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20 May 2019, Volume 40 Issue 05

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Contributions of Land Use/Cover Change to the Change of Evapotranspiration in Qinhuai River Basin

QIN Meng-sheng, HAO Lu, ZHENG Qing-zhou, JIN Kai-lun, SUN Ge

2019, 40(05):  269-283.  doi:10.3969/j.issn.1000-6362.2019.05.001

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In order to evaluate the impact of land use/cover change (LUCC) caused by the urbanization on the variation of basin-scale evapotranspiration (ET), the Qinhuai River basin in the Yangtze River Delta was selected as the research area. Based on the images of Landsat satellites in 2000 and 2013, the land use/cover maps of Qinhuai River basin were extracted by using the decision tree model, and the grid-scale ET in typical day of each season (spring: 2014-05-26, summer:2013-08-11, autumn:2013-10-14, winter:2014-01-02) were estimated by using the SEBAL model. The contributions of LUCC in 2000?2013 to the variation of ET were then analyzed. The results showed that: (1) compared to that in the year of 2000, the area of built-up land increased by 183.8%, while the areas of paddy rice field, dry land, woodland and water separately decreased by 19.1%, 10.7%, 12.8% and 9.5%. The main conversions between different land uses included paddy rice field→built-up land, dry land→built-up land, paddy rice field→dry land and dry land→paddy rice field, with the areas of 208, 168, 282 and 232km2, respectively. (2) Only with the regard to the impact of LUCC, the total daily ET at basin scale separately decreased by 13.4×105, 10.9×105, 6.0×105 and 0.5×105m3 in typical day of each season in 2013, when compared to that in 2000. In typical days of spring, summer and autumn, the positive contributions caused by the conversion from dry land to paddy rice field (16.8%, 16.3%, 5.7%, respectively) were overwhelmed by the negative contributions caused by the conversions from paddy rice field and dry land to the built-up land (-58.5%,-59.5%, -54.4% and -35.1%, -36.3%, -39.8%, respectively), which led to the decreased ET at basin scale. However, in the typical day of winter, the positive contribution caused by the conversion from dry land to paddy rice field (26.1%) was overwhelmed by the negative contributions caused by the conversions from paddy rice field to built-up land, dry land to built-up land and paddy rice field to dry land (-48.8%, -20.5%, -31.8%, respectively), which led to the decreased ET at basin scale. In a word, rapid urbanization in Qinhuai River basin caused the large-scale conversion from paddy rice field and dry land both with high ET to the built-up land with low ET, and then led to the decreased basin-scale ET in all seasons during 2000?2013.

Effects of Elevated Atmospheric CO2 Concentration on Grain Filling Dynamics of Different Spike-type Winter Wheat

WANG Dong-yan, GUO Li-ping, LI Yu-ting, ZHENG Lei, HAN Xue

2019, 40(05):  284-292.  doi:10.3969/j.issn.1000-6362.2019.05.002

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The free air CO2 Enrichment (FACE) system was used to study the grain filling dynamics of whole panicles and different positions of wheat panicle in different spike-type cultivars (medium-spike type, cv. Jindong8, large-spike type, cv. Shanhan8675 and multi-panicle type, cv. Triumph) under the elevated CO2 concentration of 550±17μL·L-1 (5：30-18：00) and the ambient CO2 concentration 400±16μL·L-1. The results showed that: (1) the initial grain weight was significantly increased under the elevated CO2 concentration. Elevated CO2 concentration increased the grain weight of Jingdong8 (medium-spike type) in the early grain filling stage with no effect on the final grain weight, and had no effect on the grain filling duration and average filling rate; Elevated CO2 prolonged the grain filling duration of Shanhan8675 (large-spike type) by 19.3% and increased grain weight significantly, the dry weight of the upper, middle and lower parts of the panicle was increased by 11.0%, 20.9% and 23.3%, respectively, and the whole panicle was increased by 18.8%; The Triumph (multi-panicle type) did not show significant increase in grain weight under elevated CO2 concentration, due to the lower grain-filling rate offset the prolonged duration effect to the mass maturity. (2) Regarding of the panicle positions, the elevated CO2 showed a positive effect of the filling parameters (the maximum grain-filling rate, the time reach maximum growth rate, grain filling duration and average grain filling rate) on the upper and lower position of wheat panicle of Jingdong8 and Shanhan8675, contrast with the Triumph’s middle panicle part of panicle. (3) Elevated CO2 shorten the duration of Jindong8 and Shanhan8675 in early grain-filling stage, whereas prolonged the duration of the middle and the last grain-filling stage, which was opposite to the average grain filling rate in the three periods; The grain filling duration of the three stages of Triumph was prolonged, while the average grain filling rate showed the opposite trends. The results suggest that the large-ear type winter wheat will have a better performance than multi-panicle type winter in a CO2-rich world.

