The use of non-destructive, continuous, and rapid canopy temperature (Tc) indices for crop stress diagnosis is of significant importance for improving crop water productivity (WP). However, the comprehensive applicability of the crop water stress index (CWSI), grounded in Tc, in diagnosing both single and combined water and salt stress, as well as characterizing physiological and growth traits, remains inadequately explored.
We aim to investigate the ability of CWSI to diagnose single and combined water and salt stress and to test whether a non-water stress baseline (NWSB) with or without growth stage and genotype differences influences CWSI to characterise maize leaf physiological and growth traits.
Here, we measured the Tc using infrared radiation thermometers of two maize genotypes (XY335 and ZD958) under both single and combined water and salt stress over two growing seasons, compared the differences of NWSB in three growth stages, and established CWSI. Our analysis involved scrutinizing the differences in characterizing crop physiology and growth traits between CWSI calculated using NWSB with and without growth stage differentiations.
Our findings indicated that Tc is modulated by an interplay of soil water content, VPD, and soil salinity. The NWSB exhibited variations with both growth stage (pslope < 0.001) and genotype (pslope or pintercept < 0.01). The CWSI can diagnose single and combined water and salt stress suffered by maize. Under no stress, and single and combined water and salt stress, CWSI was significantly correlated with stomatal conductance (R2 ≥ 0.31, p < 0.1) and net photosynthetic rate (R2 ≥ 0.38, p < 0.1), rather than with hydraulic traits. The mean CWSI across the entire growth period closely correlated with leaf area index (LAI), canopy photosynthetically active radiation interception, biomass, yield, and evapotranspiration across varying treatments (R2 ≥ 0.54, p < 0.1). Contrary to CWSI derived from NWSB without growth stage variations, utilizing CWSI with growth stage distinctions better characterized physiological traits, while the former was more suitable for delineating yield and WP.
This research underscores the efficacy of CWSI for stress diagnosis and the evaluation of gas exchange and productivity in maize under both single and combined soil water-salt stress. This investigation significantly propels forward the implementation of crop-centric irrigation strategies aimed at optimizing water utilization efficiency.
Soil organic carbon (SOC) is crucial for mitigating global warming and significantly impacts crop production. While the relationship between SOC and wheat yield is well-documented, its effect on wheat grain protein content, which is essential for food security and human health, remains unclear. This study gathered management data from wheat farmers and collected plant and soil samples in the Huang-Huai winter wheat region, China’s primary wheat-growing area, from 2015 to 2022. Boundary line analysis was used to quantify the responses of wheat yield and protein content to variations in SOC. Our findings reveal that increases in SOC significantly enhance wheat yield and protein content. The highest yields, reaching up to 10,848 kg ha–1, and a maximum protein content of 17.3 % were observed in soils with SOC ranging from 7.8–18.1 g kg–1, and high-yielding, high-protein wheat exhibited higher spike numbers and grain weights and more efficient nutrient accumulation from soil or fertilizer to shoots. Optimizing SOC levels to produce high-yielding, high-protein wheat could substantially reduce nitrogen (N), phosphorus (P), and potassium (K) fertilizer use by 9.42×104, 0.70×104, and 3.66×104 Mg per year, decrease greenhouse gas emissions by 3.36 Mt CO2 eq and generate an economic benefit of 2.77 billion USD. In conclusion, our study expands the understanding of SOC’s role in crop production beyond crop yield, providing valuable insights for producing high-yielding, high-protein wheat.
Hybrid potato crops can be grown from true potato seeds or from seedling tubers. True-seed-grown plants produce lower marketable tuber yield than seedling-tuber-grown plants, because of their low early vigour and distinct growth and development patterns, notably in term of main stem number and stem branching. These differences are pivotal for yield formation but their impacts on crop performance and yield are not well understood.
We quantified the differences between the propagule types (true seeds vs seedling tubers) in their branching responses to stem density and assessed to what extent these differences contribute to differences in crop development and tuber production.
Two field experiments were conducted in different years, planting transplants from true seeds and pre-sprouted seedling tubers from the same genotype, while controlling their stem density per unit area. Responses in stem branching and biomass partitioning to stem density were quantified on individual main stems, followed by an evaluation of the impact of these responses on crop performance.
On individual main stems in both propagule types, higher stem density decreased branch development, decreased the number of branches above- and belowground, resulted in shifts in aboveground branch distribution towards lower branching orders, and led to smaller tuber sizes. However, such branching responses were stronger in true-seed-grown plants than in seedling-tuber-grown plants. At crop level, differences between propagule types were significant in canopy duration, number of tubers, tuber size distribution and marketable yield, but there was no stem density effect.
