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20 November 2020, Volume 41 Issue 11

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Feasibility Analysis on Delayed Germination of Wine Grape Based on Climate Risk Assessment at Xichang, Sichuan Province

WANG Ke-yi, LIU Bu-chun, LIU Yuan, FANG Yu-lin, QIU Mei-juan, MAO Liu-xi, HE Yan-bo, YANG Xiao-juan, PANG Jing-yi, XIAO Nan-shu

2020, 41(11):  679-694.  doi:10.3969/j.issn.1000-6362.2020.11.001

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Wine grape is the most sensitive to climate change. Agricultural climate resources are the key environmental factors to the growth and development and fruit quality of wine grape. Under the background of climate warming, it is significance to guide the reasonable distribution of wine grape by analyzing the agricultural climate resources at Xichang of Sichuan Province. This study identified the change in agricultural climate resources and major agricultural meteorological disasters, based on the daily meteorological data from 1951 to 2018. The data on the actual growth period of wine grape from 2016 to 2018 was collected from the experimental sites of wine grape located at Xichang, an important wine grape growing region. We calculated the trend of heat, precipitation, sunshine hours and agricultural climate disasters in annual and actual growth period of wine grape, and the utilization of climate resources. Delayed germination of wine grapes refers to a cultivation technique to delays the germination period of grapes by avoiding the rain during the ripening and harvesting, so as to harvest fresh wine grapes in the middle of winter. Then we discussed the climatic feasibility of delaying the germination of wine grape at Xichang. The simulated phenology was calculated by two ways respectively, refer to the average integrated temperature with ≥10 ℃ is 3274.3℃·d as the required heat standard: ① the daily average temperature stable passing through 10℃ is the harvest period and ② the first frost day of each year was taken as the harvest period. The date of germination start was calculated by inverse calculation, and the growth period of delayed germination was obtained. In this paper, the results showed: the sufficient heat conditions, abundant precipitation resources and long sunshine hours can meet the climatic conditions for the growth and development of wine grape. The thermal resources for wine grapes had increased significantly （P＜0.05）. Precipitation was abundant and concentrated in the actual growth period. Although sunshine conditions could meet the actual requirements of wine grape but the decreasing trend had been significant （P＜0.01）. At Xichang, the occurrence frequency of low temperature was seven times one year. Excessive precipitation during the maturity period led to continuous rain disaster. Thus, delayed germination can be adopted. The simulated growth periods by delayed germination resulted in sufficient and consistent availability of precipitation resources meeting the growing water demand pattern of wine grape. Actual growth requirements of local wine grapes were met, and the decreasing trend of sunshine resources were slower than that in the actual growth period. The occurrence risk of agricultural meteorological disasters during the new growth period were lower than that in the actual growth period and can possibly be used as an effective method to minimize the impacts of agricultural meteorological disasters. In this study, we find that the delayed cultivation is one effective way to avoid some meteorological disasters at Xichang，according to these two simulated schemes. During the simulated growth period of wine grape, climate resources are feasibility, agricultural climate resources are rich and the agricultural meteorological disasters are less.

Comparison of Model’s Stability about Integrated Temperature Based on Linear Hypotheses

