Degree Days Research Articles

Genetic diversity and proximate analysis of Indonesian local mung bean (Vigna radiata)

Abstract. Afza H, Palupi ER, Herlina L, Ilyas S. 2023. Genetic diversity and proximate analysis of Indonesian local mung bean (Vigna radiata). Biodiversitas 24: 6377-6388. Mung bean is an important food crop because it has a high protein content. However, not much information is available about Indonesian local mung beans. This study aimed to obtain information about flowering and seed formation in local mung beans (Vigna radiata L.) to determine the genetic diversity of mung beans using simple sequence repeats and the protein, starch, fat, and ash content. Mung bean seeds of 15 genotypes were obtained from the Indonesian Agricultural Gene Bank collection. The experiment was arranged using a one-factor randomized complete block design. Genotypes with a low degree of non-synchrony of pod maturity (DDd) were Local Bima and Arta Koneng 01070. The highest fruit set was observed in the Madura Local accession (73.09%). The accumulated value of heat units was calculated as growing degree days; the heat units from planting to the first flowering ranged from 544.6-670°C and from planting to the first ripe pod (heatd2) and 90% ripe pod (heatd3) phases ranged from 819.7-933.7°C and 1,111.9-1,419.1°C. Phylogenetic tree construction was made based on scoring of the presence of alleles that appeared on the electrophoresis results of 12 microsatellite markers on 15 mung bean genotypes. The superior varieties, Vima1 and Walet, were separated from the other 13 local genotypes at a genetic similarity coefficient of 0.583. The protein contents of the tested mung bean genotypes were 19.19%-23.06%.

Egg-laying habitat selection of the invasive slug Krynickillus melanocephalus Kaleniczenko, 1851 (Gastropoda: Eupulmonata: Agriolimacidae)

Invasive slugs cause damage to biodiversity as well as to horticultural and agricultural crops. To develop methods to mitigate problems with recently emerging invasive species, basic ecological knowledge about them in their new environment is crucial. We investigated the egg-laying substrate preference of Krynickillus melanocephalus in a laboratory experiment in which the slugs could choose between four different substrates. Slugs were mainly observed in contact with birch leaf compost, and less so with gravel, potting soil and sphagnum moss. Almost 90% of the eggs were found buried in birch leaves, although eggs were found also in the other substrates. In addition, we tested the winter survival of the eggs by examining their susceptibility to low temperatures. Eggs subjected to freezing temperatures did not survive, and at 8 °C, 60–70% of the eggs hatched after three months (640 degree days). In areas where K. melanocephalus is present, transporting any soil, gravel or compost material could potentially contribute to spreading the species. Particularly, leaf composts may warrant attention in this areas.

The Goldilocks Zone for maize agriculture and the settlement and abandonment of the West Tavaputs Plateau

Between 2100 and 500 BP, maize farming spread throughout the American Southwest, driving changes in land use patterns and relative increases in the number of archaeological sites, which is commonly interpreted as increases in population. In the context of the Southwest, with its variable topography and limited water sources, the locations suitable for productive maize agriculture are limited. Higher elevation locations often have a greater abundance of water, both in the form of precipitation and perennial water sources but lack the growing season lengths required for maize farming. Lower elevation locations have the long growing seasons required for maize, but often have higher evaporation rates corresponding with higher temperatures, and thus decreased soil moisture retention. The relationship between elevation and maize agriculture is well recognized, and locations where both growing season length and moisture requirements can be met serve as a Goldilocks Zone in which maize farming is possible. Here, we use a regional approach to model the Goldilocks Zone for maize farming in Utah, and then contextualize patterns of settlement and abandonment on the West Tavaputs Plateau (WTP) in east-central Utah. We use archaeological sites with direct evidence of maize cultivation, modern growing degree days estimates, and modern estimates of moisture abundance to bracket the prehistoric maize farming niche in Utah. Then, we apply the model to archaeological data from the WTP to test hypotheses derived from the Ideal Free Distribution model about the effects population and precipitation changes had on prehistoric land use patterns of settlement and abandonment, and whether the patterns of settlement and abandonment differ from one another. We find that a) population drives land use patterns in the WTP, but not in the way we originally hypothesized, suggesting there is an important decision variable missing from our model, which may pertain to the specific topographic setting of the WTP and the distribution of its water sources, b) precipitation has no effect on land use patterns suggesting that maize agriculture on the WTP was dependent on irrigation, and c) that patterns of settlement and abandonment seem to mirror each other.

