Genotypic variability enhances the reproducibility of an ecological study

Many scientific disciplines are currently experiencing a “reproducibility crisis” because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that a deliberate introduction of controlled systematic variability (CSV) in experimental designs may lead to increased reproducibility. We tested this hypothesis using a multi-laboratory microcosm study in which the same ecological experiment was repeated in 14 laboratories across Europe. Each laboratory introduced environmental and genotypic CSV within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV led to lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility was generally lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the “reproducibility crisis”, deliberately including genetic variation may be a simple solution for increasing the reproducibility of ecological studies performed in controlled environments

Humidity as a determinant of heat stress tolerance in wheat (Triticum aestivum L.)

Wheat is one of the most common crops, grown worldwide on about 220 million ha of farmland. However, ongoing climate change has raised concerns about the effects of environmental variation on wheat yields. Studies on grain crops show that high spikelet (or panicle) temperature is the main reason for sterility and can be distinct from ambient air temperature. Transpirational cooling commonly lowers spikelet temperature, but the capacity of plants to cool their tissues may be affected by relative humidity. This thesis reports on findings from three consecutive years of pot and field-based experiments where two wheat cultivars, namely Blasco (bred for warm and dry conditions) and Paragon (bred for wet and cool conditions), were exposed to combinations of temperature (T), relative humidity (RH) and soil moisture treatments. The cooling capacity of Blasco was higher than Paragon under most conditions in controlled environment experiment, while the temperature of the spike was higher than that of the flag leaf in both cultivars in all three experiments. Even though we have not observed RH effect on tissue temperature in the semi-controlled pot-based and field experiments, controlled environment experiment in the cabinets showed that both RH and air T has an impact on tissue temperature, while the main driver of tissue T in both cultivars was the temperature of surrounding air regardless of the growth stage. Higher RH at low air temperature resulted in a decrease of the cooling capacity in Paragon during early grain filling in controlled climate cabinets, but a complete reversal was observed in Blasco. RH did not modify tissue temperature of the cultivars at higher air T at flowering, but high RH increased spike temperatures in both cultivars during early grain filling. Increased tissue temperatures at flowering triggered lower grain number in Paragon. Lower grain weight under high RH conditions caused lower grain yield which triggered higher total protein and gluten protein content in both cultivars in the controlled environment and field experiments. In pot-based semi-controlled experiment, higher soil moisture caused higher grain yield in Blasco and Paragon, and protein content tended to be higher at lower soil moisture conditions. In the controlled environment experiment, we have observed that high tissue temperature under high temperature caused decrease in alpha amylase activity of Paragon. Gluten protein composition in Blasco was affected from high RH and high air temperature as ω-gliadins % glutenin subunits in Blasco increased under these conditions. There was a negative correlation between grain yield and protein content in both cultivars in all three Experiments. In the semi-controlled field experiment, total nitrogen and gluten protein content in both cultivars increased under high RH and high air temperature conditions, while in pot-based semi-controlled experiment, increase in soil moisture resulted in lower SDS-sedimentation. Blasco responds to the stress factors with altering its stomata area, while Paragon altered its stomata number. High RH, high air T and low soil caused an increase in stomata are in Blasco, while High RH and high air T resulted in higher stomata number in Paragon. Lower RH caused higher stomatal conductance in Blasco under ambient temperatures. The main finding of the thesis is that atmospheric humidity affects the capacity of wheat plants to regulate tissue temperature which impacts grain quantity and quality

