Night Temperature Research Articles

Temperature and Relative Humidity Effects on Sugarcane Flowering Ability and Pollen Viability Under Natural and Seminatural Conditions

Flowering of sugarcane genotypes is important for the breeding program, but flowering is highly affected by environmental conditions. Field experiments were conducted at Sugarcane Field Station (26.52°N and 80.36°W), Canal Point, Florida, USA, during the 2015–2016 season, to explore the flowering behavior of 12 sugarcane genotypes under natural and seminatural environments concerning the effects of temperature and % relative humidity on the pollen viability to find out the best stable ones in flowering to be used in the breeding program. There were critical 57 days under the natural condition with a night temperature of ≤ 20 °C during the sensitive floral tip and full emergence period. This led to a reduction in pollen viability percentage and % pollen germination percentages. Moreover, the flowering intensity was very much reduced. On another hand, there were no appreciable differences in relative humidity % in the same floral stages. The total flowering plants decreased under natural compared with seminatural conditions. The results showed that the tested genotypes varied significantly in all traits. The interaction of genotypes × treatments interaction had a significant effect on most studied traits. Most of the Houma cane genotypes such as HO11-512, HOCP12-643, and HOCP01-517 showed stable flowering and % pollen viability than CP genotypes and L ones (CPO4-1935, CPO8-2506, L11-187, and L09-112) under both conditions. The study suggests the genotypes are stable in flowering to use them in the breeding program.

Anthropogenic impacts on recent decadal change in temperature extremes over China: relative roles of greenhouse gases and anthropogenic aerosols

Observational analysis indicates significant changes in some temperature extremes over China across the mid-1990s. The decadal changes in hot extremes are characterized as a rise in annual hottest day and night temperature (TXx and TNx) and an increase in frequencies of summer days (SU) and tropical night (TR). The decadal changes in cold extremes are distinguished by a rise in annual coldest day and night temperature (TXn and TNn) and a decrease in frequencies of ice days (ID) and frost days (FD). These decadal changes manifest not only over China as a whole, but also over individual climate sub-regions. An atmosphere-ocean-mixed-layer coupled model forced by changes in greenhouse gases (GHG) concentrations and anthropogenic aerosol (AA) emissions realistically reproduces the general spatial patterns and magnitudes of observed changes in both hot and cold extremes across the mid-1990s, suggesting a pronounced role of anthropogenic changes in these observed decadal changes. Separately, changes in GHG forcing lead to rise in TXx, TNx, TXn and TNn, increase in frequencies of SU and TR and decrease in frequencies of ID and FD over China through increased Greenhouse Effect with positive clear sky longwave radiation and play a dominant role in simulated changes of both hot and cold extremes over China. The AA forcing changes tend to cool Southern China and warm Northern China during summer via aerosol-radiation interaction and AA-induced atmosphere-cloud feedback and therefore lead to some weak decrease in hot extremes over Southeastern China and increase over Northern China. Meanwhile, AA changes lead to warming over China during winter through cloud feedbacks related to aerosol induced cooling over tropical Indian Ocean and western tropical Pacific, and also induce changes in cold extremes the same sign as those induced by GHG, but with weak magnitude.

Study of the impact of climate change on the spatial distribution of dengue cases in Rio de Janeiro

Introduction There is evidence that the distribution of dengue cases is correlated with environment variables such as temperature, precipitation and others. This study aimed to select the best variables for modelling the number of dengue cases in Rio de Janeiro city, and used data from 2015 to 2016 as comparison for results. Methods The number of cases was obtained by the Brazilian health system and the variables were mined from public satellites data, separating Rio de Janeiro city in 21-pixel blocks in image data. The data gathered from 2015 to 2016 was divided in 8-day periods, where the mean of each variable in this period was stored. The study made a comparison using the following variables and their respective lags in time: NDVI, day temperature, night temperature, precipitation, population size, latitude and longitude. The comparison between them was made using the one who fitted more a Generalized Autoregressive Log-linear Model with a negative binomial family to predict the dengue cases. Results The most significant predictors inside the model were temperature at night, precipitation three weeks before, and dengue cases from one week before. Using only these three variables and an intercept, the model showed an error mean of 0.3% and a standard deviation of 11% in a prediction against real value comparison. Conclusions This work is a first approach to understanding the determinants of dengue and only using public data. The next steps will be to extend both the temporal and spatial reach of the analysis.

