Plant Phenological Development Research Articles

Triangle area model (TAM) for predicting germination: An approach to enhance hydrothermal time model applications

A thorough examination of assumptions in hydrothermal time models revealed areas for enhancing model performance. We introduce the Triangle Area Model (TAM), which uses the area of right-angled triangles to calculate hydrothermal time for predicting population germination fractions (g). TAM is characterized by its depiction of triangles, considering insightful parameters such as the distance of germination temperature (T) to the base (Tb), optimal (To), and ceiling (Tc) temperatures, the range of Tc – To, To – Tb, and the germination water potential (Ψ), i.e. mean base water potential (Ψb(g)), along with potential g that may occur with T and Ψ combinations within Tc – Tb when Ψ > Ψb(g). Applied to germination data from Ambrosia psilostachya L., Cynanchum acutum L., and Bidens pilosa L., TAM achieves an RMSE of 0.03 for A. psilostachya and C. acutum, and 0.05 for B. pilosa. Moreover, TAM demonstrates an R2 of 0.96, 0.97, and 0.98 for the respective species. TAM significantly outperforms earlier models through a comparison with varying T and Ψ. TAM determined Tb for A. psilostachya, C. acutum, and B. pilosa as 0.19, 14.57, and 5.76 °C; To as 25.1, 39.9, and 29.8 °C; and Tc as 46.7, 53, and 41°C, for the respective species. It also estimates Ψb(g) as -1.48 for A. psilostachya, -0.98 for C. acutum, and -0.97 for B. pilosa. The TAM approach deepens our understanding of temperature-moisture processes influencing plant survival, colonization, and habitat expansion for these three invasive alien species. Furthermore, it can be more widely applied for estimating TT and HTT across different growth stages, enhancing the prediction accuracy of plant phenological development.

Phosphorus management is key to effective deployment of root ideotypes in complex soil environments

PurposeWe questioned how root ideotypes selected for deep or shallow root architecture function in complex environments with heterogeneous distributions of phosphorus (P), such as in many cropping systems in north-eastern Australia.MethodsWe used the rhizobox method to evaluate how contrasting genotypes of durum wheat and sorghum (wide and narrow root angle) responded to combinations of starter-P and deep P bands.ResultsAlthough we found evidence that root angle may influence spatio-temporal exploration for deep P bands, (early) plant access to P was the critical driver for plant growth. Without P, root system growth was retarded such that genotypic differences were hardly observed. Access to P boosted root exploration at depth by virtue of greater root system size, such that wide-angle genotypes with P outperformed narrow-angle ones without P. Plastic root responses to P benefited the expression of the broader root system architecture. We observed variation between species and individual parameters, but overall Starter-P and deep P bands tended to deliver complementary benefits when considering plant growth, P uptake, and phenological development together.ConclusionOur study highlights that nutritional constraints may limit the ability of root ideotypes to function in complex target environments. Development and deployment of root ideotypes should consider how local conditions (including soil nutrient distribution, physical and biological properties) influence crop phenotype and their ability to deliver the intended benefits. Within this, soil nutrient management is a critical determinant and an opportunity to influence the target environment.

Особенности фенологии древесных видов на северном и южном пределе их ареалов в условиях интродукционного стресса

Decorative types and varieties of trees and shrubs have long been widely used in the practice of gardening and landscape construction. Significant enrichment of the range of urban green spaces is possible due to the introduction of introduced plants. The arboretum garden is studying the possibility of growing non-district rocks in specific soil and climate conditions and selecting promising species for gardening, which will create valuable introduced objects. The processes of plant growth and phenological development are analyzed in detail. In this paper, tree and shrub species that grow on the Northern and southern borders of their introduction within the Russian Federation are selected. Observations were made in dendrological gardens in the cities of Arkhangelsk and Sochi. The phenological dates of seasonal development of these species are established and recommendations are given for the use of the studied introduced species in the urban greening system. It is established, for example, that Hungarian lilac grows successfully and bears fruit on the Northern border of introduction and has a winter hardiness score of I, while in subtropical climate this species, although it forms generative organs, has a depressed state. Western thuja in the conditions of Arkhangelsk does not bloom and does not bear fruit, it dies out in severe winters. On the southern border of its introduction, it is widely used in the urban greening system and in topiary art. The correct selection of species on the introduction site will allow you create a highly decorative, aesthetically charming, recreational-attractive, health-improving plantings.

