Double Cropping System Research Articles

Impact of straw return combined with different fertilizations on soil organic carbon stock in upland wheat and maize croplands in China: A meta-analysis

Straw return is a vital soil amendment practice in Chinese upland soils, aiming to improve the soil organic carbon (SOC) stock. However, its impact on SOC stock depends on various fertilizer practices, leading to inconclusive results. To address this, we conducted a meta-analysis of 121 peer-reviewed publications to evaluate the effect of straw return combined with different fertilization practices including balanced NPK (BFS), unbalanced NP, NK, PK, or N fertilization (UFS), and no fertilization (NFS) in the wheat-maize cropping system. The results showed that straw return with BFS led to the highest increase in SOC stock (13.3%), followed by UFS (11.4%) and NFS (6.12%), compared to straw removal under the same fertilization conditions. BFS also significantly increased the soil C (15.9%), N (9.62%), and P (6.21%) contents, as well as the C:N (2.48%) and C:P (11.4%) ratios. In contrast, UFS resulted in higher C:N ratios (6.47%) and soil acidification, affecting the SOC stock during straw return. A structural equation model revealed that the presence of BFS positively influenced the association between SOC stock and soil stoichiometry (P ​< ​0.05) compared to UFS, which was influenced by climate and initial soil properties. Additionally, the impact of BFS on SOC stock was more significant in the double cropping system (14.5%) than in the single wheat (8.32%) and single maize (10.8%) cropping systems. A lower initial SOC (<6 ​g ​kg−1) also showed a greater response to BFS compared to a higher initial SOC (>12 ​g ​kg−1). Based on C sequestration efficiency, implementing straw return with BFS could lead to a higher rate of increase in SOC sequestration.

Evaluation of some Varieties and Mutant Lines of Rice in Response to Thermal Conditions in the Double Cropping System

Evaluation of some Varieties and Mutant Lines of Rice in Response to Thermal Conditions in the Double Cropping System

Seasonal differences in yield and fertilizer use efficiency of different low-calcium-tolerant peanut varieties in response to the timing and splitting of calcium application in southern China

Soil Ca deficiency hinders the development of the peanut industry, and inappropriate Ca fertilizer application increases the risk of soil environmental degradation and reduces the fertilizer utilization rate and yield in peanuts. N fertilizer doses are frequently split and applied over different time periods. However, whether this widespread method is applicable to Ca fertilizer and improves peanut growth and yield in southern China requires further investigation. Thus, this study evaluated the effects of timing and splitting Ca applications on the dry matter accumulation and partition, fertilizer use efficiency, and yield of different low-Ca-tolerant peanut varieties (low-Ca-sensitive Jihua 16 and low-Ca-tolerant Yueyou 45) in the early and late seasons. The results showed that the early timing and splitting of Ca application significantly increased the pod yield of Jihua 16 by increasing nitrogen and calcium use efficiencies, dry matter accumulation, and assimilate transfer from vegetative parts to the pods in both years. The highest pod yield of Jihua 16 was obtained with 300 kg CaO ha−1 basal application before sowing and 300 kg CaO ha−1 top-dressing application at the flowering stage (B300:T300) in the early season and 600 kg CaO ha−1 basal application before sowing and 600 kg CaO ha−1 top-dressing application at the flowering stage (B600:T600) in the late season; the yields were significantly increased by 91.87 % in 2020, 92.15 % in 2021, and by 255.36 % in 2020, 248.22 % in 2021, respectively, compared with those obtained with no Ca fertilizer use. However, the Ca treatments did not significantly affect pod yield or the related parameters of Yueyou 45 in either season. The pod yield of both cultivars was higher in the early season than that in the late season because of the higher effective accumulated temperature and precipitation during the reproductive stage in the early season of both years. The results of this study indicate that the early season is most suitable for peanut production, and the B300:T300 and no Ca application strategies are appropriate for the Ca-sensitive and -tolerant cultivars, respectively, in the early season in southern China. Notably, additional Ca-tolerant cultivars should be selected for cultivation in southern China to reduce future fertilizer application. These results provide useful information for improving double-cropping systems, Ca fertilization strategies, and peanut cultivar breeding in southern China.