Our results emphasized the differences between propagule types in branching and its impact on crop development and tuber yield, due to the absence of stem density effects. Propagule type effects could be attributed to intrinsic differences between propagule types in branching control, growth habit and source-sink relations. These effects are relevant for hybrid potato breeding and require further research. Management practices were partly responsible for year-to-year differences in branching and yield formation, which highlights their significance for hybrid potato production.
Ultra-narrow row (UNR) cotton, a production system with rows spaced less than 40 cm apart, has been proposed as a system for earlier maturity without substantial yield loss. However, trials in the U.S.A. and Australia have found maturity benefits difficult to achieve consistently. Studies undertaken in high input cotton systems that compared UNR to conventionally (1 m) spaced cotton found yield differences but failed to demonstrate differences in crop maturity. This paper examines crop development and fruiting dynamics of the two systems in more detail to understand why there were no differences in maturity. Results showed that lack of difference in maturity between the row spacings was not influenced by differences in the time to reach crop development stages nor by lower fruit retention of early bolls in the UNR plants. Node production and fruiting site production on a per plant basis were significantly slower in the UNR plants from early in the growing season. Slower node and fruiting site production delayed maturity in the UNR plants as they set fewer fruit within the same period of time compared to plants grown in conventional spaced rows. The number of fruiting sites produced per plant was highly dependent on the amount of dry matter per plant. Fruiting site production was reduced in the UNR crop because each plant produced less total dry matter, and hence plant development was slower. To further help understand the reasons for outcomes generated in these studies, and how UNR could possibly mature earlier without impacting yield, a conceptual modelling framework was developed to integrate seasonal patterns in fruiting site production, retention, and boll growth. A key component of this framework is translating from a per plant basis to an area basis. The analysis showed that for individual UNR plants to mature earlier and maintain yield on an area basis, early node production and fruiting site production must proceed at a similar rate to conventionally spaced crops. In this scenario 90 % of final yield would be present 14 days earlier in the UNR crop compared to conventionally spaced crops. To realise any benefits of potential earlier maturity further research is needed to explore genetic or management interventions that might avoid the early competitive stress response that slows node development in UNR.
Film mulching can significantly increase crop yields, but long-term continuous mulching will reduce the soil fertility and lead to soil quality degradation. Incorporating exogenous carbon (C) is widely recognized as an effective countermeasure for improving degraded farmland soil under mulching in semiarid areas.
We compared the effects of straw and biochar on the accumulation of C and soil biochemical properties in both mulched and non-mulched farmland, and investigated the effects of various types of straw inputs on greenhouse gas (GHG) emissions.
A field experiment was conducted to test six treatments: flat planting without mulching (NN), flat planting with straw incorporation (NS), flat planting with biochar incorporation (NB), film mulching (MN), film mulching with straw incorporation (MS), and film mulching with biochar incorporation (MB)]. Comprehensive assessments were conducted in Pengyang, Ningxia, China during the two growing seasons of 2020 and 2021.
Mulching increased the soil hydrothermal conditions, maize yields (29.32 %), and GHG emissions (CO2: 10.07 %; N2O: 1.42 %) but decreased the soil organic C storage (SOCS: 6.91 %). Straw returning increased the plant fixed C (14.99 %), improved GHG emissions (CO2: 4.95 %; N2O: 4.33 %), and inhibited CH4 uptake (3.78 %). Compared with MS, MB reduced the GHG emissions (CO2: 9.93 %; N2O: 20.97 %) and net global warming potential (7.08 %), but increased the SOCS (SOCS: 3.42 %), C efficiency ratio (CER: 26.93 %), CH4 uptake (10.72 %), and soil enzyme activities (invertase: 6.48 %; urease: 13.76 %).
Incorporating biochar rather than straw has greater potential for enhancing the soil enzyme activities and C use efficiency while also reducing the GHG emissions and net global warming potential caused by mulching in dryland farming.
In this study, we comprehensively compared the effects of incorporating straw, film mulching, and biochar incorporation on C accumulation, GHG emissions, and maize yields in dryland farming. Our findings provide a scientific basis for achieving green and sustainable high-yield production in mulched dryland farming.
High nitrogen rates are important to field-grown cotton (Gossypium hirsutum L.) for recovering from stresses such as light restriction and alleviating its negative impact on yield. However, there is little information on its influence on fiber quality after shading.
The objective of this study was to examine fiber quality responses to nitrogen fertilization of shaded cotton.
