Category Archives: Wiley: Journal of Agronomy and Crop Science

Varietal effects on Greenhouse Gas emissions from rice production systems under different water management in the Vietnamese Mekong Delta

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Rice production accounts for 15% of the national Greenhouse Gas (GHG) emissions and Vietnam aims at reducing emissions from rice production by focusing on changing farming practices. However, the potential for mitigation through the selection of different rice varieties is still poorly understood. A two-year field screening of 20 rice varieties under continuous flooding (CF) and alternate wetting and drying (AWD) irrigation was conducted in the Vietnamese Mekong Delta (VMD), Vietnam, employing the closed chamber method for assessing GHG emissions. The results confirmed that varietal variation was the largest for methane (CH4) emissions under CF. Across the varietal spectrum, CH4 emissions were more important than nitrous oxide (N2O) (accounts for less than 2% of the CO2e) with the lowest emitting variety showing 243 kg CH4 ha−1 and the highest emitting variety showing 398 kg CH4 ha−1 emissions as compared to 0.07 kg N2O ha−1 and 0.76 kg N2O ha−1 emissions, respectively. Under AWD, CH4 emissions were generally strongly reduced with the varietal effect being of minor importance. Compared with IPCC default values, the data set from the two seasons yielded higher Emission Factors (EFs) under CF (2.92 and 3.00 kg ha−1 day−1) as well as lower Scaling Factors (SFs) of AWD (0.41 and 0.38). In the context of future mitigation programs in the VMD, the dry season allows good control of the water table, so varietal selection could maximize the mitigation effect of AWD that is either newly introduced or practised in some locations already. In the wet seasons, AWD may be difficult to implement whereas other mitigation options could be implemented such as selecting low-emitting cultivars.

Expression analysis of candidate genes as indicators for commencing drought stress in starch potatoes

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Drought stress is a major problem for potato production and will be of grave importance due to climate change and the resulting temperature peaks along with drought periods in the vegetative growth phase of potato. Plants, as sessile organisms, adapt to their environment morphologically as well as biochemically. To cope better with abiotic stresses like drought, plants developed strategies like reactive oxygen species (ROS) detoxification and fast reacting stomatal closure, as well as signalling cascades leading to a quick response to stress. This study aimed at analysing eight genes of interest, derived from a former proteomic study, and determining their suitability for detection of commencing drought stress in early growth stages of potato. For this aim, six starch potato genotypes, which differed in stress response in previous studies, were examined for plant growth and physiological parameters in two experiments in an open greenhouse after seven and 14 days of stress. Besides lower shoot biomass after drought stress, which was already visible after seven days and became stronger after 14 days, weaker root growth was also detected after 14 days. The observed differences between the experiments can presumably be explained by temperature peaks and high radiation prior to and during the first experiment, which took place earlier in the year. The expression of the eight genes was studied in young leaves of four genotypes after 7 days of water withdrawal. Gene expression patterns were dependent on the studied genes. Three genes, cell wall/vacuolar inhibitor of fructosidase (INH1), peroxidase 51-like (POD) and subtilase family protein (SBT1.7) showed consistent changes in gene expression after seven days of stress between all genotypes. The INH1 gene was found to be upregulated in all genotypes in two independent experiments after drought stress. This correlates with the results at the protein level, where INH1 was also found to be higher abundant in two genotypes of potato (Wellpott et al., DGG-Proceedings 10, 2021). Therefore, this gene might be an appropriate candidate for the detection of commencing drought stress in potato.

