contents. Finally, the results of this study suggest that maximum potato yield was obtained with K3 treatment (300 kg/ ha) applied during tuber bulking stage (T2).

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.

Effect of Drought Stress on Potato Production: A Review

Potato is the third most consumed crop globally after rice and wheat. It is a short-duration crop, versatile in use, suitable for growing in a wide range of environments, and its production is increasing rapidly. The modern potato is considered a drought-sensitive crop, and it is susceptible to yield loss because of drought stress. Unfortunately, drought severity, frequency, and extent have been increasing around the globe because of climate change. Potato drought susceptibility has primarily been attributed to its shallow root system. However, several studies in past decades have suggested that drought susceptibility of potato also depends upon the type, developmental stage, and the morphology of the genotype, and the duration and severity of drought stress. They have been overlooked, and root depth is considered the only significant cause of potato drought susceptibility. This review combines these studies to understand the varying response of potato genotypes. This review also explores the current potato production scenario and the effect of varying degrees of drought stress on potatoes’ growth, development, and yield. In the absence of drought-tolerant genotypes, agronomic practices should be improved to mitigate drought stress. Late maturing cultivars, nutrient management, mulching, and foliar application of plant growth regulators can be used during prolonged droughts. Irrigation at tuber initiation and the tuber bulking stage during early droughts can reduce the adverse effects of drought.

内蒙古地区甜菜临界氮浓度稀释模型的构建及应用

<p id="C3">Sugar beet is one of the two major sugar crops in China. However, both nitrogen sufficiency and deficiency will affect the yield and sugar content in sugar beet, and excessive nitrogen will cause environmental risks. Judging nitrogen nutrition of sugar beet in a reasonable range is of great significance for ensuring the yield, quality and reducing environmental risks of sugar beet. The critical nitrogen concentration dilution curve is the basis of crop nitrogen nutrition diagnosis. The objective of this present study was establishing the dilution curve model of the critical nitrogen concentration of sugar beet in China and to diagnose the nitrogen nutrition of sugar beet by using the corresponding nitrogen nutrient index. Four experiments with different N rates for two cultivars of sugar beet were conducted in Inner Mongolia from 2017 to 2018. The above-ground biomass and under-ground tubers were sampled and their nitrogen concentration was determined at seedling, leaf cluster growth, tuber bulking, sugar accumulation, and harvest stages. The total plant biomass and nitrogen concentration were calculated. Based on the calculation, the critical nitrogen concentration dilution model and the corresponding nitrogen nutrient index were established. The results indicated that the negative power relationship between the above-ground biomass and nitrogen concentration was observed. The determination coefficient (<italic>R</italic> ²) for the relationship was 0.45 on average. The <italic>R</italic> ² for the negative power relationship between total plant biomass and nitrogen concentration was 0.94 on average, which was higher than the relationship between the above-ground biomass and nitrogen concentration. It was more reasonable to establish a critical nitrogen concentration dilution model based on the total plant biomass and nitrogen concentration, which was less affected by the cultivars. The <italic>R</italic> ² for the integrated critical nitrogen concentration dilution curve of sugar beet varieties KWS9167 and KWS1676 reached 0.94. The constructed nitrogen nutrition model can be used to estimate the plant nitrogen status in sugar beet. The critical nitrogen concentration dilution model for the main sugar beet varieties in Northern China was <italic>N</italic>_c = 4.23<italic>W</italic> ^-0.49. The optimized nitrogen rate of KWS9167 and KWS1676 based on the model was about 160 kg hm ^-2 and 180 kg hm ^-2, respectively.

Potato tuber degradation is regulated by carbohydrate metabolism: Results of transcriptomic analysis.

Tuber number is an essential factor determining yield and commodity in potato production. The initiation number has long been considered the sole determinant of the final total tuber number. In this study, we observed that tuber numbers at harvest were lower than at the tuber bulking stage; some formed tubers that were smaller than 3 cm degraded during development. Carbohydrate metabolism plays a crucial role in tuber degradation by coordinating the source–sink relationship. The contents of starch and sucrose, and the C:N ratio, are dramatically reduced in degradating tubers. Transcriptomic study showed that “carbohydrate metabolic processes” are Gene Ontology (GO) terms associated with tuber degradation. A polysaccharide degradation‐related gene, LOC102601831, and a sugar transport gene, LOC102587850 (SWEET6a), are dramatically up‐regulated in degradating tubers according to transcriptomic analysis, as validated by qRT‐PCT. The terms “peptidase inhibitor activity” and “hydrolase activity” refer to the changes in molecular functions that degradating tubers exhibit. Nitrogen supplementation during potato development alleviates tuber degradation to a certain degree. This study provides novel insight into potato tuber development and possible management strategies for improving potato cultivation.

