Late Season Research Articles

Effects of long-term organic matter application on soil carbon accumulation and nitrogen use efficiency in a double-cropping rice field

Increasing soil carbon (C) sequestration in paddy field and improving rice nitrogen use efficiency (NUE) are vital for sustainable agriculture and environmental protection. It was a benefit practice for achieving these goals by taken rice straw and organic manure managements. However, there is still need to further investigate the effects of different long-term fertilizer managements on soil C sequestration and NUE under the double-cropping rice system in southern of China. Therefore, the effects of different long-term (36-years) fertilizer practices on soil C sequestration and NUE under the double-cropping rice system in southern of China were investigated in the present paper. The field experiment was included four different fertilizer treatments: chemical fertilizer alone (MF), rice straw residue and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without fertilizer input as a control (CK). This result indicated that soil C content at plough layer in paddy field with RF and OM treatments were increased, compared with MF and CK treatments. Besides input C directly into paddy field, soil original organic C accumulation with RF and OM treatments were increased by 1.54% and 3.01%, compared with MF treatment. This result indicated that soil TOC content increase rate and annual topsoil organic C sequestration rate in paddy field with RF and OM treatments increased by 55.56%, 88.89% and 48.05%, 76.62%, compared with MF treatment, respectively. Compared with MF treatment, NUE with RF and OM treatments increased by 10.43% and 22.61%, respectively, mainly due to increasing soil organic C. Grain yield of double-cropping rice with RF and OM treatments increased by 1009.5 and 1166.5 kg ha−1, compared with MF treatment, respectively. This result indicated that there was significantly correlation between NUE/NUENPK and TOC content with RF and OM treatments, at early rice and late rice growth seasons. Therefore, it was benefit practice for increasing soil carbon sequestration and improving rice NUE in the double-cropping rice system with long-term application of rice straw and organic manure managements.

Seasonal Variations in the Composition and Physicochemical Characteristics of Sheep and Goat Milks

There has been growing consumer interest in sheep and goat milk products as alternatives to cow milk products. The physicochemical characteristics of milk vary not only between ruminant species, but also during different seasons; they determine the nutritional quality and processing properties of the milk. In this study, we characterized sheep and goat milks from New Zealand over the seasons for their composition (macronutrients, macro- and micro-minerals, fatty acids, and proteins) and physicochemical properties (e.g., ionic calcium, fat globule size, casein micelle size, viscosity, and melting behavior of milk fat). Heat-induced (95 °C for 5 min) protein interactions and changes in the physical properties of the milks were also investigated. The compositional and structural features of sheep and goat milks were identified and compared with those reported for cow milk. Seasonal variations in the milk characteristics were more pronounced for sheep milk than goat milk and were probably affected by the production systems. Sheep milk, particularly in the late season, had the largest heat-induced increases in casein micelle size and viscosity, probably arising from the greater casein–whey protein and casein–casein interactions during heat treatment. This study provides comprehensive information on the properties of sheep and goat milks and highlights the interaction effects between species, season, and processing.

Starting an invasion: A five-year monitoring program of Halyomorpha halys (Hemiptera: Pentatomidae) in South Tyrol (Northern Italy)

Monitoring action are a fundamental step when non-native species are invding new areas. The phytophagous pest Halyomorpha halys (Stål), originated from north-eastern Asia, is by now introduced in several countries worldwide. Its highly polyphagous behaviour, paired with a relatively high reproduction rate under favourable conditions, makes it an im-portant pest of several agricultural crops. In South Tyrol (Northern Italy), one of the largest con-tiguous apple growing regions in Europe, first adults had been reported in March 2016. Active monitoring techniques, as well as the implementation of a Citizen Science approach, enabled to follow up the spread and settlement of stable populations of H. halys in South Tyrol. Since its first detection, H. halys showed a rapid expansion of colonized area and an increase in population densities from year to year. Established populations coincide mostly with the main apple growing area, namely the Etsch Valley from Meran to Salurn, mainly occupying lower altitudes between 200 and 500 m a.s.l. Since 2019, a further spreading in the western and eastern parts of South Tyrol can be observed. In apple orchards H. hals showed generally a continuous presence throughout the growing season from April to October, with population peaks in the late season. On the other side, populations dynamics and densities of adults and nymphs differ significantly between years ans sureveyed sites. The findings indicate that the application of pheromone baited traps is a good tool for an area wide approach in or-der to get information on its spreading, to pinpoint the main distribution area and to draw a general picture of the population dynamics at a larger scale. On the other side, an area wide approach should be interpreted cautiously, as real population densities might be underesti-mated and do not depict the real situation for singular orchards.