The effect of silicon fertilizers on agronomic performance of bread wheat under drought stress and non‐stress conditions

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Drought is one of the major constraints of wheat production, especially in rainfed wheat production systems. The objective of this study was to evaluate the effects of different silicon fertilizer formulations on the agronomic performance of diverse wheat genotypes under drought-stressed conditions. Twenty wheat genotypes were evaluated in field and greenhouse environments under non-stressed and drought-stressed and two silicon fertilizer formulations (granular and liquid potassium silicate) and untreated control. The four-way interaction involving genotype, environment, water regime and silicon formulation had a significant effect (p < .05) for aboveground biomass, productive spike number, hundred seed weight and grain yield. Granular silicon application was the most effective treatment both under non-stressed and drought-stressed conditions compared to the liquid and control treatments. Under field and drought conditions, the highest yielding genotype was MC18, which exhibited a mean grain yield of 4.17 t ha−1 with granular silicon, 2.56 t ha−1 with liquid silicon and 2.18 t ha−1 without silicon. The yield of genotype MC18 improved by 91.3% using granular silicon under drought-stressed and by 44.6% under non-stressed conditions compared with the untreated control. Granular silicon positively affected the drought stress tolerance indices compared to the liquid silicon and untreated control. The principal component biplot analysis revealed that liquid and granular silicon positively impact yield response for all test genotypes under drought-stressed and non-stressed conditions compared with the control. Silicon application reduced genotype variation for agronomic traits and enhanced agronomic trait relationships under drought-stressed conditions. Drought stress tolerance indices are influenced by silicon application. The effect of silicon has a direct and indirect effect on yield and yield components. Silicon fertilization can be considered as a mitigation measure to cope with the adverse effect of drought stress on wheat.

Genotypic stability in root system architecture and aboveground biomass revealed diverse adaptability of peanut (Arachis hypogaea L.) to moderate water deficit

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Many crop species, including cultivated peanut (Arachis hypogaea L.), modify their above- and below-ground growth to cope with water deficit stress. This acclimation to water deficit often triggers a biomass partitioning shift—allocating more biomass to the roots, to increase the accessibility of roots to water resources. However, additional carbon partitioning to roots may not always translate into increased water use and maintenance of aboveground biomass (ABM) and yield. Therefore, selecting an efficient root system architecture (RSA) should aim to sustain a high ABM production under a water deficit scenario. To better understand the associations of above and belowground biomass partitioning under moderate water deficit, this study evaluated the genotypic stability of 40 peanut genotypes in ABM and RSA in greenhouse experiments and further assessed genotypic differences in 4 site-year field experiments. Our results suggested that higher ABM-producing genotypes generally had high plasticity when subjected to water deficit whereas the low ABM-producing genotypes had relatively high stability. Hierarchical clustering analysis further revealed that genotypes with a high root-to-shoot ratio potentially had increased genotypic stability in ABM underwater deficit. Interestingly, genotypes that maintained the highest ABM underwater deficit did not have the highest total root biomass and length. Instead, these genotypes had the highest root length in the top layer of soil (0–0.3 m) and relatively fewer roots in the deeper layer of soil (0.3–1 m). Greenhouse-screened stable genotypes exhibited minimal yield reduction when subjected to mid-season water deficit in some of the field validation experiments, but it also happened to some plastic genotypes, indicating that further validation of controlled environment screenings for genotypic water-deficit tolerance in the field is necessary.

Responses of rice cultivars with different cold tolerance to chilling in booting and flowering stages: An experiment in Northeast China

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Climate change has led to an increasing trend in the intensity of global extreme weather events, including chilling. Breeding cultivars with high cold tolerance could be an important pathway to mitigate the negative effects of climate change. For rice, few studies have been focusing on the responses of different cold-tolerance cultivars on chilling stress. In this study, we selected four japonica rice cultivars and conducted a chilling treatment experiment (with three chilling temperatures and three chilling durations) at the booting and flowering stages in 2020 and 2021 in Northeast China. The results showed that chilling treatment at the booting stage affected the biomass allocation and yield traits more than the chilling treatment at the flowering stage did. Overall, the chilling treatment affected the cold-sensitive cultivars more than the cold-tolerant cultivars. Among all the study yield traits, chilling treatment affected spikelet fertility the most, followed by the number of grains per panicle. For every 10°C day increase in CDD at the booting (flowering) stage, the grain yield per plant and spikelet fertility decreased by 4.8–12.8% and 3.6–10.8% (2.1–5.3% and 2.2–4.9%), respectively. Even with the intense chilling treatment, the cold-tolerant cultivars had relatively high number of effective spikes per plant, grain weight, and stable spikelet fertility, hence they maintained relatively high grain yield. Therefore, it is important to factor in the cold tolerance of the cultivars when assessing the chilling effects on biomass allocation and yield traits for rice. In order to combat the negative effects of extremely low temperature at the reproductive stage on rice grain yield, the future breeding technology could focus on improving the spikelet fertility, grain filling size, and number of spikes per plant.