Ratoon Rice Cropping Mitigates the Greenhouse Effect by Reducing CH4 Emissions through Reduction of Biomass during the Ratoon Season.

The ratoon rice cropping system (RR) is developing rapidly in China due to its comparable annual yield and lower agricultural and labor inputs than the double rice cropping system (DR). Here, to further compare the greenhouse effects of RR and DR, a two-year field experiment was carried out in Hubei Province, central China. The ratoon season showed significantly lower cumulative CH4 emissions than the main season of RR, the early season and late season of DR. RR led to significantly lower annual cumulative CH4 emissions, but no significant difference in cumulative annual N2O emissions compared with DR. In RR, the main and ratoon seasons had significantly higher and lower grain yields than the early and late seasons of DR, respectively, resulting in comparable annual grain yields between the two systems. In addition, the ratoon season had significantly lower global warming potential (GWP) and greenhouse gas intensity-based grain yield (GHGI) than the main and late seasons. The annual GWP and GHGI of RR were significantly lower than those of DR. In general, the differences in annual CH4 emissions, GWP, and GHGI could be primarily attributed to the differences between the ratoon season and the late season. Moreover, GWP and GHGI exhibited significant positive correlations with cumulative emissions of CH4 rather than N2O. The leaf area index (LAI) and biomass accumulation in the ratoon season were significantly lower than those in the main season and late season, and CH4 emissions, GWP, and GHGI showed significant positive correlations with LAI, biomass accumulation and grain yield in the ratoon and late season. Finally, RR had significantly higher net ecosystem economic benefits (NEEB) than DR. Overall, this study indicates that RR is a green cropping system with lower annual CH4 emissions, GWP, and GHGI as well as higher NEEB.

Double cropping as an adaptation mechanism to climate change patterns in the Carpathian Basin

ABSTRACT Adapting agriculture to climate change is essential for sustainable food production. However, the development of suitable adaptation mechanisms requires a clear understanding of the plant-climate interaction. The number of growing degree days (GDD) is a good proxy for understanding plant-climate interrelationship and farm productivity. Here, using a 2-year experiment of barley-sweet corn double cropping (DC) system and 20-year climate and yield data, we found that barley and sweet corn GDD and productivity were strongly related to changes in climate patterns. Furthermore, we found a positive effect of the barley-sweet corn DC system on farm productivity (18.5 and 5.6 tonnes. ha−1 for DC and single cropping respectively) and return on investment (1.8; 1.4 as benefit:cost ratios for DC and single cropping system respectively). Altogether the results of this study suggest that the winter barley-sweet corn double cropping system is a potential strategy to boost farm productivity as well as an adaptation mechanism to be considered for the changing climate in the study region.

Mapping Cropland Intensification in Ecuador through Spectral Analysis of MODIS NDVI Time Series

Multiple cropping systems constitute an essential agricultural practice that will ensure food security within the increasing demand of basic cereals as a consequence of global population growth and climate change effects. In this regard, there is a need to develop new methodologies to adequately monitor cropland intensification. The main objective of this research was to assess cropland intensification by means of spectral analysis of MODIS NDVI time series in a high cloudiness tropical area such as Ecuador. A surface of 89,225 ha of the main staple crops in this country, which are rice and maize crops, was monitored to assess the evolution of the number of crop cycles. The 20-year period of NDVI time series was used to calculate the periodograms across four subperiods (2001–2005, 2006–2010, 2011–2015, 2016–2020). The maximum ordinate value of each periodogram was used as an indicator of the number of growing crop cycles per year identifying single-, double-, and triple-cropping systems in each subperiod. Cropland intensification was assessed by comparing the cropping system between the subperiods. Results reveal that more than half of the studied croplands experienced changes in the cropping systems, and 40% showed positive trends in terms of the number of growing crop cycles, being principally located near the main rivers where irrigation facilitates crop development during the dry season. Therefore, the area under single cropping decreased from over 60,000 ha in the first subperiod to less than 50,000 ha in the last two subperiods. The cropland surface subjected to multi-cropping practices increased during the second decade of the study period, with a double-cropping system being more widely used than growing three crops per year, reaching surfaces of 24,400 ha and 10,450 ha in the last subperiod, respectively. The robust results obtained in this research show the great potential of the periodogram approach for the discrimination of cropping systems and for mapping intensification areas in tropical regions where dealing with noisy remote sensing time series as a consequence of high cloudiness is a great challenge.

