•Greater remediation of N and P from the water column occurred in non-aerated systems.•Increased plant uptake of N and P occurred in aerated, full density systems.•Higher nitrate levels in aerated ...systems could be attributed to microbial activity.•N and P removal explained by volatilization, weed uptake, organic carbon availability.
Nutrient contamination of waterways is a growing concern, instigating the emergence of floating treatment wetland systems (FTWs) to remove nutrients from water. To determine if aeration of water systems enhances nutrient removal efficacy or nutrient fixation within plant tissues, aeration in combination with FTW installation techniques were investigated. During two separate trials with Juncus effusus and Canna flaccida, treatments consisted of either aerated or non-aerated mesocosms, with varying coverage and planting density combinations. Aeration increased the dissolved oxygen levels within each mesocosm, but reduced the removal of nitrogen and phosphorus from the water column in comparison to non-aerated systems. Plant samples collected from 100% planting density treatments that were aerated had a greater nitrogen uptake than non-aerated by as much as 55% or 13.5 g/m2 at harvest. Some discrepancies between plant uptake and water column nutrient levels can be attributed to microbially-mediated nitrogen losses (e.g., denitrification).
...these mutants could not be used in breeding because of pleiotropic detrimental effects, such as dwarfism, small ear size, and yield losses. ...identification of semi-dwarf genes is desirable for ...genetic improvement of lodging resistance in maize. Histological observation revealed that internode cells in the ZmSPL12-OE plants were significantly shorter than those of control plants (Figure 1i), indicating that the shorter internode in the ZmSPL12-OE plants is mainly caused by decreased cell length. ...measurement of stalk strength showed that the ZmSPL12-OE plants were significantly stronger than that of the control plants (Figure 1j). The ZmSPL12-OE plants had significantly reduced plant height, ear height and more grain yield than the #500-CK plants under all three planting densities (Figure 1m,n). ...the stalk strength of ZmSPL12-OE plants enhanced significantly compared with the non-transgenic plants under high planting densities (90 000 and 135 000 plants per hectare; Figure 1o).
Enhanced immune functioning in response to biodiversity may explain potential health benefits from exposure to green space. Using unique data on urban forest biodiversity at the zip code level for ...California measured from 2014 to 2019 we test whether greater diversity of street trees is associated with reduced death from cardiovascular disease. We find that urban forests with greater biodiversity measured via the Shannon Index at the genus level are associated with a lower mortality rate for heart disease and stroke. Our estimates imply that increasing the Shannon Index by one standard deviation (0.64) is associated with a decrease in the mortality rate of 21.4 per 100,000 individuals for heart disease or 13% and 7.7 per 100,000 individuals for stroke or 16%. Our estimates remain robust across several sensitivity checks. A policy simulation for tree planting in Los Angeles based on our estimates suggests that if these relationships were causal, investment in planting for a more biodiverse set of street trees would be a cost-effective way to reduce mortality related to cardiovascular disease in urban areas.
Water and nutrient absorption from soil by crops mainly depend on the morphological traits and distribution of the crop roots. Dense planting with reduced nitrogen is a sustainable strategy for ...improving grain yield and nitrogen use efficiency. However, there is little information on the effects of dense planting with reduced nitrogen on direct-seeded inbred rice. Two-year field experiments were conducted with minirhizotron techniques to characterize the root morphological traits and distributions under different nitrogen application rates and sowing densities in two representative inbred rice varieties, Huanghuazhan (HHZ) and Yuenongsimiao (YNSM), grown under three nitrogen application rates (N0: 0 kg ha.sup.-1, LN: 135 kg ha.sup.-1, HN: 180 kg ha.sup.-1) and two sowing densities (LD: 18.75 kg ha.sup.-1, HD: 22.5 kg ha.sup.-1). Our study showed that dense planting with low nitrogen improved grain yield partly due to the increased panicle number. The higher sowing density with low nitrogen significantly affected the total root number (TRN), total root length (TRL), total root surface area (TRSA), and total root volume (TRV). There was a significant positive correlation between grain yield and TRL in the 10-20-cm soil layer (P 0.05). The root morphological indexes were positively correlated with dry matter accumulation (P 0.05) and negatively correlated with nitrogen content (P 0.05) at the maturity stage. This study showed that a high sowing density with low nitrogen application can improve root morphology and distribution and increase grain yield and nitrogen use efficiency in direct-seeded inbred rice.