Photoperiod and Temperature as Dominant Environmental Drivers Triggering Plant Phenological Development of American Ginseng Along With Its Quality Formation

American ginseng (Panax quinquefolius L.) has been cultivated in many locations in China, and we have noticed that its phenological performance and quality characteristics varied from location to location. However, the exogenous factors driving this process are still poorly understood, and this reduces the successful introduction of American ginseng for quality ensuring. Here, we conducted field and cabinet experiments to explore the relationship among environmental factors, phenological development, and ginsenoside accumulation in American ginseng. In the field experiments, we found that American ginseng from different original locations showed different phenological rhythms and different ginsenoside accumulation. Especially, those from higher latitude locations (e.g., Wuchang, 44.55°N) presented delayed spring phenology and advanced autumn phenology, but higher ginsenoside contents along with higher gene expression levels of ginsenoside biosynthesis than those from lower latitude locations (e.g., Wendeng, 37.23°N). Data analysis indicated that the phenological rhythm of American ginseng is closely related to the seasonal change in environmental factors, especially winter chilling duration, spring warming, and autumn day-length shortening. In the cabinet experiments, results further proved that temperature interaction with photoperiod plays a decisive role in the phenological development and ginsenoside accumulation of American ginseng in the absence of water and nutrient limitation. Both field and cabinet experiments indicated that sufficient winter cold exposure coupled with spring long day-length photoperiod is a beneficial environmental factor for normal spring phenology development, while shortening autumn day-length coupled with autumn cooling is a beneficial environmental factor for normal autumn phenology development of American ginseng. Results also indicated that insufficient cold exposure and unsuitable day-length photoperiod are detrimental factors to both spring and autumn phenology, and are not good for ginsenoside accumulation in American ginseng. An understanding of the environmental factors influencing phenological development along with ginsenoside accumulation can provide guidance for predicting suitable cultivation locations and improving planting techniques for high yield and good quality of American ginseng.

Apple Tree Phenology in Relation to Temperature in Sauherad (Norway)

Plant's phenological development depends on multiple environmental factors and among these, temperature plays a key role during the early phenological development of plants. Temperature becomes even more significant in influencing phenological development in the areas that are covered with snow for a certain period a year. However, a rapid change in global temperature can be noticed in the scenario of climate change (CC). This study investigates the relationship between early phenological development of three apple cultivars i.e., Red Aroma, Summerred and Discovery with cumulative growing degree days (CGDDs) in the southern part of Norway and finds a strong positive correlation between them while moving from the green top stage to the fruit diameter (10mm) stage in the year 2016. In the similar way, study finds phenological development in two consecutive years i.e., 2015 and 2016 alike in a holistic approach. However, in the individual case of Discovery, phenological development of the year 2015 varies from 2016. In addition to that, CGGDs from first six months of two successive years seems to be similar. To gain all these results, this study made the use of multiple statistical tests. Study argues that; it is not always true that phenological development and CGDDs of one year vary from the next. Nevertheless, this study recommends for some long-term studies in the region that can generate concrete idea about phenology considering multiple environmental variables.

Crithmum maritimum L.: First Results on Phenological Development and Biomass Production in Mediterranean Areas

In Mediterranean cropping systems, it is important to utilise marginal lands for the cultivation of native food crops. Previous research on Crithmum maritimum L., a species native to southern Europe, has focused on its alimentary and chemical parameters. The aim of the present study was to identify the effects of irrigation and fertigation systems on C. maritimum in Mediterranean cropping systems. We planted C. maritimum seeds in an organic farm in Italy, and we carried out three experiments (fertigation, irrigation, and control) with three replications each. We evaluated plant phenological development and biomass production. We found that these treatments significantly influenced plant phenology and biomass parameters. Even with low irrigation and fertigation, this species showed a significant difference in the Bundesanstalt, Bundessortenamt, CHemischeIndustrie (BBCH) phase at harvest: in fact, there were 39 and 35 leaves on the main stem in the irrigation and fertigation treatments, respectively, while there were 29 leaves on the main stem in the rainfed unfertilised control. Biomass production also showed the same significant difference: 1.8 and 2.0 t ha−1 of total dry biomass in the irrigation and fertigation treatments, respectively, and 1.2 t ha−1 of total dry biomass in the rainfed unfertilised control. In conclusion, we recommend the use of C. maritimum for food production in Mediterranean organic cropping systems.