Phytotonic effects of thiamethoxam on sugarcane managed with glyphosate as a ripener.

Thiamethoxam and glyphosate are widely used in sugarcane production as an insecticide and ripener, respectively. In this study, the potential of these chemical products to also elicit phytotonic effects and enhance the physiological development and yield of sugarcane was evaluated. In field experiments, thiamethoxam and glyphosate were applied to sugarcane individually or in combination, and the effects of these chemical management strategies on sugarcane biometric and technological parameters were assessed. Thiamethoxam application improved biometric parameters, especially stalk yield. Glyphosate application increased sugar yield, despite reducing the number of stalks and consequently the stalk yield. Application of the insecticide thiamethoxam to sugarcane attenuates the depreciative effect of ripener (glyphosate) and has a potential phytotonic effect by increasing sugar yields in the early and late seasons. © 2022 Society of Chemical Industry.

Water and Nitrogen Management at the Booting Stage Affects Yield, Grain Quality, Nutrient Uptake, and Use Efficiency of Fragrant Rice Under the Agro-Climatic Conditions of South China.

The present study was conducted to assess the effects of water and nitrogen applications at the booting stage on yield, grain quality, and nutrient use efficiencies in fragrant rice in the early (March–July) and late (July–November) seasons of 2013. The experiment was comprised of two fragrant rice cultivars, i.e., Nongxiang 18 and Basmati; three nitrogen levels, i.e., 0 kg N ha−1 (N0), 30 kg N ha−1 (N1), and 60 kg N ha−1 (N2); and three water levels, i.e., 2–4 cm water layer well-watered (W0), water with a soil water potential of −15 ± 5 kPa (W1), and water with a soil water potential of −25 ± 5 kPa (W2), which were randomized in a split-split plot design. Results showed that Basmati produced a higher grain yield than Nongxiang 18 (16.20 and 9.61% in the early and late season, respectively), whereas the W1 exhibited the maximum grain yield and harvest index. The moderate application of nitrogen (N1) at the booting stage resulted in higher grain yield, nevertheless, cultivar, water, and nitrogen revealed different trends for some of the grain quality attributes, i.e., brown rice rate, milled rice rate, head milled rice rate, protein content, and amylose content as well as nutrient uptake and use efficiencies in the double rice production system. Basmati had a higher nitrogen harvest index (NHI; 18.28–20.23%) and P harvest index (PHI; 3.95–12.42%) but lower physiological P use efficiency for biomass (PPUEB; 7.66–23.66%) and physiological K use efficiency for biomass (PKUEB; 2.53–7.10%) than Nongxiang 18 in both seasons. Furthermore, the grain number per panicle, biomass yield, grain P uptake, and the whole plant P uptake were significantly related to the grain yield of fragrant rice. In both seasons, the interaction of water and nitrogen (W × N) had a significant effect on panicle number, grain quality attributes, and N, P uptake of straw, as well as the physiological N, P use efficiency for grain and the physiological N, K use efficiency for biomass. Overall, results suggest that moderate nitrogen and irrigation input at the booting stage could be feasible to improve the productivity and quality of the double rice production system with improved nutrient use efficiency under the agro-climatic conditions of South China.

Assessing the size at maturity, spawning, and condition of the truncate soft-shell clam (Mya truncata) of southern Baffin Island, Nunavut, Canada.

