Abstract Background Alternate wetting and drying (AWD) irrigation improves water use efficiency (WUE) in rice, but its effectiveness in ratoon rice under varying climatic conditions remains unclear. This study is the first 3-year field experiment to assess the climate-dependent impacts of AWD irrigation on ratoon rice, particularly under extreme heat conditions. Methods A 3-year field experiment (2020–2022) was conducted to examine AWD irrigation’s effects on soil properties, rice growth, yield, and WUE in a main-season–ratoon rice system. Four irrigation methods were tested: conventional irrigation (CK), AWD during the main-season rice filling period (T1), AWD during the ratoon rice filling period (T2), and AWD during both periods (T3). Weather data showed higher temperatures and lower rainfall in 2022 compared to 2020 and 2021. Results AWD irrigation increased soil bulk density and total nitrogen, and and NO3− concentrations, while reducing NH4+ concentrations in both rice seasons. In 2020 and 2021, AWD irrigation positively increased root dry weight and activity, net photosynthetic rate, chlorophyll fluorescence, nitrogen metabolism enzyme activity, yield and WUE. However, the opposite was observed in 2022. Specifically, in 2020 and 2021, compared with CK, T1 and T3 increased the yield in the main season by 12.81% and 11.66%; T1, T2 and T3 increased the yield in the ratoon season by 12.93%, 7.66% and 24.10%; T1 and T3 increased the WUE in the main season by 14.90% and 14.07%; and T1, T2 and T3 increased the WUE in the ratoon season by 11.10%, 15.01% and 33.00%, respectively. In 2022, compared with CK, T1 and T3 reduced the yield in the main season by 12.04% and 12.60% and the yield in the ratoon season by 13.72% and 16.37%, and T1 and T3 reduced the WUE in the main season by 10.34% and 10.35% and the WUE in the ratoon season by 3.45% and 10.34%, respectively. Conclusions AWD irrigation enhances yield and WUE under normal conditions but reduces them under extreme heat. This study highlights the need for adaptive irrigation strategies, integrating heat-tolerance measures to counteract the adverse effects of climate change on ratoon rice production.

Adjusting the sowing date is a crucial strategy for improving rice adaptability to climate change and improving grain yield. Among the quality traits of fragrant rice, the content of 2-Acetyl-1-Pyrroline (2-AP) in brown rice has garnered significant attention due to its impact on flavor and market value. The comprehensive effects of weather changes induced by adjusting the sowing date on the synthesis and accumulation of 2-AP in fragrant rice, as well as on yield, remain unclear. We conducted a 5-year field study in Hubei Province, China, measuring sunshine duration, temperature, and rainfall variations under six sowing dates. The research aimed to assess the comprehensive effects of these changes on the 2-AP content in brown rice and fragrant rice yield. Delaying the sowing date resulted in shortening the rice growth duration from transplanting to heading. Early sowing (March 16) resulted in the highest rice yield, while late sowing (June 1) led to the highest 2-AP content. Generally, with delayed sowing, the effective panicles and 1000-grain weight increased, while the number of spikelets per panicle and grain filling rate decreased. The contents of proline, pyrroline-5-carboxylic acid, and gamma-aminobutyric acid exhibited a trend of initially increasing and then decreasing with delayed sowing. The 2-AP content was significantly positively correlated with rainfall during the grain filling to maturity stage, while it showed significant negative correlations with sunshine duration, average air temperature, and the number of high temperature days (maximum air temperature >= 35 degrees C) during the same stage. Since the sowing date for the highest yield differed from that for the highest 2-AP content, we recommend early sowing to achieve optimal yield while implementing other strategies to mitigate the negative effects of prolonged sunshine duration and high temperatures during the grain filling to maturity stage on 2-AP content. This study reveals the relationship between 2-AP content and the yield of fragrant rice with weather factors during different growth stages, providing new insights for adjusting sowing dates to adapt to climate change in order to achieve either high yield or high 2-AP content.