Soybean-Maize Off-season Double Cropping System as Affected by Maize Intercropping with Ruzigrass and Nitrogen Rate

Soybean-Maize Off-season Double Cropping System as Affected by Maize Intercropping with Ruzigrass and Nitrogen Rate

Liming reduces nitrogen uptake from chemical fertilizer but increases that from straw in a double rice cropping system

Liming materials are widely applied to alleviate soil acidification and increase rice yield in acidic soils, but their effects on nitrogen (N) use efficiency are still unclear. Here, we conducted a field-, pot-, and micro-plot experiment to investigate how the application of slaked lime (i.e., Ca(OH)2) affects the fate of chemical fertilizer-N and straw-N in a double rice cropping system. In the field experiment, liming increased grain yield and N uptake by an average of 9.0% and 10.6%, respectively. In contrast, CaCl2 application did not affect rice yield and N uptake, suggesting that the effects of lime application were not related to the addition of Ca2+. Results from a 15N tracer experiment (i.e., 15N-labeled urea and straw) indicated that liming reduced N uptake from fertilizer (−5.7%), but increased N uptake from straw (+31.3%). Liming also reduced soil retention of both urea- and straw-N and increased their loss rates. Taken together, our results indicate that although liming increases rice yield and N uptake, it lowers the use efficiency of fertilizer N and facilitates N losses. In addition, our results emphasize the need for long-term studies on the impact of liming on soil N dynamics in paddy soils.

Long-term straw mulch underpins crop yield and improves soil quality more efficiently than plastic mulch in different maize and wheat systems

Field mulching efficiently increases crop production, yet the feasibilities of plastic mulch (PM) and straw mulch (SM) in different ecological regions are scarcely documented. This study aimed to investigate yield responses and soil quality changes following PM and SM, thereby identifying their suitability in different maize and wheat systems. A total of 202 peer-reviewed publications after 2000 that involved field experiments treated with no-mulch, PM, and SM were collected, and yield ratio of PM to SM (RPM/SM) was calculated to quantitatively understand their mulching efficacy. PM significantly increased grain yields in mono rather than double-cropping systems relative to SM, with an averaged RPM/SM at 1.28 in mono-maize, 1.11 in mono-wheat, and 1.05 for maize and 1.04 for wheat in double-cropping systems. Growing-season precipitation was significantly correlated with RPM/SM across mono and double-cropping systems, showing an RPM/SM of 1 at 530-mm for wheat in mono-cropping and 395-mm in double-cropping, and a stabilized RPM/SM observed at 1.082 in mono-cropping and 1.001 in double-cropping for maize, when growing-season precipitation exceeded 576-mm and 500-mm, respectively. Long-term field experiments illustrated significant relationships between RPM/SM and experimental duration, showing an RPM/SM of 1 at the 10.3-year for mono-maize, and 14.6-year for maize and 16.7-year for wheat in double-cropping, and a stabilized RPM/SM of 1.075 when trial time exceeded 3.7 years for mono-wheat, indicating a logged better performance of agronomic yield for SM. Owing to remarkable increases of soil organic C (SOC), total N, available K, and microbial biomass C, SM received the highest soil quality index across mono- and double-cropping systems, compared with PM and no-mulch. Growing-season precipitation, soil moisture at the sowing stage, SOC, and total N are the vital climatic and physicochemical variables mediating RPM/SM regardless of mono and double-cropping systems. Long-term SM rather than PM is an alternative for addressing the triple challenges of food security, soil degradation, and environmental mitigation. Quantifying the mulching efficacy on crop yields in different maize and wheat systems contributes to underpinning soil fertility and productivity in water-limited areas.