The truncate soft-shell clam Mya truncata is an important source of country food for Inuit communities across the territory of Nunavut, Canada. M. truncata also plays an important role in marine ecosystems, yet there is little understanding of their life history and condition in Canadian Arctic waters. To provide a foundation on which aspects of the life history and condition of M. truncata of Baffin Island can be monitored in the future with a changing climate and fishery development, this study estimated size at maturity and provides insights into the spawning cycle and weight-length condition indices of clams from inner Frobisher Bay and the north shore of the Hudson Strait. Male and female M. truncata exhibited similar lengths at 50% attainment of sexual maturity, 31 mm and 32 mm shell length (SL), respectively. Most (77%) of the sexually mature M. truncata collected from inner Frobisher Bay in late August and 35% of clams collected from the Hudson Strait in early September were in the ripe stage of gonadal development. These results lead us to suggest a spring spawning season and that M. truncata invest in gonadal development for the next year’s spawning during the late summer-early autumn ice-free season while phytoplankton concentrations are high. Dry bodyweight-SL relationships were used to show that M. truncata condition can differ significantly over small and large spatial scales based on plotted 95% confidence intervals.

Komponen Hasil dan Karakter Morfologi Penentu Hasil Kedelai pada Lahan Kering Tegalan

Correlation and path analysis between yield components and grain yield may be useful to provide the basis for planning more efficient in the selection program to obtain high yielding soybean genotype. The objectives of the experiment were to investigate the most responsible yield components to grain yield of morphologically diverse soybean varieties. Fifteen soybean varieties were evaluated on dry land in Grobogan, Central Java during the late rainy season of 2019. The experiment was arranged in randomized block design with four replications. Each of the genotypes was grown in five rows of five meters long. Plant spacing was 40cm x 20 cm with two seeds per hill. Results showed that among the yield components, days to maturity, number of productive nodes, number of pods per plant and seed size were positively and significantly correlated with grain yield (r= 0.501, 0.533, 0.404 and 0.422). Except the number of productive nodes, the direct effect of days to maturity, number of pods per plant and seed size to grain yield as indicated by path coefficient were the highest, each was 0.711, 0.503 and 0.520 respectively. The direct effect of number of productive nodes and other yield component were small or negative. Base on both analysis soybean genotypes with high grain yield showed have earlier maturity (<85 days), a high number of pods per plant (>35 Pods/plant) and large seed size (>15 g/100 grain). Therefore, days to maturity, pod per plant, and seed size can be suggested for selection criteria in selecting high yielding soybean genotypes on dry land.

Correlation Coefficients and Path Coefficient Analysis of Yield and Yield Attributing Traits in Desi Cotton (Gossypium herbaceum)

Background: Cotton is globally important crop valued for its single cell trichome called fibre. Cotton fibre is popularly called as white gold or king of fibre crops. Cotton fibre or seed cotton yield per plant is the economically important traits which is dependent other yield attributing traits and also influenced by the fibre quality traits. So present study was focused on the association of yield and yield attributing and fibre quality traits. Methods: An experiment was conducted at College of Agriculture, Vijayapur campus during late kharif season during 2020-21 to evaluate 145 advanced breeding lines of desi cotton along with checks using augmented design in 7 blocks for yield and yield attributing traits. The material used in the study was developed by College of agriculture, Dharwad at Department of Genetics and Plant Breeding. Correlation and path coefficient analysis was conducted for twelve yield and fibre quality traits. Result: Significant positive correlation of seed cotton yield per plant with boll weight, number of bolls per plant, ginning outturn and fibre fineness was reported, whereas negative significant correlation was reported by days to 50% flowering with seed cotton yield per plant. Path analysis revealed that highest positive direct effect on seed cotton yield per plant was shown by number of bolls per plant followed by boll weight and highest negative direct effect was shown by fibre fineness. Highest indirect effect on seed cotton yield per plant was contributed by. ginning outturn. The traits that are significantly positively correlated and having positive effect on seed cotton yield play a major role in the selection of high yielding seed cotton genotypes.

