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Shao G.C.,Key Laboratory of Efficient Irrigation Drainage | Shao G.C.,Hohai University | Lan J.J.,Key Laboratory of Efficient Irrigation Drainage | Lan J.J.,Hohai University | And 7 more authors.
Photosynthetica | Year: 2013

A study on photosynthetic and yield effects of waterlogging of winter wheat at four stages of growth was conducted in specially designed experimental tanks during the 2007-2008 and 2008-2009 seasons. Compared with the control, waterlogging treatments at tillering and jointing-booting stages reduced photosynthetic rate (P N) and transpiration (E) significantly, it also decreased average leaf water-use efficiency (WUE, defined as the ratio of P N to E) by 3.3% and 3.4% in both years. All parameters returned quickly to the control level after soil was drained. Damage to the photosynthetic apparatus during waterlogging resulted in a lower Fv/Fm ratio, especially at the first two stages. A strong reduction in root length, root mass, root/shoot ratio, total dry mass, and leaf area index were observed. The responses from vegetative plants at tillering and jointing-booting stages were greater than in generative plants at onset of flowering and at milky stages. The number of panicles per hectare at tillering stage and the spikelet per panicle at the stages of jointing-booting and at onset of flowering were also significantly reduced by waterlogging, giving 8.2-11.3% decrease of the grain yield relative to the control in both years. No significant difference in yield components and a grain yield was observed between the control and treatments applied at milky stages. These responses, modulated by the environmental conditions prevailing during and after waterlogging, included negative effects on the growth, photosynthetic apparatus, and the grain yield in winter wheat, but the effect was strongly stage-dependent. © 2013 Springer Science+Business Media Dordrecht.

Shao G.-C.,Key Laboratory of Efficient Irrigation Drainage | Shao G.-C.,Hohai University | Deng S.,Key Laboratory of Efficient Irrigation Drainage | Deng S.,Hohai University | And 7 more authors.
European Journal of Agronomy | Year: 2014

Rice is subjected to excessive waterlogging and flash-flooding on large areas in south China. A study on water use, growth and yield effects of controlled irrigation and drainage (CID) of paddy rice at four stages was conducted in specially designed experimental tanks. The treatments were (1) CID during Stage I of tillering stage (CID-Stage I), (2) CID during Stage II of booting stage (CID-Stage II), (3) CID during Stage III of heading to flowering stage (CID-Stage III), (4) CID during Stage IV of milky stage (CID-Stage IV), (5) alternate wetting and drying irrigation during the whole stage (CK). Compared with CK, CID reduced drainage volume with 15.8-31.3% in 2008, and 13.5-28.3% in 2009, and increased the efficiency of available rainfall and irrigation by 1.98-3.46% in both years. Irrigation water application during the whole growing season across the 2 years, on average, was only 81.8%, 91.1%, 93.9%, and 94.5%, respectively, of that applied to CK. A strong reduction in root length, root weight, root-shoot ratio and harvest index were observed, however, shoot weight and total dry mass is increased from the treatments of CID-Stage II, CID-Stage III and CID-Stage IV. The highest radiation use efficiency values were for CID-Stage IV. The responses of CID from vegetative plants at Stage I and Stage II were greater than in generative plants at the latter two stages. CID-Stage II had only a small effect on subsequent development and grain yield. This decrease in grain yield to less than 7.88% and 5.72% of CK was due to reduced number of spikelets per panicle in one trial, and reduced panicle number per unit area in another. The CID-Stage I treatment showed the lowest grain yield among the treatments and reduced it by 23.3% in 2008 and by 17.3% in 2009, due to the decreases in the percentage of filled grains and total number of panicles. The effect of stress was associated with low dry matter production during the flooding stress period as well as during the stress withdrawal period following the stress. With regards to irrigation water use efficiency, it was increased under the first two treatments, and by from a minimum of 101% to a maximum of 110%. © 2013 Elsevier B.V.