EFFECT OF A SHORT-TERM DAILY TEMPERATURE DROP ON THE COLD TOLERANCE OF LEAVES OF DIFFERENT AGE

The enhancement of chilling tolerance in leaves of different age in cucumber ( Cucumis sativus L.) and wheat ( Triticum aestevum L.) plants treated by a daily short-term temperature drop was studied. Plants were subjected to short-term (2 h at the end of the night)temperature drops to 12 ° C (cucumber) or 4 ° C (wheat) for 6 days in the phase of the actively growing first (wheat) or true second (cucumber) leaf (DROP1) or growth-completing, i. e. mature first or second leaf, respectively (DROP2). DROP3 plants were treated by DROP throughout the first or second leaf growth period (12 days). The leaf cold tolerance was assessed by the resistance of leaf cells to short-term freezing. Cell membrane permeability was estimated by relative electrolyte leakage. Both young and mature leaves responded to DROP treatments by enhanced leaf cold tolerance, but in mature leaves that have completed their growth, cold tolerance was higher than in young, actively growing leaves. Relative electrolyte leakage from tissues of mature leaves was lower than from young leaves, which testifies to higher membrane stability of mature DROP-treated leaves. It is hypothesized that the differences detected in the tolerance of DROP-treated leaves of different age are associated with their structural (anatomical-morphological) and metabolic features.

Effect of ambient temperature fluctuation on the timing of the transition to the generative stage in cauliflower

Cauliflower (Brassica oleracea ssp. botrytis) is an important vegetable that is grown worldwide from the tropics to temperate zones. The harvested product is the curd, which consists of arrested inflorescence meristems. The switch from vegetative development to curd formation in cauliflower, referred to as the generative switch, is strongly temperature responsive in the majority of varieties. We aimed at measuring the delay in timing of the generative switch by high ambient temperature, and how temperature affects the expression of genes with a potential role in timing of this switch. A seven day increase of six degrees in day and night temperature during vegetative development, results in a substantial delay of the generative switch and increased variation in timing of this switch in sensitive cultivars only. The expression level of the Cauliflower FRUITFULL-like gene BoFULc increased significantly at the generative switch and therefore can be used as marker for this developmental phase change. The expression profiles of the majority of the other investigated cauliflower flowering time genes resembled the expression behaviour of their homologous genes in the model plant Arabidopsis thaliana during the vegetative stage and flowering induction. An exception was the expression of two FLC paralogues BoFLC-1 and BoFLC-3, which showed opposite expression profiles of which the pattern of BoFLC-1 resembles the pattern expected based on Arabidopsis FLC. This interesting observation suggests different roles for these two FLC paralogs in regulation of the timing of the generative switch in cauliflower. Unexpectedly, high temperatures did not delay timing of expression of the majority of investigated genes in meristems and leaves of sensitive cultivars that were delayed in the switch to the generative stage. However, expression of a few potential flowering-time genes was affected by the high temperature treatment in a sensitive cultivar, making them potential candidates to be causal for the observed delay in generative switch.

