Moisture Stress Research Articles

Adaptation study of Haricot bean (Phaseolus vulgaris L.) varieties in moisture stress areas of Abergelle, Northern Ethiopia

Adaptation study of Haricot bean (Phaseolus vulgaris L.) varieties in moisture stress areas of Abergelle, Northern Ethiopia

Optimizing Geotechnical Data Input Based on Light Weight Deflectometer for Road Design and Performance Analysis

This study explores alternative methods for assessing critical parameters in pavement design, specifically Young’s modulus and Poisson’s ratio. While repeated load triaxial testing is traditionally used, its high cost and time requirements drive the search for more efficient methods. Falling weight deflectometer tests are also resource-intensive, leading to the investigation of light weight deflectometer tests. Utilizing EraPave software for analysis, which employs a multi-layer elastic theory back-calculation tool, the research examines material properties through laboratory tests on unbound granular material, sandy soil, silty sand soil, and sandy silty clay soil, providing data for field tests. Field LWD tests, conducted under various moisture contents and dynamic loads, provided data processed through EraPave to predict layer moduli. Results demonstrate LWD’s effectiveness in predicting layer moduli for different construction materials. Despite variations in root mean square error values, LWD data consistently align well with EraPave predictions, underscoring its reliability for pavement evaluation. Case studies illustrate LWD and EraPave’s adaptability to different moisture contents and stresses. This study advocates for LWD tests’ efficiency and highlights the importance of analytical tools like EraPave for accurate pavement assessments, contributing to optimized pavement evaluation processes and informed road construction and maintenance decisions.

Experimental Study on Cyclic Simple Shear Test of Coastal Tidal Soft Soil

Based on undrained cyclic simple shear tests conducted on coastal tidal soft soil under various conditions of cyclic stress ratios and moisture contents, this study investigated the influence of these factors on the dynamic properties of the soil. The findings indicated that with increasing moisture content and stress cycle ratio, the stress–strain hysteresis loop gradually expanded, resulting in a higher strain difference and a transition from a dense to a sparse curve pattern. Moreover, the symmetry of the hysteresis loop was lost in the later stages of shearing. With an increase in the number of cycles, the cumulative shear strain gradually increased, and the increase in the cyclic ratio of water content to stress reduced the number of cyclic shear cycles required to achieve failure, thereby accelerating the soil’s failure rate. A predictive formula was developed based on the experimental results to estimate the failure cycles as a function of the cyclic stress ratio and moisture content. Furthermore, the softening index decreased gradually with an increasing number of cycles, and a higher moisture content and cyclic stress ratio accelerated the soil’s softening process. It was observed that under the conditions of optimal moisture content, the soil exhibited a slower softening rate during the initial stage of shearing.

Effect of Mid-Season Moisture Stress on Fatty Acid Composition of Groundnut (Arachis hypogaea L.) Genotypes

Effect of Mid-Season Moisture Stress on Fatty Acid Composition of Groundnut (Arachis hypogaea L.) Genotypes

Siberian Pine and Larch Response to Warming-Drying Climate in the Southern Boundary of Their Range