The Accumulation of Biomass Pre- and Post-Silking Associated with Gains in Yield for Both Seasons under Maize–Rice Double Cropping System

Due to relatively low yield as well as low resources use efficiency with double rice (Oryza sativa L.) cropping systems (RR), exploring new cropping systems to increase yield and resources use efficiency simultaneously has become a large challenge of the middle reaches of the Yangtze River (MRYR). Our previous study demonstrated that the maize (Zea mays L.)–rice cropping system (MR) exhibited higher superiority of yield and resource use efficiency compared with the conventional double-rice cropping system. However, the reason for the yield increases in both maize and rice and the physiological processes involved in those two crops under MR are poorly understood. A 3-year field experiment was conducted at two sites (Wuxue and Jingmen) from 2016 to 2018 to examine the differences in dry matter (DM) accumulation, soil properties, and resources use efficiency between the MR and RR cropping systems. Compared with RR, the annual yield of MR was 18.2–26.3% and 15.4–31.5% higher across three years at Wuxue and Jingmen, respectively. The average yield of maize in MR was 36.5% and 21.9% higher than that of early rice in RR at Wuxue and Jingmen, respectively. The yield increase for maize was mainly attributed to the 29.7% (Wuxue) and 28.5% (Jingmen) increases in post-silking DM accumulation due to the higher plant growth rate promoted by the higher net assimilation rate and radiation use efficiency. For the late rice in MR, the average yield was 10.9% and 14.5% higher than that of late rice in RR at Wuxue and Jingmen, respectively, which was promoted by the 7.8–23.3% increase in pre-anthesis DM accumulation due to improved soil properties. Compared with RR, the MR cropping system exhibited increased soil pH, total organic carbon, and mineral nitrogen, and decreased the bulk density in the late rice season. As a result of greater yield in both seasons under MR, the annual accumulated temperature and radiation use efficiency, partial factor productivity from applied nitrogen, and water use efficiency of MR were 17.7–26.4%, 22.2–25.5%, 5.5–7.8%, and 33.6–48.7% higher than those of RR, respectively. We conclude that the higher yield in the MR than in the RR cropping system was mainly attributed to the accumulation of post-silking biomass due to maximized use of radiation in the maize season, and the accumulation of pre-anthesis biomass due to improved soil nutrients in the late rice season.

The impacts of post-anthesis warming on grain yield and quality of double-cropping high-quality indica rice in Jiangxi Province, China

In southern China, climate warming threatens rice production in double rice cropping systems. However, the actual responses of grain yield and quality of high-quality indica rice to climate warming in double rice cropping systems are still unclear. Therefore, a 2-year field post-anthesis warming experiment was conducted by using two high-quality indica rice cultivars (e.g., Qiliangyou2012, early rice; Taiyou398, late rice). The results showed that post-anthesis warming (PAW) increased the rice canopy daily mean temperatures from heading to maturity by an average of 1.9 °C and 2.0 °C over the two years in the early and late rice seasons, respectively. The grain yield, filled grain percentage, and grain weight were not affected by PAW for either early or late rice in the two years. For early rice, PAW decreased the head rice rate and setback, whereas it increased the chalky grain rate, chalkiness, peak viscosity, breakdown, pasting temperature, protein and most amino acid contents. Similarly, the head rice rate, amylose content, and setback of late rice were decreased, whereas the chalky grain rate, chalkiness, peak viscosity, breakdown, protein and most amino acid contents were increased under PAW conditions. These results suggested that PAW worsened the grain milling and appearance qualities and improved the rice eating and nutritional qualities for both early and late rice, while it reduced the cooking quality of early rice. This study provides new insight into improving the grain yield and quality of high-quality indica rice in a double rice cropping system under future climate warming conditions.

A Dynamic Threshold Approach for Tarnished Plant Bug (Hemiptera: Miridae) Management in the Midsouthern U.S. Cotton.

One of the most economically important pests of cotton, Gossypium hirsutum L., in the midsouth region of the United States is the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois, Hemiptera: Miridae). Tarnished plant bug populations across the region have exhibited widespread resistance to numerous insecticide classes. To minimize late season resistance development, reducing unwarranted applications during the late flowering period can aid in resistance management and potentially reduce input costs. Trials were conducted during 2019 and 2020 to evaluate the impacts of tarnished plant bug populations in the later flowering period of cotton by modifying or terminating threshold regimes during the later weeks of bloom. Results showed that dynamic thresholds altered at the fourth week of bloom or later can reduce the number of late season applications made with no penalty to yield. Additionally, when utilizing a week of bloom termination approach, no significant yield losses were seen when terminating applications after the fourth week of bloom. These data may offer an alternative method to managing tarnished plant bug populations during the later flowering period of midsouth cotton.