LUAN Qing, GUO Jian-ping,  MA Ya-li, ZHANG Li-min, WANG Jing-xuan, LI Wei-wei

2020, 41(11):  695-706.  doi:10.3969/j.issn.1000-6362.2020.11.002

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Integrated temperature, as a measure of heat, has been widely used in the prediction of crop development period, yield, diseases and insect pests. However, more and more studies showed that the integrated temperature is unstable, and the stability of different integrated temperature models is different. Therefore, it is great significant to analyze and understand the stability of different integrated temperature models for the application of integrated temperature in agricultural meteorological work. In this paper, four linear hypotheses about response of growth and development rate to temperature and five integrated temperature models were made. The first linear hypothesis is that the growth and development rate of crops increases linearly with the increase of temperature when the average daily temperature (T) is higher than the lower limit temperature (Tb). It is the hypothesis of the active integrated temperature model (Aa) and the first effective integrated temperature model (Ae1). The second hypothesis is that when the T is between the lower limit temperature (Tb) and the upper limit temperature (Tu) of crops, the growth and development rate of crops increases linearly with the increase of temperature and reaches the maximum (1.0); when the T exceeds Tu, the growth and development rate of crops remains constant with the increase of temperature. It is the hypothesis of the second effective integrated temperature model (Ae2). The third hypothesis is that when the T is between Tb and Tu, the growth and development rate of crops increases linearly with the increase of temperature and reaches the maximum (1.0); when the T exceeds Tu, the growth and development of crops stagnate. It is the hypothesis of the third effective integrated temperature model (Ae3). The fourth hypothesis is that when the T is between Tb and the optimum temperature (T0), the growth and development rate of crops increases linearly with the increase of temperature and reaches the maximum (1.0); when the T is between T0 and Tu, the growth and development rate of crops decreases linearly with the increase of temperature and decreases to 0.0; when the T exceeds Tu, the growth and development of crops stagnate. It is the hypothesis of the fourth effective integrated temperature model (Ae4). Based on these hypotheses, long time series of crop development period observation data and surface meteorological observation data of two winter wheat stations, three spring maize stations and three summer maize stations in Shanxi Province were selected to calculate the active integrated temperature and four effective integrated temperature. Using the coefficient of variation, the average simulation deviation of the crop growth period and the simulation accuracy of the crop growth period as indicators, the stability of the five integrated temperature models were evaluated. The result showed that the coefficient of variation (CV) of Aa model during different growth stages for three representative crops in each station were between 0.062 and 0.143; the CV of Ae1, Ae2 and Ae3 models were between 0.073 and 0.201; the CV of Ae4 model were between 0.072 and 0.179. That is, when using the CV as an indicator to test the stability of each model, the stability of Aa model was highest, that of the Ae4 model was the second and that of the Ae1, Ae2 and Ae3 models were the weakest. The average simulation deviation (SD) of Aa model for different growth periods of three representative crops in each station were between 1.3 and 5.8 days; the SD of Ae1, Ae2 and Ae3 models were between 1.5 and 6.6 days; the SD of Ae4 model were between 2.2 and 6.7 days. The simulation accuracy (SA) of Aa model for different growth periods of three representative crops in each station were between 39.5% and 92.3%; the SA of Ae1, Ae2 and Ae3 models were between 28.6% and 87.2%; the SA of Ae4 model were between 26.5% and 84.6%. That is, when using the SD and SA as the indicators, the Aa model had the best simulation effect for different growth periods of the crops and had the highest stability. The simulation accuracy and stability of Ae1, Ae2 and Ae3 models had no significant difference and were higher than those of Ae4 model. For spring maize and summer maize, the stability of each integrated temperature model was consistent from emergence to tasseling and from tasseling to maturity, and the stability of each integrated temperature model from emergence to tasseling was higher than that from tasseling to maturity. While the stability of each integrated temperature model for winter wheat from jointing to heading and from heading to maturity varied from region to region. Therefore, in practical applications, it is also necessary to select the appropriate base point temperature according to the crop planting region, variety relationship and growth period, and to select a more stable integrated temperature model based on the comprehensive analysis of the stability of multiple integrated temperature models.

Mechanism Analysis on Photosynthetic Attenuation in Chrysanthemum Leaves under Low Light Condition

