Field Crops Research最新文献

Contexts

Intercropping facilitates agricultural sustainability and intensification by increasing crop diversity at the spatial scale. However, the spatial configuration of intercropped crops, which is essential for enhancing crop-soil interactions and ecological services to achieve increased productivity and efficiency, remains understudied.

Objectives

We aimed to evaluate the effect of spatial configuration of hairy vetch/rapeseed intercropping on forage yield, economic benefits, and soil quality, and to elucidate the underlying mechanisms.

Methods

Three different spatial configurations of intercropping including 2:1, 1:1, and 0.5:1 ratios of hairy vetch (with variable planting density and position) and rapeseed (with fixed density and position) were designed and investigated through a two-year field experiment, compared with rapeseed (SR, 0:1) and hairy vetch sole cropping (SH, 1:0). The evaluation criteria included forage yield, crude protein yield, soil characteristics, nutrient accumulation, radiation use efficiency (RUE), land equivalent ratio (LER), and economic benefits.

Results

Intercropping rapeseed with hairy vetch showed significant competitiveness compared to rapeseed and hairy vetch sole cropping. Among the five systems evaluated, the 2:1 spatial configuration achieved the maximum biomass yield (18.4 Mg ha⁻¹), net profit value (29,598.9 CNY ha⁻¹), and LER (1.48) at the final flowering stage, followed by the 0.5:1 and 1:1 spatial configuration. Moreover, intercropping rapeseed with hairy vetch significantly increased soil available phosphorus (AP) and potassium (AK) content, as well as soil enzyme activity. However, it led to a significant decrease in soil pH compared to rapeseed sole cropping. Principal component analysis indicated a negative correlation between soil pH and AP, AK contents, while a positive correlation was observed between soil AP, AK contents and the accumulation of P and K in all intercropping configurations. Additionally, structure equation modeling analysis revealed that intercropping systems enhanced forage productivity by improving RUE and the total accumulation of N, P, K.

Conclusions

In conclusion, rapeseed-hairy vetch intercropping, particularly the 2:1 spatial configuration could be considered a high-yield and high-quality winter forage intercropping system that alleviates forage shortages and promotes the development of herbivorous animal husbandry.

Significance

Optimizing the intercropping spatial configuration represents a promising strategy for developing ecologically sound and high-quality forage cropping systems, which holds great significance for the sustainable development of agriculture in the Yangtze River Basin and beyond.

Context

Feeding a growing human population with limited arable land requires greater crop yield that is, in turn, driven by improved agronomy, better varieties, and their synergy. Here we focus on faba bean, Vicia faba L., an under-researched grain legume for which on-farm yield in Australia has increased at 0.8 % y⁻¹ since 1990.

Objective

We aimed to quantify genetic gain in seed yield of Australian faba bean varieties released since 1980, and to identify associated shifts in physiological and agronomic traits.

Methods

We combined three studies: the complete historical collection of Australian faba bean varieties was grown in 1) a vintage experiment of three field trials; and 2) a pot experiment inoculated with old and new strains of Ascochyta fabae. Since most varieties were grown in a national network of trials, we 3) estimated genetic gain in seed yield and individual seed weight in 129 environments.

Results

In the vintage experiment, genetic gain in seed yield varied from 0.4 % y⁻¹ to almost zero; low rates of genetic gain were also apparent in the national network of trials. Biomass, harvest index, and crop growth rate in the critical period had low rates of genetic change, and there were strong trade-offs between yield components and in their responses to selection. Breeding increased seed size at 0.5 % y⁻¹. Visual lodging scores decreased at 4.9 % y⁻¹. There was breakdown in resistance to Ascochyta blight, but it was restored in new varieties.

Conclusions

Australian faba bean breeding contributed to on-farm yield and profitability through improved agronomic traits and seed quality. Low genetic gain in yield can be partially attributed to physiological trade-offs between traits, economic trade-offs between multiple breeding targets, and genotype-by-environment interaction.