Abstract The field experiment was conducted during the agricultural season 2021-2022 at the research station of the Department of Horticulture and Landscape Engineering / University of Diyala in ...order to study the effect of planting date and spraying with nutrients containing amino acids on the growth and production of dry onions and the production of its seeds. The experiment included two factors, the first planting date: 1/12, 21/12, 7/1 and 1/2, and the second factor was spraying with nutrients containing amino acids, namely: without spraying, spraying with Tecamin Max and spraying with Ascophila. And spray with Amino Quelant-K. The experiment included sixteen treatments with three replications, so the total experimental units became forty-eight experimental units. The split plot design (R.C.B.D) was used, and the results were analyzed statistically using the SAS statistical program, and the results were compared using Duncan’s multiple test at the probability level of 0.05. The results showed the superiority of the plants grown in the first date (1/12) in the characteristics of vegetative growth represented by plant height (76.69 cm) and the number of tubular leaves (14.30 leaf −1 ), compared to date 1/2, which reached 42.17 cm, and 8.27 leaf −1 , respectively. The same treatment also excelled in yield characteristics, represented by the average bulb weight (90.57 gm) and the total yield of bulbs (35.29 tons ha −1 ), compared to date 1/2, which amounted to 51.58 g and 19.92 tons ha −1 , respectively. The same treatment also excelled in the characteristics of the seed yield represented by the seed yield of one plant (5.05 g) and the total seed yield (2055.7 kg ha −1 ), compared to date 1/2, which amounted to 2.83 g and 1106.8 kg ha −1 , respectively. As for spraying with amino nutrients, the results showed that there was a significant superiority when spraying with the amino nutrient Tecamin Max in the vegetative growth characteristics represented by plant height (73.32 cm) and the number of tubular leaves (13.75 leaf −1 ), compared to 54.42 cm and 9.72 leaf −1 , respectively. It also excelled in yield characteristics represented by the average bulb weight (84.17 gm) and the total yield of bulbs (32.85 ton ha −1 ), compared to a comparison whose values were low to 60.07 gm and 23.40 ton ha −1 , respectively. It also excelled in the characteristics of the seed yield, represented by the seed yield of one plant (5.07 g) and the total seed yield (2060.7 kg ha −1 ), compared to 3.10 g and 1212.3 kg ha −1 , respectively. The effect of the interaction between planting date 1/12 and the amino nutrient Tecamin Max on the characteristics of vegetative growth, as the interaction gave a significant increase in plant height (87.26 cm) and the number of tubular leaves (16.70 leaf plant −1 ) compared to the date 1/2 with the comparison treatment, which amounted to 37.87 cm and 7.30 leaf in order, as well as the effect of the interaction between the sowing date 1/12 and the amino nutrient Tecamin Max on yield characteristics, as the interaction gave a significant increase in the average bulb weight (105.0 g) and the total yield of bulbs (40.67 tons ha −1 ) compared to the date 1/2 with the comparison treatment, which amounted to 50 g and 18.96 tons ha −1 , respectively. The same treatment also outperformed the seed yield of one plant (6.12 g) and the total seed yield (2692.8 kg ha −1 ), compared to the date 1/2 with the comparison treatment, which amounted to 2.56 g and 1001.2 kg ha −1 , respectively.
Accurate measurements of maize yields at field or subfield scales are useful for guiding agronomic practices and investments and policies for improving food security. Data on smallholder maize ...systems are currently sparse, but satellite remote sensing offers promise for accelerating learning about these systems. Here we document the use of Google Earth Engine (GEE) to build “wall-to-wall” 10 m resolution maps of (i) cropland presence, (ii) maize presence, and (iii) maize yields for the main 2017 maize season in Kenya and Tanzania. Mapping these outcomes at this scale is extremely challenging because of very heterogeneous landscapes, lack of cloud-free satellite imagery, and the low quantity of quality ground-based data in these regions.