Trees’ growth and areal responses to changing climate are primarily expected within the edges of the species range. Here, we compared the responses of Siberian pine (Pinus sibirica Du Tour), a moisture-sensitive species, and drought-resistant larch (Larix sibirica Ledeb.) at the southern part of their ranges in the Siberian Mountains (the Tannu-Ola Ridge). We study the species’ growth and proportion in the forests from forest-steppe to treeline ecotone along the elevation gradient. These studies are based on radial growth index (GI) analysis and GI dependence on the climate variables. We used satellite time series to detect the land cover changes (areas of larch and Siberian pine, as well as shrubs and birch). We compared trees’ GI before and after warming “restart” in the late 1990s. Generally, GI dependence on the air temperature was negative at elevations below c. 1600 m a.s.l., whereas GI dependence on the moisture variables (precipitation, vapor pressure deficit, and soil moisture) was positive for both species. Above 1600 m, increasing air temperatures stimulated species growth, whereas the influence of moisture variables was negative (for larch) or neutral (for Siberian pine). After the warming restart, the GI of both conifers increased in moisture-sufficient high elevations and treeline ecotone, whereas within low elevations (<1300 m), the GI was stagnant or suppressed. Both species’, especially Siberian pine, negative growth dependence on air temperature and positive dependence on the moisture variables strongly increased since the warming restart. We found a risen growth dependence of both species on the soil-stored water during the previous year (September–October), which smoothed moisture stress at the beginning of the growing season. Yet both species’ growth also suffered as a result of early spring warms. We found that larch is migrating in both uphill and downhill directions, while Siberian pine is migrating uphill only. Forests loss occurred at low elevations (<1300 m), whereas forest and shrub gain occurred at high (>2000 m) ones. The upper boundary of the forests and shrubs is migrating uphill at rates of about 0.8 and 0.3 m/y, respectively. We observed a decrease in Siberian pine proportion in the forests, whereas areas of larch and birch strongly increased (by 150% and 100%, respectively), which indicates the retreat of Siberian pine from its southern habitat. We suggested afforestation of the areas of Siberian pine mortality by the drought-tolerant larch species.

Understanding the Regular Biological Mechanism of Susceptibility of Tomato Plants to Low Incidences of Blossom-End Rot

Blossom-end rot (BER) is a physiological disorder caused by calcium deficiency, often paired with moisture stress and irregular traditional watering practices. To understand the biological mechanism affecting the incidence of BER, different tomato genotypes were cultivated in sandy soil and were traditionally irrigated. Nine tomato genotypes were investigated to assess their susceptibility to BER, and the incidence rate varied from 7.1% in “Voskhod” to 57.6% in “Majnat” genotypes. This study also comprehensively analyzed various physiological and biochemical parameters to elucidate their correlation with BER incidence in tomato plants. Our findings revealed a range of parameters positively correlated with BER incidence, including the relative water content of roots, the number of fruits per plant, vitamin C content, and potassium content. Parameters related to fruit quality, such as titratable acidity, peroxidase content, and firmness degree, also showed positive correlations with BER incidence. Conversely, parameters such as total yield per hectare, chlorophyll content, average plant height, and calcium content demonstrated strong negative correlations with BER incidence, suggesting potential protective effects against this disorder. This study highlights that genotypes with higher marketable yields, such as ‘Voskhod’ (65 tons/ha), showed lower BER incidence, underscoring the importance of selecting the appropriate genotype in improving yield and reducing blossom-end rot in tomato fields. Conversely, cultivars with high BER sensitivity, such as ‘Chelnok’ (26.3 tons/ha), require specially designed cultivation management to avoid production declines.

Anomaly-Based Variable Models: Examples of Unusual Track and Extreme Precipitation of Tropical Cyclones

Tropical cyclones (TCs) can cause severe wind and rain hazards. Unusual TC tracks and their extreme precipitation forecasts have become two difficult problems faced by conventional models of primitive equations. The case study in this paper finds that the numerical computation of the climatological component in conventional models restricts the prediction of unusual TC tracks. The climatological component should be a forcing quantity, not a predictor in the numerical integration of all models. Anomaly-based variable models can overcome the bottleneck of forecast time length or the one-week forecasting barrier, which is limited to less than one week for conventional models. The challenge in extreme precipitation forecasting is how to physically get the vertical velocity. The anomalous moisture stress modulus (AMSM), as an indicator of heavy rainfall presented in this paper, considers the two conditions associated with vertical velocity and anomalous specific humidity in the lower troposphere. Vertical velocity is produced by the orthogonal collision of horizontal anomalous airflows.