Implication

Under-researched crops require greater investment to match the genetic gain in yield of major crops.

The development of double-season rice cropping is advantageous for maximizing the utilization of radiation and temperature resources in rice production, while ensuring food security. However, late sowing often renders the late-season rice susceptible to cold stress during heading and flowering, leading to a low grain-setting rate and significant yield loss in subtropical zones. Despite this, the precise mechanisms through which low temperatures impact grain setting, along with the sensitivities of heading, flowering and pollination to cold stress, remain unclear across different types of rice. In this study, a field experiment involving multiple sowing dates and a pot experiment simulating low-temperature conditions during the booting and heading stages were conducted, using various late-season rice cultivars as materials. The heading degree, glume openness, anther dehiscence and pollen fertility were measured to determine their responses to ambient temperature. The results showed that late sowing significantly delayed the heading time of rice, exposing the plants to low temperatures during their heading and flowering in autumn. Under late sowing or simulated low-temperature conditions, the heading degree, anther dehiscence coefficient, and fertile pollen rate significantly decreased, resulting in lower grain-setting rates and grain yield across all rice types. However, glume opening remained unaffected in this study. The critical lowest daily temperatures for safe heading were identified as 18.5°C, 19.3°C and 22°C, and for safe anther dehiscence at heading, they were 19.9°C, 20°C and 22.3°C for japonica, indica-japonica hybrid and indica rice, respectively. Furthermore, the critical lowest daily temperatures for safe pollen fertility averaged 19.1°C, 20.2°C and 21.7°C in the 4–7 days prior to full heading for japonica, indica-japonica hybrid and indica rice, respectively. The cold tolerance in anther dehiscence of indica-japonica hybrid rice was similar to that of japonica rice but higher than that of indica rice, while the cold tolerance in heading and pollen fertility of indica-japonica hybrid rice was intermediate between japonica and indica rice. Path analysis revealed that low temperature decreased the grain-setting rate primarily by reducing anther dehiscence coefficient across all types of rice. Lower pollen fertility was another significant pathway through which low temperature decreased the grain-setting rate in indica rice. Planting japonica rice is recommended for the safe production of late-season rice in subtropical zones.

Leaf carbon isotope composition (δ¹³C) is a promising trait for assessing genotypic differences in responses to environmental stress, particularly drought. Despite its potential, comprehensive evaluations of δ¹³C across various carbohydrate pools and leaf positions, in comparison with other traits, are still lacking for cassava (Manihot esculenta). This study aimed to estimate the genotypic effect size and the correlation with yield for δ¹³C and other commonly assessed traits in cassava. We compared the δ¹³C values at bulk root initiation stage of fourteen genotypes grown in the wet (1450 mm annual rainfall) and dry Caribbean (950 mm annual rainfall). We focused on both non-structural (soluble sugars) as well as structural (cellulose) carbohydrate pools across multiple leaf positions. Our results revealed significant genotypic effects across nearly all pools and leaf positions, which were equal or larger than other commonly measured traits. Interestingly, correlations between isotope composition and root yield were only observed in the dry location, with upper leaves exhibiting weaker correlations across all carbohydrate pools. Notably, while soluble sugars displayed stronger correlations with yield, they also demonstrated higher susceptibility to within-field variations. Furthermore, complementary information was found when combining δ¹³C with other traits such as leaf retention. Combining isotope compositions across various carbohydrate pools may reveal insights into source-sink dynamics. These results underscore the potential of δ¹³C as a tool for improving drought tolerance in cassava and provide a basis for its integration into cassava breeding programs, when used under dry conditions. To enhance the practical utility of δ¹³C as a screening technique, further research is advised to validate these findings across multiple locations, growing seasons and growth stages.

Context or problem

Sustainable farming practices, including precision fertilization, water-saving irrigation and recycling of organic materials, have been implemented worldwide in recent decades to achieve high crop yields and minimize nonpoint source pollution. However, the comprehensive impacts of these agricultural practices have seldom been systematically evaluated in field production. As agricultural intensification started in the 1980s, most previous studies focused on a single practice in the context of low land productivity.