First, we computed seasonal median composites of Sentinel-1 radar backscatter and Sentinel-2 optical reflectance measures for each pixel in the region, and used them to build both crop/non-crop and maize/non-maize Random Forest (RF) classifiers. Several thousand crop/non-crop labels were collected through an in-house GEE labeler, and thousands of crop type labels from the 2015–2017 growing seasons were obtained from various sources. Results show that the crop/non-crop classifier successfully identified cropland with over 85% out-of-sample accuracy in both countries, with Sentinel-1 being particularly useful for prediction. Among the cropped pixels, the maize/non-maize classier had an accuracy of 79% in Tanzania and 63% in Kenya.
To map maize yields, we build on past work using a scalable crop yield mapper (SCYM) that utilizes simulations from a crop model to train a regression that predicts yields from observations. Here we advance past approaches by (i) grouping simulations by Global Agro-Environmental Stratification (GAES) zones across the two countries, in order to account for landscape heterogeneity, (ii) utilizing gridded datasets on soil and sowing and harvest dates to setup model simulations in a scalable way; and (iii) utilizing all available satellite observations during the growing season in a parsimonious way by using harmonic regression fits implemented in GEE. SCYM estimates were able to capture about 50% of the variation in the yields at the district level in Western Kenya as measured by objective ground-based crop cuts.
Finally, we illustrated the utility of our yield maps with two case studies. First, we document the magnitude and interannual variability of spatial heterogeneity of yields in each district, and how it varies for different parts of the region. Second, we combine our estimates with recently released soil databases in the region to investigate the most important soil constraints in the region. Soil factors explain a high fraction (72%) of variation in predicted yields, with the predominant factor being soil nitrogen levels. Overall, this study illustrates the power of combining Sentinel-1 and Sentinel-2 imagery, the GEE platform, and advanced classification and yield mapping algorithms to advance understanding of smallholder agricultural systems.
•National maps of crop and maize areas are generated at 10 m resolution in Africa.•Maize yields are mapped accurately without any ground calibration.•Independent soil data can explain over 70% of variability in yield estimates.•Soil nitrogen and organic carbon exhibit the strongest association with yields.•Google Earth Engine and Sentinel data offer new opportunities for mapping agriculture.
Identifying the rapeseed (Brassica napus L.) flowering dates are important for planting area estimation, growth monitoring, and yield estimation. However, there is currently a lack of data on ...rapeseed flowering dates at the parcel scale. In this study, a new spectral index (Normalized Rapeseed Flowering Index, NRFI) is proposed to detect rapeseed flowering dates from time series data generated from Landsat 8 OLI and Sentinel-2 sensors. This study also analyzed the feasibility of using the backscattering coefficients (VV, VH, and VV/VH) of Sentinel-1 to detect the flowering dates of rapeseed at the parcel scale. Based on the spectral and polarization characteristics of 718 rapeseed parcels collected in 2018, we developed a method to automatically identify peak flowering dates by the local maximum of NRFI series and the local minimum of VH and VV, along with the maximum of VV/VH. The results show that most of the peak flowering dates derived from Sentinel-1 and Sentinel-2 can be confirmed by the in-situ phenological observations at the Deutscher Wetterdienst (DWD) stations in Germany. The NRFI outperforms the Normalized Difference Yellow Index (NDYI) in identifying the peak flowering dates from Landsat 8. The derived medians of peak flowering dates by NRFI, NDYI (Sentinel-2), and VH are similar, while a systematic delay is observed by NDYI (Landsat 8). The method with the spectrum and backscattering coefficients will be a potential tool to identify crop flowering dynamics and map crop planting area.
Light has a significant impact on crop production. The objective of this study was to explore the optimal lighting structure parameters and the corresponding planting strategy of Chinese solar ...greenhouses (CSG). Taking CSG-grown melons as the experimental subject, we have developed a detailed 3D model capable of calculating the light interception at a single organ level, e.g., for individual leaves. The quantitative research was carried out after verifying the proposed model using field data. The results indicated that the reasonable ridge height for the most common 9 m span CSG was 4.9 m, and the horizontal projection on rear roof was 1.6 m in Shenyang area. In comparison with the experimental greenhouse, the optimized greenhouse improved crop light interception by 0.5 % and increased the average air temperature by 9.3 % during winter. The suitable planting strategy was E-W row orientation, with a ridge spacing of 1.2 m, a row spacing of 0.4 m, and a plant spacing of 0.38 m. Compared with the N–S row orientation, the crop light interception increased by 7.1 % and 10.8 % in the two growing seasons, respectively. The model described herein can serve as a foundation for the production of CSG.