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.

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.

Effects of Different Irrigation Management Practices on Potato (Solanum tuberosum L.)

Decisions in irrigation management can greatly impact the overall sustainability of potato production. A field study was conducted in 2018 and 2019 to evaluate the impacts of different irrigation regimes on yield and quality of three russet potato varieties. For Russet Burbank, fry quality at harvest and at 4 and 8 months after harvest was assessed. During early growth stages, the standard practice of irrigating to maintain 60–80% soil moisture was employed. The irrigation treatments were applied during the late tuber bulking and maturation growth stages, and consisted of irrigation at 125%, 100%, 75%, and 50% of daily evapotranspiration (ET). We found that 125%ET provided no increase in total yield and marketable yield compared to other treatments in 2018, and it produced similar marketable yield to 100%ET in 2019. Total yield, but not marketable yield, of 125%ET and 100%ET was significantly higher than the number under 50%ET in 2019. In both years, increasing irrigation rate led to a decrease in irrigation efficiency and water-use efficiency. Irrigation rate had no significant effects on tuber quality at harvest and during storage. This study indicated that over-irrigation at 125%ET was not beneficial to profitable potato production in the Upper Midwest of the US, and deficit irrigation at 75%ET during late tuber bulking and tuber maturation could potentially result in more sustainable water use while not jeopardizing tuber growth. The results support the possibility of adopting late-season deficit irrigation for growing potatoes in the region, though more years of research would allow for a better understanding of the impacts of this practice.

Estimating Above-Ground Biomass of Potato Using Random Forest and Optimized Hyperspectral Indices

Spectral indices rarely show consistency in estimating crop traits across growth stages; thus, it is critical to simultaneously evaluate a group of spectral variables and select the most informative spectral indices for retrieving crop traits. The objective of this study was to explore the optimal spectral predictors for above-ground biomass (AGB) by applying Random Forest (RF) on three types of spectral predictors: the full spectrum, published spectral indices (Pub-SIs), and optimized spectral indices (Opt-SIs). Canopy hyperspectral reflectance of potato plants, treated with seven nitrogen (N) rates, was obtained during the tuber formation and tuber bulking from 2015 to 2016. Twelve Pub-SIs were selected, and their spectral bands were optimized using band optimization algorithms. Results showed that the Opt-SIs were the best input variables of RF models. Compared to the best empirical model based on Opt-SIs, the Opt-SIs based RF model improved the prediction of AGB, with R2 increased by 6%, 10%, and 16% at the tuber formation, tuber bulking, and for across the two growth stages, respectively. The Opt-SIs can significantly reduce the number of input variables. The optimized Blue nitrogen index (Opt-BNI) and Modified red-edge normalized difference vegetation index (Opt-mND705) combined with an RF model showed the best performance in estimating potato AGB at the tuber formation stage (R2 = 0.88). In the tuber bulking stage, only using optimized Nitrogen planar domain index (Opt-NPDI) as the input variable of the RF model produced satisfactory accuracy in training and testing datasets, with the R2, RMSE, and RE being 0.92, 208.6 kg/ha, and 10.3%, respectively. The Opt-BNI and Double-peak nitrogen index (Opt-NDDA) coupling with an RF model explained 86% of the variations in potato AGB, with the lowest RMSE (262.9 kg/ha) and RE (14.8%) across two growth stages. This study shows that combining the Opt-SIs and RF can greatly enhance the prediction accuracy for crop AGB while significantly reduces collinearity and redundancies of spectral data.

Effects of Irrigation Management on Chipping Potato (Solanum tuberosum L.) Production in the Upper Midwest of the U.S.