Characterization of hygrothermal, gas pressure and stress characteristics for poplar wood during unilateral surface densification

Unilateral surface compression in wood presents notable benefits, including reduced wood volume loss and energy consumption, rendering a highly promising and extensive utilization. However, shortcomings in compressed wood arise due to unclear gas pressure, temperature, and moisture content distribution within the wood during hot pressing. In this paper, the temperature and pressure distribution were analyzed utilizing an optical fiber temperature and pressure measurement system within the wood during hot pressing. Moreover, the moisture content, stress and strain in each layer at the end of hot pressing were discussed extensively. The results showed that the wood surface layer (SL) and subsurface layer (SSL) maximum temperature values were similar even with different layer thicknesses. Under sealing conditions, SL and SSL temperatures were generally 6 ℃ to 7 ℃ higher compared to unsealing conditions. The gas pressure maximum value exhibited an opposite order, gradually transferring to the core layer (CL) and declining as the processing time extended. During compression treatment, moisture migrated from the hot end to the cold within the wood. The moisture content displayed significant differences between the middle and end parts of the wood under unsealed conditions, with the disparity becoming more pronounced further away from the hot end. The transition region of the compressed wood served as a stress concentration area, experiencing the highest levels of stress. The dense region followed with the second highest stress levels, while the un-densified region exhibited the least amount of stress. Under the same process parameters, the thickness had little influence on the distribution of dense layers.

Drought and its ecological risk bundle from the perspective of watershed hydrological cycle

The mechanisms underlying the impacts of climate change and vegetation dynamics on hydrological drought in humid regions are still lacking. In this study, we connected the four components of meteorology-soil-vegetation-runoff to investigate the spatio-temporal response relationship between vegetation growth and different drought types. Based on the Variable Infiltration Capacity model and the Self-organizing Map Algorithm, we proposed ecological risk bundles at the grid scale to characterize the potential impacts of different types and levels of drought on vegetation. Furthermore, we quantified the driving impact of temporal and spatial changes in vegetation coverage on the propagation of meteorological-hydrological drought. The study found that the centers of gravity for the occurrence frequencies of extreme and mild drought shifted towards regions where vegetation growth was influenced by climate change. In certain regions of the watershed, vegetation exhibits significant spatial and temporal heterogeneity in its response to stress caused by different drought types. From 2004 to 2014, the stress on vegetation caused by moderate and mild meteorological droughts weakened, while soil moisture stress intensified after 2014. Simultaneously, the impacts of climate change and vegetation growth on runoff reached 48.25 % and 35.13 % respectively, and their synergistic effects triggered changes in the risk of co-concurrent return periods for hydrological drought events. Under the 100-year design return period, the co-occurrence return period of runoff shifted from its natural state of 162.9 years to 52.8 years, and the joint return period reversed its scenario, becoming shorter than the co-occurrence return period.

Water use and water use efficiency of three Brassicaceae oilseeds under high‐ and low‐yielding environments

AbstractBrassicaceae oilseed crops have proven potential as vegetable oil feedstock for biofuels and food uses. However, meeting a growing demand for vegetable oils for food and industrial uses will require identifying oilseed species that are best suited for various growing environments within a particular region. The objective of this study was to compare growth dynamics, seasonal water use (WU), seed yields, and water use efficiency (WUE) of canola (Brassica napus L.), camelina (Camelina sativa L.), and white mustard (Sinapis alba L.) to determine their suitability under three different environments within the northern Great Plains. Comparisons were made among these species over three growing seasons between 2013 and 2016 at Morris, MN; Mandan, ND; and Sidney, MT, situated along a strong precipitation gradient from east to west. Generally, growing season precipitation was similar at Morris and Mandan, but both were considerably greater than at Sidney. Seasonal WU was similar among these oilseed species at Morris and Mandan but was greatest for camelina at the drier Sidney environment. Canola seed yield was the greatest at Morris and had higher WUE than camelina and white mustard. At Mandan and Sidney, canola and camelina had similar seed yields and WUE, which were generally greater than white mustard. Under abundant moisture and low stress (e.g., Morris), seed yield per millimeter of water used could be maximized by growing canola, while in a drier more stressful environment like Sidney, seed yield per millimeter of water used could be maximized by growing camelina.