Kuzey Kıbrıs’ta yıllık ve mevsimsel iklim değişikliği trendleri

In order to meet water needs for the present and future to sustain life, applying sustainable water resources management is vital. Changes in temperature and precipitation regimes affect the agriculture and ecosystem. Therefore, investigation of the changes in the spatial and temporal rainfall and temperature patterns is important for sustainable water resources management. The meteorological data used in this study was obtained from North Cyprus Meteorological Office. Annual, seasonal, and monthly rainfall variables are studied in order to examine the changes in precipitation regimes, while average and maximum of monthly maximum, average and minimum of monthly minimum, average of monthly average, and monthly diurnal temperature variables are used for the study of temperature regimes. Nonparametric Mann-Kendall rank correlation, Seasonal Kendall, Sen‟s T, and Seasonal Sen‟s T tests are employed to identify the existence of linear trend in rainfall and temperature variables. 10% significance level is used to extract significant trends. After filling in missing data and testing for homogeneity of time series for the period of 1978-2011, these trend tests are applied to the observed rainfall data from 20 rain-gauge stations, and temperature data from 8 temperature-gauge stations, all located in the northern part of the island. Inverse Distance Method has been used to fill in the missing values in the temperature and precipitation data. Furthermore, Standard Normal Homogeneity Test (SNHT) is employed in this study to determine the non-homogeneities in the data. The results show that there is no nonhomogeneity in the records of both temperature and precipitation variables. Trend tests indicate that there is no trend in the annual rainfall. However, upward trends in September rainfall and downward trends in March rainfall have been observed in most of the stations. This indicates that there is a shift in monthly rainfall regime. On the other hand, there are strong increasing trends in temperature variables, except downward trends in monthly diurnal temperatures. These upward trends have been observed mostly in summer months and almost in all stations. Diurnal temperature range indicates the differential value between average maximum and minimum temperatures. Since trends in average minimum temperatures have increased at a faster rate, decreasing trends have been observed in Diurnal temperature ranges in most of the stations. Trends in more extreme temperature variables, minimum of monthly minimum and maximum of monthly maximum temperatures, also increased during the period mostly in summer season, although the trends are not strong as the trends in the other temperature variables.Hayatın devamlılığı için gerekli su ihtiyacının karşılanabilmesi için su kaynaklarının sürdürülebilir şekilde yönetimi hayati önem taşımaktadır. Sıcaklık ve yağış rejimlerindeki değişiklikler tarım ve ekosistemi etkilemektedir. Bu sebepten dolayı, mekansal ve zamansal yağış ve sıcaklık verileri ile yapılan araştırmalar sürdürülebilir su yönetimi için çok büyük önem taşımaktadır. Bu çalışmada kullanılan meteorolojik veriler K.K.T.C. Meteoroloji Dairesinden temin edilmiştir. Yağışlardaki değişiklikleri çalışmak için yıllık, aylık ve mevsimlik yağış verileri dikkate alınmıştır. Sıcaklıklardaki değişiklikler için ise en yüksek aylık verilerin en yüksek ve ortalama değerleri, en düşük aylık verilerin en düşük ve ortalama değerleri, aylık ortalamaların ortalama değerleri ve ortalama en yüksek ve ortalama en düşük verilerin farkı çalışılmıştır. Sıcaklık ve yağış değerlerindeki trendler parametrik olmayan MannKendall, Seasonal Kendall, Sen‟s T ve Seasonal Sen‟s T yöntemleri kullanılarak elde edilmiştir. Kayda değer bir trend olup olmadığını belirlemek için ise %10 önem düzeyinde çalışma yapılmıştır. Eksik verilerin doldurulması ve homojenlik testinin ardından yukarıda bahsedilen trend testleri Kuzey Kıbrıs‟taki 20 yağış ve 8 sıcaklık istasyonlarından elde edilen 1978‟den 2011 yılına kadar olan verilere uygulanmıştır. Inverse Distance Method yağış ve sıcaklık verilerindeki eksik kısımların doldurulmasında kullanılmıştır. Daha sonra, kullanılacak olan verilerin homojen olduğundan emin olabilmek için Standard Normal Homogeneity Test (SNHT) kullanılarak homojenlik testi yapılmıştır. Elde edilen sonuçlara göre analizlerde kullanılacak olan sıcaklık ve yağış verilerinin homojen olduğu ortaya çıkmıştır. Yapılan trend çalışmaları sonucunda yıllık yağışlarda bir değişiklik gözlenmezken, Eylül ayındaki yağışlarda artma ve Mart ayındaki yağışlarda azalma gözlenmiştir. Buda bize toplam yağışlarda bir değişiklik olmaması ile birlikte aylık yağışlarda bir kayma olduğunu göstermektedir. Bunun yanı sıra, birçok istasyonda sıcaklık trendlerinde özellikle yaz aylarında ciddi artışlar olduğu belirlenmiştir. Ortalama en düşük sıcaklıklardaki değişikliklerin ortalama en yüksek sıcaklıklardakine oranla daha yüksek olmasından dolayı aralarındaki farklarda azalmalar gözlemlenmiştir. En uç sıcaklık değerlerinde de, en düşük/yüksek uç sıcaklıklarda, diğer verilerdeki şiddetle olmasa da artış gözlemlenmiştirM.S. - Master of Scienc

Data from 14 labortories testing the impact of introduced variability on the reproducibility of a microcosm ecological experiment

Although microcosm experiments are a frequent tool used to address fundamental ecological questions, there has been no quantitative assessment of the reproducibility of any microcosm experiment. This dataset contains the response variables measured in a multi-laboratory microcosm study in which the same microcosm experiment was repeated in 14 laboratories across Europe. All laboratories simultaneously run a simple microcosm experiment using grass (Brachypodium distachyon L.) monocultures and grass and legume (Medicago truncatula Gaertn.) mixtures. All twelve variables were then used to calculate the effect of the presence of nitrogen-fixing legume on the grass-legume mixtures (i.e. the net legume effect). The project tested a controversial hypotheses postulating that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in the experimental design. This implies that the deliberate introduction of controlled systematic variability (CSV) in experimental designs can increase reproducibility. To test this hypothesis, each laboratory followed the same experimental protocol and introduced environmental and genotypic controlled systematic variability (CSV) within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). Data were used to test the extent to which the effect size of the net legume effect varied with the CSV treatment and to estimate the number of laboratories that produced results that can be considered reproducible