Irrigation is required for profitable commercial potato (Solanum tuberosum L.) production. Excessive or deficit soil water availability during the growing season can have adverse effects on tuber yield, quality, and storability. A field study was conducted during the 2018 and 2019 field and storage seasons in Central Wisconsin, a region in the U.S. with a high volume of potato production, to evaluate the impacts of different irrigation rates on three chipping potato varieties, Hodag, Lamoka, and Snowden. The treatments were implemented during the late-tuber bulking and tuber maturation growth stages, and consisted of irrigation at 125%, 100%, 75%, and 50% of crop evapotranspiration (ET). Irrigation before the treatment period was at 100%ET for all plots. With the industry standard irrigation practice being at 100%ET, other treatments were designated as over-irrigation or deficit irrigation. The impact of these watering rates on tuber yield and quality was evaluated at harvest, and tuber storage quality was assessed by measuring chip fry color and sugar concentrations at 0, 4, and 8 months of storage. It was found that compared to the standard practice, the over-irrigation treatment at 125%ET when tubers reached late bulking resulted in no significant increase in total yield, marketable yield, tuber quality at harvest and during storage, as well as reduced irrigation efficiency (IE) and water-use efficiency (WUE). This treatment also increased nitrate leaching potential in both years. In comparison, deficit irrigation at 75%ET or even 50%ET during the late season had no impact on tuber growth, could increase IE and WUE in one of the two years, and showed reduced drainage. In both years, irrigation rate had no significant effects on hollow heart incidence, tuber specific gravity at harvest, and fry quality during the 8-month storage period. This study suggested that over-irrigation was not beneficial for potato production in Central Wisconsin of the U.S., and deficit irrigation during late tuber bulking and tuber maturation stages could potentially result in more sustainable water use while not penalizing tuber yield, quality and storability of chipping potatoes.

Study of PAR interception, energy balance studies and microclimatic profiles in potato (Solanum tuberosum) cultivars under varying planting dates

The crop experiments were carried out during Rabi season 2016-17 & 2017-18. The experiment conducted at Research farm adjacent to agromet observatory (Latitude: 29° 10’ N; Longitude: 75° 46’ E & Altitude: 215 m), Department of Agricultural Meteorology, CCS HAU, Hisar, Haryana. The main aim and objectives of this work were to be accesses the microclimatic condition of potato under varying planting dates and varieties. Results revealed that micrometeorological parameters observed more favourable in 3rd week of October (D2) planted crop as compared to other planting dates. The absorbed PAR was recorded higher in 3rd week of October (D2) sown crop and Kufri Pushkar then other treatments at phenophases, respectively higher in during both seasons. PAR transmitted (watt/m2) at bottom, Soil heat flux pattern was observed in decreasing trend from advanced vegetative stage to tuber bulking stage may be due to more cover of ground and absorption percentage of PAR. The consumption of PAR, bright sun shine and assimilation rate were more in second planting dates. Among planting dates, the net radiation (Rn) was higher at early vegetative stage in 3rd week of October (D2) and 1st week of November (D3) during both crop seasons. The major portion of Rn (Net radiation) was utilized by latent heat of vaporization (LE). The 2nd week of October (D1) was received higher values of soil heat flux (G) during both the crop seasons. The minimum value of G was observed at tuber bulking stage in 1st week of November (D3) during both crop seasons. LE was higher at all phenophases in 3rd week of October (D2) at early vegetative stage during both the crop seasons. G was highest at initiation of tuber and early vegetative stage in 3rd week of November (D4) respectively, during both season. Temperature profiles were inverse throughout the day within the canopy at all phenophases. Over the top of the crop canopy the temperature profile was lapse. The relative humidity profiles were lapse inside the crop canopy throughout the day at 9:00 hours where it was iso-humic. Further concluded that the microclimate profile condition pattern was optimum in second sown crops and produced higher tuber yield.

Tuber Yield and Quality of Two Potato Cultivars in Response to Nitrogen Fertilizer Management