Evaluating effects of selected water conservation techniques and manure on sorghum yields and rainwater use efficiency in dry region of Zimbabwe

Sorghum production in semi-arid areas of Zimbabwe is constrained by low and erratic rainfall, low fertility and soil moisture stress. Sorghum grain yields ranges from 0.2 to 0.4 t ha−1 in sandy-to-sandy loam soils respectively. The objective of the study was to assess cattle manure and rainwater harvesting techniques in improving sorghum grain yield in a semi-arid region of Zimbabwe. The experiment used a randomised complete block design with rainwater harvesting technique as a main treatment factor at three levels. Sub-plot factor was cattle manure at five levels (0, 2.5, 5, 10 and 15 t ha−1) and two sorghum varieties (Macia and SV1) as sub-sub plot factor. Sorghum grain yields were improved significantly (p < 0.05) for both varieties using tied contours. Increasing application rates of cattle manure, showed significant increase (p < 0.05) in sorghum grain yield over the control (0 t ha−1). Tied contour had higher grain yield (1.15 t ha−1) with the use of Macia variety. Stover yield was highly influenced by rainwater harvesting method of tied contour (p < 0.05) compared with infiltration pit and standard contour. Increase in application levels of cattle manure show significant (p < 0.05) increase in stover yields. Tied contour had the highest (3.11 kg ha−1 mm−1) rainwater use efficiency which show significant differences (p < 0.05) from infiltration pits and standard contour. Interaction of tied contour and different rates of cattle manure showed significant increments in rainwater use efficiency with increases in manure application rates. Tied contours, 15 t ha−1 cattle manure and Macia variety are potential strategy to achieve climate smart agriculture and improve food security in semi-arid areas. Sorghum production in marginalised areas can be productive with adoption of tested techniques.

Explicit Consideration of Plant Xylem Hydraulic Transport Improves the Simulation of Crop Response to Atmospheric Dryness in the U.S. Corn Belt

AbstractAtmospheric dryness (i.e., high vapor pressure deficit, VPD), together with soil moisture stress, limits plant photosynthesis and threatens ecosystem functioning. Regions where rainfall and soil moisture are relatively sufficient, such as the rainfed part of the U.S. Corn Belt, are especially prone to high VPD stress. With globally projected rising VPD under climate change, it is crucial to understand, simulate, and manage its negative impacts on agricultural ecosystems. However, most existing models simulating crop response to VPD are highly empirical and insufficient in capturing plant response to high VPD, and improved modeling approaches are urgently required. In this study, by leveraging recent advances in plant hydraulic theory, we demonstrate that the VPD constraints in the widely used coupled photosynthesis‐stomatal conductance models alone are inadequate to fully capture VPD stress effects. Incorporating plant xylem hydraulic transport significantly improves the simulation of transpiration under high VPD, even when soil moisture is sufficient. Our results indicate that the limited water transport capability from the plant root to the leaf stoma could be a major mechanism of plant response to high VPD stress. We then introduce a Demand‐side Hydraulic Limitation Factor (DHLF) that simplifies the xylem and the leaf segments of the plant hydraulic model to only one parameter yet captures the effect of plant hydraulic transport on transpiration response to high VPD with similar accuracy. We expect the improved understanding and modeling of crop response to high VPD to help contribute to better management and adaptation of agricultural systems in a changing climate.

Comparative effects of two elicitors on the essential oil biosynthesis of simulated hail-damaged rose geranium (Pelargonium graveolens L’Hér. cv. ‘BOURBON’)

