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Waterlogging and salinization are considered to be the main threats to agricultural productivity and land resources in coastal areas of China. Thus far, drainage and field soil improvement programs have been ineffective. In this article, we investigated the effect of subsurface drainage combined with biochar (B–S) on soil physicochemical properties and soil bacterial community structure in coastal saline soil. In this study, B–S significantly reduced soil electrical conductivity (EC) and soil water content (W) by 35% and 10.65% compared to no drainage (CK). Compared to CK and drainage alone (S), B–S significantly increased soil total nitrogen (TN) by 24.78% and 39.62%, soil available phosphorus (AP) by 28.29% and 69.82%, soil nitrate (NO3−-N) by 64.65% and 35.45%, and significantly increased soil organic matter (SOM) by 74.69% and 66.10%, respectively. It also significantly increased alkaline phosphatase (ALP) and urease activities. The results of redundancy analysis (RDA) showed that CAT and urease made the greatest response to changes in environmental factors, indicating that CAT is more sensitive to changes in environmental alterations than ALP. AP was the dominant factor in the change in enzyme activity (R2 = 53.0%, p < 0.05), followed by NO3−-N (R2 = 14.8%). SOM was the dominant factor in the variation in microbial abundance content (R2 = 38.5%, p < 0.05), followed by ALP (R2 = 20.0%, p < 0.05). The results of the study can provide guidance for effective land use and sustainable development of agricultural soil ecology in coastal areas. [ABSTRACT FROM AUTHOR]

Soil salinization is a global issue that results in soil degradation and affects the sustainable development of irrigated agriculture. A 2-year study was conducted in 2018 and 2019 to identify the effect of subsurface drainage spacing on soil moisture, salt, cotton growth, and yield under the Tarim Basin oasis in China. The tests involved three subsurface drainage treatments, with a pipe spacing of 10 m (W10), 20 m (W20), and 30 m (W30), respectively, and a drainage-absent treatment (CK). Compared with CK, subsurface drainage reduced soil salinity, resulted in better uniform water distribution and reduced inorganic salt concentration in shallow soil solution. In addition to improving soil moisture and salinity conditions, subsurface drainage increased seedling emergence rate (28%), root vigor (23%), and chlorophyll content (44%) of cotton, which in turn led to increases in cotton plant height (18%), leaf area (33%), dry matter weight (32%), and reproductive organ weight (39%), thereby resulting in high cotton yield (45%). A path analysis revealed that under subsurface drainage, the seedling emergence rate of cotton had the greatest impact on cotton yield, and subsurface drainage contributed the most to the increase in cotton yield. It increased the seedling emergence rate by reducing soil salinity. Moreover, cotton yield and next-year soil arability increased with decreasing drainage pipe spacing, suggesting that it is advantageous to adopt a drainage pipe layout with small pipe spacing when economic costs are not a concern. [ABSTRACT FROM AUTHOR]

In recent years, the alternating occurrence of high temperature and waterlogging disasters in South China has seriously reduced the yield of single cropping rice. Studying the changes in anatomical structure of the rice root system could provide theoretical basis for understanding the mechanisms of high temperature and waterlogging stress. To examine interactions between temperature and waterlogging stress, an experiment was set up in a growth chamber consisting of two temperatures (moderate, 30–34 °C and high, 35–38 °C) with three depths of flooding (0–5, 10 and 15 cm). Treatments commenced at the booting stage and lasted five days, after which all treatments were returned to a 0–5 cm flooding depth and the same temperature regime. Observations were made immediately after cessation of treatments, then after 5, 10 and 20 d to test the effect of treatments on subsequent root anatomical development. The low-stress control (0–5 cm, medium temperature) showed no change with time in aerenchyma area, thickness of the outer root, stele diameter, and the number nor diameter of xylem vessels. Root diameter and stele diameter under the high-stress control (0–5 cm, high temperature) were decreased by 29.09% and 15.28%, respectively, at the booting stage, whereas the high stress control (15 cm, high temperature) affected only the vessel diameter, reducing it by 14.11% compared with that in the low-stress control (0–5 cm, medium temperature). Compared to the high-stress control (0–5 cm, high temperature), the interaction of high temperature and waterlogging stress alleviated the inhibiting effect of the changes in the root system, especially after the end of the stress. We thought that waterlogging could reduce the damage of high temperature on rice root growth. Low water depth waterlogging has little effect on rice root system and aerenchyma area root diameter at 0, 5, 10 and 20 d after the stress ended, and the thickness of the outer root, stele diameter and the number and diameter of vessels at 0 d under M15 (15 cm, medium temperature) had no significant difference compared with M5 (0–5 cm, medium temperature). However, the increase in rice root diameter, stele diameter, thickness of the outer root cortex depth and vessel diameter were inhibited under high temperature stress at the booting stage. Root diameter and stele diameter under H5 (0–5 cm, high temperature) were decreased by 29.09% and 15.28%, respectively, at the booting stage, whereas H15 (15 cm, high temperature) affected only the vessel diameter, reducing it by 14.11% compared with that in the M5. Compared to H5, the interaction of high temperature and waterlogging stress alleviated the inhibiting effect of the changes in the root system, especially after the end of the stress. We thought that waterlogging could lighten the damage of high temperature on rice root growth. [ABSTRACT FROM AUTHOR]