Effect Analysis of Anti-UV-B Enhancement of Two Sweet Potato Cultivars

MENG Fan-lai, GUO Hua-chun

2019, 40(05):  293-300.  doi:10.3969/j.issn.1000-6362.2019.05.003

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The effects of artificial UV-B enhancement on osmoregulation substance contents and specific activity of the antioxidant enzymes and their interspecific differences of the mature leaves of potted ‘Dianziganshu24’(‘DZS24’) and ‘Huishu’(‘HS’) were studied by using colorimetry. The results showed that: under enhanced UV-B, the soluble sugar contents (SSC) significantly reduced with the UV-B enhancement, the soluble protein contents (SPC) decreased at the earlier stage and increased at the later stage with the enhancement for two cultivars. Moreover, the variation range of SSC and SPC of ‘HS’ was larger than that in ‘DZS24’. The free proline contents (FPC) increased in ‘DZS24’ and decreased in ‘HS’ with the enhancement. The specific activity of superoxide dismutase (SOD) and catalase (CAT) increased, while the peroxidase (POD) specific activity decreased with the enhancement for the two cultivars. However, the increasing range of SOD specific activity of ‘DZS24’ was larger than ‘HS’ and the variation range of POD and CAT specific activity was less than ‘HS’ under the same UV-B. Therefore the osmotic regulation and antioxidant capacity of ‘DZS24’ is stronger than ‘HS’ and more suitable for planting in low latitude plateau with the intense UV-B.

Effects of Planting Population under Poor Light on the Canopy Temperature and Humidity and Grain-filling Properties of Winter Wheat

ZHANG Yong-qiang，CHEN Chuan-xin，FANG Hui，SAILIHAN Sai，XUE Li-hua，CHEN Xing-wu，LEI Jun-jie

2019, 40(05):  301-307.  doi:10.3969/j.issn.1000-6362.2019.05.004

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To study the effects of planting population under poor light on the canopy temperature, humidity and grain-filling properties of winter wheat, a white nylon mesh with a light transmittance of 50% was used to simulate the shading environment from jointing to maturity of winter wheat in 2016, a two factors split-plot field experiment including five plant population: 4.5 (M1), 5.25 (M2), 6.0 (M3), 6.75 (M4) and 7.5 million plants·ha?1 (M5) were conducted at circumstance of natural light and shading to observe and compare the variation of canopy temperature, humidity and grain filling characteristics of winter wheat. The results showed that, compared with natural light, the canopy temperature of winter wheat was significantly reduced under shading treatment, and the duration of high temperature at noon was significantly shortened. Under shading treatment, the canopy humidity increased significantly, the duration of humidity low valley at noon was shortened, and the grain filling rate, effective panicle number, grain weight per spike and 1000-grain weight were all decreased. Thus, under shading conditions, high yield could be obtained by appropriately reducing the planting population, improving the temperature and humidity of the canopy, increasing the grain filling rate, grain number per spike and 1000-grain weight.

Temperature Index of Quercus variabilis Leaf PSII Activity Damage under High Temperature Combined with Drought

WANG Qian, CHEN Ling-shu, ZHAO Wei, CHEN Jing-ling, ZHANG Jin-shong, YANG Xi-tian,ZHAO Yong

2019, 40(05):  308-316.  doi:10.3969/j.issn.1000-6362.2019.05.005

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The temperature index of Quercus variabilis seedling in high temperature and drought stress was determined using method of soil water controlling in pot and temperature controlling in climate box. Soil volumetric humidity >14.5% was set as no drought stress (T0), 12.5%?14.5% was set as mild drought (T1), 9.5%?11.5% was set as moderate drought (T2) and 5.5%?7.5% was set as severe drought (T3). The temperature was controlled at 35，37，39，…，49℃ and at any temperature of which keeping treating time as 1，2，…，6h. The parameters of Chlorophyll Fluorescence measured were Fv/Fm, Y(II), ETR, Y(NPQ) and Y(NO), which were used to determine stress temperature index. The results showed: (1) from mild, moderate to severe drought, the changing curves of Fv/Fm, Y(II) adapt to temperature decreased more rapidly, which indicated the drought serious level had obvious significance on temperature stress index. (2)The temperature indices of different drought levels indicating PSII damaging determined by Fv/Fm were 51.6?57.5℃; The temperature indices of different drought levels indicating PSII efficiency of photosynthesis determined by Y(II) were 40.7?52.5℃; (3) Regulatory heat dissipation Y(NPQ) began to rise at 45℃ by T0 and T1, and at 43℃ by T2, 41℃ by T3; (4) Nonregulatory heat dissipation Y(NO) of T0 hardly rise, and T1 began to rise at 47℃, T2 and T3 began to rise at 45℃. The results above indicated the temperature indices of PSII damaged and photosynthetic efficiency decreased under superimposed drought conditions were significantly different from those without drought. The more drought, the lower the stress temperature index. Both active and passive heat dissipations of Quercus variabilis were increased by drought stress, and the temperature at which excess light energy of active dissipation began to increase was lower than that at which passive heat dissipation began to increase.