In Brazil, the potato cultivar Agata is used for fresh market, while the cultivar Markies is used for both fresh market and frying industry. However, these cultivars may respond differently to nitrogen (N) management. Thus, field experiments with these cultivars were conducted to evaluate marketable tuber yield and physico-chemical and nutritional quality of tubers in response to four different early N managements (80p: 80 kg N ha−1 at planting; 160p: 160 kg N ha−1 at planting; 40 + 120: 40 kg N ha−1 at planting plus 120 kg N ha−1 at hilling; and 80 + 80: 80 kg N ha−1 at planting plus 80 kg N ha−1 at hilling) combined with late N application rates at tuber bulking stage (0, 20, 40 and 80 kg N ha−1). For both cultivars, the application of only 80 kg N ha−1 at planting was enough to have satisfactory marketable tuber yield and the late N application did not provide benefit to yield. The 80 + 80 treatment reduced the concentrations of starch and carbohydrate and increased the protein concentration in tubers of cultivar Agata, and promoted the Ca biofortification of tubers in both cultivars. Tuber Fe concentration of cultivar Agata was higher with the 80p treatment. The early N managements with N supplied at planting increased tuber Cu concentration of both cultivars. Late N application increased the concentration of protein, Ca and Fe only in the Agata tubers. For cultivar Markies, the tuber reducing sugar concentration was increased by the late application of 40 kg N ha−1 combined with the early N application treatments 160p and 40 + 120, but only small variations in the colour intensity or yellow tonality of the fried potatoes were observed.

Growth Stages Classification of Potato Crop Based on Analysis of Spectral Response and Variables Optimization.

Potato is the world’s fourth-largest food crop, following rice, wheat, and maize. Unlike other crops, it is a typical root crop with a special growth cycle pattern and underground tubers, which makes it harder to track the progress of potatoes and to provide automated crop management. The classification of growth stages has great significance for right time management in the potato field. This paper aims to study how to classify the growth stage of potato crops accurately on the basis of spectroscopy technology. To develop a classification model that monitors the growth stage of potato crops, the field experiments were conducted at the tillering stage (S1), tuber formation stage (S2), tuber bulking stage (S3), and tuber maturation stage (S4), respectively. After spectral data pre-processing, the dynamic changes in chlorophyll content and spectral response during growth were analyzed. A classification model was then established using the support vector machine (SVM) algorithm based on spectral bands and the wavelet coefficients obtained from the continuous wavelet transform (CWT) of reflectance spectra. The spectral variables, which include sensitive spectral bands and feature wavelet coefficients, were optimized using three selection algorithms to improve the classification performance of the model. The selection algorithms include correlation analysis (CA), the successive projection algorithm (SPA), and the random frog (RF) algorithm. The model results were used to compare the performance of various methods. The CWT-SPA-SVM model exhibited excellent performance. The classification accuracies on the training set (Atrain) and the test set (Atest) were respectively 100% and 97.37%, demonstrating the good classification capability of the model. The difference between the Atrain and accuracy of cross-validation (Acv) was 1%, which showed that the model has good stability. Therefore, the CWT-SPA-SVM model can be used to classify the growth stages of potato crops accurately. This study provides an important support method for the classification of growth stages in the potato field.

Detection of chlorophyll content in growth potato based on spectral variable analysis

Monitoring the chlorophyll content in tuber formation and tuber bulking stage has great significance for the nutritional status diagnosis in the potato field. In this paper, the 314 canopy spectra of potato crops were collected at four stages, respectively. The leaves were collected simultaneously to measure the chlorophyll content. After spectra pre-processing, the dynamic changes in chlorophyll content and spectral response during growth were analyzed. Two variable selection algorithms (successive projection algorithm, and random frog algorithm) were employed to select chlorophyll characteristic wavelengths. The partial least square algorithm was used for modeling analysis. The performance of sensitive wavelengths selected by two algorithms was compared, respectively, from the perspective of correlation with chlorophyll, reflecting leaf information, and model result. The sensitive wavelengths selected by random frog was optimal. The determination coefficient of calibration and validation set of the detection model established based on above sensitive wavelengths was respectively 0.827 and 0.798. The results showed the chlorophyll content of potato could be detected accurately based on the spectroscopy method.

Effects of Different Growing Media on Yield and Growth Parameters of Potato Minitubers (solanum Tuberosum L.)