Smoke pollution must be part of the savanna fire management equation: A case study from Darwin, Australia

Savanna fire management is a topic of global debate, with early dry season burning promoted as a large-scale emissions reduction opportunity. To date, discussions have centred on carbon abatement efficacy, biodiversity and cultural benefits and/or risks. Here we use a case study of Darwin, Australia to highlight smoke pollution as another critical consideration. Smoke pollution from savanna fires is a major public health issue, yet absent so far from discussions of program design. Here, we assess the likely impacts of increased early dry season burning on smoke pollution in Darwin between 2004 and 2019, spanning the introduction and expansion of carbon abatement programs. We found increased smoke pollution in the early dry season but little change in the late dry season, contributing to a net annual increase in air quality standard exceedances. Geospatial analysis suggests this relates to increased burning in the path of early dry season trade winds. This study highlights the complex health trade-offs involved with any large-scale prescribed burning, including for carbon abatement.

Distribution and phenology of monarch butterfly larvae and their milkweed hosts in the South Central US

South Central US milkweeds (Asclepias) are critical adult nectar and larval food resources for producing the first spring and last summer/fall generations of declining eastern migratory monarch butterflies (Danaus plexippus). This study addresses multiple gaps in assessment of monarch conservation priorities for the South Central US through analyses of monarch larval host selectivity, phenology, and spatial density, as well as the phenology, niche modeled distribution, and land cover selectivity of important milkweed hosts. Results are synthesized to estimate seasonal milkweed resource areas. About 70% of monarch larval activity occurred from mid-March to mid-July (early season) and 30% from mid-August to late November (late season). Twenty-six wild milkweed (Apocynaceae) hosts were mapped, including four new records for North America. Important hosts included Asclepias a. ssp. capricornu, A. viridis, and A. oenotheroides, that were utilized more frequently during early season, and Asclepias latifolia, utilized more frequently during late season. Landscape host selectivity was positive for A. viridis and A. a. ssp. capricornu in late and early seasons, respectively, and negative for A. oenotheroides in late season. Milkweed land cover selectivity was positive for Developed-Open Space and Grassland Herbaceous, and negative for Cultivated Crops and Shrub/Scrub. Seasonal milkweed resource areas and larval spatial densities resolved interior and coastal corridors providing functional connectivity for monarch spring and fall migrations. A potential gap in milkweed resource areas was identified in South Texas. The novel merging of milkweed niche models with larval phenology, host selectivity, milkweed phenology, and land cover selectivity informs conservation assessment.

Livestock feed markets across seasons in periurban areas of Niger: seller and buyer profiles, feed price and quality

Livestock productivity in West African Sahel is constrained by seasonal scarcity of feed and by its low quality in the dry season. Feed resources scarcity in the region has also been aggravated by the increase in livestock population, which has heightened the demand for feed, particularly in periurban areas. Livestock feed markets have thus sprung up in many cities and towns. To understand the dynamics of these markets, surveys were conducted in five of them in Maradi and five others in Niamey, Niger, in the early dry season (October-November 2019), late dry season (March-June 2020), and wet season (August-September 2020) with a semi-structured questionnaire. Results showed that diverse feed types were sold or bought, and mainly by adult male vendors or buyers, in both markets across seasons. The buyers gave as major reasons for purchasing livestock feed the insufficient household feed biomass, the poor-quality household feed, and the need for supplementary feeds to maintain and improve animal performance. Prices of livestock feeds at both markets varied significantly with season, market location and feed type. In both sites, prices of legume residues (cowpea hay, cowpea husk, groundnut haulm) were higher than the other feed types. Results further showed that there was no clear relationship between price and nutritional quality across seasons.