Alpine hillslope failure in the western US: insights from the Chaos Canyon landslide, Rocky Mountain National Park, USA

Abstract. The Chaos Canyon landslide, which collapsed on the afternoon of 28 June 2022 in Rocky Mountain National Park, presents an opportunity to evaluate instabilities within alpine regions faced with a warming and dynamic climate. Video documentation of the landslide was captured by several eyewitnesses and motivated a rapid field campaign. Initial estimates put the failure area at 66 630 m2, with an average elevation of 3555 m above sea level. We undertook an investigation of previous movement of this landslide, measured the volume of material involved, evaluated the potential presence of interstitial ice and snow within the failed deposit, and examined potential climatological impacts on the collapse of the slope. Satellite radar and optical measurements were used to calculate deformation of the landslide in the 5 years leading up to collapse. From 2017 to 2019, the landslide moved ∼5 m yr−1, accelerating to 17 m yr−1 in 2019. Movement took place through both internal deformation and basal sliding. Climate analysis reveals that the collapse took place during peak snowmelt, and 2022 followed 10 years of higher than average positive degree day sums. We also made use of slope stability modeling to test what factors controlled the stability of the area. Models indicate that even a small increase in the water table reduces the factor of safety to <1, leading to failure. We posit that a combination of permafrost thaw from increasing average temperatures, progressive weakening of the basal shear zone from several years of movement, and an increase in pore-fluid pressure from snowmelt led to the 28 June collapse. Material volumes were estimated using structure from motion (SfM) models incorporating photographs from two field expeditions on 8 July 2022 – 10 d after the slide. Detailed mapping and SfM models indicate that ∼1 258 000 ± 150 000 m3 of material was deposited at the slide toe and ∼1 340 000 ± 133 000 m3 of material was evacuated from the source area. The Chaos Canyon landslide may be representative of future dynamic alpine topography, wherein slope failures become more common in a warming climate.

Effects of winter water quality conditions on Atlantic Salmon embryo mortality and deformity rates in the Serpentine River (New Brunswick, Canada)

In-stream incubation of Atlantic Salmon (Salmo salar) embryos within artificial redds using Jordan/Scotty fish egg incubator boxes is an alternative to traditional hatchery-based incubation methods. Winter water quality conditions, such as temperature and dissolved oxygen vary within natural redds and influence wild embryo development and survival. The differences in landscape characteristics and in-stream habitat features at catchment-, reach-, and site spatial scales were investigated to determine how they influenced water quality conditions within the Serpentine River, New Brunswick. A total of 14,400 hatchery-fertilized salmon embryos were incubated within river substrates from November 2020 to January 2021. The proportion of embryo mortalities within our experiment was high (44.9%), but still within the range observed in the literature from other incubation experiments, and the proportion of embryo deformities between our sites was very low (2.7%). Despite variations in average water temperature, cumulative degree days, and coefficient of variation in dissolved oxygen (DO) concentration, none were statistically significant for explaining embryo mortalities or deformities. Patterns were, however, evident across sites showing trends towards a decrease in mortality with cumulative degree days, and an increase in deformities with greater variation in DO. Improving our knowledge on Atlantic Salmon incubation habitat supports future research and restoration opportunities for adaptation under a changing climate.

Surrogate model of adaptive thermal comfort of a social housing in the Dominican Republic micro-climates: a predictive approach toward sustainable buildings

ABSTRACTAdaptive thermal comfort is essential for guaranteeing the well-being of building occupants. Therefore, this study emphasizes its importance and applies advanced computational techniques as a surrogate model and sensitivity analysis for an in-depth analysis of a social housing in the Dominican Republic evaluated under five micro-climates. The methodology includes a computational design with an energetic simulation. An adaptive model was developed following the ASHRAE-55 standard, and an artificial neural network was trained to predict comfort temperature. The results showed that Neiba city, corresponding to a hot semi-arid climate, presented the maximum hours of discomfort (8463), representing 96.6% of the total annual hours with a cooling degree day of 157.5, whereas Constanza city, corresponding to the oceanic climate, reported 2025 hours of discomfort (23.1%) and a cooling degree day of 48. The surrogate model based on artificial neural networks achieved a coefficient of determination of 0.9998, and the sensitivity analysis revealed a more significant influence of radiant temperature (55.96%) over comfort temperature. Finally, this study highlights the significance of adaptive thermal comfort in building design and the potential of surrogate models for energy analysis. Therefore, it is necessary to implement passive strategies to enhance indoor thermal comfort in a sustainable building sector.

