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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 Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery 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.)

Vascular bundle is the main microstructure of rice plants, which is conducive to the growth of leaf and photosynthetic rate, and the greater the vascular bundle, the more the number, the better the supply of nutrients. Pot experiments were performed to research the effects of alternative stress of drought and waterlogging at tillering stage on rice leaf anatomical structure, including the number, area and perimeter of large (small) vascular bundles, sectional area and perimeter of major vein, area of bulliform cell group and sectional area of side blade, and 2 treatments were set up in 2013: waterlogging - light drought (LD) and waterlogging - severe drought (HD), in which the water depth of waterlogging was 10 cm, using regular irrigation (CK) as the control. The experiments were conducted in the greenhouse of Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China (Hohai University), Ministry of Education. The results showed that alternative stress of drought and waterlogging decreased the number of large (small) vascular bundles, but there was no significant difference compared to the CK; after the first drought for 5 d (Stage I), the sectional area of major vein of LD treatment was reduced by 31.13% compared to the CK (P<0.05), and that of HD treatment was reduced by 13.9?104 μm2, which yet had no significant difference with the CK; the area and perimeter of large vascular bundle of side blade were reduced by 28.87% and 15.79% for LD treatment, respectively, and by 24.74% and 13.16% for HD treatment, respectively, and the area and perimeter of small vascular bundle of side blade for LD and HD treatments were also lower than that of the CK. After waterlogging for 5 d (Stage II), the perimeter of small vascular bundle of side blade for LD and HD treatments had no significant difference with the CK, and that of LD treatment was reduced by 0.13?102 μm compared to HD treatment. Except large vascular bundle, other indices of HD treatment were all over than the CK, indicating that leaf development showed a certain compensation effect. Five days after waterlogging (Stage III), the sectional area of major vein of LD and HD treatments was significantly reduced by 24.6?104 and 29.1?104 μm2 respectively compared to the CK, and the development of side blade organ was also behind the CK. After the second drought for 5 d (Stage IV), the area of large vascular bundle of major vein for LD and HD treatments was significantly reduced by 19.42% and 29.13% respectively compared to the CK; the area and perimeter of large vascular bundle of side blade under LD treatment had no significant difference with the CK, and those under HD treatment were significantly lower than LD treatment and CK. The areas of bulliform cell group of LD and HD treatments were lower than the CK when the rice was in drought, and especially in Stage III, the areas of bulliform cell group were significantly reduced by 0.38?102 and 0.57?102 μm2, respectively; the sectional areas of side blade of LD and HD treatments in Stage I, III and IV were lower than the CK, while in Stage II, the sectional area of side blade of HD treatment was higher than the CK, but the difference was not significant. After the water stress, the development of the main vein's large vascular bundle was inhibited, and the development of side blade was also subject to certain persecution, but the persecution of rice leaves under severe drought treatment was increased after the second drought stage, while it was reduced under light drought treatment, indicating that the rice drought tolerance was enhanced, and after the drought stress, the waterlogging tolerance of rice was still strong. The results of this study can provide the basis for the development of appropriate water management plan and the research of rice photosynthesis. [ABSTRACT FROM AUTHOR]

Lodging is one of the important constraints to high quality and stable production of rice. This study was conducted in the Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil Water Environment in Southern China, Ministry of Education, Nanjing, China from May to October in 2013 to investigate the response of alternate flooding and drought stress on biomass production and distribution in different organs of rice (Oryza sativa L. Nanjing 44) and their relationships with morphological and mechanical traits as well as chemical concentration relating to stem lodging characteristics under alternate drought and flooding stress during different growth stages. Five treatments, alternate stress of light drought-flooding-light drought in tillering stage (T-LD), alternate stress of heavy