Prototyping extracts from Artemisia absinthium L. for their biostimulating properties yield-enhancing, and farmer income-increasing properties

A number of alternative solutions to be implemented in the sustainable agriculture have appeared in recent years that not only improve crop yield but also reduce environmental pollution. They include, i.a., the use of biostimulants which are believed to stimulate plants growth. The objective of study was to produce a novel and natural biostimulant from leaves of Artemisia absinthium L. and to evaluate its properties under field conditions. This work is the first ever to report a complex approach to the use of plant extracts in soybean [Glycine max (L.) Merr.] cultivation based on the evaluation of not only crop yield but also economic effects. To accomplish this goal, two methods of aqueous extraction were applied, and the extracts obtained were administered to soybean plants, in the form of foliar application and soil treatment, at two stages of plant phenological development. Nineteen phenolic compounds were identified in the infusions, whereas eleven in the cold-soaked extracts. The total concentration of phenolics was over twofold higher in infusions. The extracts differed in terms of contents of macro- and microelements. The cold-soaked extracts were rich especially in macroelements (they had twofold higher contents of calcium, potassium, magnesium, sodium, phosphorus, and sulfur). The reported study proved the extracts examined can be successfully used as effective biostimulants in soybean cultivation. The improvement in soybean yield (in each tested combination) was noted as an effect of the application of the extracts from Artemisia absinthium, regardless of the method of their application. Nevertheless treating plants with cold-soaked extracts and infusions, in the form of foliar application, caused the average highest yield increase (31.41 % and 23.70 % respectively increasing over control). Considering both their effect on crop yield and also the economic concerns, they should be administered in the form of spraying. Our findings indicate that foliar application of both the infusions and the cold-soaked extracts brought similar profits from soybean cultivation (average 181 EUR ha−1). In addition, results allowed verifying the advanced hypothesis that extracts from Artemisia absinthium are candidates for ideal biostimulants. This study was the first to prove that this agronomic practice would represent a designed tool that would meet requirements of farmers by ensuring incomes from cultivation.

Assessment of suspended growth biological process for treatment and reuse of mixed wastewater for irrigation of edible crops under hydroponic conditions

Due to the increasing freshwater deterioration and demand for irrigation, there is pressing need to reclaim and reuse wastewater for agricultural operations. While this practice is gaining significant traction in developed world, it is quite rare in most developing countries with inadequate or no functional sewerage facilities and treatment systems at both municipal and industrial levels occasioned by high investment and operational costs. Consequently, wastewaters generated are in complex heterogenous mix of industrial, domestic, municipal and agricultural runoff wastewater. Biological technologies which utilize the expertise of microorganisms are considered robust, efficient and economically attractive for treatment of wide range of wastewaters and they have high suitability in developing countries. This work therefore assessed the potential of suspended growth biological process (SGBP) for reclamation and reuse of mixed wastewater composed a mixture of domestic effluent, pharmaceutical, textile, petroleum discharges and agricultural runoff for irrigation of edible crops (lettuce and beets) with plants phenological parameters as measuring indicators. The germination and phenological characteristics of crops were studied in a hydroponic unit under four irrigation regimes: tap water as control, mixed wastewater, SGBP treated wastewater, and tap water mixed with nutrient solution as upper control, for a duration of 45-d. The results proved that the SGBP treated wastewater had no negative impact on germination responses of the seed crops. However, residual recalcitrant compounds caused early stunted growth in plant root systems with resultant limited access to nutrients. Consequently, plant vegetative growth and phenological development as well as chlorophyll production were reduced. In comparison to nutrients supplemented solution, nutrients deficiency and imbalance in treated wastewater contributed to the poor development in irrigated plants. The outcomes of seed germination and plant growth experiments show a positive indication for reuse of mixed wastewater in agriculture. However, there is need for further research to explore the long-term benefits and limitations of reusing such treated wastewater.