Effects of tillage systems on soil water distribution, crop development, and evaporation and transpiration rates of soybean

Tillage practices are known to affect soil water retention, plant available water and, consequently, crop production. Impacts can be determined by assessing soil hydraulic properties and crop characteristics. In this study, three tillage practices were investigated with respect to vertical soil water distribution and development of soybean. A specific focus was set on determining evaporation and transpiration as fractions of evapotranspiration to obtain additional information on water availability and crop water use. The agricultural practices included conventional tillage, reduced tillage (no plow), and no-tillage. The study site was a long-term field experiment under rainfed conditions. The investigations covered a vegetation period of soybean. The measurements comprised weather and soil water monitoring using sensors and manual monitoring of crop development. Evapotranspiration and its components were determined using scintillometer measurements and an isotope-based water balance technique. In the researched vegetation period with limited water availability, the conservative tillage practices showed better water storage, water use, and crop yields compared to the conventional practice. The weekly evaporation and transpiration rates progressed according to the respective canopy development. Thus, delayed plant development of the no-till practice led to extended green cover and productive water use during the late season, where a large part of the precipitation has fallen. The tillage-induced differences of soil hydraulic properties had a substantial impact on soil water distribution, but a comparatively small impact on the soil surface wetness and thus directly on the evaporation rate. The tillage-induced impacts on soil cover by plant residues, however, showed the substantial reduction effect of plant residue cover on evaporation losses. Hence, assessment of evaporation and transpiration rates contributes to the understanding of differences in water productivity and promotes the efficient use of the available water resources.

Optimizing Irrigation and Nitrogen Management to Increase Yield and Nitrogen Recovery Efficiency in Double-Cropping Rice

Water and nitrogen are the key factors affecting the yield and nitrogen recovery efficiency of double-cropping rice, but information about optimizing nitrogen fertilizer and irrigation management to achieve high yield is still limited. The purpose was to study the effects of different nitrogen application rates (D1, D2, D3, D4 (0, 112.5, 150.0, and 187.5 kg ha−1 for early-season rice and 0, 135, 180, and 225 kg ha−1 for late-season rice)) and irrigation conditions (G1, Alternate wetting and drying irrigation, G2, flooding irrigation) on rice yield and nitrogen recovery efficiency. Field experiments were carried out in the early and late seasons of the subtropical environment in Heshan County, Hunan Province, China in 2018 and 2019. The results showed that the yield was increased by the comprehensive action of reasonable irrigation mode and nitrogen management. Under G1D4 and G1D3 treatments, the maximum grain yield of early-season rice was 7.42 t ha−1, which was 0.8~35.9% higher than other treatments, and that of late-season rice was 8.20 t ha−1, which was 13.3~67.0% higher than other treatments. The increase of yield in G1D4 and G1D3 treatments was due to the increase in dry matter accumulation, effective Panicles number, and Spikelets per panicle, whose increase was due to an increase in photosynthesis and nitrate reductase activity. Compared with other treatments, late-season rice G1D3 treatment achieved a higher yield with less nitrogen fertilizer, while early-season rice G1D4 treatment achieved the highest yield, but the nitrogen recovery efficiency decreased. We should focus on more effective nitrogen fertilizer and irrigation management to further improve the yield potential of double-cropping rice.

Integrated assessment of trypanosomosis challenge on cow health and milk based on The Gambia's agropastoralism

To improve understanding of African Animal Trypanosomosis (AAT) and associated host-parasite relationship's challenges on cow and milk, The Gambia was examined given its enzootic status. Based on an integrated assessment framework, semi-structured questionnaires which were pre-tested and then administered in five regions were used. Relationships among the investigated variables were statistically explored with Pearson chi-square test and strength of association quantified with Phi or Cramer's V coefficient. Rough coat, eye and nose discharge, loss of appetite and weight were more consistently observed as signs of AAT in infected lactating cows. Older cows with more than three calving (75.8%) were indicated as the most susceptible and there is no fixed number of times (85.2%) a cow is treated for AAT in a year. The most commonly recognized effect (91.7%) of AAT is milk reduction. Statistically significant positive but moderate relationship exist between milk reduction and late dry season (phi coefficient of 0.221), between milk contamination and early dry season (phi coefficient of 0.226), and also between wateriness and rainy season (phi coefficient of 0.220). Milk discolouration is not statistically related to any season with highest AAT infection rates. The need for integrated assessment of veterinary challenges based on factors such as herd affiliation status, ethnic affiliation, and farmers’ objectives before preventive veterinary and production interventions are designed or implemented is implied. Useful information to advance research in this direction are presented.