Development and validation of phenological models for eight varieties of sweet cherry (Prunus avium L.) growing under Mediterranean climate condition

The projected increase in temperatures caused by climate change will modify the phenological stages of sweet cherry in Mediterranean-type climate regions. This study aimed to develop and validate phenology models for eight sweet cherry varieties (Sam, Lapins, Rainier, Royal D, Santina, Regina, Kordia, Sweet Heart) in the Maule Region, Chile. The models were based on growing degree days (GDD), and the stochastic monomolecular model was employed to account for the randomness caused by measurement errors affecting the prediction of phenological states. A dataset of phenological stages was compiled over four growing seasons: 2017-2018, 2018-2019, 2019-2020, and 2020-2021. The results revealed a significant correlation (with R2 values between 0.96 and 0.98) the modified phenological (PS) scale of Biologische Bundesanstalt, Bundessortenamt, and Chemical Industry (BBCH) and GDD for all eight varieties. The validation of the model demonstrated root mean square error (RMSE), mean absolute error (MAE), and model efficiency (FE) values ranging from 1 to 1.3, 0.79 to 1.1, and 0.82 to 0.92, respectively. Finally, monomolecular model estimated the modified scale of BBCH with errors less than 2 %.

Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic-alpine plants.

Climate refugia can serve as remnant habitat for cold-adapted species and delay forest transitions. The world's largest freshwater lake by surface area, Lake Superior, serves as a model system for understanding cooling-mediated refugia effects, as its cool summer water temperatures have maintained disjunct populations of arctic-alpine plants on its shoreline since deglaciation. It is known to affect local inland climates by providing a summer cooling effect; however, the inland temperature gradient and spatial patterns of cooling have not been well quantified. Here, we describe the extent, degree, and patterns of temperature buffering and examine drivers of buffering and disjunct plant occurrence for Lake Superior's north shore over a 3-year period at distances of 10, 100 m, 1, 10, and 100 km inland. We analyzed temperature data by year, month, summer maximum (July), and growing degree days (GDD0) for each site. Average summertime cooling at shore sites (10 m) was ~5°C cooler than reference sites (100 km inland), with a maximum difference of -19.2°C. The magnitude of cooling varied geographically, with sites further west and southeast showing little to no cooling effect, while the exposed north-central shore showed the highest degree of buffering (5.8°C cooler) and had a shorter growing season than reference sites. Finally, north-central shorelines had fewer days above 16°C, a threshold above which disjunct plants are unlikely to grow. These sites also showed the highest proportion of disjunct arctic-alpine species, reflecting the highest buffering from inland sites. On north-central shores, sites up to 10 km inland had less than 10 days per year warmer than 20°C, a threshold identified for boreal forest transition. An understanding of the extent of lake-mediated cooling on adjacent forests can better inform the risk to disjunct species, inland forests, and vegetation transition models on Lake Superior's north shore.

Genetic Diversity and Genome-Wide Association Study for the Phenology Response of Winter Wheats of North America, Western Asia, and Europe