[Objective] Transplant is a cultivation commonly used in ratooning rice production in southern China and other eastern Asian countries. Its impact on rice growth and yield depends on a range of factors. This paper presents an experimental study of the effect of transplanting density on yield composition of different panicle-typed varieties. [Method] The field experiment compared three rice varieties: Tianyou Huazhan, Huiliangyou 898 and Yliangyou 900. The transplanting density treatments for all three varieties were the same: 1.5x104 points/hm² (D1), 187 500 points/hm² (D2), 225 000 points/hm² (D3), 262 500 points/hm² (D4), 300 000 points/hm² (D5), and 337 500 points/hm² (D6). In the experiment, we measured rice growth and its ultimate yield formation in each treatment. [Result] Transplanting density affected composition of both seasonal and annual rice yields significantly, but the effect varied with rice varieties. There was a lack of variety-planting density interaction on the yield. The variety Huiliangyou 898 had the highest seasonal and annual yields, strong coordination ability among yield factors, high seed setting rate; variety Tianyou Huazhan had strong tillering ability, high ear-setting rate and full panicle numbers per unit area. All these were significantly higher than those of the variety YLY900. The variety YLY900 had fast population growth rate and high grain numbers per panicle, but its tillering ability was poor, and ear-setting rate and low harvest index were low; it hence produced the lowest seasonal and annual yields. On average, the optimal transplanting density for the three varieties was D5, producing highest seasonal and annual yields, faster tillering rate and more tillers per unit area; it also significantly increased the panicle numbers and sink capacity, population growth rate, and dry matter accumulation. [Conclusion] Selecting rice varieties with panicle and grain for the initial season in ratooning rice production should consider its tillering ability to achieve high yield. For the three rice varieties we compared, the optimal transplanting density is 300 000 holes/hm². [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil properties and microbial diversity are markedly enhanced by the long-term effects of organic fertilizers. However, the short-term impacts of inorganic and organic fertilizers vary in different agroecosystems, especially when combined with different irrigation conditions. Here, we examined the influence of different fertilizer types (NPK: mineral fertilizer, NPKM: mineral fertilizer plus organic fertilizer, NPKWS: mineral fertilizer plus straw) combined with different irrigation regimes (AWMID: shallow water layer, AWMOD: alternate wetting and moderate drying, AWSD: alternate wetting and severe drying) on the soil properties and bacterial communities at the wheat harvest stage of a one-year rice-wheat rotation system (RWRS), in the rice zone along the Yellow River of China. Our results revealed that the irrigation mode had a stronger impact on the soil properties, and bacterial community than the fertilizer regime, although most indicators did not differ significantly, probably owing to the short duration of the trial. Several low-abundance bacteria were recognized to be strongly (P < 0.05) influenced by different irrigation and fertilizer regimes in the RWRS using LEfSe analysis, but no definite trends were observed among the treatments. A co-occurrence network uncovered the modular clustering patterns of bacteria, which were significantly correlated with the available phosphorus content and some soil enzyme activities. Moreover, the denitrification, nitrite respiration, and sulfur respiration capacities of soil microbes were significantly improved in the mineral fertilizer combined with the alternate wetting and moderate drying treatment. In addition, the wheat yield did not significantly (P < 0.05) decrease after water-saving irrigation regime during the previous rice season. Further research is warranted to elucidate the long-term effects of partial substitution of chemical nitrogen with organic nitrogen and water-saving irrigation regimes on an RWRS. • Irrigation impacts the soil properties and bacterial community stronger than fertilization. • AWD can save irrigation water without reducing crops yield in RWRS for short-term. • Irrigation and fertilization regimes in RWRS strongly influenced several low-abundance bacteria. [ABSTRACT FROM AUTHOR]

The rhizosphere harbors complex bacterial communities, which are critical for plant growth and health. Significant differences exist between bacterial communities in the rhizosphere and bulk soils, however, limited research has explored co-occurrence patterns, environmental adaptations, and assembly mechanisms of rhizosphere bacterial communities. Using 16S rRNA high-throughput sequencing, we investigated the taxonomic and phylogenetic diversity of bacterial communities in both rhizosphere and bulk soils from a rice cropping experimental system in China. In addition to investigating differences in bacterial composition, we examined co-occurrence patterns, estimated environmental breadth and phylogenetic signals, and analyzed community assembly processes in these environments. Significant differences were observed between rhizosphere composition and bulk soil (p < 0.05) even some bacteria in the rice rhizosphere may come from the bulk soil around roots. The distribution patterns and ecological functions between communities in the rice rhizosphere and bulk soil were also significantly different. Lower β-diversity values among bacterial communities in the rice rhizosphere indicated that they had a higher stability than those in the bulk soils. In addition, rice rhizosphere communities had a wider phylogenetic diversity and lower functional redundancy when compared with bulk soils. Moreover, the results of environmental breadth analysis revealed that communities in bulk soils were more environmentally constrained than rhizosphere communities. Our null model revealed that deterministic processes drove community assembly in bulk soils (59.57%), whereas stochastic processes determined those in the rice rhizosphere (53.85%). Available potassium was decisive in determining the balance between stochasticity and determinism in both communities. Our study provides insights on the mechanisms underlying the assembly and maintenance of bacterial diversity in rice cropping soils, in response to environmental changes. • Bacterial communities in the rhizosphere and bulk soils had significant differences. • Bacterial communities in rhizosphere had higher stability than those in bulk soils. • Communities in bulk soils were more environmentally constrained than rhizosphere. • Available potassium was decisive in regulating the bacterial community assemblies. [ABSTRACT FROM AUTHOR]