Ratoon rice occupies an important position in rice production owing to its time-saving, labor-saving and low-pollution planting, and increased benefits. However, the impact of tillage management on the yield in rice ratooning system has not yet been reported. Thus, field experiments were carried out to investigate the impact of seven tillage methods on the yield of ratoon rice crop in Jingzhou City in 2021–2022. The managements included winter plowing + rotary 2 times (PTw + RT2) or 3 times (PTw + RT3), spring plowing + rotary 2 times (PTs + RT2) or 3 times (PTs + RT3), no plowing + rotary 2 times (P0 + RT2) or 3 times (P0 + RT3) and no tillage (NT). PTw + RT3 had the highest total rice yield. The experimental data were collected in 2021 and 2022. In terms of main season rice yield, the order of ranking was PTw > PTs ≈ NT ≈ P0, while for ratoon rice yield, the ranking was NT > PTw ≈ PTs > P0. Generally, the root function ranked as PTw > PTs > P0 > NT. The photosynthetic capacity of the main season rice always maximized in PTw, those of the ratoon rice all maximized in NT, and those of both the main season rice and ratoon rice always minimized in P0. In the three tillage modes (PTw, PTs, P0), an additional rotary tillage did not affect the growth or yield of rice. PTw + 3RT was the highest yielding tillage management, but it is still necessary to explore other PTw + 3RT methods and more economical tillage management to increase the yield of ratoon rice.

Research findings suggest that alternate wet and dry irrigation (AWD) can potentially reduce water consumption and enhance the water use efficiency (WUE) of rice cultivation. However, the impact of AWD on the main season-ratoon rice system remains less explored. A three-year field experiment (2020-2022) was conducted in Jingzhou City, Hubei Province, China, aimed at investigating the effects of AWD on soil physicochemical properties, rice growth, yield, and WUE in main season-ratoon rice system, accounting for different weather conditions. Employing a single-factor experimental design, four irrigation methods were tested: conventional irrigation (CK), AWD during the filling period of the main season rice (T1), AWD during the filling period of the ratoon rice (T2), and AWD during the filling period of both main season rice and ratoon rice (T3). Results indicate that AWD led to increased soil bulk density at a depth of 0-20cm and elevated concentrations of total nitrogen and NO3−, while reducing NH4+ concentrations. In 2020 and 2021, the AWD positively influenced root dry weight and activity, net photosynthetic rate, nitrogen metabolism enzyme activity, yield, and water use efficiency, while in 2022, the opposite was true. Specifically, in 2020 and 2021, compared to CK, T1 and T3 increased the yield in main season by 12.81% and 11.66%, T1, T2 and T3 increased the yield in ratoon season by 12.93%, 7.66%, and 24.10%, respectively. In 2022, compared to CK, T1 and T3 reduced the yield in main season by 12.04% and 12.60%, the yield in ratoon season by 13.72% and 16.37%, respectively. In summary, the effect of AWD on improving the yield and WUE of main season rice and ratoon rice is regulated by weather. In situations where extreme high temperatures weather could damage rice growth, AWD should be carefully selected in ratoon rice systems.

Background Improving the yield and aroma content of fragrant rice is the focus of fragrant rice research. Light and Zinc (Zn) management generally cause regulations in the 2-acetyl-1-pyrroline (2AP) accumulation in fragrant rice. In addition, Zn promotes rice growth and improves rice yield, which has the potential to compensate for the negative impact of low light on fragrant rice yield. However, the potential of Zn to improve fragrant rice yield and 2AP content under shading conditions has not been verified. Methods Field experiments were conducted in the rice season (May–September) in 2019 to 2021. Two light i.e., normal light (NL) and low light (LL) and four Zn levels i.e., 0 kg Zn ha − 1 (N0), 1 kg Zn ha − 1 (Zn1), 2 kg Zn ha − 1 (Zn2), and 3 kg Zn ha − 1 (Zn3), which applied at booting stage was set up. The grain yield, 2AP contents, Zn content in polished rice, photosynthesis related indicators, MDA content, antioxidant enzyme activity and the biochemical parameters related to 2AP formation were investigated. Results Shading reduced yield by 8.74% and increased 2AP content by 24.37%. In addition, shading reduced net photosynthetic rate (Pn), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and increased proline, γ-aminobutyric acid (GABA), and pyrroline-5-carboxylic acid (P5C), proline dehydrogenase (PDH), △1-pyrroline-5-carboxylic acid synthetase (P5CS), malondialdehyde (MDA). With increasing Zn application levels, yield, 2AP, Zn content in polished rice, Pn, proline, P5C, GABA, PDH, P5CS, SOD, CAT and POD increased, and MDA decreased. Significant Light and Zn interaction effect on 2AP content was detected, and both shading and increasing Zn application increased the 2AP content. Conclusion Shading can increase the 2AP content but reduce the yield of fragrant rice. Increasing Zn application under shading conditions can further promote the biosynthesis of 2AP, but the effect of improving yield is limited.

