Changes of heating and cooling degree days over China in response toglobal warming of 1.5℃, 2℃, 3℃ and 4℃

Future changes of heating degree days （HDD） and cooling degree days （CDD） in the 21st century with and without considering populationfactor are investigated based on four sets of climate change simulations over East Asia using the regional climate model version 4.4 （RegCM4.4）driven by the global models of CSIRO-Mk3-6-0, EC-EARTH, HadGEM2-ES, and MPI-ESM-MR. Under global warming of 1.5℃, 2℃, 3℃,and 4℃, significant decrease of HDD can be found over China without considering population factor, with greater decrease over high elevationand high latitude regions, including the Tibetan Plateau, the northern part of Northeast China, and Northwest China; while population-weightedHDD increased in areas where population will increase in the future, such as Beijing, Tianjin, parts of southern Hebei, northern Shandong andHenan provinces. Similarly, the CDD projections with and without considering population factor are largely different. Specifically, withoutconsidering population, increase of CDD were observed over most parts of China except the Tibetan Plateau where the CDD remained zerobecause of the cold climate even under global warming; while considering population factor, the future CDD decreases in South China andincreases in North China, the Sichuan Basin, and the southeastern coastal areas, which is directly related to the population changes. The differentfuture changes of HDD and CDD when considering and disregarding the effects of population show that population distribution plays animportant role in energy consumption, which should be considered in future research.

Estimate the Emergence of Pectinophora gossypiella Saunders, （Lepidoptera： Gelechiidae） with Degree Days in the Region of Thessaly, Greece

The pink bollworm （Pectinophora gossypiella）, is one of the most damaging pests_of cotton growing in the region of Thessaly in Greece. The time of exit of the adults in spring is an important factor that affects the infestation index in the crop during the summer. Mathematical models by Sevacherian ＆ El-Zik, and Huber, which were implemented in California, were used in this study to determine the beginning, the peak of the adults output and the end of them during the summer. A data comparison between California and region of Thessaly were applied since California and Thessaly are on the same latitude with similar meteorological conditions. The results showed that the emergence occurs when the insect completes 259 DD according to the method described by Sevacherian ＆ EI-Zik, while according to the method described by Huber 430-454 DD are needed. It was observed that either according to the method described by Sevacherian and El-Zik or according to the method described by Huber, the values （DD） showed that the appearance of adults varies between -262 DD to 59 DD and -872 DD to 115 DD respectively.

Optimizing Eastern Gamagrass Forage Harvests Using Growing Degree Days

Tripsacum dactyloides (L.) L., commonly known as eastern gamagrass, is useful for grazing, stored forage, soil amelioration and conservation, and as a biofuel feedstock. Our goal was to calculate accumulated growing degree days (GDD) from existing datasets collected for eastern gamagrass forage production experiments in northwestern Oklahoma, and discuss the use of GDD, instead of calendar harvest dates, in the production of eastern gamagrass forage. Growing degree days were calculated from 1 January each year using the “optimum day method”. For 10 harvest years, the first eastern gamagrass harvest required 690 ± 26 cumulative GDD. Based on long-term weather data from Woodward, Oklahoma, this would place the first harvest on or near 1 June. The second harvest required 635 ± 27 cumulative GDD which would place the second harvest on or near 15 July and the third harvest required 690 ± 23 cumulative GDD placing it on or near 30 August. Each of the 30 harvest required an average of 670 ± 15 cumulative GDD. Using GDD to predict harvest events is a useful tool that forage producer can use in the production of eastern gamagrass forage in the USA and possibly elsewhere.

Estimation of Accumulated Degree Day Value of Six Landmarks within the Pupal Stage of Lucilia sericata

The present paper investigates the pupal development times ofLucilia sericata which were studied in the laboratory at six different constant temperatures （20, 22, 24, 26, 28 ℃ each ± ℃）. Lower thresholds （tL） for development were estimated from the linear regression of the developmental rates on each temperature. These data have made it possible to calculate the ADD （Accumulated Degree-Days） necessary for L. sericata to complete the larval stage and to achieve adult emergence. The minimal duration of development from oviposition to adult emergence was found to be inversely related to temperature. Additionally, six landmarks in pupal development are showed and for each of the landmarks the ADD value was calculated for every rearing temperature involved. These data assist in calculating the duration of the pupal stage based on morphological characteristics and would be of great value for future forensic entomological casework.