Objective or research question

The objective of this research is to investigate and evaluate how holistic farming practices affect both crop production and environmental quality.

Methods

We reported findings from a 12-year experiment (2008–2020) in the highly intensive North China Plain (NCP) farming region, and conventional and optimized farming measures were compared. Three field treatments with annual double cropping (winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.)) were chosen in the study, i.e., control without nitrogen (N) application (CK), farmers’ conventional practices (CON), and optimized practices (OPT), were chosen for this study.

Results

Compared with the CON treatment, OPT reduced N fertilizer input by 41.4 % and irrigation water by 27.1 % but produced similar grain yields; OPT increased the N recovery efficiency (RE_N) and N utilization efficiency (NUT₂E) by 90.4 % and 53.0 %, respectively; these values were much greater than the increases in RE_N (+56.1 %) and NUT₂E (+25.5 %) when soil N change was not considered. Similarly, compared with those in the CON treatment, the soil N stock (0–60 cm) in the OPT treatment increased by 8.4 %, and the N loss via leaching, ammonia volatilization and N₂O + NO + N₂ decreased by 47.1 %, 11.4 % and 28.6 %, respectively.

Conclusions

Our study revealed that the integration of optimized practices of organic material recycling, precision fertilization and water-saving irrigation substantially reduced N losses, mainly through decreased N leaching, but maintained fertilizer N in the root-zone soil layer, which is important for a sustainable and high-yield crop production.

Implications or significances

The dissemination of these optimized practices to other regions in China and beyond will be highly important for achieving the dual goals of food security and environmental protection.

Context

Subsurface drip irrigation can potentially increase nutrient uptake by altering the spatial distribution of nutrients and roots, but the efficiency enhancement potential of different phosphorus (P) sources combined with varying dripline depths still requires further evaluation.

Methods

We established a 2-year field experiment with spring maize in 2021 and 2022 to determine the regulatory effects of three P sources [P1, monoammonium phosphate (MAP); P2, ammonium polyphosphate (APP); and P0, no P] and three dripline depths (D0, surface drip irrigation, 0 cm; D15, subsurface at 15 cm depth; and D30, subsurface at 30 cm depth) on the soil NO₃-N, NH₄-N and Olsen-P distribution, root distribution, nitrogen (N) fertilizer partial factor productivity (PFPN) and P use efficiency (PUE), and grain yield.

Results

We found a significant coupling effect between the P source and dripline depth, both of which significantly impacted soil nutrients and root distribution, grain yield, PFPN, and PUE. In P1D15 and P2D15, the highest soil NO₃-N and Olsen-P contents were observed at soil depths of 0–30 and 10–20 cm and at 0–30 and 10–30 cm, respectively. Similarly, in P1D30 and P2D30, which were 20–40 and 20–40 cm, and 20–40 and 30–60 cm, respectively. Compared to the other treatments, P2D15 and P1D30 exhibited considerable increases in root length density at the 30–60 cm soil depth of 37∼52 % and 28∼58 %, respectively. Regardless of the dripline depth, P0 resulted in the lowest yield during both growing seasons. P1D30 and P2D15 were found to be the optimal combinations for achieving higher grain yield, PFPN, and PUE, as they were able to achieve a high degree of coordination between soil available N and Olsen-P, as well as root distribution.

Conclusions

The recommended approach for optimizing nutrient and root spatial distributions under subsurface drip irrigation systems involves the use of poly-P fertilizer (APP) in conjunction with shallow dripline depth and ortho-P fertilizer (MAP) paired with deep dripline depth, which provides valuable guidance for co-fertigation practices involving N and P fertilizers.

Purpose

Substituting chemical fertilizers with biogas digestate can mitigate the negative impacts of fertilizers on soil quality to promote the recycling of livestock manure. This study aims to evaluate the effects of chicken manure biogas digestate as a replacement for chemical fertilizers in rice cultivation, assessing soil nutrients dynamics, bacterial communities, nitrogen (N) metabolism enzyme activity, and rice growth.