Phenology-adjusted dynamic curve number for improved hydrologic modeling

The Soil Conservation Service Curve Number (SCS-CN, or CN) is a widely used method to estimate runoff from rainfall events. It has been adapted to many parts of the world with different land uses, land cover types, and climatic conditions and successfully applied to situations ranging from simple runoff calculations and land use change assessment to comprehensive hydrologic/water quality simulations. However, the CN method lacks the ability to incorporate seasonal variations in vegetated surface conditions, and unnoticed landuse/landcover (LULC) change that shape infiltration and storm runoff. Plant phenology is a main determinant of changes in hydrologic processes and water balances across seasons through its influence on surface roughness and evapotranspiration. This study used regression analysis to develop a dynamic CN (CNNDVI) based on seasonal variations in the remotely-sensed Normalized Difference Vegetation Index (NDVI) to monitor intra-annual plant phenological development. A time series of 16-day MODIS NDVI (MOD13Q1 Collection 5) images were used to monitor vegetation development and provide NDVI data necessary for CNNDVI model calibration and validation. Twelve years of rainfall and runoff data (2001–2012) from four small watersheds located in the Konza Prairie Biological Station, Kansas were used to develop, calibrate, and validate the method. Results showed CNNDVI performed significantly better in predicting runoff with calibrated CNNDVI runoff increasing by approximately 0.74 for every unit increase in observed runoff compared to 0.46 for SCS-CN runoff and was more highly correlated to observed runoff (r = 0.78 vs. r = 0.38). In addition, CNNDVI runoff had better NSE (0.53) and PBIAS (4.22) compared to the SCS-CN runoff (−0.87 and −94.86 respectively). In the validated model, CNNDVI runoff increased by approximately 0.96 for every unit of observed runoff, while SCS-CN runoff increased by 0.49. Validated runoff was also better correlated to observed runoff than SCS-CN runoff (r = 0.52 vs. r = 0.33). These findings suggest that the CNNDVI can yield improved estimates of surface runoff from precipitation events, leading to more informed water and land management decisions.

Seasonally contrasting responses of evapotranspiration to warming and elevated CO2 in a semiarid grassland

AbstractGlobal climate change is expected to alter seasonal patterns and rates of evapotranspiration in dry regions. Although climate change will involve elevated CO2 and increased temperatures, independently, these factors may have different impacts on actual evapotranspiration (AET) due to their opposing effects on transpiration. We used canopy gas exchange chambers to quantify AET in a semiarid grassland experimentally altered by elevated CO2 and warming over 3 years with contrasting ambient precipitation. Seasonal and interannual variations in AET due to background climate variability were larger than the effects of climate manipulation treatments. However, in a year with average precipitation, cumulative growing season AET was suppressed by warming by 23%. Across years, warming increased AET early in the growing season and suppressed it later in the growing season. By contrast, elevated CO2 suppressed AET early in the growing season and enhanced it later, but only in years with average or above‐average precipitation. Vegetation greenness (a proxy for photosynthetically active leaf area) was consistently the strongest predictor of AET, whereas soil moisture and vapor pressure deficit were secondary drivers. Our research demonstrates that effects of increased atmospheric CO2 and temperature on AET will be mediated by plant phenological development and seasonal climatic conditions.

Interpreting canopy development and physiology using a European phenology camera network at flux sites