Degree-Day Analysis for Different Locations in Turkey and Effect on Architecture Conceptualism

Energy analysis plays an important role in developing an optimum and cost effective design of HVAC （heating, ventilating and air conditioning） system for an architecture. Although there are different energy analysis methods, which vary in complexity, the degree-day methods are the simplest methods and well-established tools. Energy consumption increases as the number of heating and cooling degree days increases and falls as the number of heating and cooling degree days falls. The value of degree days is a measure which can be used to indicate the demand for energy to heat or cool buildings and spaces. The monthly or annual cooling and heating requirements of specific buildings in different locations can be estimated by means of the degree-day concept. The base temperature is the outdoor temperature below or above which heating or cooling is needed. In this study, the degree days for the period of 2008-2012 were calculated for Turkey （10 cities） and also to develop new software for easy analysis about cooling degree days. This paper can be helpful for designing facade and also contribute to degree-day analyses.

Introducing Degree Days to Building Thermal Climatic Zoning in China

Building thermal climatic zoning is a key issue in building energy efficiency.Heating degree days(HDD) and cooling degree days(CDD) are often employed as indexes to represent the heating and cooling energy demand in climatic zoning.However,only using degree days may oversimplify the climatic zoning in regions with complex climatic conditions.In the present study,the application of degree days to current building thermal climatic zoning in China was assessed based on performance simulations.To investigate the key indexes for thermal climatic zoning,the climate characteristics of typical cities were analyzed and the relationships between the climate indexes and heating/cooling demand were obtained.The results reveal that the annual cumulative heating load had a linear correlation with HDD 18 only in regions with small differences in altitude.Therefore,HDD is unsuitable for representing the heating demand in regions with large differences in altitude.A comprehensive index(winter climatic severity index) should be employed instead of HDD,or complementary indexes(daily global solar radiation or altitude) could be used to further divide climate zones.In the current official climatic zoning,the base temperature of 26℃ for CDD is excessively high.The appropriate base temperature range is 18℃ to 22℃.This study provides a reference for selecting indexes to improve thermal climatic zoning in regions with similar climates.

Improving Quantitative and Qualitative Characteristics of Wheat (Triticum aestivum L.) through Nitrogen Application under Semiarid Conditions

Nitrogen(N),the building block of plant proteins and enzymes,is an essential macronutrient for plant functions.A field experiment was conducted to investigate the impact of different N application rates(28,57,85,114,142,171,and 200 kg ha^(−1))on the performance of spring wheat(cv.Ujala-2016)during the 2017–2018 and 2018–2019 growing seasons.A control without N application was kept for comparison.Two years mean data showed optimum seed yield(5,461.3 kg ha^(−1))for N-application at 142 kg ha^(−1) whereas application of lower and higher rates of N did not result in significant and economically higher seed yield.A higher seed yield was obtained in the 2017–2018(5,595 kg ha^(−1))than in the 2018–2019(5,328 kg ha^(−1))growing seasons under an N application of 142 kg ha^(−1).It was attributed to the greater number of growing degree days in the first(1,942.35°C days)than in the second year(1,813.75°C).Higher rates of N(171 and 200 kg ha^(−1))than 142 kg ha^(−1) produced more number of tillers(i.e.,948,300 and 666,650 ha^(−1),respectively).However,this increase did not contribute in achieving higher yields.Application of 142,171,and 200 kg ha^(−1) resulted in 14.15%,15.0%and 15.35%grain protein concentrations in comparison to 13.15%with the application of 114 kg ha^(−1).It is concluded that the application of N at 142 kg ha^(−1) could be beneficial for attaining higher grain yields and protein concentrations of wheat cultivar Ujala-2016.