YANG Li, YANG Zai-qiang, ZHANG Yuan-da, ZHENG Han, LU Si-yu

2020, 41(11):  707-718.  doi:10.3969/j.issn.1000-6362.2020.11.003

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In this paper, the changes of photosynthetic characteristics and fluorescence kinetic characteristics of chrysanthemum leaves under different low light levels were discussed, so as to analyze the internal mechanism of photosynthetic attenuation of chrysanthemum leaves under low light conditions, with the purpose of providing reference for the defense against low light disasters and the regulation of light environment in the seedling stage of chrysanthemum. In order to reveal the influence of shading treatments on greenhouse chrysanthemum leaf photosynthetic characteristics, a controlled experiment with varieties of cut-flower chrysanthemum ‘Hongmian’ was conducted in August 2019 to October 2019 in Nanjing University of Information Science and Technology experimental greenhouse. Chrysanthemum seedlings were planted in the greenhouse pools. When the height of seedlings reached 30cm, shelves were set up 1.5m above the ground, and the shelves were covered with black sunshade nets of 60%(L1) and 30%(L2) light transmittance respectively. Treatments lasted 3(T1), 6(T2), 9(T3) and 12(T4) days, contrasting with normal natural light intensity(CK). Photosynthetic parameters and fast chlorophyll fluorescence induction kinetic parameters of chrysanthemum were determined under different treatments. The results showed that, (1)the light saturation point(LSP), photosynthetic rate at irradiation saturation(Pmax), apparent quantum efficiency(AQE), stomatal conductance(Gs) and transpiration rate(Tr) of chrysanthemum leaves decreased with the increase of treatment days under different shading treatments, while the light compensation point(LCP), dark respiration rate(Rd), stomatal limit value(Ls) and water use efficiency(WUE) were opposite. In addition, the variation range of all indicators treated by L2 is larger than that of L1. After 12 days of shading, Pmax decreased to 51.1%, Gs decreased to 62.4%, while LCP increased to 2.75 times, compared with CK. (2)The maximum fluorescence(P) of chrysanthemum leaves increased with the shading time and shading degree. (3)In terms of PSⅡ energy distribution ratio, the effects of shading treatment on chrysanthemum leaves were to increase the quantum yield captured by the reaction center(φPo) and the quantum yield for electron transfer(φEo), while decreasing the quantum ratio for heat dissipation(φRo). Among them, φPo reaches a maximum value of 0.85 after L2T3 treatment, and φRo drops to a minimum value of 0.16 after L1T4 treatment. These results indicated that shading increased the probability that the light absorbed by chrysanthemum leaves captured by PSⅡ reaction center, while the part used for heat dissipation decreased. (4)In terms of PSⅡ reaction center activity, the values of light energy absorbed by the unit active reaction center(ABS/RC), the energy dissipated by the unit reaction center(DIo/RC), energy recovered by the unit reaction center for reducing QA(TRo/RC) and the unit reaction center for electron transfer(ETo/RC) all decreased after shading treatments. Among them, ABS/RC and DIo/RC reached their minimum values under L2T3 treatment, which were 1.176 and 0.198, respectively. This study confirmed that weak light treatments reduce the chrysanthemum leaf intercellular CO2 concentration, the activity of the PSⅡ reaction center and the ability to restore the PQ, QB. The light energy absorbed and captured by the antenna pigment is also reduced. In conclusion, the photosynthesis of chrysanthemum leaves is reduced.

Effect of Chelating Agent HIDS on Summer Squash Seedlings Cultured in Low Formula Nutrient Solution

DUAN Xu-jin, LI Ling-zhi, ZHANG Wei, GAO Qing-lan, LIANG Yun-xiang, CHANG Ling-shan, ZHANG Jie-chun, ZHANG Guo-xiang, LI Hai-ping

2020, 41(11):  719-729.  doi:10.3969/j.issn.1000-6362.2020.11.004

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The utilization rate of cucurbit vegetable to fertilizer is low in China. Summer squash is one of the main vegetables cultivated in solar greenhouse in north China. In order to improve fertilizer utilization efficiency, "Nongyuan No.1" summer squash was taken as the test material for hydroponics experiment. Seven nutrient solution treatments were set in the experiment. T1: General nutrient solution formula (control), 1/2 times Yamazaki cucumber nutrient solution formula; T2: Low formula nutrient solution, 1/3 times Yamazaki cucumber nutrient solution; Treatment T3, T4, T5, T6 and T7 were added with 7, 35, 70, 105 and 140 mg HIDS per liter of nutrient solution on the basis of T2 formula. That was to say, HIDS concentration in nutrient solution is 7, 35, 70, 105, 140mg·L−1. When summer squash seedlings had two leaves, they were planted in a 4.5L bucket of the treatment solution (2 plants per bucket). The effects of adding HIDS to low formula nutrient solution on growth, antioxidant enzyme activity, soluble sugar, protein, photosynthesis and fluorescence of summer squash were analyzed after 12 days of hydroponics in solar greenhouse. The results showed that the growth status, antioxidant enzyme activity and photosynthetic capacity of T2 summer squash treated with low formula nutrient solution were all worse than those treated with general nutrient solution T1. The addition of HIDS promoted the growth of summer squash in the low formula nutrient solution, and the concentration of HIDS in the nutrient solution was 70mg·L−1, which had the best effects on T5. Compared with T2 treatment, the leaf area, root volume, fresh and dry weight of the whole plant, soluble protein, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in T5 treatment were significantly increased by 13.17%, 21.69%, 12.19%, 21.28%, 23.57%, 132.22%, 44.32%, 39.61% and malondiadehyde (MDA) content was significantly reduced by 102.55%. The photosynthetic rate, transpiration rate, stomatal conductance, daily mean value of intercellular carbon dioxide and total chlorophyll content of T5 were significantly increased by 41.77%, 19.11%, 8.84%, 40.26% and 37.50% compared with T2. In addition, the addition of HIDS increased Fv/Fm, Fv'/Fm', ETR, qP and decreased NPQ in the leaves of summer squash under low nutrient solution, and alleviated the low nutrition to the summer squash photosynthesis organ damage. There was no significant difference in each index between T5 and T1. Therefore, the HIDS concentration of 70mg·L−1 in low nutrient solution could promote the growth, photosynthesis and increase the activity of protective enzymes of summer squash and could save 16.67% fertilizer.