Abstract. Plant phenological development is orchestrated through subtle changes in photoperiod, temperature, soil moisture and nutrient availability. Presently, the exact timing of plant development stages and their response to climate and management practices are crudely represented in land surface models. As visual observations of phenology are laborious, there is a need to supplement long-term observations with automated techniques such as those provided by digital repeat photography at high temporal and spatial resolution. We present the first synthesis from a growing observational network of digital cameras installed on towers across Europe above deciduous and evergreen forests, grasslands and croplands, where vegetation and atmosphere CO2 fluxes are measured continuously. Using colour indices from digital images and using piecewise regression analysis of time series, we explored whether key changes in canopy phenology could be detected automatically across different land use types in the network. The piecewise regression approach could capture the start and end of the growing season, in addition to identifying striking changes in colour signals caused by flowering and management practices such as mowing. Exploring the dates of green-up and senescence of deciduous forests extracted by the piecewise regression approach against dates estimated from visual observations, we found that these phenological events could be detected adequately (RMSE < 8 and 11 days for leaf out and leaf fall, respectively). We also investigated whether the seasonal patterns of red, green and blue colour fractions derived from digital images could be modelled mechanistically using the PROSAIL model parameterised with information of seasonal changes in canopy leaf area and leaf chlorophyll and carotenoid concentrations. From a model sensitivity analysis we found that variations in colour fractions, and in particular the late spring `green hump' observed repeatedly in deciduous broadleaf canopies across the network, are essentially dominated by changes in the respective pigment concentrations. Using the model we were able to explain why this spring maximum in green signal is often observed out of phase with the maximum period of canopy photosynthesis in ecosystems across Europe. Coupling such quasi-continuous digital records of canopy colours with co-located CO2 flux measurements will improve our understanding of how changes in growing season length are likely to shape the capacity of European ecosystems to sequester CO2 in the future.

Response of vetch varieties to Sitona lineatus L. in organic farming

Sitona lineatus L. (Coleoptera: Curculionidae) is an important pest of field vetch in Bulgaria. The response of vetch varieties to S. lineatus was determined on the basis of seedling vigour, plant phenological development and chemical analysis of the feed. The susceptibility to attack by S. lineatus of the vetch, Vicia sativa L., varieties, Liya, Loryna, Villena, Moldavskaya 82 and Vicia villosa Roth varieties, Violeta and Viola, was tested. Vetch varieties with high vitality and rapidly growing seedlings such as Liya and Loryna were considerably less preferred by S. lineatus. They were distinguished with low damage degree and leaf damage intensity. Weather conditions during the years affected population density and food activity of Sitona weevils as the harm was particularly great in the dry spring in 2013, when the plants had suppressed growth and did not develop normally. The least preferred variety with a low S. lineatus density was Liya followed by Loryna, which were characterized with the shortest vegetative season (67 days), high seedling vigour and high fibre content. The most preferred varieties with the highest density of weevils were winter varieties Violeta and Viola, which had high crude protein content.

Temperature regulation of plant phenological development

Gradual and abrupt changes in temperature under current and future climates pose a serious threat to ecological diversity and in sustaining global food security. Plants possess a robust network of thermal sensors to program their metabolic and hormonal framework, providing acclimation to short-term abrupt fluctuations or adaptation to gradual temperature change. Several cellular thermosensors are reported in plants and understanding their mode of operation in a potentially coordinated framework continues to be a persistent challenge. Despite growing insight into the molecular control of thermal perception, physiological significance of plant thermal responses under a complex interaction with other environmental cues is largely unaddressed. Plant thermal perception and signaling could be similar across growth habits such as herbaceous to perennial woody species while developmental transitions such as vegetative to reproductive stage, influenced by their immediate microclimate, are generally altered across growth habits. The overall aim is to connect the knowledge gained with thermal perception and the signaling that drives plant responses, with major focus on the latter.

Modelling and mapping of plant phenological stages as bio-meteorological indicators for climate change