Cotton plants were exposed to a 42 % reduction in global radiation for 16–25 days during early flowering, and fertilizer with different N rates in the Center-West (Primavera do Leste - PL and Chapadão do Sul - CS) and Southeast (Itapeva - IT) Brazil. Four N rates were used in PL and IT, and 3 N rates and an early (FM 906GLT) and a late-cycle (FM 983GLT) cotton cultivar were used in CS. Fiber quality from bolls taken from entire plots (nonportioned plants) and from the lower, middle, and upper thirds of the canopy (portioned plants) was assessed.
The lack of interaction in most analyses indicated shading and nitrogen effects on fiber quality as independent. Shading resulted in occasional effects on micronaire, strength, length, length uniformity, and short fiber index. Micronaire of nonportioned plants decreased in response to N inputs, wherein values at the maximum N rate were lower than those at the minimum one by 5.21 % and 7.91 % in PL and IT, respectively. Increasing N rates also decreased micronaire in all canopy portions in IT and the lower third in CS but had nonconclusive effects on other fiber properties. Fiber length and strength were generally greater in the late-maturing cultivar, which had higher micronaire readings in the lower third of the canopy and lower readings in the upper canopy compared with the early cultivar.
In conclusion, shading during early flowering has limited and inconsistent effects on cotton fiber quality. Conversely, N fertilization leads to more predictable results, so higher N rates increase the risk of heightened immature fiber percentage.
The findings of this work provide new insights into how nitrogen fertilization management affects cotton fiber quality. Future research should consider other management techniques, such as the timing of the crop termination, to avoid the occurrence of low micronaire.
The rising demand for animal protein has intensified forage shortages and restricted pasture availability, underscoring the critical need for effective dual-purpose animal feeds.
This study aims to evaluate the potential of vegetative soybeans as animal feed by assessing their nutritional value and productivity. Specifically, it explores the feasibility of using late-maturing soybean varieties, adapted to low latitudes, as forage in high-latitude regions and examines the impact of different planting dates on their growth and effectiveness during limited growing seasons.
To achieve these objectives, a series of field and controlled experiments were conducted. The first experiment assessed 418 mid-maturing soybean varieties from the Huang-Huai-Hai Basin in China for their nutritional value as forage during 2020 and 2021. The second experiment tested late-maturing and photoperiod-sensitive soybean varieties, including "ZGDD" and the methionine-enhanced material "Ox-CGS," under tropical conditions with extended daylight. The third experiment evaluated forage soybeans sown on June 19th, July 14th, and August 8th, 2022, to determine their yield and protein content.
Results showed that the first experiment yielded an average protein content of 24.7 %, ether extract content of 1.9 %, neutral detergent fiber content of 41.9 %, and acid detergent fiber content of 27.3 %, with a relative feeding value of 153, surpassing local standards for high-quality leguminous forage. The second experiment demonstrated that extended daylight increased crude protein yield by 3.7 times compared to Chinese soybean seed yields, and "Ox-CGS" showed a 24.2 % increase in methionine content. The third experiment revealed that forage soybeans achieved a crude protein yield of 0.95 t/ha within 60 days, exceeding the 2022 average of 0.68 t/ha for seed soybeans in China.
The findings indicate that photoperiod-sensitive soybeans can be effectively used as forage over extended periods, utilizing artificial lighting or cultivation in higher latitudes, and that short growth cycles enhance crude protein accumulation.
This research highlights the potential of soybeans to alleviate forage shortages, improve land use efficiency, and contribute to food security and agricultural development, especially on marginal lands and in regions with limited growing seasons.
As the frequency of intensive storm events increases in the U.S. Corn Belt, reduced stature maize hybrids could provide a new approach to improved climate resilience in maize production. We designed gene-edited D8 (dwarf8, zm-D8) maize germplasm with reduced stature to evaluate morphometric traits and grain yield. Four elite edited zm-D8 maize hybrids and their isogenic standard height hybrid comparators were evaluated over a total of 17 field locations in 2021 and 2022. Across three plant densities (80 K, 100 K and 120 K plants ha−1), plant height of the edited zm-D8 reduced stature hybrids was reduced 34 % and ear height was decreased 32 %. In each of the three plant densities, grain yield of the edited zm-D8 reduced stature hybrids was comparable to the isogenic standard height hybrids. Also, edited zm-D8 hybrids had significantly less lodging than the standard hybrids. In a separate study, DP202216 (ZmGos2:zmm28) a transgenic event with increased and extended expression of the zmm28 transcription factor, was crossed with reduced stature edited zm-D8 hybrids. Combining edited zm-D8 with event DP202216 significantly increased hybrid yields over those of edited zm-D8 hybrids under high density (120 K plants ha−1). These results support a maize production system where edited zm-D8 reduced stature hybrids, alone or in combination with DP202216, provide improved climate resilience with grain yields competitive to standard height hybrids.
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