The application of selenium (Se) can promote the growth of potatoes and increase the Se content of potato tubers. Nitrogen (N) can promote nutrient absorption and potato yield. However, the effects of Se and N on the yield and Se content of potato tubers have not been reported. Field experiments were conducted in 2019–2020 and 2020–2021. Three N levels, i.e., 0 kg N ha−1 (N0), 150 kg N ha−1 (N1) and 200 kg N ha−1 (N2), and three Se levels, i.e., 0 g Se ha−1 (Se0), 500 g Se ha−1 (Se1) and 1000 g Se ha−1 (Se2), were set up. Potato yield, root dry weight, root activity, leaf area index (LAI), net photosynthetic rate (Pn), malondialdehyde (MDA) content, antioxidant enzyme activity and Se content were investigated. N application increased root dry weight and activity, LAI, antioxidant enzymes activities, Se content and decreased MDA content. Pn, total potato yield and commercial potato yield first increased and then decreased with the increase in N application level. Se application increased root activity, Pn, antioxidant enzyme activities, total yield, commercial potato yield, commercial potato rate, Se content and decreased MDA content. In general, compared with the single application, the combination of N and Se fertilizers further promoted the growth of potatoes, increased the yield of potatoes and the Se content of potato pieces.

In wheat production, improving resource utilization and grain yield is the goal researcher have been pursuing. This study aimed to investigate if a regulated nitrogen (N) and selenium (Se) fertilizer management could increase wheat yield and N use efficiency (NUE). This study reports the effects of three N application levels (N0: 0 kg N ha−1, N1: 180 kg N ha−1, N2: 270 kg N ha−1) and a combination of three Se application levels (Se0: 0 g Se ha−1, Se1: 450 g Se ha−1, Se2: 900 g Se ha−1) on N metabolism, NUE and yield in wheat in 2020–2021. Compared with N0, wheat yield increased by 44.76% in N1 and by 54.32% in N2, and the activity of N-metabolizing enzymes increased by 25.15~35.03% in N1 and by 32.01~51.27% in N2. Compared with N1, the apparent recovery efficiency of N, the agronomic N use efficiency and the partial factor productivity of applied N decreased by 15.71%, 28.00% and 28.93% in N2, respectively. Compared with Se0, the 1000-grain weight increased by 3.93% in Se1 and by 4.87% in Se2, and the activity of nitrogen-metabolizing enzymes increased by 4.23~4.91% in Se1 and by 6.65~8.46% in Se2. We conclude that Se could improve the wheat 1000-grain weigh and N metabolism and has the potential to increase wheat yield and NUE.

Ratooning rice has the advantages of saving production costs and improving grain yield. However, there are less reports on the effect of the combination of nitrogen fertilizer and organic materials on the soil in the ratooning rice mode. This study compared the effects of different nitrogen fertilizer combinations with organic materials on the soil properties of ratooning rice paddy fields to provide a reference for the sustainable development of ratooning rice models. A two-year (2020–2021) single-factor experiment was conducted in Jingzhou, Hubei, China. The experiment included five base fertilizer treatments: no nitrogen fertilizer (N0), base fertilizer nitrogen from conventional urea (CK), 50% base fertilizer nitrogen from conventional urea and 50% from slow-release urea (T1), biochar (T2), or animal manure (T3). The fertilization mode of T2 was only conducted in 2020, which was the same as that of CK in 2021; The fertilization modes of the other treatments were the same for both years. Compared with N0, the bulk density (BD) in the 0–20 cm soil layer at the heading stage of the main season rice and at the heading stage of the ratooning season rice decreased by 3.92%–6.15% in CK and by 4.38%–6.74% in T1, whereas the BD at the 0–40 cm soil layer during the whole growth period decreased by 9.82%–17.87% in T2 and by 9.48%–14.21% in T3. The order of soil pH in 2020 was T2>T3>N0>T1>CK. Compared with CK, pH in 2020 increased by 0.51−0.68 in T2. The order of soil pH in 2021 was T3>T2>N0>T1>CK. Compared with CK, the pH in 2021 increased by 0.14−0.32 in T3. The content of soil organic carbon (SOC) and total nitrogen (TN) in the 0–20 cm and 20–40 cm soil layers were T2>T3>T1>CK>N0. Compared with N0, other treatments increased the content of SOC and TN in the 0−20 cm soil layer by 4.79%−29.12% and 11.36%−28.49%, respectively; and they increased the contents of SOC and TN in the 20−40 cm soil layer by 5.43%−30.79% and 6.08%−20.02%, respectively. The contents of NH4+ and NO3− at the tillering and heading stages of the main season rice and the heading stage of the ratooning season rice were the highest under the CK, T1, and T3 treatments. Compared with N0, the contents of NH4+ and NO3− at the tillering stage of the main season rice increased by 131.26% and 153.59% under the CK treatment, respectively; the contents NH4+ and NO3− at the heading stage of the main season rice increased by 217.15% and 153.91%, respectively, under the T1 treatment; and the contents of NH4+ and NO3− at the heading stage of ratooning season rice increased by 246.76% and 126.70%, respectively, under the T3 treatment. Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and urease (UR) activity in T2 and T3 were higher than in the other treatments. Compared with N0, MBC content increased by 18.29%−45.18% in T2 and 21.46%−46.10% in T3, MBN content increased by 49.25%−140.37% in T2 and 59.62%−142.57% in T3, and UR activity increased by 31.45%−225.04% in T2 and 60.83%−246.65% in T3. The β-glucosidase (BG) activity was the highest in the T3 treatment. Compared with N0, the BG activity increased by 21.26%−44.87% under the T3 treatment. A comparative analysis showed that the effect of animal manure on reducing BD and improving SOC and TN was similar to that of biochar, and its effect on improving inorganic nitrogen, microbial biomass, and soil enzyme activity was better than that of biochar. Therefore, animal manure and chemical fertilizers should be used as base fertilizers, and animal manure should replace 50% of the chemical fertilizer nitrogen.