TEMPERATURE DEPENDENT DEVELOPMENT OF ASIAN CORN BORER Ostrinia furnacalis

Temperature dependent development in the Asian corn borer, Ostrinia furnacalis (Guenee) was determined at nine constant temperatures between 10℃ and 34℃. Except for 10℃ development of all life stages occurred at the temperatures tested, however, mortality was significantly great at the extreme temperatures(12℃ and 34℃). Egg, larvae and pupae duration accounted for 17%, 57% and 25% of total one of immature stage, respectively Lower developmental thresholds estimated to be 10 38, 10 06 and 11 07℃ for eggs, larvae and pupae, respectively. Upper limited thresholds were 28 00, 31 00 and 31 00℃ for eggs, larvae and pupae, respectively. The heat unit requirements for egg stage were 79 15 degree days, for larval stage were 339 73 degree days, and for pupal stage were 128 82 degree days, respectively. Overall, heat unit requirements for development from egg to adult were 539 91 degree days between lower developmental threshold 10 35℃ and upper limited threshold 32℃.

矿业城市景观生态安全研究--一种双层复杂网络分析方法

以土地利用变化(LUC)和景观生态安全指标(LESI)分别作为上、下层网络,通过确定LUC和LESI单层网络的节点、节点重要度和节点连接强度,以及LUC与LESI上下层网络之间的节点连接系数,形成LUC-LESI双层复杂网络模型,并构建度中心性、聚类相关性和节点影响强度等3个复杂网络指标,定量分析区域土地利用变化与景观生态安全之间的内在有机联系,为土地利用调控提供指导.大冶市案例研究结果表明,2005~2015年大冶市景观生态安全状况相对稳定,7个乡镇景观生态安全状况得到提高,8个乡镇景观生态安全状况降低,景观生态安全总体处于第4等级;耕地减少和建设用地增加在LUC网络中处于核心位置,是整个网络的骨架,香农多样性指数SHDI在LESI网络中处于核心位置,对区域景观生态安全的影响最大,耕地减少和建设用地增加在区域景观生态安全变化中起主导作用;建设用地扩张主要占用耕地,耕地-建设既有相对集中的大面积开发区,又存在工矿建设的遍地开花,且建设主要沿道路线性展开,导致耕地-建设的平均斑块面积大､斑块聚集度较低､斑块形状指数较高;耕地改种树木现象在各乡镇已较为普遍,单块面积较大且相对集中,而耕地抛荒主要发生在山丘区域,虽集中度高但单块面积较小,耕地改种树木和耕地抛荒多表现为成片进行,导致耕地-林地平均斑块面积较大而耕地-草地平均斑块面积小,两者斑块聚集度均较高,斑块形状指数均较低.LUC-LESI双层复杂网络实现了景观生态安全与土地利用变化之间关系的定量化表达,可以作为区域景观生态安全研究的一种有效分析工具.

Predictions of future hydrological conditions and contribution of snow and ice melt in total discharge of Shigar River Basin in Central Karakoram,Pakistan

The high mountains of Hindu-Kush Karakoram and Himalaya(HKKH) contain a large volume of snow and ice, which are the primary sources of water for the entire mountainous population of HKKH. Thus, knowledge of these available resources is very important in relation to their sustainable use. A Modified Positive Degree Day Model was used to simulate daily discharge with the contribution of snow and ice melt from the Shigar River Basin, Central Karakoram, Pakistan. The basin covers an area of 6,921 km2 with an elevation range of 2,204 to 8,611 m a.s.l.. Forty percent of the total area is glaciated among which 20% is covered by debris and remaining 80% by clean ice and permanent snow. To simulate daily discharge, the entire basin was divided into 26 altitude belts. Remotely sensed land cover types are derived by classifying Landsat images of 2009. Daily temperature and precipitation from Skardu meteorological station is used to calibrate the glacio-hydrological model as an input variable after correlating data with the Shigar station data(r=0.88). Local temperature lapse rate of 0.0075 °C/m is used. 2 °C critical temperature is used to separate rain and snow from precipitation. The model is calibrated for 1988~1991 and validated for 1992~1997. The model shows a good Nash-Sutcliffe efficiency and volume difference in calibration(0.86% and 0.90%) and validation(0.78% and 6.85%). Contribution of snow and ice melt in discharge is 32.37% in calibration period and 33.01% is validation period. The model is also used to predict future hydrological regime up to 2099 by using CORDEX South Asia RCM considering RCP4.5 and RCP8.5 climate scenarios.Predicted future snow and ice melt contributions in both RCP4.5 and RCP8.5 are 36% and 37%, respectively. Temperature seems to be more sensitive as compared to other input variables, which is why the contribution of snow and ice in discharge varies significantly throughout the whole century.