ABSTRACTSeed potatoes (Solanum tuberosum L.) are increasingly produced by minitubers originated from tissue culture techniques to eliminate the chance of infections by viruses. The aim of this study was to evaluate the suitability of several potting media for minituber production in the greenhouse environment. Six growing media treatments were used in a randomized complete block design with four replications. Treatments included perlite, soil, perlite + vermiculite (1:1 v/v), perlite + peat moss (1:1, v/v), perlite + soil (1:1, v/v), perlite + soil + composted cattle manure (4:3:3 v/v), and perlite + soil + vermicompost (4:3:3v/v). All treatments except treatments that contained composted cattle manure or vermicompost were subjected to daily application of nutrient solution. Growing media were analyzed for a selected number of physical and chemical properties. Tuber yield and yield parameters were determined 75 days after planting. Leaf area, shoots, and root DW and FW and concentrations of N in roots and shoots were measured at tuber bulking stage. The highest value of particle density and bulk density and the lowest value of porosity and EC were obtained for the media that contained Perlite. The greatest value of leaf chlorophyll index throughout the growing period was observed at perlite + soil + composted cattle manure and perlite + soil + vermicompost, likely due to excess availability of N. The maximum contents of N in the shoot root and tubers were observed in perlite + soil + composted cattle manure. Fresh and dry minituber yield and number of minituber per m2 shoot and root FM and DM yield were greater in growing media without soil than the containing Compound with soil. The fertigated perlite + peat moss (1:1, v/v) resulted in the greatest yield among treatments likely due to desirable EC, pH, and porosity. This treatment can be recommended as a suitable media for the production of potato minitubers in greenhouse environment.Abbreviations B: Boron; Ca: Calcium; CEC: Cation exchangeable capacity; Cu: Copper; Db: Bulk density; Dp: Particle density; DM: dry matter; DW: dry weight; EC: Electrical conductivity; Fe: Iron; FW: fresh weight; K: Potassium; LAI: leaf area index; Mg: Magnesium; Mn: Manganese; Mo: Molybdenum; N: Nitrogen; n: Porosity; Na: Sodium; OC: Organic carbon; P: Phosphorus; S: Sulfur; Zn: Zinc.

Patatesde (Solanum tuberosum L.) kurağa tepki veren transpozonların ve transkripsiyon faktörlerin in siliko analizi

Potato (Solanum tuberosum L.) is the most important non-grainfood crop and is essential for global food security. Drought is one of the major abiotic stress factors resulting in huge yield loss in the production of crops and similarly, it negativelly affects the tuberization, tuber yield and tuber quality of potato. Transposable elements (TEs) account for a large portion of the genome in many eukaryotic species. Several studies have identified the molecular mechanism that cause the activation of TEs under stress. Stresses and environmental challenges, in particular, are known to alter the expression or stimulate the transposition of mobile elements in plants. Transcription of these stress-responsive genes is largely controlled by transcription factors (TFs). A number of transcription factors playing an essential role in drought tolerance of plants have been identified in the past few years. In this work, a subset of drought responsive TE families and TFs in potato at tuber bulking stage was defined, based on genome-wide transposon homology and annotation. Our results indicated that, the read numbers for TE subfamilies yielded different distributions between DNA and RNA transposons. In addition, many TFs such as bHLH, WRKY, NAC, AP2/ERF may have important functions in regulation of drought tolerance in potato. Identification of TEs and TFs which are taking part in stress can offer useful information for functional genomics and designing novel breeding strategies for developing stress tolerant plants.

Nitrogen release and synchrony in organic and conventional farming systems of the Central Highlands of Kenya

To match Nitrogen (N) supply to crop N demand, it is essential to understand N release and uptake patterns in different farming systems and crops. To assesses the dynamics of N released in organic and conventional systems and potential synchrony and asynchrony in crop N uptake, a study was conducted over three cropping seasons (potato, maize and leafy vegetables) at two sites in the Central Highlands of Kenya. Mineral-N release and synchrony were monitored in conventional and organic systems at high (recommended N, P, pesticides and irrigation) and low input (low N, P, pesticide use and rainfed) systems. Mineral-N release was assessed using in situ buried bags and N synchrony was measured by the daily differences in N fluxes. The percentage of N applied released during potato (38%) and vegetable (44%) cropping seasons were similar between systems. However, under maize strong temporal N immobilization from inputs occurred, particularly at Thika, related to the poor quality of manure and compost (lignin:N ratio > 13). In all systems, excess-asynchrony of available N was pronounced during vegetative stages and at harvest, while insufficient-asynchrony occurred at reproductive stages. During potato cropping season at Thika, Org-High showed highest positive N fluxes (> 20 kg N ha−1 day−1) at planting and tuber bulking stage. At early stages of maize and vegetables Org-Low and Org-High experienced up to 5 times larger negative N fluxes (insufficiency) compared to conventional treatments at Chuka site. The study recommends reducing N applications at planting and increasing N dosages at reproductive stages of crops.