Abstract Ratoon rice is resource efficient to produce economically sound and environmentally sustainable rice production. However, there is no more information on the relative impact of soil tillage practices on soil physical and chemical properties, microbial biomass, and enzymatic activity, and grain yield in a rice–ratoon rice cropping system remains to be tested. Systematic study of soil under ratooning rice model is a problem to be solved in the development of ratooning rice model. This study primarily investigated the long‐term (from 2014 to 2020) changes in soil bulk density (BD), soil organic carbon (SOC) concentration, total nitrogen (TN) concentration, microbial biomass, β‐glucosidase activity (BG), urease activity (UR), and yield under four treatments: no‐tillage (NT), no plowing tillage + rotatory tillage (RT), plowing tillage in winter + rotatory tillage (PTW), and plowing tillage in spring + rotatory tillage (PTS). NT increased BD by 9.65%–12.97%, and RT increased the 20–40 cm soil layer BD by 8.80% in 2020, compared with the baseline initial value (in 2014). Plowing tillage (PT) time had no significant effect on BD. All tillage methods decreased the SOC concentration in the 0–20 cm soil layer, and only RT increased the TN concentration. PT was the only treatment that increased the SOC and TN concentrations in the 20–40 cm soil layer. Both the main‐season rice yield and the ratoon season rice yield ranked PTW > PTS > NT > RT, in which the main‐season rice yield increased by 28.15% and the ratoon season rice yield increased by 25.19% in PTW. Overall, the PTW treatment had the highest microbial biomass, enzyme activity, and grain yield compared with the other tillage methods. In conclusion, plowing tillage in winter + rotatory tillage is a more suitable tillage method under the mode of ratooning rice.

The Chinese government regards ensuring food security and developing water-saving agriculture as an important national strategy and that carrying out relevant research has important practical significance and production application value. A two-year field experiment was conducted to explore the compensation potential in rice yield by using rice varieties with different panicle size under two water management regimes (conventional water management or CWM and alternate wetting and drying or AWD). The results showed that the large panicle rice variety resulted in greater yield, crop water productivity, spikelet density, dry matter accumulation and translocation, and photosynthesis. Compared with the CWM, the AWD had little effect on rice yield. However, with an appropriate planting density, the AWD achieved a greater grain yield compared with the CWM. Moreover, the AWD increased crop water productivity and the grain-filling efficiency. The loss of spikelets under the AWD could be compensated by increasing the planting density. Although AWD reduced tillering number, it increased the photosynthetic rate, dry matter accumulation and its translocation to grain, and leaf area index. In addition, the adverse effects on rice growth and the yield caused by the AWD could be alleviated by increasing planting density of rice. Therefore, an appropriate planting density can be used to save water and maintain high grain yield of rice under alternate wetting and drying.