The Effect of Different Day and Night Temperatures on the Growth and Physiology of Theobroma cacao under Controlled Environment Condition

Aims: An experiment was conducted to investigate the effect of a wide range of temperatures on the growth and physiology of Theobroma cacao, to study the differences between night and day temperatures and to determine the optimum temperature for the cocoa growth. Study Design: The experiment used five combinations of night and day temperatures (18°C and 30°C [18N30N], 18°C and 36°C; [18N 36D], 24°C and 24°C [24N24D], 24°C and 30°C [24N30D] and 24°C and 36°C [24N36D]) using complete randomized design (CRD). Place and Duration of Study: Crops and Environment Laboratory University of Reading and International Cocoa Quarantine Centre, between 23rd May 2016 and 25th July 2016. Methodology: The cocoa seedlings were put into five growth cabinets with five different night and day temperatures combinations (18°C and 30°C, 18°C and 36°C, 24°C and 24°C, 24°C and 30°C, 24°C and 36°C) for two months (63 days) under controlled environment condition where the relative humidity and vapor pressure deficit were controlled. Destructive harvest data was taken at end of the experiment which included fresh weight, dry weight, leaf area and root weight. Non-destructive measurements were height of the plant, photosynthetic rate, chlorophyll fluorescence and total chlorophyll content. Results: Treatment 24N30D have the best growth and treatment 24N36D had the lowest growth performances compared to other treatments. Conclusion: The growth was not only dependent on the day temperature, but also on the night temperature. A large gap between night and day temperatures (DIF) reduced the cocoa growth. The result also showed the optimum temperature amongst those studied for cocoa growth is the combination of 24°C night temperature and 30°C day temperature.

Temporal and spatial variation of extreme temperatures in an agro-pastoral ecotone of northern China from 1960 to 2016

The agro-pastoral ecotone of northern China is one of the areas most sensitive to global temperature change. To analyze the temporal and spatial trends of extreme temperature events in this area, we calculated the values of 16 extreme-temperature indices from 1960 to 2016 based on data from 45 national meteorological stations. We found that the coldest-temperature indices decreased significantly and the warmest-temperature indices increased significantly. The warming of night temperatures contributed more than warming of day temperatures to the overall warming trend. In addition, the warm-temperature indices appeared to be increasing since the late 1980s and early 1990s. Overall, though the four extremal indices showed an increasing trend, the rate of change in the minimum temperature was greater than that of the maximum temperature; thus, the minimum temperature contributed most strongly to the overall temperature increases. The growing season is being prolonged in higher-elevation areas, but vegetation maturation in lower-elevation areas has been accelerated by the high temperatures, potentially leading to a shorter growing season at low altitudes. However, the impacts of land-use changes caused by human activities on the temperature increases will require additional study.

Analysis of CsPAP-fib regulation of cucumber female differentiation in response to low night temperature conditions

Abstract In this study, the expression pattern of CsPAP-fib under different night temperature conditions (12 °C, 18 °C, and 24 °C) was analyzed using qRT-PCR, the subcellular localization of CsPAP-fib protein was determined, and sense and antisense CsPAP-fib were transformed into cucumber. The first node with female flowers and the female flower rate were calculated and recorded. Next, the ethylene and gibberellin contents were determined. The expression of CsPAP-fib in cucumber leaves was the highest under the low night temperature (12 °C) condition and was significantly higher than that in the roots, stems and shoot tips; however, under the high night temperature (24 °C) and normal night temperature (18 °C) conditions, no significant differences in CsPAP-fib expression in the roots, stems, leaves, shoot tips and other organs were observed. The expression of CsPAP-fib was the highest in cucumber leaves during the two-leaf stage and was significantly higher than that during the four-leaf stage. CsPAP-fib played a functional role mainly in chloroplasts. The overexpression of CsPAP-fib significantly improved the rate of cucumber female flowering and reduced the first node with a female flower. Thus, CsPAP-fib is a relevant gene for the regulation of cucumber female differentiation under low night temperature conditions. Altogether, CsPAP-fib is induced by a low night temperature (12 °C) and promotes the formation of cucumber femaleness by increasing the female flowering rate and decreasing the first node with a female flower. CsPAP-fib may be a relevant gene for cucumber femaleness differentiation at a low night temperature.

Low night temperature at veraison enhances the accumulation of anthocyanins in Corvina grapes (Vitis Vinifera L.)