Determination and Regionalization of Forest Fire Risk Rate in China Based on Equilibrium Theory

FU Li-sha, PAN Huan-xue, QIN Tao, ZHANG Xi

2020, 41(11):  730-743.  doi:10.3969/j.issn.1000-6362.2020.11.005

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Scientific and reasonable rate determination could effectively promote the enthusiasm of both supply and demand sides in the forest fire insurance market, which is an important basis for the fine development of forest fire insurance products. In order to achieve the fine-grained determination of the forest fire insurance rate in China, based on the equilibrium theory and the related data of forest fire insurance from 1993 to 2018, 29 provinces (cities, districts) in China were selected as the research areas, starting from the expected utility of insured forest farmers and the risk of forest disasters, the principle of determining forest fire insurance rate that could meet the balance between supply and demand was discussed. Based on this, the Holecy model was improved to solve the problem that the distribution parameter model in the original model is limited to Weibull distribution and the variables don’t conform to the reality. The improved Holecy model was used to calculate and partition the forest fire insurance rate, and the results were compared with the actual average annual compensation ratio. The results showed that, firstly, there was a big difference in the expected pure rate of forest fire insurance among different regions based on the improved Holecy model, Tibet had the lowest expected pure rate of 0.0093‰, while Heilongjiang had the highest expected pure rate of 51.7641‰. Meanwhile, the risk pure rate of forest fire insurance varied greatly from region to region, under the condition of 100% participation rate, the risk pure rate of Heilongjiang was the highest, at 4.107‰, while that of Anhui was less than 0.001‰. And the risk pure rate of forest fire insurance was higher on the whole, which indicated that it’s necessary to reflect the annual risk and disaster loss difference among different regions through the pure risk premium rate. Moreover, the pure rate of forest fire insurance calculated by the sum of the expected pure rate and the risk pure rate of each region also had great differences. Under the 100% participation rate, the pure rate of forest fire insurance in Heilongjiang was the highest, 52.955‰, while that in Gansu was the lowest, 0.164‰. It could be seen that there were significant differences in forest fire risks in different regions of China, and it was urgent to refine and differentiate forest fire insurance rates and risk zoning. Secondly, the risk pure rate and the pure rate of forest fire insurance in different regions were subject to the insured rate, the rate level of forest fire insurance decreased with the increase of the insured rate, and the decline range varied with the different rate values. Therefore, encouraging farmers to participate in forest insurance to improve the insurance rate would be a crucial way to achieve risk dispersion and reduce the insurance premiums. Thirdly, according to >5‰, 1.0‰−5.0‰, 0.5‰−1.0‰ and <0.5‰, the pure rate of forest fire insurance was divided into high risk area, general risk area, lower risk area and low risk area. By comparing the actual occurrence and disaster situation of forest fires in different regions, the calculated pure rate of forest fire insurance and the zoning results were in line with the actual risk levels in different regions. Fourthly, the simple compensation ratio of national forest insurance was relatively low, with an average of about 30%, and the compensation ratio was highly differentiated in different regions, which further reflected the necessity of implementing fine rate determination and zoning of forest insurance, and also verified that forest insurance could be divided into risk zones. What’s more, the results of forest fire insurance pure rate partition were basically consistent with the forest insurance compensation ratio grouping results.