Effects of High Temperature and Different Air Humidity on Water Physiology of Flowering Tomato Seedlings

WEI Ting-ting, YANG Zai-qiang, WANG Ming-tian, ZHAO He-li, ZHAGN Xu-ran, LI Jia-shuai, SUN Qing, WANG Lin

2019, 40(05):  317-326.  doi:10.3969/j.issn.1000-6362.2019.05.006

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Used tomato variety “Jinguan 5” as the test material, and orthogonal test was carried out in the artificial climate chamber to design the daily maximum temperature(℃)/lowest temperature(℃). For the 32/22℃, 35/25℃, 38/28℃, 41/31℃ levels, the relative humidity of the air is 3 levels: 50%±5%, 70%±5%, 90%±5%, and the treatment days is 3, 6, 9, 12 days, and set 28/18℃, 50%±5% as control (CK), the changes of physiological indices of tomato under different treatments were determined. The results showed that under the high temperature treatment of 32?41℃, the stomatal conductance (Gs) and transpiration rate (Tr) were the highest at 35℃, respectively, 0.109μmol·m-2·s-1, 0.21μmol·m-2·s-1; leaf water potential (ψw), root system vigorous (Rv), root-shoot ratio (R/S), net photosynthetic rate (Pn) and water use efficiency (WUE) decreased with increasing stress temperature, and decreased by 163.76%, 66.63%, 28.59%, 73.90% and 65.11% at 41℃ compared with CK. After increasing the humidity to 70% under high temperature conditions, ψw, Gs, Pn, Tr and WUE were significantly improved compared with 50% treatment and can basically recover to CK level within 28 days, the root system also recovered better and maintained a higher WUE during the recovery period; but after increased the humidity to 90%, Gs and ψw increased, but Pn, Rv, R/S, WUE failed to increase significantly, and WUE was lower during the recovery period. Therefore, in the high temperature environment of 35℃ and above, increasing the humidity of the air to 70% can effectively reduce the damage of high temperature to tomato, and it was also conducive to tomato recovery. This study provides a theoretical basis for the optimal management of summer greenhouse tomato.

Effects of Biochar on Soil Conditions and Rice Growth in Ningxia Irrigated Area under Optimized Nitrogen Application Conditions

GAO Yue, ZHANG Ai-ping, DU Zhang-liu, LIU Ru-liang, HONG Yu, HU Shi-min, YANG Zheng-li

2019, 40(05):  327-336.  doi:10.3969/j.issn.1000-6362.2019.05.007

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Taking rice variety Ningjing43 as materials, the cracking test was carried out under nitrogen and biochar addition condition in Ningxia irrigation area. None nitrogen (0kg·ha-1), optimization of nitrogen (240kg·ha-1), routine nitrogen (300kg·ha-1) and three levels of biochar addition including C0(0kg·ha-1), C1(4500kg·ha-1), C2(9000kg·ha-1), C3(13500kg·ha-1), 12 treatments in total, were designed. Soil samples were collected in harvest stage of rice by soil-drills to determine basic properties. Plants samples were randomly selected in tillering stage, jointing stage and filling stage to measure the growth index such as root length, root surface area, root tips and root-shoot ratio, aboveground biomass. Rice production was tested in harvest stage through five-point sampling method. The 3 measurements aimed to study the effect of adding biochar under different nitrogen applications on soil conditions and rice growth in Ningxia irrigation area. The main results were as followed, (1) application of nitrogen fertilizer did not improve soil nutrient status, while biochar addition increased soil nutrient content. (2) Application of nitrogen fertilizer and addition of biochar both promoted root growth, and there was no significant difference between optimized nitrogen application and conventional nitrogen application. (3) There was no significant difference in rice yield between optimized nitrogen application and conventional nitrogen application, and biochar addition increased rice yield. 9000kg·ha-1 of biochar addition in optimized nitrogen application increased the theoretical yield by 15.5%. Therefore, the addition of biochar improved soil nutrient status, promoted rice growth, and increased rice yield. And moreover, biochar addition can be applied to Ningxia rice fields in combination with nitrogen fertilizer reduction.