Climate change is a major concern in grape production worldwide. Nights have been warming much faster than the days, raising attention on the effect of night temperatures on grape and wine composition. In this study we evaluated the effect of night temperatures on grape coloration in the cv. Corvina (Vitis vinifera L.). In 2015 and 2016 potted plants were cooled overnight (10–11 °C) during two berry ripening phases, veraison (TV) or post-veraison (TPV), and compared to control vines (C) grown at ambient night temperature (15–20 °C on average). Cooling treatment around veraison (TV) hastened berry anthocyanin accumulation, while the same treatment applied after veraison (TPV) was ineffective. Molecular analysis revealed an increased transcription of four key genes in anthocyanin biosynthesis (CHS3, F3H1, MYBA1 and UFGT) in TV treatment. These results suggest that the anthocyanin biosynthesis capacity was enhanced by cool nights during veraison. However, since the gene expression was not always temporally correlated to the increase in anthocyanin concentration, we speculate on the presence of mechanisms, such as enzymatic regulation or anthocyanin transport, which may contribute in determining the anthocyanin accumulation under low night temperatures.

The Effects of Windows and Reduced Night Temperature on the Heating Energy Demand in Different Regions of Russia

An energetic model of a typical log home was placed in ten different regions of Russia and examined the yearly heating energy demand. The building was supplied with three different types of windows to demonstrate the effect of windows on the heating energy demand. In a 108 m2 building, changing the 3.5 W/m2K thermal insulation capacity windows to 1.4 W/m2K and 0.7 W/m2K windows caused an energy saving of 11.9% and 15.9% heating energy respectively. In a heated space reducing the night temperature by 2 degrees Celsius can result in only a 2.7% (1 865 kWh) saving in the colder Magadan region, while in the Mediterranean Krasnodar, there was a 4.48% (1 151 kWh) saving of the net heating energy amount. Calculations estimated that Russia possesses a very significant heating potential savings.

English

English

Impact of heat stress during seed filling on seed quality and seed yield in lentil (Lens culinaris Medikus) genotypes.

Lentil, a cool-season food legume, is highly sensitive to high temperatures, which drastically reduce biomass and seed yield. The effects of heat stress on qualitative and quantitative aspects of seeds are not yet known. In this study, we assessed the effects of high temperatures on quantitative and qualitative aspects of seeds in a heat-tolerant (HT; FLIP2009) and heat-sensitive (HS; IG4242) genotypes in a controlled environment. Initially, the plants were raised in a natural, outdoor environment (22/10 °C mean day/night temperature, 1350 µmol m-2 s-1 light intensity, 60-65% relative humidity) from November to mid-February until 50% flowering (114-115 days after sowing). After that, one set of plants was maintained in a controlled environment (28/23 °C, as mean day and night temperature, 500 µmol m-2 s-1 light intensity, 60-65% relative humidity;control) and one set was exposed to heat stress (33/28 °C, as mean day and night temperature, 500 µmol m-2 s-1 light intensity, 60-65% relative humidity), where they remained until maturity. Compared to control, heat stress reduced the seed growth rate by 30-44% and the seed-filling duration by 5.5-8.1 days, which ultimately reduced the seed yield by 38-58% and individual seed weights by 20-39%. Heat stress significantly damaged cell membranes and reduced chlorophyll concentration and fluorescence, and the photosynthetic rate, which was associated with a significant reduction in relative leaf water content. The proximate analysis of seed reserves showed that heat stress reduced starch (25-43%), protein (26-41%) and fat (39-57%) content, and increased total sugars (36-68%), relative to the controls. Heat stress also inhibited the accumulation of storage proteins including albumins, globulins, prolamins and glutelins (22-42%). Most of the amino acids decreased significantly under heat stress in comparison to control, whereas some, such as proline, followed by glycine, alanine, isoleucine, leucine and lysine, increased. Heat stress reduced Ca (13-28%), Fe (17-52%), P (10-54%), K (12.4-28.3%) and Zn (36-59%) content in seeds, compared to the controls. High temperatures during seed filling are detrimental for seed yield and quality components in lentil genotypes, with severe impacts on heat-sensitive genotypes. © 2018 Society of Chemical Industry.