drought-flooding-heavy drought in tillering stage (T-HD), alternate stress of light drought-flooding-light drought in jointing stage (J-LD), alternate stress heavy drought-flooding-heavy drought in jointing stage (J-HD) as well as irrigation with shallow water depth (0-5 cm) for all the stages except for yellow maturity (CK), were set up. In this experiment, changes of chlorophyll contents and photosynthesis rates of flag leaves after the flowering stage as well as the percentage of dry-matter exportation from stem-sheath (PDESS) and the percentage of the dry-matter transformation from the stem-sheath part to the grain part (PDTSS) were investigated. In addition, the stem morphological and mechanical traits as well as chemical concentrations and their relationships with stem lodging characteristic were studied. The results showed that there were significant quadratic curve relationships between chlorophyll contents and days after transplanting (P<0.01). In addition, there were significant positive linear relationships between chlorophyll contents and photosynthesis rate of flag leaves after the flowering stage (P<0.001). Compared with the CK, T-LD and T-HD treatments significantly increased the leaf areas, chlorophyll contents and photosynthesis rates of flag leaves after the flowering stage, but significantly decreased the PDESS and the PDTSS; the leaf areas, chlorophyll contents and photosynthesis rates of flag leaves after the flowering stage of alternate stress of drought-flooding-drought in the tillering stage were about 1.1-1.2 times as those of CK, respectively; the PDESS and PDTSS were 32% and 22% of those of CK, respectively. Compared with the CK, J-LD and J-HD treatments significantly increased the chlorophyll contents and photosynthesis rates of flag leaves after the flowering stage but did not significantly increase the leaf areas, the PDESS and the PDTSS. The leaf areas of flag leaves, the PDESS and the PDTSS of alternate stress of drought-flooding- drought in the jointing stage were 84%, 33% and 37% of those of CK, respectively; the photosynthesis rates of flag leaves after the flowering stage were 1.19 times as those of CK, respectively. Compared with the CK, J-LD and J-HD treatments significantly increased the safety factor against stem breakage, which might be related to the improved dry-matter translocation amount and translocation efficiency from stem-sheath to grain part of rice plants as well as the increased gravity center height and the ratio of gravity center caused by the improved translocation amount of carbohydrate generated in flag leaves to the grains. There were significant negative relationships between harvest index and safety factor. This study could provide valuable information for keeping high grain yield as well as improving lodging resistance of rice plant by irrigation methods. [ABSTRACT FROM AUTHOR]

Photosynthesis determines the growth and dry matter accumulation of rice, and drought and waterlogging stress can inhibit the photosynthesis of rice. Study on the light response curve would help to understand the photosynthetic characteristics of rice in a more detailed way. Pot experiments were performed to research the effects of alternative stress of drought and waterlogging (ASDW) at tillering and jointing stage on rice leaf photosynthesis, light response and CO2 response, including net photosynthetic rate, stomatal conductance, potential water use efficiency and intercellular carbon dioxide concentration. Four treatments were set up in 2013 at tillering stage of rice (the water depth of waterlogging was 10 cm) including light drought (T-LD) and severe drought (T-HD), at jointing stage (the water depth of waterlogging was 15 cm) including light drought (S-LD) and severe drought (S-HD). Irrigation with water depth at 0-5 cm except for drying yellow ripening stage (CK) was the control. The experiments were conducted in the greenhouse of Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China (Hohai University), Ministry of Education. The results indicated that rice leaf photosynthesis was inhibited by ASDW at the both tillering and jointing stage, and photosynthetic capacity recovered as the stress changing from drought to waterlogging; At the end of water stress, the net photosynthetic rate of T-HD treatment was lower than that of T-LD and CK (P＜0.01); The stomatal conductance of T-LD and T-HD treatment was reduced by 72.93% and 85.01% and the intercellular carbon dioxide concentration was also significantly lower than CK, but the potential water use efficiency was more than two times of CK; The net photosynthetic rate of S-HD treatment was significantly lower than that of CK (P＜0.01), while S-LD was lower than CK by 18.66%; The stomatal conductance of S-LD was close to CK, and that of S-HD was 62.73% lower than that of CK (P＜0.01); and The