Extreme abiotic stress factors such as hail, defoliation, salinity, and moisture stress can affect the biosynthesis of essential oils. To mitigate this, most commercial farmers globally use agricultural crop insurance; however, this is not the case for most smallholder and emerging farmers in southern Africa, as agricultural insurance tends to be expensive when included in the production system. Therefore, this study aimed to investigate the comparative effects between two elicitors: abscisic acid (ABA) and methyl jasmonate (MeJA) on essential oil biosynthesis of simulated hail-damaged rose geranium (Pelargonium graveolens L’Hér.) as an alternative strategy to improve the essential oil biosynthesis following severe hail damage of rose geranium. The study was conducted in a 72 m2 temperature-controlled greenhouse, using a 4 x 2 factorial treatment design arranged in a randomized complete block design. Treatments comprised four levels of two elicitors at 75 µM (ABA), 150 μM (ABA), 10 mM (MeJA), and 20 mM (MeJA), applied in two different application periods (daily application for either 7 or 14 days). The simulation of hail damage was through 100% defoliation, with decapitation of the terminal buds. A significant interaction was observed between the elicitor treatment, and length of the period of application on essential oil yield (mass), where the highest yield was observed when MeJA (10 mM) was applied for seven consecutive days compared to the 14-day treatment. Geraniol esters were partially improved by the application of MeJA at 10 mM. Application of the two elicitors improved citronellol, geraniol, and linalool, regardless of the length of the period of application. The citronellol to geraniol ratio, a determining factor of essential oil quality, was 2.7:1 when MeJA was applied at 10 mM, significantly better than any application level of ABA. Therefore, it could be concluded that the application of MeJA at 10 mM may improve the essential oil biosynthesis of hail-damaged rose geranium plants compared to ABA at any level, and this may be adopted as a possible mitigating strategy by the emerging farmers and growers in southern Africa for improving the biosynthesis of rose geranium post hail damage. On the other hand, where growers are interested in higher contents of linalool and citronellol, ABA may be used at any level. Key words: Defoliation, essential oil, yield, phytohormone, citronellol, geraniol, linalool

Identification of drought tolerant inbred lines and assessment of combining ability in maize (Zea mays L.)

AbstractMaize is an important agricultural crop ensuring food and nutritional security throughout the globe. It is highly sensitive to many of the biotic and abiotic stresses, and among them, drought is the most severe abiotic stress limiting maize production. Climate change tends to worsen this scenario by changing precipitation patterns and decreasing water availability. Hence, the present study was undertaken to identify drought‐tolerant inbred lines under well‐irrigated and managed stress conditions in the field toward developing drought‐resilient maize hybrids. The initial in vitro screening of 65 agronomically elite maize inbred lines was undertaken at 15%, 20%, and 25% polyethylene glycol (PEG) concentrations. Subsequently, the 15 inbreds selected for their promising performance under varying concentrations of PEG were evaluated in the pot (100%, 60%, and 40% of field capacity [FC]) and managed field experiments (moisture stress). Various physiological, biochemical, and yield attributing traits were measured among the inbreds to assess their drought tolerance potential. The analysis of variance in the pot and field experiments indicated significant genotypic differences among the inbreds and genotype × treatment interaction for different traits considered. In the pot experiment, the phenotypic correlation analysis showed a significant positive association of shoot fresh weight with plant height (r = .71), number of leaves (r = .58), relative water content (r = .60), root fresh weight (r = .58), shoot dry weight (r = .60), and SPAD meter readings under (r = .71) moisture stress condition. In the field experiment, the grain yield had a significant positive association with plant height, relative water content, SPAD before stress, ear length, ear girth, kernel rows per ear, kernels per row, and per day productivity under stress. Proline accumulation in inbreds during stress was found to be higher compared to nonstress conditions. The inbred lines CML 505, CML 444, CML 451, CML 504, QM 11408, and MAI 214 were promising for most of the drought tolerance imparting traits. These six inbreds along with four inbreds having low DRI (SKV 50, MAI E2‐163, MAI 16, and MAI E2‐241) were crossed in half diallel manner, and crosses involving low × high or high × low DRI inbreds showed higher grain yield. The current study also revealed the need of combining various physiological and yield attributing traits in drought breeding programmes.