IMPACT OF CLIMATE ON SUMMER RESIDENTIAL ELECTRICITY CONSUMPTION IN HONG KONG

The influence of climatic variables and cooling degree days (CDD) on summer residential electricity consumption for the period 1980 through 1994 in Hong Kong was investigated. The association between Clo, a measure of amount of Clothing insulation to maintain comfort, and residential electricity consumption was also examined. Utilizing monthly data and multiple regression analyses, it is discovered vapor pressure was not significantly related to electricity consumption while Cloud cover was negatively associated with electricity use. Climatic variables, CDD and Clo provided highly comparable results in modeling summer residential electricity consumption. Mean temperature and Cloud gave the best result. Clo yielded a slightly higher R2 value (0.867) than that of CDD (0.865) in the models. These results indicated that Clo could replace the weather variables and CDD to model electricity consumption.

Climate change and finger millet: Perception, trend and impact on yield in different ecological regions in Central Nepal

The views of local people on climate change along different ecological regions are relatively unexplored in Nepal. This study was conducted in 13 villages in central Nepal at different altitudes to document the views of small holder farmers and compare their perception with trends of climatic variables, finger millet yield, natural disasters, plant phenology(flowering and fruiting), status of forest and wild life, as well as the spread of diseases and pests. Analysis on the climatic data of stations for 36-41 years between 1975 and 2016 showed significant increases in the minimum temperature in lower tropical climatic region(<500 m), upper tropical to subtropical climatic region(500-2000 m) and temperate climatic region(2000-3000 m) by 0.01, 0.026 and 0.054℃/year, respectively, and an increase of maximum temperature by 0.008, 0.018, and 0.019℃/year, respectively. Rainfall showed a strongly significant decreasing trend in all elevation regions. This result matches with the views of respondents except 38% respondent from temperate climatic region. People from the temperate climatic region also mentioned that current onset of snowfall is delayed but amount of snowfall remained the same. From the documented records, except events of wild fire, frequency of natural disasters events have increased in the recent years, which was in harmony with the views of local people. Multi-linear regression analysis showed that contribution of climatic variables on finger millet yield in lower tropical climatic region and upper tropical to subtropical regions was 23% and 57.3%, respectively, which was supported by increasing trend on average growing degree day(GDD) temperature at the rate of 0.01℃ in upper tropical to subtropical region and 0.007℃ in lower tropical climatic region yearly. Finger millet yield has been increasing at the rate of 7.39 and 36.9 kg/ha yearly in lower tropical climatic region and upper tropical to subtropical climatic region, respectively. This result provides deeper understanding of people's perception of causes and effects of climate change on diverse variables along different elevation and related magnitude which can contribute to policy making in Nepal.

Deduction of a meteorological phenology indicator from reconstructed MODIS LST imagery

Phenology is a valuable attribute of vegetation to assess the biological impacts from climate change.A challenge of phenological research is to obtain information on both high temporal resolution and fine spatial scale observations.Here,we constructed an air temperature map based on temporal merging and spatial interpolation algorithms to overcome the cloud-related problem from the MODIS LST product.Then,we derived the accumulated growing degree days(AGDD)from the constructed mean air temperature map to use as a meteorological indicator.Further,we verified the indicator with the seasonal mean air temperature and the green-up date of a Quercus mongolica forest determined from the field-based measurements.The AGDD threshold for each Q.mongolica forest when the first leaf has unfolded was detected from the EXG trajectory extracted from digital camera images.A comparison between meteorological and MODIS-derived AGDD showed good agreement between them.There was also high consistency between DoYs extracted from AGDD and EVI based on curvature K for Q.mongolica forests of 30 sampling sites throughout South Korea.The results prove that microclimatic factors such as elevation,waterbody,and land-use intensity were faithfully reflected in the reconstructed images.Therefore,the results of this study could be applied effectively in areas where microclimatic variation is very severe and for monitoring phenology of undergrowth,which is difficult to detect from reflectance imaging.

