Characteristics and risk assessment of chilling injury on Morchella esculenta in Western Sichuan Plateau, China.

The development of precise climate risk zoning for chilling injury of Morchella esculenta can provide scientific basis for agricultural cultivation planning, dynamic assessment of chilling injury, and disaster prevention strategies. Based on meteorological data from 17 counties (cities) that located below the altitude of 3000 m in the Western Sichuan Plateau from 2011 to 2020, we analyzed the critical meteorological conditions for M. esculenta disasters in typical years. With the average yearly cold accumulation and cold injury frequency during the first day when the temperature remained stable between 5 ℃ and 10 ℃ during mushroom emergence as zoning indicators, we established a geographical spatial distribution model of the cold injury index, and then divided the risk level of M. esculenta cold injury in the Western Sichuan Plateau, evaluated the risk of cold injury. The results showed that the temperature index for chilling injury risk of M. esculenta in the study area was the daily minimum temperature ≤2.0 ℃. The daily average temperature <6.0 ℃ would cause slow growth or the cessation of growth, which was set as a warning indicator for chilling injury risk. Along the Dadu River and Minjiang River basins, the frequency of chilling injury on M. esculenta increased from south to north. Wenchuan, Maoxian, and Lixian had the fewest overall chilling injuries during the study period, whereas Jiulong, Yajiang, and Batang had the most. The duration for cold injury was mainly 1-3 d, followed by 4-5 d, and rarely for >5 d. The frequency of chilling injury lasting for more than 5 d in Xiangcheng, Batang, Jiulong, Yajiang, and Xiaojin was more than that lasting for 4-5 d. The annual average days of chilling injury of was 3.0-27.4 d, the daily average minimum temperature was -0.84-1.36 ℃, the extreme lowest temperature was -5.8-0.1 ℃, and the average accumulated cold was 0.16-9.64 ℃·d during the period of chilling injury. With the increases of elevation and latitude, the average days of chilling injury and the average accumulated cold increased. The largest duration of chilling injury was 3-20 d, the maximum accumulated cold was 0.44-13.34 ℃·d. The risk of chilling injury to M. esculenta increased from south to north and from low elevation to high elevation. The suitable planting areas were distributed in strips and branches along the direction of mountains and rivers, mainly in the flat areas of low mountains and valleys below the altitude of 2200 m, including Kangding, Luding, Danba, Wenchuan, Lixian, Maoxian, Jiuzhaigou, and Songpan.

[Variation characteristics of normalized difference vegetation index in Northwestern Sichuan Plateau and its response to extreme climate during 2001-2020]. / 2001­2020å¹´å·è¥¿åŒ—é«˜åŽŸå½’ä¸€åŒ–æ¤è¢«æŒ‡æ•°æ¼”å˜ç‰¹å¾åŠå ¶å¯¹æžç«¯æ°”å€™çš„å“åº”.

The northwestern Sichuan Plateau is a typical eco-climate sensitive area, where vegetation condition is closely related to climate change. We used the MODIS-NDVI and the meteorological data during 2001-2020 to investigate the change trend of normalized difference vegetation index (NDVI) and the mechanism underlying its responses to climate factors in the growing season of northwestern Sichuan Plateau by using the methods of maximum value composite, geodetector model, trend analysis, and correlation analysis. The results showed that vegetation coverage in northwestern Sichuan Plateau was overall good during the study period. 86.8% of the regional vegetation was stable, 12.6% of the regional NDVI was weakly and continuously increasing, and 0.6% of the regional NDVI was decreasing. The ecological environment of the whole region exhibited a steady and good development trend. The vegetation coverage in the study area exhibited apparent spatial variation with a general tendency of increase from southwest to northeast, as well as obvious variation with elevation. The NDVI rose with elevation below 1350 m, varied slightly from 1350 to 3650 m, dropped from 3650 to 5900 m, with a rapid drop between 4750 to 5900 m. There was almost no vegetation above 5900 m. The NDVI of northwestern Sichuan Plateau was affected by the interactions of natural factors. Thermal factors were the dominant climate factors, including monthly maximum value of daily maximum temperature, monthly minimum value of daily minimum temperature, growing season length, annual mean temperature, mean temperature over the growing season. All these factors were positively correlated with NDVI excepted for monthly maximum value of daily maximum temperature. The response of NDVI to temperature index was higher than that of precipitation index. Under the background of climate warming, extreme temperature warming index played a major role in promoting the growth and improvement of vegetation in northwestern Sichuan Plateau, especially in high-altitude areas.