Response of spiny cocklebur (Xanthium spinosum) and common cocklebur (X. strumarium) seed germination to environmental and soil factors

Context Seed germination and seedling emergence are affected by many environmental factors. Knowledge regarding factors affecting seed germination of spiny cocklebur (Xanthium spinosum L.) and common cocklebur (X. strumarium L.) could help determine their potential distribution and control strategies. Aims The present study was conducted to investigate the effect of key environmental factors on seed germination and seedling emergence of spiny cocklebur and common cocklebur. Methods Seed germination of spiny cocklebur and common cocklebur was tested at various constant and alternating temperatures, pH, salinity and moisture stress. The effect of flooding height, burial depth and soil type on seedling emergence was also investigated. Key results The optimum constant temperature for germination of spiny cocklebur was 25°C, and 35°C and higher for common cocklebur. Under alternating temperature, maximal germination was at 25/15°C and 35/15°C for spiny cocklebur and common cocklebur, respectively. Maximum germination of both spiny cocklebur and common cocklebur was at neutral pH. Spiny cocklebur germination was not suppressed as much by lower and higher pH or by an increasing salinity as was common cocklebur germination. Conclusions Common cocklebur appears to be better adapted to warmer environments than is spiny cocklebur, but less so to a broad range of soil pH and salinity stress. Implications The different germination responses of common cocklebur and spiny cocklebur to the environmental factors of temperature, pH and salinity imply that the two species may occupy different niches across the landscape. Our knowledge of these responses can help in identifying potential areas for invasion for increased monitoring and management.

Increase in ascorbate content in leaves of Hordeum vulgare after spraying with cold atmospheric plasma-treated water in combination with waterlogging and re-aeration

Flood events are likely to increase in the near future and are one of the events most threatening to agricultural production. Barley is the fourth most important crop and the cereal most sensitive to excessive moisture stress. Improving the stress tolerance of crops to a variety of stress factors caused by a more volatile climate is an important task for the coming years. The aim of this study was to investigate the efficacy of cold atmospheric plasma-treated water (PTW) as a foliar spray to stimulate the antioxidant system of Hordeum vulgare and thereby improve plant stress tolerance. For this purpose, we analysed the components of the ascorbate-glutathione cycle in barley leaves and roots without stress and under waterlogging conditions. PTW increased the content of total and reduced ascorbate in leaves as well as the content of reduced ascorbate in roots four weeks after treatment. This was observed both, under stress free conditions and after waterlogging and re-aeration. In leaves, enzyme activities also increased after re-aeration, and in roots, total and reduced glutathione levels increased after waterlogging compared to the control. The accumulation of low molecular weight antioxidants may increase tolerance to a variety of stress factors through more efficient scavenging of ROS. Overall, treatment of plants with PTW may trigger an adaptive response that leads to mitigation of the negative effects of stress, and thus, could be used as a priming agent for protection against subsequent more severe stress factors that occur in the plants' natural environment.

Hydrological Factor and Land Use/Land Cover Change Explain the Vegetation Browning in the Dosso Reserve, Niger

The West Sahel is facing significant threats to its vegetation and wildlife due to the land degradation and habitat fragmentation. It is crucial to assess the regional vegetation greenness dynamics in order to comprehensively evaluate the effectiveness of protection in the natural reserves. This study analyzes the vegetation greenness trends and the driving factors in the Dosso Partial Faunal Reserve in Niger and nearby unprotected regions—one of the most important habitats for endemic African fauna—using satellite time series data from 2001 to 2020. An overall vegetation browning trend was observed throughout the entire region with significant spatial variability. Vegetation browning dominated in the Dosso Reserve with 17.7% of the area showing a significant trend, while the area with significant greening was 6.8%. In a comparison, the nearby unprotected regions to the north and the east were found to be dominated by vegetation browning and greening, respectively. These results suggest that the vegetation protection practice was not fully effective throughout the Dosso Reserve. The dominant drivers were also diagnosed using the Random Forest model-based method and the Partial Dependence Plot tool, showing that water availability (expressed as soil moisture) and land use/land cover change were the most critical factors affecting vegetation greenness in the study region. Specifically, soil moisture stress and specific land management practices associated with logging, grazing, and land clearing appeared to dominate vegetation browning in the Dosso Reserve. In contrast, the vegetation greening in the central Dosso Reserve and the nearby unprotected region to the east was probably caused by the increase in shrubland/forest, which was related to the effective implementation of protection. These findings improve our understanding of how regional vegetation greenness dynamics respond to environmental changes in the Dosso Reserve and also highlight the need for more effective conservation planning and implementation to ensure sustainable socio-ecological development in the West Sahel.