Some of the major challenges facing rice researchers are how to improve yield and also increase the aroma content of fragrant rice. It has been established that light and Nitrogen (N) management affect the accumulation of 2-acetyl-1-pyrroline (2AP) in fragrant rice. However, the ability of N to improve yield in fragrant rice and improve its 2AP content has not been established. Nevertheless, N promotes rice growth and improves rice yield, which has the ability to compensate for the negative impact of low light on fragrant rice yield. The aim of this study was to investigate the impact of N application rates on rice yield and 2AP accumulation under shading conditions. Field experiments were conducted between May and September from 2019 to 2021. The experiments were conducted in ambient light condition (AL) and low light condition (LL); using four different levels of N-0 kg N ha-1 (N0), 20 kg N ha-1 (N1), 40 kg N ha- 1(N2),and 60 kg N ha-1 (N3)-which were applied during the booting stage. The grain yield, 2AP content, photosynthetic related indicators, N content in rice, Malondialdehyde (MDA) content, antioxidant enzyme activity and the biochemical parameters related to 2AP formation were all investigated. Our results showed that shading reduced yield by 5.00 % and increased 2AP content by 23.40 %. In addition, shading reduced net photosynthetic rate (Pn), leaf area index (LAI), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and N content in rice, and increased proline, gamma-aminobutyric acid (GABA), and pyrroline-5-carboxylic acid (P5C), proline dehydrogenase (PDH), o1-pyrroline-5-carboxylic acid synthetase (P5CS), malondialdehyde (MDA). Although increased N application levels increased the yield, 2AP, Pn, LAI, proline, P5C, GABA, PDH, P5CS, SOD, CAT, POD and N content of rice, the ornithine aminotransferase (OAT), diamine oxidase (DAO) and MDA levels all decreased. The findings of this study showed that shading increased 2AP content of fragrant rice, but reduced its yield. However, increase in N application under shading conditions increased both the biosynthesis of 2AP and yield in rice.

Cadmium (Cd) contamination in agricultural soils has become a serious issue owing to its high toxicity threat to human health through the food chain. The purpose of this paper is to explore the availability of foliar selenium (Se) application in reducing Cd enrichment in brown rice. A field experiment from 2017 to 2019 was conducted to investigate the effects of foliar Se application on the physiology and yields of three rice cultivars and their accumulation of Cd in low-Cd and high-Cd soils. The grain protein contents and yields of rice plants grown in the high-Cd soil were lower than those of plants cultivated in the low-Cd soil by 27.85% and 6.82%, whereas the malondialdehyde (MDA) and Cd contents were higher by 66.06% and 91.47%, respectively. Se application reduced Cd translocation from the stems and leaves to the spikes, decreasing the Cd content in brown rice by 40.36%. Additionally, Se enhanced the antioxidative activity, glutathione and protein contents, and rice yield (7.58%) and decreased the MDA and proline contents. However, these Se effects weakened under the high-Cd soil. Foliar Se application can alleviate Cd-induced physiological stress in brown rice while improving its yield and reducing its Cd content.

探究复合肥、缓/控施肥、有机无机互混肥和不施氮肥对传统中稻模式和稻虾共生模式下水稻生长动态及产量的影响,为不同稻作模式下优化氮肥管理和提高水稻产量提供理论依据.采用裂区设计,2种稻作模式为主区,4种氮肥施用类型为裂区,于水稻主要生育期内调查水稻叶面积指数(LAI)和光合势(LAD)、干物质积累量(DW)和生长速率、光合特征,成熟后测定产量及产量构成因子,计算收获指数和氮肥偏生产力.结果表明:稻虾共生模式下水稻生育期延长,抽穗期LAI、抽穗期和成熟期DW、生长速率、抽穗期SPAD值和净光合速率、产量显著降低,抽穗期至成熟期LAD显著增加.常规中稻模式下未施氮处理的生殖生长期和全生育期短于3个施氮处理,稻虾共生模式下未施氮处理的营养生长期和全生育期长于3个施氮处理.有机无机互混肥的各时期LAI、LAD、抽穗期光合能力和千粒重最高,复合肥的分蘖期光合能力和抽穗期至成熟期生长速率最高,缓/控释肥的各时期DW、分蘖期至抽穗期生长速率、有效穗数、产量和氮肥偏生产力最高.缓/控释肥是两种稻作模式下水稻产量和氮肥偏生产力最高的最佳氮肥类型.