Gluten subfractions of wheat storage proteins are affected by high night temperature during grain formation

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Gluten (gliadin + glutenin) protein in wheat flour is affected by high temperature (day and/or night) resulting in undesirable consequences on dough quality. A study was conducted with early and late-maturing wheat genotypes, to assess the spatial (superior- central and inferior- apical and basal spikelets) variation in the composition of gluten subfractions in the developing ear under high night temperature (HNT). We hypothesised that protein content in the superior and inferior grains may show a differential quantitative and qualitative response to HNT. HNT resulted in a significant increase in protein content which exhibited a strong (r = −0.44*) negative correlation with sedimentation volume (SV) that determines baking quality. The late-maturity genotypes were more responsive to HNT with changes in ω-5 and γ gliadin subfractions of both superior and inferior spikelets, though a consistent trend was not established. The proportion of high molecular weight (HMW) glutenins increased, whereas low molecular weight (LMW) glutenins reduced in most of the genotypes under HNT. Both HMW and LMW glutenins revealed significant positive (r = 0.43* and r = 0.81***, respectively) correlation with SV. The expression analysis of genes for gluten subfractions showed a significant decrease in transcript abundance of α, ω-5, γ, HMW, and LMW fractions under HNT.

Varietal effects on methane intensity of paddy fields under different irrigation management

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Alternate wetting and drying irrigation (AWD) has been shown to decrease water use and trace gas emissions from paddy fields. Whereas genotypic water use shows little variation, it has been shown that rice varieties differ in the magnitude of their methane emissions. Management and variety-related emission factors have been proposed for modelling the impact of paddy production on climate change; however, the magnitude of a potential reduction in greenhouse gas emissions by changing varieties has not yet been fully assessed. AWD has been shown to affect genotypic yields and high-yielding varieties suffer the greatest loss when grown under AWD. The highest yielding varieties may not have the highest methane emissions; thus, a potential yield loss could be compensated by a larger reduction in methane emissions. However, AWD can only be implemented under full control of irrigation water, leaving the rainy seasons with little scope to reduce methane emissions from paddy fields. Employing low-emitting varieties during the rainy season may be an option to reduce methane emissions but may compromise farmers’ income if such varieties perform less well than the current standard. Methane emissions and rice yields were determined in field trials over two consecutive winter/spring seasons with continuously flooded and AWD irrigation treatments for 20 lowland rice varieties in the Mekong Delta of Vietnam. Based on the results, this paper investigates the magnitude of methane savings through varietal choice for both AWD and continuous flooding in relation to genotypic yields and explores potential options for compensating farmers’ mitigation efforts.

Evaluation of the effectiveness of irrigation methods and fertilization strategies for alfalfa: A meta‐analysis