An Approach to Quantify the Heat Wave Strength and Price a Heat Derivative for Risk Hedging

Mitigating the heat stress via a derivative policy is a vital financial option for agricultural producers and other business sectors to strategically adapt to the climate change scenario. This study has provided an approach to identifying heat stress events and pricing the heat stress weather derivative due to persistent days of high surface air temperature （SAT）. Cooling degree days （CDD） are used as the weather index for trade. In this study, a call-option model was used as an example for calculating the price of the index. Two heat stress indices were developed to describe the severity and physical impact of heat waves. The daily Global Historical Climatology Network （GHCN-D） SAT data from 1901 to 2007 from the southern California, USA, were used. A major California heat wave that occurred 20-25 October 1965 was studied. The derivative price was calculated based on the call-option model for both long-term station data and the interpolated grid point data at a regular 0.1~ x0.1~ latitude-longitude grid. The resulting comparison indicates that （a） the interpolated data can be used as reliable proxy to price the CDD and （b） a normal distribution model cannot always be used to reliably calculate the CDD price. In conclusion, the data, models, and procedures described in this study have potential application in hedging agricultural and other risks.

Impact of temperature on yield and related traits in cotton genotypes

Cotton growth and development is influenced by various uncontrollable environmental conditions. Temperature variations in the field can be created by planting at different dates. The objective of the present study was to evaluate the effect of planting dates and thermal temperatures（growing degree days） on yield of 4 cotton genotypes, viz., CIM-598, CIM-599, CIM-602 and Ali Akbar-703. Plants were subjected to 6 planting dates during 2013 and 2014 in a trial conducted in randomized complete block design with four replications. For boll number, boll weight and seed cotton yield, cotton genotypes exhibited significant differences, CIM-599 produced the highest seed cotton yield of 2 062 kg ha^（–1） on account of maximum boll number and boll weight. The highest seed cotton yield was recorded in planting dates from 15 th April to 1st May whereas early and delayed planting reduced the yield due to less accumulation of heat units. Regression analysis revealed that increase of one unit（15 days） from early to optimum date（15th March to 15 th April） increased yield by 93.58 kg ha^–1. Delay in planting also decreased the seed cotton yield with the same ratio. Thus it is concluded that cotton must be sown from 15 th April to 1st May to have good productivity in this kind of environment.

Multi-model assessment of glacio-hydrological changes in central Karakoram, Pakistan

The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing components of the river discharge.This study examined and compared the hydrological responses in the glacier-dominated Shigar River basin(SRB)under various climatic scenarios using a semi-distributed Modified Positive Degree Day Model(MPDDM)and a distributed Glacio-hydrological Degree-day Model(GDM).Both glacio-hydrological models were calibrated and validated against the observed hydro-meteorological data from 1988–1992 and 1993–1997.Temperature and precipitation data from Shigar and Skardu meteorological stations were used along with field estimated degree-day factor,temperature,and precipitation gradients.The results from both models indicate that the snow and ice melt are vital contributors to sustain river flow in the catchment.However,MPDDM estimated 68%of rain and baseflow contribution to annual river runoff despite low precipitation during the summer monsoon,while GDM estimated 14%rain and baseflow contribution.Likewise,MPDDM calculated 32%,and GDM generated 86%of the annual river runoff from snow and ice melt.MPDDM simulated river discharge with 0.86 and 0.78 NSE for calibration and validation,respectively.Similarly,GDM simulated river discharge with improved accuracy of 0.87 for calibration and 0.84 NSE for the validation period.The snow and ice melt is significant in sustaining river flow in the SRB,and substantial changes in melt characteristics of snow and ice are expected to have severe consequences on seasonal water availability.Based on the sensitivity analysis,both models’outputs are highly sensitive to the variation in temperature.Furthermore,compared to MPDDM,GDM simulated considerable variation in the river discharge in climate scenarios,RCP4.5 and 8.5,mainly due to the higher sensitivity of GDM model outputs to temperature change.The integration of an updated melt module and two reservoir baseflow module in GDM is anticipated to advance the representation of hydrological components,unlike one reservoir baseflow module used separately in MPDDM.The restructured melt and baseflow modules in GDM have fundamentally enriched our perception of glacio-hydrological dynamics in the catchment.