Wheat is a staple food in many areas around the World. In the 20th century, breeders and scientists were able to boost wheat yield considerably. However, a yield plateau has become a concern and is threatening food security. Investments in cutting-edge technologies, including genomics and precision phenology measurements, can provide valuable tools to drive crop improvement. The objectives of this study were to (i) investigate the genetic diversity in a set of winter wheat lines, (ii) characterize their phenological response under different vernalization and photoperiod conditions, and (iii) identify effective markers associated with the phenological traits. A total of 249 adapted genotypes of different geographical origin were genotyped using the 35K Axiom® Wheat Breeder’s Array. A total of 11,476 SNPs were used for genetic analysis. The set showed an average polymorphism information content of 0.37 and a genetic diversity of 0.43. A population structure analysis revealed three distinct subpopulations mainly related to their geographical origin (Europe, North America, and Western Asia). The lines of CGIAR origin showed the largest diversity and the lowest genetic distance to all other subpopulations. The phenology of the set was studied under controlled conditions using four combinations of long (19 h light) and short photoperiod (13 h light) and long vernalization (49 days at 5 °C) and no vernalization. With this, phenological traits such as earliness per se (Eps), relative response to vernalization (RRV), and relative response to photoperiod (RRP) were calculated. The phenotypic variation of growing degree days was significant in all phenology combinations. RRV ranged from 0 to 0.56, while RRP was higher with an overall average of 0.25. The GWAS analysis detected 30 marker-trait associations linked to five phenological traits. The highest significant marker was detected on chromosome 2D with a value of −log10(p) = 11.69. Only four loci known to regulate flowering exceeded the Bonferroni correction threshold of −log10(p) > 5.1. These results outline a solid foundation to address global food security and offer tremendous opportunities for advancing crop improvement strategies.

How have thermal conditions changed in different phenological stages of apple (Malus domestica) in Northeastern Hungary?

In temperate climates, most fruit trees need cold weather, low temperatures in winter, and a certain amount of heat during the growing season until harvest. One of the most apparent effects of climate change is the elevated temperature in all seasons of the year. In our study, the changes in thermal conditions have been calculated in Hungary's most significant growing region of apples using the Chill Unit for winters and the Growing Degree Days for summers. The meteorological data were obtained from the gridded dataset of the Hungarian Meteorological Service on a 10 km × 10 km grid, so the whole studied area is well-covered over the last 50 years. The results show that the trees are more exposed to early budding than a few decades ago. Furthermore, the accumulated heat amount in summers has increased drastically, which may increase the heat stress and lead to higher yield losses.

Using ethephon for seedhead suppression of ‘KSUZ 0802’ (Innovation) zoysiagrass

Abstract‘KSUZ 0802’ zoysiagrass (Innovation zoysiagrass, Zoysia matrella × Z. japonica) is a new cultivar that provides a high‐quality playing surface on golf course fairways and tees. However, seedheads produced in late spring disrupt the playing surface. The plant growth regulator (PGR) ethephon has produced variable results in prior studies in suppressing zoysiagrass seedheads, and information for KSUZ 0802 is lacking. A two‐year field experiment was conducted from 2019–2021 in Manhattan, KS, to assess the performance of ethephon (Proxy) on seedhead suppression of KSUZ 0802 zoysiagrass. Treatments included ethephon applied in a single application at 5 fl. oz. 1000 ft−2 on multiple dates between August and November. Seedhead suppression was determined by counting seedheads in late spring. Ethephon applied in September provided >60% seedhead suppression; however, when applied during other months, variations were large between the two study years. Applying ethephon when accumulated cooling degree days (68°F base) were <37 resulted in >70% seedhead suppression, except for application on September 25, 2019. Late August ethephon applications, despite achieving good seedhead suppression (ranging from 54 to 80%), caused transient yet commercially unacceptable injury to KSUZ 0802 in both years. Application timing affected turf quality in late spring as KSUZ 0802 with fewer seedheads had better quality post‐mowing, but no effect on spring greenup was observed. Ethephon can be an effective PGR for seedhead suppression in KSUZ 0802 zoysiagrass. However, careful consideration of application timing is essential as applying ethephon in late summer or late autumn can produce undesirable results.

Reproductive phenology and the influence of temperature in two sympatric New Zealand freshwater mussel species

Context Phenology plays a key role in shaping population dynamics, community structure and evolutionary adaptations. For freshwater mussels that rely on a parasitic larval (glochidia) phase on fish, shifts in reproductive phenology driven by environmental conditions may result in mismatches between glochidia release and host fish availability. Aims We investigated intra- and interspecific reproductive timing variations in sympatric Echyridella aucklandica and E. menziesii, and identified thermal cues (accumulated degree days, ADD) associated with brooding and glochidia maturation. Methods Brooding activity and glochidia maturation were assessed fortnightly–monthly over 1 year within four New Zealand streams. Results The previously unknown phenology of E. aucklandica showed earlier brooding (May–July) and longer gravidity (9–11 months) than for E. menziesii (August; 6–7 months). Both species exhibited peak brooding in late austral spring–summer (November–December). ADD played a key role in regulating the timing of brooding onset in both species, as evidenced by the narrow ADD range observed across sites, and the relationship between ADD and brooding onset in both species. Conclusion The demonstrated link between ADD and reproductive phenology has broad implications in the context of climate change. Specifically, it raises concerns about potential timing mismatches in glochidia release and host-fish availability, which could affect the survival and reproductive success of freshwater mussels.