In Hesse, a federal state in central Germany, the average air temperature of the period 1991 to 2009 was by 0.9°C higher compared to that of 1961 to 1990. A further rise in air temperature of up to 3.7°C compared to the reference period 1971 to 2000 is expected until the end of the twenty-first century. This may affect the beginning and length of phenological stages of plants. Hence, this project should analyse and model spatiotemporal trends of plant phenology as being an indicator for climate change-related biological effects. Meteorological data together with data on 35 phenological phases of plants indicating different phenological seasons and observed at 6,500 sites in Germany (553 in Hesse) between 1961 and 2009 were analysed in a GIS. Estimations on phenological developments in the future periods 2031 to 2060 and 2071 to 2100 were based on data from four regional climate models. Thirty-one out of 35 phases started earlier in the years 1991 to 2009 compared with 1961 to 1990. These shifts were stronger in Hesse (8 days) than in Germany (6 days). As winter phases tend to shift towards the end of the year, a prolongation of the vegetation period of up to 3 weeks was observed. More than 70% of the phases were correlated with air temperature by r ≥ 0.5, more than 50% even by r ≥ 0.7. Since the 1990s, phenological shifts and regional differences in phase onsets amplified. In many cases, the shifts between 2071 to 2100 and 1961 to 1990 are expected to be at least twice as high as those between 1991 to 2009 and 1961 to 1990. The presented approach allows revealing statistical relationships between air temperatures and phenological onsets. Thus, shifts in plant phenology are an appropriate bioindicator to map early signs of ecosystem transitions under climate change. The phenological records allow estimating future trends of plant phenological development. Using phenological maps as presented in this article, efficient adaption strategies may be planned and implemented in terms of, e.g. adjusting delineation, shape and allocation of protected areas.

Interaction between plant physiology and pasture feeding value: a review

Plant–animal interactions impact on all elements of pasture and animal performance in grazing systems. The quality of pastures for animals can be described in terms of feeding value (FV), which is a combination of feed nutritive value (NV) and voluntary intake. There are numerous complex interactions between plant physiology and pasture FV and NV. This review focuses on these interactions in four key areas (plant growth strategies, phenological development, pasture regrowth, and response to environmental stress), extracting key principles and illustrating how plant breeding or management may be used to manipulate such interactions to improve FV. The FV is low in pastures with native species that have evolved in nutrient-poor environments, especially if there are greater proportions of C4 than C3 species in the sward. Reproductive development of grasses and long grazing intervals (which affect stage of regrowth) reduce the proportion of leaf and increase stem or dead matter content in the sward. This is exacerbated by environmental stresses such as warmer temperatures and water deficit. Management decisions provide a means of manipulating many of these interactions to improve the FV of pasture, especially by improving soil nutrient status, using irrigation where possible, introducing exotic perennial pasture species such as perennial ryegrass, phalaris and tall fescue, linking the timing of grazing to stage of regrowth, and carefully managing post-grazing residual sward state. Likewise, plant breeding has focused on altering the flowering date of grasses, reducing aftermath heading, and reducing lignification within the plant to improve the FV of pasture for livestock.

Phenological changes in the chemical content of wild and greenhouse-grown Hypericum pruinatum: flavonoids

The present study was conducted to determine the phenological changes in the content of main flavonoids, namely amentoflavone, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, (+)-catechin, and (-)-epicatechin in different tissues of Hypericum pruinatum, a promising medicinal herb of the Turkish flora. The wild-growing and greenhouse-grown plants were harvested at vegetative, floral budding, full flowering, fresh fruiting, and mature fruiting stages and dissected into stem, leaf, and reproductive tissues, which were dried separately and subsequently assayed for flavonoid contents by high performance liquid chromatography (HPLC). Chemical contents in whole plants increased during plant phenology and were similar quantitatively for both wild and greenhouse-grown plants. Depending on development stages, reproductive parts produced higher amounts of rutin, quercetin, (+)-catechin, (-)-epicatectin, and amentoflavone; however, leaves accumulated the highest level of hyperoside, isoquercitrin, quercitrin, and avicularin. The present results indicated a close relationship between flavonoid content in plant parts and phenological development of plants. It is suggested that the raw plant should be harvested during flowering for medicinal purposes.

Growth and phenology of Dittrichia graveolens, a rapidly spreading invasive plant in California

Dittrichia graveolens is a rapidly spreading invasive plant in California. While populations are observed primarily in disturbed areas, there is concern it may expand into adjacent undisturbed areas, particularly grasslands and riparian corridors. In a field experiment conducted in two successive years, we compared plant growth and phenological development of fall, winter, and spring sown seeds. Plants establish equally well in disturbed upland sites in both above and below average precipitation years but the absence of late spring rainfall negatively affected total plant biomass. In a greenhouse experiment, we compared growth in four light environments (100, 50, 27 and 9 % available light). Total plant growth decreased exponentially with decreasing light. This suggests that D. graveolens is not competitive in low light environments, such as woodlands and riparian forests. All plants flowered in early- to mid-September, coinciding with flowering in field grown plants, suggesting that photoperiod is the primary signal for reproductive growth. Using a minirhizotron system, we measured root growth over time in D. graveolens and three common California annual grassland species, two non-natives, Centaurea solstitialis and Bromus hordeaceus, and the native forb Holocarpha virgata. Root growth of D. graveolens began later in the season than the other species, reaching depths >1 m by late May. Roots of C. solstitialis and H. virgata reached >1 m earlier in the season. The temporal difference in root growth suggests that D. graveolens may be less competitive for soil moisture with other early season annuals than other deep-rooted broadleaf species found in grasslands.