Phenology and population dynamics of sand flies in a new focus of visceral leishmaniasis in Eastern Azarbaijan Province,North western of Iran

Objective:To investigate species composition,density,accumulated degree-day and diversity of sand flies during April to October 2010 in Azarshahr district,a new focus of visceral leishmaniasis in north western Iran.Methods:Sand flies were collected using sticky traps biweekly and were stored in 96%ethanol.All specimens were mounted in Puri’s medium for species identification using valid keys of sandflies.The density was calculated by the formula: number of specimens/m of sticky traps and number of specimens/ number of traps.Degree-day was calculated as follows:(Maximum temperature + Minimum temperature)/2—Minimum threshold.Diversity indices of the collected sand flies within different villages were estimated by the Shannon- weaver formula(H’=sum form(i=1) to s Pi log_e Pi ).Results:Totally 5 557 specimens comprising 16 Species(14 Phlebotomus,and 2 Sergentomyia) were indentified.The activity of the species extended from April to October.Common sand-flies in resting places were Phlebotomus papatasi, Phlebotomus sergenti and Phlebotomus mongolensis.The monthly average density was 37.6.41.1, 40.23,30.38 and 30.67 for Almalodash,Jaragil,Segaiesh,Amirdizaj and Germezgol villages, respectively.Accumulated degree-day from early January to late May was approximately 289 degree days.The minimum threshold temperature for calculating of accumulated degree-day was 17.32℃.According on the Shannon-weaver(H’),diversity of sand flies within area study were estimated as 0.917,1.867,1.339,1.673,and 1.562 in Almalodash,Jaragil,Segaiesh,Amirdizaj and Germezgol villages,respectively.Conclusions:This study is the first detailed research in terms of species composition,density,accumulated degree-day and diversity of sand flies in an endemic focus of visceral leishamaniasis in Azarshahr district.The population dynamics of sand flies in Azarshahr district were greatly affected by climatic factors.According to this study the highest activity of the collected sand fly species occurs at the teritary week of August.It could help health authorities to predicate period of maximum risk of visceral leishamaniasis transmission and implement control program.

A New Scheme for Predicting Leaf Onset in Summer-Green Vegetation in the Northern Hemisphere

A modified thermal time model(MTM) was developed to reproduce the leaf onset for summer-green vegetation in the Northern Hemisphere. The model adopts the basic concept of a thermal time model(TM) in that leaf onset is primarily triggered by growing degree days(GDD). Based on global phenology data derived from satellite observations, a new parameterization for the critical model parameter Tb(i.e., baseline temperature for GDD calculation) has been introduced, and the spatial distribution of Tb was calculated. Simulations of leaf onset during 1982–2000 in the range 30–90°N showed a significant improvement of MTM over the standard TM model with constant Tb. The mean error and mean absolute error of the climatological simulation were 1.11 and 6.8 days, respectively, and 90% of the model error(5th and 95 th percentiles) was between-12.4 and 13.7 days.

Does heat accumulation alter crop phenology, fibre yield and fibre properties of sunnhemp(Crotalaria juncea L.) genotypes with changing seasons?