Effect of genetic background on the stability ofsunflower fatty acid composition in different high oleic mutations.

The effect of genetic background on the stability of fatty acid composition in sunflower near isogenic lines (NILs) carrying high-oleic Pervenets (P) or high-oleic NM1 mutations was studied. The materials were field-tested in different locations and at different sowing dates to evaluate a wide range of environmental conditions. Relationships were established between the fatty acids and the minimum night temperature (MNT) and the response was characterized. A genetic background effect for the fatty acid composition was found in both groups of NILs. The NM1-NILs showed an oleic level higher than 910 g kg-1 and they were more stable across environments with a zero or low dependence on the genetic background; on the other hand, high oleic materials bearing the P mutation showed lower levels of oleic acid, with a higher variation in fatty acid composition and a highly significant dependence on the genetic background. The NM1 mutation is the best option to develop ultra-high oleic sunflower oil that is stable across environments and genetic backgrounds, making its agronomical production more efficient and predictable. © 2018 Society of Chemical Industry.

Timing of Avian Breeding in an Urbanised World

A large part of the world is urbanised, and the process of urbanisation is ongoing. This causes dramatic alterations of species' habitat such as increased night light, sound levels and temperature, along with direct disturbance by human activity. We used eight years of citizen science data from ten common bird species breeding in nest boxes throughout The Netherlands to study the relationship between urbanisation and a key life history trait, timing of breeding. We used nightly light levels in the form of sky brightness and light emission as a proxy for urbanisation as the dramatic change of the night-time environment is a prominent effect of urbanisation. We expected birds to lay earlier in areas with more light at night, i.e. in more urbanised areas. We found, however, no relationship between light levels and seasonal timing in the ten species studied. A limitation of our study is that there was only limited data for the areas that were urbanised most (e.g. inside cities). Most nest box study areas are located in areas with a limited level of urbanisation, and hence with relatively low light levels of light at night. The lack of data on breeding birds in more urbanised environments, which is a rapidly expanding habitat for an increasing number of species worldwide, should be the focus of attention and citizen science would be highly suitable to also provide data for such areas.

Effects of Dissociation/Recombination on the Day–Night Temperature Contrasts of Ultra-hot Jupiters

Secondary eclipse observations of ultra-hot Jupiters have found evidence that hydrogen is dissociated on their daysides. Additionally, full-phase light curve observations of ultra-hot Jupiters show a smaller day-night emitted flux contrast than that expected from previous theory. Recently, it was proposed by Bell & Cowan (2018) that the heat intake to dissociate hydrogen and heat release due to recombination of dissociated hydrogen can affect the atmospheric circulation of ultra-hot Jupiters. In this work, we add cooling/heating due to dissociation/recombination into the analytic theory of Komacek & Showman (2016) and Zhang & Showman (2017) for the dayside-nightside temperature contrasts of hot Jupiters. We find that at high values of incident stellar flux, the day-night temperature contrast of ultra-hot Jupiters may decrease with increasing incident stellar flux due to dissociation/recombination, the opposite of that expected without including the effects of dissociation/recombination. We propose that a combination of a greater number of full-phase light curve observations of ultra-hot Jupiters and future General Circulation Models that include the effects of dissociation/recombination could determine in detail how the atmospheric circulation of ultra-hot Jupiters differs from that of cooler planets.