Abstract Background: Improving the yield and aroma content of fragrant rice is the focus of fragrant rice research. Light (L) and Zinc (Zn) management generally cause regulations in the 2-acetyl-1-pyrroline (2AP) accumulation in fragrant rice. In addition, Zn promotes rice growth and improves rice yield, which has the potential to compensate for the negative impact of low light on fragrant rice yield. However, the potential of Zn to improve fragrant rice yield and 2AP content under shading conditions has not been verified.Methods: Field experiments were conducted in the rice season (May-September) in 2019 to 2021. Two light i.e., normal light (NL) and low light (LL) and four Zn levels i.e., 0 kg Zn ha−1 (N0), 1 kg Zn ha−1 (Zn1), 2 kg Zn ha−1(Zn2), and 3 kg Zn ha−1 (Zn3), which applied at booting stage was set up. The grain yield, 2AP contents, Zn content in polish rice, photosynthesis related indicators, MDA content, antioxidant enzyme activity and the biochemical parameters related to 2AP formation were investigated.Results: Shading reduced yield by 8.74% and increased 2AP content by 24.37%. In addition, shading reduced net photosynthetic rate (Pn), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and increased proline, γ-aminobutyric acid (GABA), and pyrroline-5-carboxylic acid (P5C), proline dehydrogenase (PDH), △1-pyrroline-5-carboxylic acid synthetase (P5CS), malondialdehyde (MDA). With increasing Zn application levels, yield, 2AP, Zn content in polish rice, Pn, proline, P5C, GABA, PDH, P5CS, SOD, CAT and POD increased, and MDA decreased. Significant L and Zn interaction effect on 2AP content was detected, and both shading and increasing Zn application increased the 2AP content.Conclusion: Shading can increase the 2AP content but reduce the yield of fragrant rice. Increasing Zn application under shading conditions can further promote the biosynthesis of 2AP, but the effect of improving yield is limited.

Prevalent irregular rainfall, flooding for weed control, and unleveled fields in the middle and lower reaches of the Yangtze River all contribute to flooding stress on germination and growth of direct-seeded rice (Oryza sativa L.). Herein, some experiments were conducted so as to assess the effects of seed priming with selenium (Se) on the germination and growth of rice under hypoxia. The experiment was arranged in a completely randomized factorial design with two factors and five replicates. Factors included Se concentration (0, 30, and 60 μmol/L) and duration of flooding stress (0, 2, 4, and 8 days). The experimental results showed that Se accelerated seed germination and increased emergence index and final emergence percentage. Additionally, Se increased shoot and root lengths and dry weights, but high Se concentration (60 μmol/L) reduced 18-day-old seedling dry weight under long-term flooding (8 days). Furthermore, Se reduced malondialdehyde content and increased starch hydrolysis efficiency in seeds, superoxide dismutase, peroxidase, catalase, and glutathione peroxidase activities and seedling soluble protein and total chlorophyll contents. Se improved seedling total Se and organic Se contents while increasing total dry weight and yield. Notably, the highest yield was obtained after a 4-day flooding period. Although Se priming favored rice seedling emergence and growth under flooding conditions, Se concentrations equal or above 60 μmol/L increased the risk of seedling death during long-term flooding (≥8 days).

为研究不同栽培措施对江汉平原中稻的影响,采用L9(34)正交试验设计,对中稻"黄华占"连续两年采用播种期、施氮量、基本苗、水层进行不同栽培因素组合试验,探索不同栽培措施对中稻"黄华占"生长和产量的影响.结果表明,播种期和施氮量能显著影响生育期,播种期每推迟1期生育期缩短1.7～2d,施氮量每增加50kg/hm2生育期延长0.3～2d;施氮量与基本苗对产量关系密切,施氮量为150kg/hm2和移栽的基本苗60×104株/hm2时产量最高,平均达到8898.30kg/hm2;施氮量与基本苗主要通过影响单位面积有效穗进而影响产量,单位面积有效穗与产量呈显著正相关(R2=0.6859,P＜0.05).综合考虑,"黄华占"最佳的栽培因素组合为播种期4月25日,施氮量纯N 150kg/hm2,基本苗60×104株/hm2,移栽后7d内统一灌水5cm.