Effects of Partial Substitution of Organic Fertilizer for Synthetic N Fertilizer on Yield and N Use Efficiencies in a Semiarid Winter Wheat–Summer Maize Rotation

Finding field management techniques that increase crop output while protecting soil sustainability is essential for maintaining a long-term food supply in a changing environment. However, comprehensive evaluation of the effects of nitrogen (N) reduction combined with organic fertilizer on grain yield, N use efficiency (NUE), water use efficiency (WUE), and soil organic carbon (SOC) and total N (TN) contents of winter wheat–summer maize double cropping systems in drought-prone areas remains limited. Therefore, a 3-year field experiment (2018–2021) was conducted in a winter wheat–summer maize double cropping system with five treatments: no N fertilizer (CK), conventional farmer fertilization (CF), recommended fertilization (R), organic N substitution of 20% of the recommended synthetic N (R20), and organic N substitution of 40% of the recommended synthetic N (R40). When results were averaged from 2018 to 2021, R20 had the highest annual grain yield, which increased by 42.15%, 7.69%, 7.58%, and 12.50% compared with CK, CF, R, and R40, respectively. Compared with CF, R20 increased winter wheat and summer maize NAE, NPFP, NUE, and WUE. In addition, the soil organic carbon content of R20 and R40 treatment increased with the increase in years. In conclusion, R20 was considered ideal for improving crop yield, promoting soil fertility, and increasing the fertilizer utilization rate in a semiarid winter wheat–summer maize rotation.

Revisiting Climate-Related Agricultural Losses across South America and Their Future Perspectives

Climate plays a major role in the spatiotemporal distribution of most agricultural systems, and the economic losses related to climate and weather extremes have escalated significantly in the last decades. South America is one of the most productive agricultural areas of the globe. In recent years, remote sensing data and geographic information systems have been used to improve geo-environmental hazard assessment. However, food security is still highly dependent on small farmer practices that are frequently the most vulnerable to climate extremes. This work reviews climate and weather extremes’ impacts on crop production for South American countries, focusing on the projected ones considering different climate scenarios and countries. A positive trend in the productivity of maize, mainly related to agricultural improvements, was recently observed in Colombia, Ecuador, and Uruguay by up to 200%, as well as in the case of soybean in Bolivia and Uruguay by about 125%. Despite the generalized adverse impacts of climate extremes, results from agrometeorological models generally indicate an increase in crop production in southern regions of Chile (and highlands) and Brazil mainly related to increased temperature. Positive impacts in response to CO2 fertilization are also foreseen in Peru and Brazil (southeast, south, and Minas Gerais); in particular, in Brazil, increases in productivity can be raised by about 40%. The use of double-cropping systems, although with very good results in recent years, may also be at risk in a few decades, mainly due to forecasted precipitation decrease, delay in rainy season onset, and temperature increase. The development of timely early warning systems is imperative to produce technically accurate alerts and the interpretation of the risk assessment based on the link between producers and consumers. Promoting climate index insurance is crucial to build resilient food production, but its implementation should rely on regional or international support systems. Moreover, the implementation of adaptation and mitigation also requires climate-resilient technologies that involve an interdisciplinary approach.

Supplemental irrigation at the jointing stage of late sown winter wheat for increased production and water use efficiency

ContextThe sowing of winter wheat (Triticum aestivum L.) in the winter wheat-summer maize double cropping system is considerably delayed due to late harvest of the maize. This delayed sowing leads to reduction in spike numbers and ultimately the yield. Supplemental irrigation at the jointing stage (SIJ) can effectively regulate the population of winter wheat, but few studies have reported the impacts of SIJ on water utilization, wheat stem number fluctuations, and yield formation of late sown wheat. ObjectiveThe aim of this study was to determine the effects of sowing scheme accompanied with SIJ on wheat yield and water use efficiency (WUE). MethodsA two-year field experiment with two treatment factors (sowing date and irrigation schemes) in a split-plot design was laid out during 2018–2020 in the wheat growing seasons. The main plots were divided into two levels: normal sown date (A1) and late sown date (A2). The split plots included two irrigation schemes: no SIJ (W0) and SIJ (W1). ResultsThe soil water consumption at 20–120 cm soil depth during sowing to jointing stage in late sown wheat (A2) was significantly lower than the normal sown wheat (A1) but it increased considerably at 100–200 cm soil depth from jointing to maturity in A2. SIJ (W1) in late sown wheat produced better yield and WUE than no SIJ (W0). Under W1 conditions, A2 significantly promoted water consumption from jointing to maturity compared with A1, but, because water consumption from sowing to jointing was very low, seasonal water consumption remained significantly low. Additionally, A2 showed accelerated dry matter accumulation after jointing, increased grain numbers per spike and per unit area, improved net photosynthetic rate (Pn) of flag leaf and post-anthesis assimilate production. ConclusionsSIJ accelerated Pn and dry matter accumulation after jointing in late sown wheat, increased grain numbers per unit area, grain yield, and WUE without increasing seasonal water consumption. The seasonal water consumption in the normal sown period were higher. Although the number of spikes in normal sown wheat with higher water consumption, total stem number and dry matter accumulation before jointing was higher, after SIJ, the yield and WUE were lower than those of late sown wheat owing to the reduction in grain numbers per spike. SignificanceThis study explains how the sowing scheme and SIJ affect wheat yield and WUE, and demonstrates that SIJ was particularly crucial for late sown wheat to achieve the synergistic improvement of grain yield and WUE.