Coupling night ventilative and active cooling to reduce energy use in supermarkets with high refrigeration loads

Supermarkets are energy intensive buildings and present a unique space conditioning challenge because of the interaction between the HVAC system and the refrigerated display cabinets. HVAC system is the largest consumer of energy after refrigeration depending on system design, geographical location and controls. Night ventilation is used extensively as a low energy strategy to cool buildings in climates where night temperatures are suitable. This paper presents a study of cooling benefits of night ventilation for supermarkets with high cooling demand. Energy and environmental data from two stores with high percentage of frozen and chilled goods and with different HVAC systems are presented. Validated models in EnergyPlus are developed for the two stores and their systems. A parametric study of the coupled operation of night ventilation and active cooling for the climatic conditions of south east England is carried out and optimisation strategies are modelled. Results indicate that effective night ventilation can reduce the duration of active cooling during trading times and achieve 17% reduction in cooling annual energy use, 3.3% in total annual energy use while refrigeration energy use is not affected.

Seasonal Analysis of Urban Heat Island of Greater Hyderabad Using Thermal Remote Sensing

Urban areas are characterized by densely built-up area. Due to urbanization and consequent urban growth, green spaces, water bodies and other land use changes are resulting in several environmental issues and concerns. One such urban environmental issue is the emergence of Urban Heat Island. An Urban Heat Island (UHI) is the characteristics of elevated temperaturere of both atmosphere and land surface in urban areas as compared with the un-urbanized surrounding or rural areas. In this work, the Land Surface Temperature (LST) of mega city of Hyderabad is extracted with the help of remote sensing data. For the present study, Moderate-resolution Imaging Spectroradiometer ( MODIS) data pertaining to the year 2015 is used. The main objective this study is to identify and map Urban Heat Island. Seasonal variations in the Land Surface Temperature (LST) are analyzed for the month of May and December. It is seen from the analysis of Land Surface Temperature (LST) that, the urban areas have recorded higher temperature as compared to its rural counterpart. It is also seen that emergence of Urban Heat Island is very conspicuous during the night time. The temperature variation between urban-rural surroundings varies between 29.11 and 21.69°C in the month of May (summer) whereas it ranged between 23.71 and 16.14°C in the month of December (winter). The variations in the night temperature is maximum during summer season. Keywords: Urbanization, remote sensing, land surface temperature, urban heat island Cite this Article Sridhar N, Vijaya Bhole. Seasonal Analysis of Urban Heat Island of Greater Hyderabad Using Thermal Remote Sensing. Journal of Remote Sensing & GIS. 2018; 9(1): 49–56p.

Impact of irrigation management on paddy soil N supply and depth distribution of abiotic drivers

In rice production, water-saving irrigation management is expanding and likely alters depth profiles of soil moisture, redox potential (Eh) and microbial activity. It is, however, unclear how such conditions then impact net soil N-release and availability to the rice crop, because we do not know well enough how water-saving irrigation management shapes depth-distribution of Eh and reductive processes, and microbial activity. A field experiment with rice was laid out on a typical young floodplain paddy soil of Bangladesh with three irrigation schemes, viz. continuous flooding (CF), safe alternate wetting and drying (AWD) and direct seeded rice (DSR), with 120 kg N ha−1 (N120) or without (N0) urea application. We evaluated changes in soil mineral N and plant N uptake, CH4 and CO2 emissions and soil pH, and at multiple depths soil Eh and temperature, dissolved C, Fe and Mn throughout 2015 dry (Boro) season (Jan–Apr). Eh stayed at or above ∼+300 mV except for sudden drops to ∼−200 mV with irrigation events in DSR. Eh quickly dropped to methanogenic conditions, under both AWD and CF; rises to ∼+200 mV were observed during AWD-drainage events but were restricted to upper 5.5 or 12.5 cm depths. Throughout the growing season there was a pronounced increase in reductive dissolution of Fe and Mn (hydro-) oxides, buildup of dissolved C, and CH4 effluxes under AWD and CF but not DSR, likely at least partially driven by the gradual soil warming from ∼20 °C till 28 °C. Predominant aerobic conditions under DSR lead to a nearly doubled C-emissions (CO2 + CH4) compared to AWD and CF, suggesting more soil organic matter (OM) degradation in the former case, while soil mineral N plus plant N build-up rate followed an opposite order. Urea application did not raise soil exchangeable N levels, even prior to significant plant uptake from 28 DAT (days after transplanting), and we forward temporal abiotic NH4+-fixation and N-removal processes as explanations. We conclude that regardless of some distinctions in temporal evolutions of puddle layer Eh, solution C, Fe and Mn, and CH4-emission, soil N-supply was quite comparable under AWD and CF, as was rice yield. In the context of N availability, AWD could be safely adopted for rice growth in the Bangladeshi Boro season. The eventual fertilizer N recovery efficiency was higher for CF (42%) than for AWD (32%), but AWD saved 12% irrigation water. While DSR saved 45% water there was a large yield penalty, likely due to drought stress but also by poor germination caused by cold night temperatures in mid-January, while seedling transplantation in CF and AWD plots was only later on 28 January. Further research should be conducted to investigate the fast and pronounced removal of exchangeable inorganic N after initial N buildup by soil OM mineralization, especially in CF and AWD. At this moment most likely candidate processes appear clay-NH4+ fixation and anaerobic NH4+-oxidation.