Tillage intensity and planting density are closely related to rice growth and its yield, in order to understand the comprehensive effects of them on rice, such field experiment was made. Before the experiment, conventional tillage (one-time plowing and one-time rotary tillage) was used for the experimental paddy fields for long term. In the experimental years of 2019 and 2020, three tillage intensities and planting densities were designed. The tillage treatments were no tillage, reduced tillage (only one-time rotary tillage), and conventional tillage, and the three designed planting densities had the same number of planting pit (166,667 pits/ha, the distance between adjacent planting pits is 30 cm and 20 cm), and different number of transplanted seedling each pit which was 2 seedlings (D1), 5 seedlings (D2), and 8 seedlings (D3). The filed experimental results showed that under no tillage there was the highest value in rice yield, spike density, spikelets per panicle, 1000-grain weight, net photosynthetic rate (Pn), chlorophyll content, leaf area index (LAI), and above-ground biomass; compared with reduced tillage (or conventional tillage), no tillage increased rice yield by 7.35% (22.07%) and rice spike density by 5.09%(10.08%), increasing the number of transplanted seedling per planting pit to D2 from D1 significantly increased the spikes density, LAI, and above-ground biomass, while did not decrease significantly the spikelets per panicle, Pn, and chlorophyll content; meanwhile, the number of transplanted seedling per planting pit increased to D3 from D2, the above growth indicators did not increase significantly, and the correspondingly photosynthetic indexes decreased significantly; compared with D1(D3), D2 increased rice yield by 3.74% (6.99%). Obviously, it is an effective way for stable and high yield of rice to optimize planting density and tillage intensity.

针对江汉平原早稻-再生稻模式不利种植越冬作物的突出问题,研究中稻-再生稻模式培肥增效可为提高土地利用率提供科学依据.以水稻品种两优1208为试验材料,针对头季稻进行施肥处理,以施磷钾肥不施氮肥为对照(CK),设置3种基肥与追肥组合处理,各处理的总有效养分相同(N-P2O5-K2O=120-63-135 kg/hm2),钾肥作基施和穗肥分2次等量施用,氮肥作基肥、分蘖肥和穗肥分3次施用,其施用比例对于处理CRF(基施缓控释复合肥)为8:0:2,对于处理CF(基施复合肥)和OCF(基施有机无机复混肥)为5:3:2.结果表明,两优1208作为再生稻用种,全生育期为156～157 d;通过观测不同施肥处理下水稻叶面积指数、SPAD值和干物质积累发现,基施复合肥可促进头季稻前期至中期生长,基施缓控释复合肥可促进头季稻后期和再生稻的生长,基施有机无机复混肥可促进再生季水稻生长.

通过试验了解不同耕作方式下土壤无机氮动态和水稻生长状况,为再生稻稻田土壤培肥提供科学依据.按冬前是否翻耕和插秧前旋耕情况设置4种耕作方式:翻耕1次旋耕1次(T1)、翻耕1次旋耕2次(T2)、不翻耕旋耕2次(T3)和不翻耕旋耕3次(T4),观察4种耕作方式下土壤无机氮动态变化和水稻生长情况.结果表明:在水稻主要生育期,不同耕作处理下土壤无机氮含量、植株干物质积累和水稻产量均呈现T2>T1>T4>T3的趋势,翻耕与旋耕结合的效果明显好于旋耕.因此,翻耕1次旋耕2次(T2)可提高土壤无机氮供应,促进水稻生长发育,有利干物质积累和提高水稻产量,是值得推荐采用的适宜早稻-再生稻生产的耕作方式.

Conservation tillage is an environmentally friendly and economical farming method, but its impact on rice yield is controversial. Artificially applied side deep fertilizing of machine-transplanted rice is when fertilizer is applied to the deep soil along with the machine transplantation of rice; this may improve the fertilizer utilization rate and rice yield and eliminate the possible negative effects of conservation tillage on rice yield. Using on machine-transplanted rice, this study aims to compare the effects of side deep fertilizing (SDF). We investigated the effects of artificially applying fertilizer (AAF) on rice growth and yield under conventional tillage (CT), reduced tillage (RT), and no tillage (NT). The rice root activity, root dry weight, leaf area index (LAI), net photosynthetic rate (Pn), chlorophyll content, panicle density, spikelets per panicle, and yield were all ranked as NT > RT > CT and SDF > AAF. The 1000-grain weight was also ranked as SDF > AAF. In addition, under NT conditions, the positive effect of SDF on rice growth and yield was higher than under RT and CT conditions. In general, conservation tillage combined with SDF saved costs and increased rice yield.