The dynamics of potassium uptake and use, leaf gas exchange and root growth throughout plant phenological development and its effects on seed yield in wheat (Triticum aestivum) on a low-K sandy soil

Aims There is still limited information about the dynamics of potassium (K) uptake and use over the growth cycle in cereals, but quantification of such relationships is necessary to model crop response to K and improve K fertiliser practice. This study examined the effects of varying K supply on K use efficiency, leaf gas exchange, root and shoot growth at successive stages of plant phenological development, and on seed yield in wheat (Triticum aestivum L.).

Developmental patterns of a large set of barley (Hordeum vulgare) cultivars in response to ambient temperature

AbstractAmbient temperature plays an important role in plant development. In cereals, little is known about the exact effects of ambient temperature in the range between it being a vernalising agent and an abiotic stress factor; thus the genetic determinants involved in the registering and response to ambient temperature, and their natural variation has not been dissected either. Principally, we wished to establish the level of natural variation in response to ambient temperature in barley via studying plant phenological development. The responses to temperature of 168 barley genotypes of different provenances and seasonal growth habit groups were observed in controlled environments. The effects of four temperature regimes (13°C, 16.5°C, 18°C and 23°C) on the duration of plant phenophases were examined. The plant development was characterised in a series of consecutive phenophases that span the plant life cycle from germination through flowering to attainment of maximum plant height. Ambient temperature affected significantly plant development, with substantial variation in responses among the genotypes. Six major types of responses were identified, which depended strongly on seasonal growth habit, with only a small degree of overlap. Although the differences in the timing of development among clusters were significant under each temperature regime, the 23°C treatment resulted in the largest diversity of responses, with significant changes in the ranking of the six clusters compared to other treatments. Two clusters showed particularly unusual responses to 23°C: the development of one winter barley cluster was extremely accelerated by the 23°C treatment, whereas the development of one spring barley cluster was significantly delayed. Ambient temperature assumes importance as a regulatory cue in the intricate and complex temporal and spatial regulation network of plant development in cereals and acts mostly through its regulatory effect on certain developmental phases such as the onset and duration of the intensive stem elongation.

Comparing carbon flux and high-resolution spring phenological measurements in a northern mixed forest

Vegetative canopies play a crucial role in the energy balance and composition of the atmospheric boundary layer via biotic control over evapotranspiration and carbon sources/sinks. Accurately predicting the onset/increase of carbon uptake/transpiration during the spring leaf development period using coarse resolution tower-based and satellite-derived data alone is difficult. Thus, understanding stand-level spatial patterns of spring plant phenological development and the processes that drive them may be crucial for improving landscape level estimates of evapotranspiration and carbon accumulation.In this study, high-resolution spatial and temporal tree phenology data were recorded in field campaigns over approximately 5 weeks during spring 2006 and 2007 (within a 625m×275m area), and over similar periods during spring 2008, 2009, and 2010 (within two 625m×625m areas) near the WLEF eddy covariance flux tower site near Park Falls in northern Wisconsin. Our findings demonstrate that phenological variations between individual trees in a specific microclimate can be adequately represented with a sample of 30 or more individuals. Further, visual phenological observations can be generally related to under-canopy light levels, and for spring phenology measurements in similar microclimates, a sampling interval of every 4 days minimizes data uncertainty and field work expenses. An analysis of the relationships among phenology, climate, and gross primary productivity (GPP) during the spring indicate that the phenology of the dominant tree species is responsible for an overall positive trend in carbon assimilation, but climate is the cause of day-to-day variation.