Exploring Genotype × Environment × Management synergies to manage fusarium head blight in wheat

Fusarium head blight (FHB) is a devastating disease of wheat because of direct detrimental effects on grain yield, quality, and marketability and production of mycotoxins (e.g. deoxynivalenol or DON). Conditions most favourable for the development of FHB are high humidity, frequent rainfall and relatively warm night temperatures at heading, especially in regions where host crop residues are present. These risk factors have resulted in a significant westward expansion of FHB in the Canadian prairies, while favouring continued development in Ontario, Quebec and the Maritimes. Since cultivar selection is a key integrated pest management (IPM) strategy, a systems approach that couples genetic resistance with management tactics is required. Thus, successful FHB mitigation is an ideal case study in Genotype (G) × Environment (E) × Management (M) interactions where more resistant cultivars (G) are grown in at-risk regions (E), and unique approaches to management (M) for sustainable wheat production are required. Since no cultivar is completely resistant to FHB, greater attention to management strategies is needed. The over-arching principle for FHB management is the manipulation of agronomic factors that facilitate completion of critical crop developmental phases, such as flowering, while doing so rapidly and uniformly, as a consequence of early sowing and increased seeding rates. These strategies and the adoption of practices involving proper fungicide selection, and optimal application timings and methods will lead to improved yield stability and quality in high-risk environments. This paper explores the potential synergies that exist for FHB mitigation when appropriate genetics are combined with an array of key agronomic strategies.

Pollen viability of Tepary bean (Phaseolus acutifolius A. Gray.) mutant lines under water stress conditions and inoculation with rhizobia

El fríjol tépari, Phaseolus acutifolius A. Gray destaca por su tolerancia al estrés por sequía y altas temperaturas, sin embargo, presenta baja diversidad genética en sus formas cultivadas. Por lo que se inició un programa de inducción de mutaciones. El objetivo de este estudio fue establecer el efecto de diferentes parámetros agro-morfofisiológicos asociados sobre la viabilidad y cantidad del polen en 123 líneas mutantes de la quinta generación M5 de P. acutifolius y genotipos parentales, por medio del procesamiento de microfotografías de preparaciones de polen con tinción de acetocarmin. El experimento se realizó en condiciones de invernadero y el diseño experimental fue de subparcelas divididas con 3 repeticiones; adicionalmente, los factores evaluados fueron: condiciones de humedad del suelo, inoculación con cepas de Bradyrhizobium sp. o Rhizobium tropici, y las líneas o accesiones evaluadas (6 mutantes y 2 no mutantes). El experimento fue realizado manteniendo la temperatura nocturna superior a 25°C. No hubo diferencias significativas entre los tratamientos, se encontraron correlaciones positivas de la viabilidad de polen con otras variables.