Distribution characteristics and influencing factors of household consumption carbon emissions in China from a spatial perspective

Household consumption carbon emissions (HCCEs) have become the main growth point of China's carbon emissions in the future. It is important to investigate the factors affecting the demand-side carbon emissions in order to find the accurate entry point of emission reduction and achieve carbon peaking and carbon neutrality goals. Different from previous studies, this study analyzed the spatial and temporal evolution characteristics of provincial HCCEs in China from a spatial perspective by using the Theil index and spatial auto-correlation and explored the key influencing factors and spatial spillover effects of HCCEs in different regions by using an econometric model. The results of the study showed that: (1) Per capita HCCEs increased by 11.90% annually, and the eastern region > northeastern region > western region > central region. (2) There were regional differences in per capita HCCEs, but the decrease was significant at 40.32%. (3) The spatial agglomeration effect of per capita HCCEs was significant, and the hot spots were mainly concentrated in the eastern coastal areas. (4) From the national level, every 1% increase in residents' consumption power would increase HCCEs by 2.489%. Which was the main factor for the growth of HCCEs, while the increase in fixed asset investment would restrain HCCEs. At the regional level, the change in population size significantly increased the HCCEs in the eastern and central regions. While for the western region, a 1% increase in population would reduce the HCCEs by 0.542%. For the eastern and central regions, the degree of aging and the consumption structure of residents could suppress regional HCCEs. However, the consumption structure of residents drove the growth of HCCEs in the western region. For the Northeast region, residents' consumption capacity and cooling degree days were the main factors for the growth of residents' consumption, while fixed asset investment could inhibit the growth of HCCEs.

Phenology, heat unit requirement and heat use efficiency of African marigold under year-round transplanting conditions of Punjab, India

The present study was conducted during 2021-22 and 2022-23 to study crop phenology, heat unit requirement and heat use efficiency (HUE) in African marigold under year-round transplanting at Punjab Agricultural University, Ludhiana, Punjab, India. The highest heat use efficiency for seed and flower production were recorded in crop transplanted in rainy season particularly in the month of August. Higher growing degree days (GDD) and photothermal units (PTU) for attaining bud visibility and 50 % flowering stages were recorded under spring and summer transplanting (February to June) due to longer day length conditions which forced the crop to witness shorter seed filling period with lesser seed yield and HUE. Optimum seed yield period in marigold (rainy season transplanting), however, recorded lesser GDD and PTU for attainment of bud visibility and 50 % flowering as compared to summer transplanting dates and consequently had longer seed filling period resulting in higher seed yield. Notably, GDD and PTU for seed filling period recorded higher values in rainy season transplanted crop as compared to crop transplanted in other seasons of year. Correlation studies were conducted to understand the role of weather variables for high seed yield obtained under rainy season transplanting. Seed yield in African marigold recorded the highest value of correlation with HUE for seed production (r2= 0.978) followed by GDD for seed filling period (r2= 0.810), HUE for flower production (r2= 0.787) and PTU for seed filling period (r2= 0.774), respectively. Apparently, mean temperature and sunshine hours during seed filling period are the most important determinants of seed yield in African marigold.