intercellular carbon dioxide concentration of S-LD and S-HD treatments showed an increasing trend, and S-LD was 21.57% higher than CK (P＜0.05), S-HD reached 1.50 times of CK, but potential water use efficiency of S-HD and S-LD treatments were lower than that of CK, and S-HD was 29.58% lower than CK (P＜0.01). After stress, water stress treatments showed obvious compensation effect; On October 10th, the net photosynthetic rate, stomatal conductance, and intercellular carbon dioxide concentration of water stress treatments were significantly higher than those of CK (P＜0.05); The potential water use efficiency of S-LD treatment was higher than that of other water stress treatments, but was still lower than CK by 21.35%. The net photosynthetic rate of water stress treatments was lower than CK under the same light intensity, but the light compensation point (LCP), light saturation point (LSP) and dark respiration rate were higher than that of CK, and net photosynthetic rate of rice CO2 response curve was increased. In the tillering stage, the photosynthetic capacity of the light drought treatment was strong, which was weak of the light drought treatment at jointing stage. But in the ripening period, photosynthetic rate of the two severe drought stress treatments were higher than that of light drought treatments. Alternative stress of drought and waterlogging decreased the maximal rate of photosynthesis, but improve the carboxylation efficiency, change the photosynthetic rate turning point of CO2 response curve. After the stress, increasing the light intensity appropriately and prolong the illumination time would be conducive to the rapid growth of rice. But the final yield of each treatment was significantly lower than that of CK (P＜0.05). The results can provide valuable information for analyzing the accumulation of dry matter and irrigation water use efficiency of rice, and further proved that drought stress in the early did not reduce the ability of waterlogging tolerance of rice in the late, and slight drought-waterlogging stress in the early stage would be helpful for enhancing rice drought ability from the perspective of photosynthesis. [ABSTRACT FROM AUTHOR]

Heavy rains occur frequently in South China during rice growth stages. The large amount of discharge from paddy field combined with high fertilization has caused serious environmental problems. The present controlled drainage methods pay much attention to holding more water in basins and reducing pollutant from basins, however, how to control runoff from field ditches and non-cultivated areas are often ignored. Coordinated Controlled Drainage (CCD) was proposed in the paper to solve the problem above by making most use of the wetland effects of both paddy field and field ditches that were widely distributed in the farmland in South China. The CCD technique tries to store rainwater in basins as much as possible by using rain-catching and controlled irrigation (RCCI) technique that maintains lower irrigation limit and higher water depth after rain depending on the waterlogging-tolerant and drought-tolerant ability of rice so as to reduce runoff from basins. Furthermore, it also impouned runoff from basins and non-cultivation lands such as roads, ditches and canals by a construction at the outlet of the field ditch. Field experiments were conducted in 2013 to verify the feasibility of the model. Controlled and uncontrolled drainages treatments were designed in rice field. Each controlled field of 4.5 hm2. Three replicates were designed. During the experiment, the drainage from field and trench were collected for determination of total nitrogen and phosphorus (TN and TP). Rice yield was measured. The results showed that at field scale, CCD could reduce evaportanspiration and water consumption by 18.8% and 15.3%, compared with frequent and shallow irrigation technique (FSI) respectively. Irrigation quote, drainage quote and irrigation frequency declined 28%, 60.6% and 4 times while TN and TP loss reduced 58.6% and 58.8%. At field control scale, surface drainage volume, the TN and TP burden from controlled ditch decreased by 55.9%, 59.7% and 66.7%, respectively under CCD without reduction of grain yield compared with uncontrolled ditch combined with FSI. The investigation also found that TP and TN concentrations were high both in basin water and ditch water at early stage after rainfall and decreased rapidly with time, indicting that holding water in basins and ditches at that time could remove TN and TN more efficiently. Runoff from non-cultivated area accounted for 31.3%-38.7% of the total runoff from ditches, indicating it was an important source of pollutant. The results above suggested CCD was an effective method to reduce water application, cost of labor, and pollutant burden in paddy field in South China. [ABSTRACT FROM AUTHOR]