Biochar amendment increases the abundance and alters the community composition of diazotrophs in a double rice cropping system

Biochar amendment increases the abundance and alters the community composition of diazotrophs in a double rice cropping system

Alternatives for sustainable weed control in single‐ and double‐cropped soybean: A case study for Mediterranean irrigated conditions

AbstractThe irrigated cropping systems in South Europe could benefit from soybean [Glycine max (L.) Merr.] introduction in their maize (Zea mays L.)‐based crop rotations. However, sustainable weed management strategies are needed for soybean growers under Mediterranean irrigated conditions. This work aimed to assess the weed control efficacy, and the soybean performance, of alternative management practices for single‐ and double‐cropped soybean. Two field experiments were carried out in northeast Spain in the period 2019–2021. Row width narrowing (75–37.5 cm), herbicide application (yes/no), and roller‐crimped rye [Secale cereal (L.) M.Bieb.] cover crop (yes/no) were assessed in the single cropping system experiment (SCS). In the barley‐soybean double cropping system experiment (DCS), row width narrowing and herbicide application were assessed. In the SCS, the presence of rye cover crop reduced weed biomass up to 92% compared to the controls without herbicide and cover crop in 2020. In 2021, no effect of the cover crop on weed pressure was found due to the low amount of rye biomass accumulated (11.8 and 3.4 ton DM ha−1 in 2020 and 2021, respectively). In the DCS, herbicide application attained the expected weed control. Row width narrowing to 37.5 cm did not have an impact on weed pressure nor on soybean yield in either experiment. We concluded that herbicide reduction for single‐cropped soybean under Mediterranean irrigated conditions can be achieved by roller‐crimping a rye cover crop, provided enough rye biomass is accumulated. In the DCS, our results indicated that further research is needed to find alternatives to chemical weed control.

A robust and unified land surface phenology algorithm for diverse biomes and growth cycles in China by using harmonized Landsat and Sentinel-2 imagery

Land surface phenology (LSP) is beneficial to understand ecosystem response to climate change, vegetation and crop type discrimination, and ecological modeling. However, the existing efforts based on coarse resolution data (≥500 m) cannot perform well in regions with higher spatial heterogeneity and multi-cropping system, such as China. Given that the majority of 10 m/30 m-based phenological research has focused on North America and Europe, developing spatiotemporally explicit LSP data in China is imperative. More importantly, the existing 30 m LSP products are mainly suitable for vegetation types with a single vegetation cycle, but cannot work well for biomes with complex seasonality (e.g., multiple growth cycles). Here we first harmonized three vegetation indices, i.e., the normalized difference vegetation index (NDVI), two-band enhanced vegetation index (EVI2), and land surface water index (LSWI) from Landsat-7/8 and Sentinel-2 imagery on the Google Earth Engine (GEE) platform. We then developed a new 30 m LSP algorithm that unified different phenological cycle-seeking processes per vegetation type and improved the existing algorithm. Furthermore, we used the algorithm to estimate the LSP product (LSP30CHN) for 2016–2019 across China, suitable for all vegetation types. The validation results showed a reasonably high accuracy (R2 > 0.6, RMSE < 15 days, mostly) of the LSP30CHN data against multi-sources in-situ observational (e.g., PhenoCam) and satellite-retrieved vegetation phenology data. Moreover, LSP30CHN data showed a consistent pattern but finer spatial details with the 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) phenology product (MCD12Q2) at the homogenous area. We also found that phenological differences between LSP30CHN and MCD12Q2 increased with surface fragmentation, suggesting the potential of LSP30CHN to delineate phenological information on more fragmented landscapes. In contrast, the 500 m LSP data cannot provide such details in the regions with mixed cropping structures (e.g., corn, rice, and soybean) and multiple cropping index (e.g., single- and double-cropping systems). This study offers high accuracy of the LSP map for China, valuable for finer phenology-based services such as field-level crop management and agricultural phenology monitoring. It opens up new insights about exploring large-scale refined agricultural management and ecological assessment for other regions with complicated, fragmented landscapes and vegetation seasonality.