Modelling adaptation measures to improve maize production and reduce soil N2O emissions under climate change in Northeast China

Optimizing management practices is essential to guarantee crop yield and reduce greenhouse gas emissions for the sustainable agricultural production under climate change. The objectives of this study were to i) calibrate and evaluate the Denitrification-Decomposition (DNDC) model using the measurements of maize yield, nitrogen (N) uptake, soil temperature, soil moisture, soil inorganic N and nitrous oxide (N2O) emissions from a 5-year maize field experiment in Northeast China (NEC) and ii) simulate the impacts of climate change on maize yield and N2O emissions and explore adaptation strategies based on DNDC modelling. For N-fertilized treatments (farmers’ practice, FP-N; current optimized management, OPT-N), the DNDC model overall showed “good” performance in simulating maize yield, aboveground biomass, N uptake and soil inorganic N based on the average statistical values. The model also performed well in simulating soil moisture, soil temperature and N2O emissions. For N-unfertilized treatments, however, the DNDC model overestimated crop yield and N uptake mainly due to the overestimation of crop growth under low-temperature stress conditions, and the underestimation of soil inorganic N resulted from the underestimated N mineralization and N availability from the dissolved inorganic N pools under continuous N deficiency. The DNDC model showed that compared to the baseline scenario, future climate change would improve the maize yield (1.4–8.8%) while increasing the N2O emissions (37.6–83.4%) without adaptation measures in NEC. Compared to OPT-N management, solely adjusting N fertilization rate (200–220 kg N ha−1) would concurrently increase maize yield (5.0–8.7%) and N2O emissions (0.9–18.6%), while the adoption of optimized planting dates (April 27th to May 18th), new cultivars (with thermal degree days ranging from 2550 to 2700 °C), and the implementation of no-tillage and maize-soybean rotation would increase the maize yield by 1.8–8.9% and reduce the N2O emissions by 0.7–26.5% under future climate change scenarios. This study provided insights into the adaptive management strategies for the sustainable maize production under climate change in NEC.

Physiological components of seed quality in runner‐type peanut during seed formation

AbstractSeed is one of the most expensive costs in peanut (Arachis hypogaea L.) production, and the use of high‐quality seed is important to provide the greatest yield potential. Physiological seed quality, represented by a combination of germination, vigor, desiccation tolerance, and longevity, is progressively acquired during seed formation. When all components reach their maximum, seeds achieve the highest physiological quality. The objectives of this study were to identify the acquisition pattern of the physiological components of seed quality, to determine the timing in which the maximum physiological quality is achieved during seed formation, and to define the timing in which seeds acquire and further break primary dormancy in peanut. A 3‐year field study was conducted using the cultivar Georgia‐06G. Plants were inverted when growing degree days reached 2500 for all fields, and a maturity board profile was used to classify the pods into the maturity classes. Seeds were split into two groups, treated and non‐treated, with ethephon to break potential primary dormancy. Water content, germination, vigor, desiccation tolerance, and longevity were tested in the seeds. Seed mass maturity was reached in the “orange” class. Maximum germination and vigor were achieved between “brown 1” and “brown 2”. Primary dormancy was acquired between “orange” and “brown 1” and broken after artificial drying. Maximum desiccation tolerance was observed in “brown 1”, whereas maximum longevity was achieved only in “black 2”. Considering all physiological quality components, peanut seeds achieved the maximum physiological quality between “brown 1” and “brown 2”.

Effect of Elevated Air Temperature on the Growth and Yield of Paddy Rice

Rice is one of the major food crops, particularly in Asia. However, it is vulnerable to high temperature and has high yield fluctuations. Monitoring crop growth and physiological responses to high temperatures can help us better understand the agricultural impacts of global warming. The aim of this study is to monitor growth, development, and physiological responses to high temperature conditions on paddy rice and to assess their combined effects on yield. In this study, changes to growth, maturity, and senescence in paddy rice throughout the growing season were identified under elevated air temperature conditions created by a temperature gradient field chamber (TGFC). That facility provides a gradient from the ambient air temperature (AT) to 3 °C above AT (AT + 3 °C). To represent crop physiology and productivity, we measured the plant height, chlorophyll, normalized difference vegetation index (NDVI), and maximum photosynthetic rate (Amax) to assess growth and physiological processes, and heat stress effects on four yield measurements were assessed using the heating degree day index. Rice height increased more rapidly in the AT + 3 °C treatment from the early growth stage to heading, while SPAD and NDVI decreased more rapidly at AT after heading. The Amax of AT and AT + 3 °C was not significantly different in the tillering stage. However, it was higher at AT in the booting stage but higher at AT + 3 °C in the grain filling stage. These results indicate that paddy rice was not affected by heat stress at the tillering stage, but a cumulative effect emerged by the booting stage. Further, photosynthetic capacity was maintained much later into the grain filling stage at AT + 3 °C. These results will be useful for understanding the growth and physiological responses of paddy rice to global warming.