•The optimal lighting structure of CSG was determined through model analysis.•The average air temperature of the optimized greenhouse was increased by 1.37 °C.•A calculation model for light interception of individual melon leaf was established.•The feasibility of E-W row planting configuration within greenhouse were clarified.
Rice–crayfish continuous production system offers high economic and ecology benefits, which developed rapidly in China. To investigate the effects of different mechanical transplanting methods and ...planting densities on rice yield and quality, Nanjing 2728 was used to determine rice growth performance under mechanically transplanted carpet seedling (MTCS) with equal row spacing (30 cm) at five spacings and mechanically transplanted pot seedling (MTPS) with wide and narrow rows (23 + 33 cm) at five spacings. The results showed that MTPS presented significantly higher rice yields than MTCS as more spikelets per panicle. Rice yields of both mechanical transplanting methods first increased and then reduced with decreasing planting density, and its highest value was obtained at 77.9 × 104 seedlings ha−1. Compared with MTCS at the same stage, rice tiller dynamics of MTPS first increased and then decreased. Additionally, its dry matter accumulation per stem at jointing, heading, and maturity stages, leaf area index, photosynthetic potential, crop growth rate, and net assimilation rate were all significantly higher relative to MTCS. For each mechanical transplanting method, dry matter accumulation per panicle, leaf area index, photosynthetic potential, crop growth rate, and net assimilation rate from the sowing to jointing stages declined with decreasing planting density, while dry matter accumulation per stem and net assimilation rate from the heading to maturity stages increased. Compared with MTCS, MTPS significantly improved rice milling and appearance quality, decreasing density was also beneficial to rice milling and appearance quality, while grain content of amylose and protein were not sensitive to both transplanting method and planting density. Consequently, MTPS with 13.8 cm plant spacing is a suitable mechanical transplanting method for Nanjing 2728 to obtain better yield and quality under rice–crayfish continuous production system.
Patterns, mechanisms, projections, and consequences of tree mortality and associated broad-scale forest die-off due to drought accompanied by warmer temperatures-"hotter drought", an emerging ...characteristic of the Anthropocene-are the focus of rapidly expanding literature. Despite recent observational, experimental, and modeling studies suggesting increased vulnerability of trees to hotter drought and associated pests and pathogens, substantial debate remains among research, management and policy-making communities regarding future tree mortality risks. We summarize key mortality-relevant findings, differentiating between those implying lesser versus greater levels of vulnerability. Evidence suggesting lesser vulnerability includes forest benefits of elevated CO
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and increased water-use efficiency; observed and modeled increases in forest growth and canopy greening; widespread increases in woody-plant biomass, density, and extent; compensatory physiological, morphological, and genetic mechanisms; dampening ecological feedbacks; and potential mitigation by forest management. In contrast, recent studies document more rapid mortality under hotter drought due to negative tree physiological responses and accelerated biotic attacks. Additional evidence suggesting greater vulnerability includes rising background mortality rates; projected increases in drought frequency, intensity, and duration; limitations of vegetation models such as inadequately represented mortality processes; warming feedbacks from die-off; and wildfire synergies. Grouping these findings we identify ten contrasting perspectives that shape the vulnerability debate but have not been discussed collectively. We also present a set of global vulnerability drivers that are known with high confidence: (1) droughts eventually occur everywhere; (2) warming produces hotter droughts; (3) atmospheric moisture demand increases nonlinearly with temperature during drought; (4) mortality can occur faster in hotter drought, consistent with fundamental physiology; (5) shorter droughts occur more frequently than longer droughts and can become lethal under warming, increasing the frequency of lethal drought nonlinearly; and (6) mortality happens rapidly relative to growth intervals needed for forest recovery. These high-confidence drivers, in concert with research supporting greater vulnerability perspectives, support an overall viewpoint of greater forest vulnerability globally. We surmise that mortality vulnerability is being discounted in part due to difficulties in predicting threshold responses to extreme climate events. Given the profound ecological and societal implications of underestimating global vulnerability to hotter drought, we highlight urgent challenges for research, management, and policy-making communities.
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