Field experiments were carried out in split plot design during the dry and wet seasons for two years(two seasons each in 2016–2017 and 2017–2018) with two genotypes(SH4 and SUIN053), two plant geometry(30×15 cm and 45×15 cm main plots) and three levels of NPK(20 kg N ha^(–1), 40 kg P ha^(–1) and 40 kg K ha^(–1);20 kg N ha^(–1), 60 kg P ha^(–1) and 60 kg K ha^(–1);20 kg N ha^(–1), 80 kg P ha^(–1) and 80 kg K ha^(–1)) with an objective to study the relationship between fibre yield of sunhmep and thermal indices. The results indicated that the thermal units such as cumulative heat unit(CHU), photo thermal unit(PTU) and helio thermal unit(HTU) were the highest during dry seasons, while relative temperature disparity(RTD) was the highest during wet seasons irrespective of the genotypes, plant geometry and fertilizer levels. The combined analysis of variance showed that the suitability of sunnhemp genotypes for obtaining fibre and seed yields varied with season. The results further indicated that sunnhemp grew during dry seasons with longer photoperiod and higher values of growing degree days(GDD), HTU and PTU resulted in a higher fibre yield, while a higher seed yield and relatively longer, finer and stronger fibres were obtained during wet seasons with higher RTD values. Regression analysis indicated that CHU was positively related to fibre yield, while RTD was positively related to seed yield. CHU beyond 2 000 °C d reduced seed yield and favoured fibre production. In contrary to CHU, RTD values were positively related to seed yield and negatively related to fibre yield. Similarly, HTU had an inverse relationship with fibre yield while PTU had a positive relationship with fibre yield. The genotype SH4 produced a seed yield of 1 361 kg ha^(–1) during wet seasons, which was significantly higher than SUIN053, while a fibre yield of 990 kg ha^(–1)(significantly higher than that of SH4) was obtained for SUIN053 that required less CHU to attain the phenological events during dry seasons. The per unit area yields of seed and fibre with the closer spacing(30 cm×15 cm) by virtue of higher plant density were 17.0 and 14.9% higher than those with the spacing of 45 cm×15 cm, respectively. Higher doses of P and K resulted in higher seed and fibre yields.

Alpine tundra species phenology is mostly driven by climate-related variables rather than by photoperiod

The study of plant phenology has frequently been used to link phenological events to various factors,such as temperature or photoperiod.In the high-alpine environment,proper timing of the phenological cycle has always been crucial to overcome harsh conditions and potential extreme events(i.e.spring frosts)but little is known about the response dynamics of the vegetation,which could shape the alpine landscape in a future of changing climate.Alpine tundra vegetation is composed by an array of species belonging to different phytosociological optima and with various survival strategies,and snowbed communities are a relevant expression of such an extreme-climate adapted flora.We set eight permanent plots with each one in a snowbed located on the Cimalegna plateau in Northwestern Italy and then we selected 10 most recurring species among our plots,all typical of the alpine tundra environment and classified in 3different pools:snowbed specialists,grassland species and rocky debris species.For 3 years we registered the phenophases of each species during the whole growing season using an adaptation of the BBCH scale.We later focused on the three most biologically relevant phenophases,i.e.,flower buds visible,full flowering,and beginning of seed dispersion.Three important season-related variables were chosen to investigate their relationship with the phenological cycle of the studied species:(i)the Day Of Year(DOY),the progressive number of days starting from the 1 st of January,used as a proxy of photoperiod,(ii)Days From Snow Melt(DFSM),selected to include the relevance of the snow dynamics,and(iii)Growing Degree Days(GDD),computed as a thermal sum.Our analysis highlighted that phenological development correlated better with DFSM and GDD than with DOY.Indeed,models showed that DOY was always a worse predictor since it failed to overcome interannual variations,while DFSM and marginally GDD were better suited to predict the phenological development of most of the species,despite differences intemperature and snowmelt date among the three years.Even if the response pattern to the three variables was mainly consistent for all the species,the timing of their phenological response was different.Indeed,species such as Salix herbacea and Ranunculus glacialis were always earlier in the achievement of the phenophases,while Agrostis rupestris and Euphrasia minima developed later and the remaining species showed an intermediate behavior.However,we did not detect significant differences among the three functional pools of species.