Excessive N applications reduces yield and biological N fixation of summer-peanut in the North China Plain

ContextThe North China Plain (NCP) is China’s largest peanut producing area, where winter-wheat summer-peanut is an important double cropping system. Excessive nitrogen (N) applications are widely used leading to declined N use efficiency (NUE) and biological N fixation (BNF). However, the influence of excessive fertilizer N inputs on yield and BNF of summer-peanut remains uncertain. ObjectiveThe study aims to evaluate the impacts of different fertilizer N inputs on yield and BNF of summer-peanut in the NCP, and explore the optimal N rates for achieving high NUE and low N losses without sacrificing yield. MethodsA three-year field experiment and pot experiment involving five N treatments (N rates with 0, 50, 100, 150, and 200 kg N ha−1, defined as N0, N50, N100, N150 and N200 in the study, respectively) were conducted in the NCP. The jointing use of field experiment and pot experiment were adopted to measure BNF of summer-peanut, and the partial least squares path model and a nightingale rose diagram were both included in the study. ResultsSummer-peanut yield increased quadratically with increasing N application, but N rates larger than 150 kg N ha−1 caused inadequate seed filling and thus led to slightly reduced yield. Generally, increased N applications significantly increased soil mineral N (SMN) between 0 and 60 cm depth, and dramatically reduced BNF as high SMN strongly inhibits biological nitrogenase activity. ConclusionsThe N application required to obtain an optimum yield of 3915 kg ha−1 with relatively high NUEoi (the ratio of N output and N input, 73.0%) and low N losses in the summer-peanut production was 150 kg N ha−1 in the NCP. ImplicationsThe sustainable development of summer-peanut systems will involve reduced N application rates, and N optimization in the winter-wheat summer-peanut rotation should receive further attention considering the N legacy effects.

Water Requirements and Comprehensive Benefit Evaluation of Diversified Crop Rotations in the Huang-Huai Plain

An intensified farming system can significantly increase crop productivity but can also cause major groundwater overdraft for irrigation and the loss of crop diversity. It is imperative to develop alternative crop rotations beyond the simplified conventional winter wheat–summer maize (W–M) rotation for alleviating the groundwater over-extraction in China’s Huang-Huai Plain. This study systematically quantified crop water requirement (ETc) and irrigation water requirement (ETaw) of eight crops from 2013 to 2018 based on the SIMETAW model applied to the Shangqiu area in the Huang-Huai Plain. Fourteen crop rotations (CI (i.e., crop harvests per rotation cycle year) 1.5 or 2) were constructed based on the ROTAT model. Results showed that compared to W–M rotation, the alternative rotations (CI = 1.5) significantly reduced the annual ETc in wet, normal, and dry years by 9–21%. Replacing winter wheat in the double cropping system did not significantly decrease annual ETc. Wheat–soybean rotation had similar annual ETc and ETaw accompanied by higher economic output and equivalent yield about 1.2 times, with 9% more protein output than the W–M rotation. There were eight crop rotations having greater comprehensive evaluation index (CEI) than W–M rotation by Entropy-TOPSIS when considering 10 indicators including water requirements, yield, economic benefits, water use efficiency, energy, and nutritional values. Spring potato–summer soybean had the highest CEI of 0.627. Sweet potato and potato showed advantages when included in rotations by increasing yield. “Wheat–soybean”-based rotations (CI = 1.5) also performed well in profitability and protein output. Replacing summer maize with soybean is promising for profitability and nutrition output without increasing irrigation requirements. Therefore, decreasing the cropping index, or involving soybean or sweet potato in rotations can be a useful way to improve sustainable land use, save water, and ensure food products in this water stressed region.