Shao G.-C.,Key Laboratory of Efficient Irrigation Drainage | Shao G.-C.,Hohai University | Lan J.-J.,Key Laboratory of Efficient Irrigation Drainage | Lan J.-J.,Hohai University | And 3 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

In order to investigate the response of photosynthesis, chlorophyll fluorescence and growth of hot pepper (Capsicum annuum L.) to deficit irrigation. Two drought treatments (in which 50% and 75% irrigation water of the control supplied to both sides of the root system) (DI50, DI75) were imposed on greenhouse grown hot pepper during the growing stages in 2006. Both DI75 and DI50 treatments decreased shoot biomass by 24.97% and 43.83%, total dry mass by 7.29% and 44.10% compared to the control, but increased the root-shoot ratio by 12.50% and 35.40% in relation to the control and with significant differences between DI50 and the control. Deficit irrigation decreased relative leaf water content by about 5.22-22.09% at four stages. DI50 reduced photosynthesis rate (Pn) slightly and transpiration rate (Tr) significantly, and it improved leaf water use efficiency (WUEL, defined as the ratio of Pnto Tr) by 24.24%. During the phase of drought, some impairment of photochemical activity was observed, as revealed by decreases in the maximum quantum yield of PSII (Fv/Fm). However, the difference between DI50 and DI75 and the control was not significant. The mean values of variable fluorescence (Fv), maximal fluorescence (Fm), photochemical quenching (qP) at four stages decreased and minimum fluorescence (F0) and non-photochemical quenching (qN) increased in the soil drought environment. Development of non-radiative energy dissipation mechanisms was evidenced during stress by increases in non-photochemical quenching and decreases in efficiency of excitation capture by open centers. The coordinated changes in fluorescence parameters suggest that the more efficient irrigation strategy are those which can lessen or escape the influence of drought stress on crops during growing period.

Chen L.-H.,Hohai University | Chen L.-H.,Key Laboratory of Efficient Irrigation Drainage | Zheng J.-H.,Hohai University | Shao X.-H.,Hohai University | And 9 more authors.
Ecological Engineering | Year: 2016

Sustainable biotechnological techniques can transform coastal saline soil into agriculturally viable soil. In the current study, the T83 strain of Trichoderma harzianum was isolated and shown to promote growth of Suaeda salsa L., a halophytic species. We assayed the effects of T83 conidia powder and fertilizer on the physiology of S. salsa as well as the physical and biological properties of the treated soil. Compared to the control plants, the experimental S. salsa plants that received conidia powder and fertilizer exhibited increased fresh masses by 50.5% and 82.7% and increased dry masses by 67.3% and 119.3%, respectively (P < 0.05). The concentrations of proline, organic acids, amino acids, soluble sugars, K+, and Ca2+ were increased in conidia powder and fertilizer treatments (P < 0.05), and increased by 77.5%, 58.3%, 86.9%, 58.7%, 79.3% and 38.8% in fertilizer treatment, respectively. Both powder and fertilizer treatments significantly increased the enzyme activity of peroxidase and superoxide dismutase as well as root vigor (P < 0.05) and decreased malondialdehyde concentration (P < 0.05). Additionally, fertilizer treatments increased enzyme activity of phenol oxidase and catalase. Conidia powder and fertilizer treatments significantly decreased soil bulk density and soil salt concentration, while increasing soil total porosity and field water capacity (P < 0.05). Powder and fertilizer significantly (P < 0.05) increased the populations of total bacteria, total actinomyces, total fungi, ammonifying bacteria (AB), nitrifying bacteria (NB), phosphate-solubilizing bacteria (PHB), and potassium-solubilizing bacteria (PTB). Compared to the control, the fertilizer treatment exhibited populations of total bacteria, total actinomyces, total fungi, AB, NB, PHB, and PTB that had increased by factors of 9.2, 55.9, 6.0, 21.1, 4.0, 9.2 and 5.2, respectively. The T83 fertilizer effectively promoted the growth of S. salsa in saline soil and improved the coastal saline soil quality. © 2016 Elsevier B.V.

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