Global warming is projected to lead to increased freshwater growth potential and changes in pace of life in Atlantic salmon Salmo salar.

Global warming has been implicated in widespread demographic changes in Atlantic salmon Salmo salar populations, but projections of life-history responses to future climate change are lacking. Here, we first exploit multiple decades of climate and biological data from the Burrishoole catchment in the west of Ireland to model statistical relationships between atmospheric variables, water temperature, and freshwater growth of juvenile Atlantic salmon. We then use this information to project potential changes in juvenile growth and life-history scheduling under three shared socioeconomic pathway and representative concentration pathway scenarios from 1961 to 2100, based on an ensemble of five climate models. Historical water temperatures were well predicted with a recurrent neural network, using observation-based atmospheric forcing data. Length-at-age was in turn also well predicted by cumulative growing degree days calculated from these water temperatures. Most juveniles in the Burrishoole population migrated to sea as 2-year-old smolts, but our future projections indicate that the system should start producing a greater proportion of 1-year-old smolts, as increasingly more juveniles cross a size-based threshold in their first summer for smoltification the following spring. Those failing to cross the size-based threshold will instead become 2-year-old smolts, but at a larger length relative to 2-year-old smolts observed currently, owing to greater overall freshwater growth opportunity. These changes in age- and size-at-seaward migration could have cascading effects on age- and size-at-maturity and reproductive output. Consequently, the seemingly small changes that our results demonstrate have the potential to cause significant shifts in population dynamics over the full life cycle. This workflow is highly applicable across the range of the Atlantic salmon, as well as to other anadromous species, as it uses openly accessible climate data and a length-at-age model with minimal input requirements, fostering improved general understanding of phenotypic and demographic responses to climate change and management implications.

Agro-Climatic Indices, Plant Growth and Yield of Bt Cotton as Influenced by Planting Time and Spacing

A field experiment was conducted in kharif season 2020 to study the effect of sowing time and row spacing on growth, yield and agro-climatic indices of Cotton at Research Farm, Department of Agricultural Meteorology, CCS Haryana Agricultural University, Hisar. The experiment was performed in split-plot design and replicated thrice. The experiment included nine treatment combinations with three sowing dates and row spacings. Among different sowing times, cotton sown on 19th April had significantly higher plant height (176.3 cm), dry matter accumulation (453.39 g plant-1), LAI (1.92), GDD (Growing Degree Days), HTU (Heliothermal Units), PTU (Photothermal Units) and seed cotton yield (3057 kg ha-1) in comparison to sowing in May i.e. May 8th and May 28th. Among various row spacings, cotton planted with a row spacing of 67.5 cm x 60 cm produced significantly higher seed cotton (2657 kg ha-1) and plant height (156.40 cm), although growth parameters i.e. LAI (2.26) and dry matter accumulation (397.92 g plant-1) alongwith Agro-climatic indices (GDD, HTU, PTU) were observed to be greater with a row spacing of 100 x 60 cm.

Agroclimatic Indices, Phenology and Growth Response of Clusterbean to Different Dates of Sowing and Varieties

A field experiment was performed to study the effect of different sowing times and varieties on agroclimatic indices, phenology and growth of clusterbean at CCS Haryana Agricultural University, Hisar (Haryana). Experiment was laid out in factorial randomized block design with three replications. Treatments consists of two factors i.e. sowing time and varieties. Three clusterbean varieties i.e. HG 365 (V1), HG 563 (V2) and HG 2-20 (V3) with each sown at three different dates of sowing i.e first (D1), third (D2) and fourth (D3) week of July. Clusterbean variety HG 563(V2), sown in first week of July (D1) resulted in significantly higher accumulation of agroclimatic indices i.e. growing degree days, photo thermal units, heliothermal units and heat use efficiency because the early sown crop had a fully developed normal reproductive phase and took longer time to attain maturity. Similarly, more number of days were taken for emergence, days to 50% flowering, days to 50% pod formation and days to maturity in variety HG 563, sown in first week of July. Significantly higher leaf area index and dry matter accumulation were observed in HG 563 sown on 1st week of July than rest of the varieties and date of sowings.