Fate of fertilizer N applied to maize intercropped with forage grass and recovery of residual N by soybean in a double cropping system

Fate of fertilizer N applied to maize intercropped with forage grass and recovery of residual N by soybean in a double cropping system

Integrated Transcriptome and Metabolome Analysis Revealed the Causal Agent of Primary Bud Necrosis in 'Summer Black' Grape.

Primary bud necrosis of grape buds is a physiological disorder that leads to decreased berry yield and has a catastrophic impact on the double cropping system in sub-tropical areas. The pathogenic mechanisms and potential solutions remain unknown. In this study, the progression and irreversibility patterns of primary bud necrosis in 'Summer Black' were examined via staining and transmission electron microscopy observation. Primary bud necrosis was initiated at 60 days after bud break and was characterized by plasmolysis, mitochondrial swelling, and severe damage to other organelles. To reveal the underlying regulatory networks, winter buds were collected during primary bud necrosis progression for integrated transcriptome and metabolome analysis. The accumulation of reactive oxygen species and subsequent signaling cascades disrupted the regulation systems for cellular protein quality. ROS cascade reactions were related to mitochondrial stress that can lead to mitochondrial dysfunction, lipid peroxidation causing damage to membrane structure, and endoplasmic reticulum stress leading to misfolded protein aggregates. All these factors ultimately resulted in primary bud necrosis. Visible tissue browning was associated with the oxidation and decreased levels of flavonoids during primary bud necrosis, while the products of polyunsaturated fatty acids and stilbenes exhibited an increasing trend, leading to a shift in carbon flow from flavonoids to stilbene. Increased ethylene may be closely related to primary bud necrosis, while auxin accelerated cell growth and alleviated necrosis by co-chaperone VvP23-regulated redistribution of auxin in meristem cells. Altogether, this study provides important clues for further study on primary bud necrosis.

Impacts of straw return coupled with tillage practices on soil organic carbon stock in upland wheat and maize croplands in China: A meta-analysis

Despite numerous individual studies evaluating the impact of straw return on soil organic carbon (SOC) stock in upland wheat and maize croplands in China using no-tillage (NTS), rotary tillage (RTS), and deep tillage (DTS) practices, the results have shown inconsistency. In addition, several factors influence the effects of various tillage practices with straw return on SOC stock that are not well understand. In this study, we conducted a meta-analysis of 764 comparisons to determine the combined impact of SOC stock in the topsoil (0–20 cm) and subsoil (20–40 cm) layers, while considering factors such as climate conditions, management practices, and initial soil properties. The results indicate that straw return with different tillage practices significantly improved SOC stock in both soil layers compared to straws removal. The increase in topsoil SOC stock was nearly identical for NTS (7.38 %) and DTS (7.17 %), compared to the RTS. However, the increase in subsoil SOC stock was significantly higher for DTS (28.8 %). According to subgroup analysis, NTS has been more effective in increasing topsoil SOC stock in regions with medium temperature (10–15 °C) and low precipitation (<400 mm), when used in a single cropping system. However, in regions with higher temperature (>15 °C) and precipitation (>800 mm), DTS is more effective in increasing SOC stock in both topsoil and subsoil layers in a double cropping system. Long-term (11–20 years) DTS resulted in a significant increase in SOC stock in the topsoil (19.2 %) and subsoil (18.5 %), while the increased effects of NTS on SOC stock were only in topsoil layer (17.1 %). The effects of straw return on SOC stock were also found to be associated with soil texture, with NTS having a greater impact on sandy to loam soils, and DTS having a greater impact on clay soils. Furthermore, a significant (P < 0.01) positive linear relationship was observed between annual carbon (C) input and SOC sequestration in the topsoil under NTS, as well as in both soil layers under DTS. These findings have important implications for enhancing SOC in Chinese upland wheat and maize cropland soils through optimizing straw return, given that more than 518 million tons of crop straw are produced annually.