Evaluating the Effects of Drought Stress on Biomass and Yield Traits in Sorghum Genotypes

The study aimed to identify drought-tolerant sorghum genotypes by evaluating twenty sorghum genotypes over two Rabi seasons (2021-22 and 2022-23) under irrigated and rainfed conditions using a split plot design. Results showed that moisture stress significantly affected sorghum performance, including leaf and stem dry matter accumulation, grain yield per plant, stover yield, and harvest index. Among the genotypes, BJV-44 and M-35-1 exhibited the least decline in grain yield per plant under rainfed conditions, with yields of 76.17 and 73.50 g/plant, respectively, compared to irrigated conditions. Conversely, genotypes M 148-138 and Tandur L experienced the most significant reductions in grain yield per plant under rainfed conditions. Basavana pada exhibited the highest harvest index. The study concluded that BJV-44 and M-35-1 are drought-tolerant sorghum genotypes with relatively higher grain yields per plant under rainfed conditions, providing valuable insights into sorghum genotype performance and resource utilization in drought-prone regions.

THE ROLE OF CYTOKININ AND GIBBERELLIN IN POTATO TUBER SPROUTING

Potato (Solanum tuberosum L.) is a highly sensitive crop to tuber dormancy. This can be initiated by various factors, including moisture stress, high or low temperature, day length, hormonal imbalance, and heredity. Breaking of tuber dormancy is therefore important for seed potato multiplication, rapid post-harvest disease testing, and early production in the field or green house. Cytokinin (CK) and gibberellin (GA) in combination will terminate dormancy and increase sprout growth earlier than using GAs alone. And also using only CK will terminate dormancy earlier than using GAs alone, but subsequent sprout growth will be hampered. In this review, the current knowledge and possible utilization of CK and GA, which can be used for termination of dormancy and sprout growth of potato tubers, have been reviewed and discussed. The role of CK and GA to mitigate the harmful effects of endogenous and environmental stresses in potato sprouting is also examined. In addition, numerous biochemical and physiological processes principal to improved potato sprouting under the consequence of these hormones are discoursed in detail.

Genetic characterization and evaluation of pigmented maize (Zea mays L.) landraces of the North East Hill Region of India-an established centre of maize diversity

Abstract The North East Hill Region (NEHR) of India is home to diverse maize landraces including pigmented accessions rich in antioxidants and nutritional properties. The present study attempted to characterize a representative collection of this mostly unexplored diversity. Altogether eighty-three local maize landraces from the seven hill states of the NEHR were studied with special emphasis on pigmentation diversity. For the morphological traits, a significant ANOVA indicated the presence of substantial genetic variability for which selection would be fruitful. A number of these accessions were found to have traits that help cope with moisture stress, improve stalk strength and optimize photosynthesis. Principal component analysis studies for the yield attributing traits indicated that ear weight was most variable. The bleaching/histological studies confirmed that anthocyanin pigment when present was always restricted to the aleurone layer of the kernels, typical of blue maize. Quantitative analysis for kernel anthocyanin/phlobaphene content also revealed genetic differences among the accessions. Genetic analysis using the model-based STRUCTURE indicated significant population structuring among the accessions. Specifically, for the pigmentation diversity studies both principal coordinate analysis and neighbour joining methods revealed near concurrent population structuring due in part to the high differentiation of seven of the twenty-one pigmentation specific loci studied. The results obtained provide comprehensive evidence of a significant amount of genetic differentiation among the landraces under study. Landraces are valuable reservoirs of favourable alleles for which selection can be made and, as in this study, identify accessions for breeding maize with enhanced levels of beneficial secondary metabolites.