Primary and secondary host selection by Ips typographus depends on Norway spruce crown characteristics and phenolic-based defenses

Climate change is expected to intensify bark beetle population outbreaks in forests globally, affecting biodiversity and trajectories of change. Aspects of individual tree resistance remain poorly quantified, particularly with regard to the role of phenolic compounds, hindering robust predictions of forest response to future conditions. In 2003, we conducted a mechanical wounding experiment in a Norway spruce forest that coincided with an outbreak of the bark beetle, Ips typographus. We collected phloem samples from 97 trees and monitored tree survival for 5 months. Using high-performance liquid chromatography, we quantified induced changes in the concentrations of phenolics. Classification and regression tools were used to evaluate relationships between phenolic production and bark beetle resistance, in the context of other survival factors. The proximity of beetle source populations was a principal determinant of survival. Proxy measures of tree vigor, such as crown defoliation, mediated tree resistance. Controlling for these factors, synthesis of catechin was found to exponentially increase tree survival probability. However, even resistant trees were susceptible in late season due to high insect population growth. Our results show that incorporating trait-mediated effects improves predictions of survival. Using an integrated analytical approach, we demonstrate that phenolics play a direct role in tree defense to herbivory.

Future Land Precipitation Changes Over the North American Monsoon Region Using CMIP5 and CMIP6 Simulations

AbstractChanges in the North American Monsoon (NAM), a circulation system that transports moisture into western Mexico and the southwest U.S., can have substantial impacts on water resources and agriculture. Here, we utilize future projections from Phase 6 and 5 of the Coupled Model Intercomparison Project (CMIP) to assess monthly changes in land precipitation and the leading mechanisms resulting from anthropogenic climate change. Historical CMIP6 simulations of seasonal precipitation demonstrate skill in reproducing NAM rainfall, but mimic precipitation biases observed in previous CMIP generations. Future climate projections from the SSP5‐8.5 pathway produce reductions in precipitation that persist throughout the monsoon season (June–August) but are balanced by precipitation increases during the late monsoon season (September–October) but are not shown in CMIP5 projections. Atmospheric moisture budget analysis reveals that early monsoon rainfall deficits are associated with a combination of greater evaporative demand, a negative dynamic response of vertical moisture advection, and anomalous subsidence. Increases in late monsoon season rainfall are attributed to a positive change in the dynamical term of vertical moisture advection and increases in upward motion. Although minimal changes in total land NAM rainfall are observed, seasonal shifts and the persistence of drier conditions can have significant ecological and societal consequences.

Fast and Slow Responses of the Indian Summer Monsoon to the Direct Radiative Effect of West Asian Dust Aerosols

The direct radiative effect (DRE) of west Asian dust aerosols can modulate the Indian summer monsoon (ISM) through by directly heating the atmosphere (fast response) and cooling the sea surface (slow response). However, the relative contributions between fast and slow responses are unclear. In this study, the Community Atmospheric Model 4 (CAM4) with an updated Bulk Aerosol Model (BAM) has been used to identify these different responses of the ISM to the dust DRE. Our results show that the DRE of the west Asian deserts (WAD) dust significantly enhances ISM during the early monsoon season (May–June) but weakens it during the late monsoon (July–August). Further analysis shows that the fast response heats the lower troposphere over WAD and the adjacent ocean, strengthens the southwesterly flows over the Arabian Sea, and thus increases the precipitation in central and eastern India (CEI), which dominates the ISM enhancement during the early monsoon season. During the late monsoon season, the slow response cools the sea surface temperature (SST) and the lower troposphere over Arabian Sea, creates the easterly flows to inhibit the moisture transport and decreases the CEI precipitation, ultimately weakening the ISM. Additionally, observational evidence of the trends in the WAD and CEI precipitation from 1980 to 2015 supports our simulated results. Our results suggest that the dust DRE induced ocean feedback plays a non-negligible role in modulating cross-seasonal climate effect of dust aerosols.