Methods

In this study, six treatments were established: no fertilizer (CK), conventional fertilization (CF), and varying proportions of biogas digestate and other N substitution fertilizers (25 %, 50 %, 75 %, and 100 %TP). A three-year field experiment was conducted to evaluate soil nutrient levels, bacterial community abundance, N functional gene expression, rice growth conditions, and N metabolism enzyme activities using standard physical and chemical methods, high-throughput sequencing, and enzyme activity assays.

Results

Our experimental results showed that biogas digestate application promoted rice growth, while the higher biogas digestate doses increased the leaf chlorophyll SPAD values and delayed rice maturity. Compared to the CF treatment, the 75 % TP treatment significantly enhanced rice yield and economic returns. Biogas digestate increased the activities of nitrate reductase (NTR), glutamate synthase (GTS), glutamine synthetase (GLS), glutamic oxalacetic transaminase (GOT), and glutamic pyruvic transaminase (GPT) in rice leaves and grains, leading to the higher amino acid and soluble protein contents in the grains. Compared to the CK treatment, biogas digestate application increased soil pH, soil organic matter, alkaline N, available phosphorus, and available potassium by 22.14 %, 37.04 %, 39.38 %, and 39.40 %, respectively. It also enhanced the levels of nitrate N, ammonium N, and soluble organic N in soil. Furthermore, biogas digestate application significantly (p < 0.05) improved soil bacterial community diversity and stability, as well as the abundance of N metabolism functional genes.

Conclusions

Our findings suggest that substituting 75 % of chemical fertilizers with biogas digestate can serve as an optimal application rate for rice cultivation. This application in paddy field does not only reduce chemical fertilizer usage but also enhance soil nutrient content and microbial diversity. It further promotes rice growth and N metabolism enzyme activity, benefiting the increase of both rice yield and quality.

Context or problem

Partially substituting synthetic fertilizer by animal manure has been proposed as a sustainable agricultural practice, from the perspectives of improving soil quality and mitigating climate warming.

Objective or research question

Previous studies showed that manure application combined with synthetic fertilizer (MACSF) also altered soil nitrous oxide (N₂O) emissions, while the magnitude varied substantially among experiments. We hypothesized that the difference in local conditions may be responsible for the contrasting impact of MACSF on N₂O emissions, while their significance and relative importance have not been explicitly assessed.

Methods

In order to quantify the response of N₂O emissions to MACSF and its geographic variability, we conducted a meta-analysis by combining 291 observations from 103 sites across the globe. Also, we evaluated the impact of local conditions on N₂O emissions and compared their relative importance using the gradient boosting decision tree (GBDT) algorithm.

Results

Overall, MACSF did not have significant effect on soil N₂O emissions, with a global average effect size (ES) of 1.07 ± 0.10 (95 % confidence interval, CI) relative to the same amount of synthetic nitrogen fertilizer. The corresponding N₂O emission factor (EF) was estimated as 0.93 ± 0.13 % (95 % CI). However, both ES and EF varied substantially with local conditions, of which the substitution ratio (SR) and soil pH were identified as the most important factors. The ES increased significantly (p < 0.01) with the increasing SR. Critical SR was approx. 50 %, above which MACSF may exacerbate N₂O emissions. Moreover, both response indices increased significantly with the decreasing soil pH. MACSF in acidic soils (pH < 6.5) tended to increase N₂O emissions, with ES significantly (p < 0.05) higher than 1.0.

Conclusion

The contribution of MACSF to N₂O mitigation varies subustantially with local conditions, of which SR and soil pH are the most important two. MACSF reduces N₂O emissions only in the cases with low SR and neutral to alkaline soils.

Implications or significance

This study offers an integrative global synthesis of the impact of MACSF on N₂O emissions. By identifying the key controlling factors, the findings serve to guide the development of region-specific tailored substitution strategies, considering its contribution to N₂O emission mitigation.