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Alfalfa (Medicago sativa L.) plays an important role in livestock production in most regions of the world, but the quantity and quality of alfalfa have been critically affected by drought events in recent years. Thus, quantifying the efficacy of widely used strategies, irrigation methods and fertilization that are aimed at improving drought resistance in alfalfa is a worthy topic that has been addressed in a variety of ways using both field observations and simulation models. Although such strategies play a critical role in climate change adaptation, the global patterns of these strategies in a changing world remain elusive due to regional differences, such as drought features, strategy design and environmental conditions. Thus, by using effect size and statistical analyses, we synthesized three variables, namely, alfalfa yield, water use efficiency (WUE) and crude protein (CP), to examine the efficacy of irrigation methods and fertilization in drought areas based on peer-reviewed papers from 1990 to 2022. Our results showed that increasing drought stress reduces the alfalfa yield (−34.4%) but can increase the WUE (+13.7%). Both yield and WUE showed a negative relationship with the water deficit, but this phenomenon can be improved by using appropriate irrigation. The yield losses of alfalfa can be offset by implementing a fertilization strategy (+22%) under drought stress, especially for phosphate fertilizer. Overall, our results provide some evidence for the climate change adaptation of alfalfa under drought stress and indicate that fertilization is a more effective adaptation to improve alfalfa drought resistance (both yield and WUE, and yield and CP) than the irrigation method, which shows better performance in improving alfalfa WUE. Our synthesis of the effectiveness of irrigation methods and fertilization on alfalfa drought resistance can be used to develop scientific strategies for climate change adaptation for alfalfa and agriculture under climate change.

Dilemma between yield and quality: Multigenerational effect of elevated CO2 and nitrogen supply on wheat cultivars

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Studying the long-term effect of elevated atmospheric CO2 concentration (e[CO2]) on wheat (Triticum aestivum L.) over multiple generations has received increasing attention. Here, five wheat cultivars were grown under ambient CO2 concentration (a[CO2], 400 ppm) and e[CO2] (800 ppm), respectively, for three consecutive generations (G1 to G3) under two nitrogen (N) levels (1N and 2N). Compared to plants grown under a[CO2], e[CO2] increased shoot biomass and grain yield (GY) over three generations and the enhancement was greater in G3 than in G1. However, plant N concentration was lowered by e[CO2] and the reduction was not mitigated by higher N supply. The carbon (C) concentration significantly increased in leaf and stem but decreased in grain, indicating an inhibited C translocation to grain under e[CO2]. Most importantly, these negative impacts were exacerbated in G3. Concentrations of mineral nutrients in grain were significantly lowered by e[CO2] with larger reduction in G3 than in G1 in some micronutrients such as Zn, Cu and Fe. These findings suggest that long-term exposure to e[CO2] sustained the positive effects on plant growth and production but aggravated the reduction of grain quality over multiple generations. Among the five cultivars, 325Jimai showed the greatest increase in shoot biomass and GY, and a greater sink capacity compared with the other cultivars, indicating its potential for future breeding strategies.

Tree lines do not reduce grassland productivity and herbage quality in alley cropping under drought

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In alley cropping, woody perennials are combined with agricultural crops or grassland in order to benefit from favourable interactions between trees and crops. Trees influence growth and senescence processes in grassland as well as plant chemical composition and plant water use. In a field experiment with grassland and alley-cropped willow coppices, we analysed the impact of distance and position relative to the tree line on grassland herbage biomass, proportion of dead herbage and herbage quality in two successive growth periods of two experimental years. The experimental years were chosen so that growth periods among years showed a similar rainfall pattern. Relative ET (evapotranspiration) as defined by actual divided by potential evapotranspiration reflected the severity of water shortage with a moderately dry (relative ET ~ 0.5) first growth period with increasing dryness in the second growth period of each year. We determined bulk stomatal conductivity of the grass shoot by measuring δ13C (carbon) signatures. Stomatal conductivities were higher close to the trees in drier periods (i.e. more negative δ13C values). Herbage biomass decreased with decreasing relative ET, but showed no systematic influence of the tree line. We found that vegetation composition changed with distance to the tree line. The proportion of dead herbage was equal at all distances from the tree line under very dry conditions, but smaller close to the trees under moderately dry conditions. Herbage quality, as approximated by crude protein and ADF concentrations in live biomass, was higher closer to the tree line. We conclude that the tree line does not adversely affect grassland productivity under drought and improves the plant water status as reflected by the δ13C signature.