Spatiotemporal evolution characteristics of the late frost damage risk to shrubby tea trees in tea region, southwest China from 1971 to 2020.

Understanding the spatiotemporal evolution characteristics of the risk of late frost damage has scientific guiding significance for optimizing the regional agricultural production layout and varie-ty tuning. Based on the daily meteorological data of 65 weather stations in the southwest China tea region from 1971 to 2020, we analyzed variation characteristics of the last frost date (LFD), tea bud open date (BOD), and their relationships, constructed frost damage probability index and frost damage severity index of spring shoots of shrubby tea trees, and analyzed the spatiotemporal evolution chara-cteristics of the late frost damage risk of shrub tea trees in the southwest tea region. The results showed that both the BOD and LFD had a significant ahead of trend from 1971 to 2020 and the early rate of the LFD was relatively faster than that of the BOD in the southwest tea region. The number of days that the tea buds were exposed to late frost damage after germination showed an non-significant declining trend. The risk of late frost damage of shrubby tea trees in most parts of the southwest tea region showed a declining trend, but Guizhou tea planting region showed an insignificant increasing trend. The risk of late frost damage to shrubby tea trees was high in the western marginal mountai-nous areas of Sichuan tea region, and the junction of Guizhou and Yunnan tea region. The risk of late frost damage was at low level in Sichuan Basin, southern Yunnan tea region, and southern Guizhou tea region. The risk of late frost damage to shrubby tea trees in the northern and central-eastern parts of Yunnan tea region showed an obvious decreasing trend, but increased significantly in the central and eastern parts of Guizhou tea region.

[Continuous-rain hazard of transplanting and direct-sowing rice in Sichuan Basin, China]. / å››å·ç›†åŒºç›´æ’­å’Œç§»æ ½æ°´ç¨»çš„è¿žé˜´é›¨ç¾å®³å±é™©æ€§.

Continuous rain disaster is a kind of complex disaster with high frequency in the Basin area of Sichuan Province. Continuous rainy weather may appear in every growing stage of rice, with consequences on the yield and quality. Based on the meteorological data of 105 meteorological stations between 1981 and 2019, combining the observation data of rise production, agricultural statistics and the basic geographic information, we quantitatively evaluated and compared the continuous-rain disasters in the whole growth period and the four growth stages (sowing-jointing, jointing-booting, booting-early filling, mid-late filling-maturity) between transplanted rice and direct-seeded rice in the basin area of Sichuan Province. The results showed that the disaster index of continuous-rain for rice was higher in the sowing-jointing stage and the mid-late filling-maturity stage, higher in the northern and southwest edges of the basin, and lower in the middle, western and southern basin. The area with high-risk was relatively limited, which concentrated in the northern edge of the basin and scattered in the southern region of the basin. The low-risk area was the most widely distributed, which concentrated in the western and central parts of the basin. The total area of high-disaster areas for transplanted rice was 2.4 times as large as that for direct-seeded rice.

Climatic ecological suitability and potential distribution of Tricholoma matsutake in western Sichuan Plateau, China based on MaxEnt model.

Based on the distribution data of Tricholoma matsutake obtained from field investigation and literature, the ecological-niche factor analysis (ENFA) and the maximum entropy model (MaxEnt) were used to simulate the distribution law and suitable area of T. matsutake in the western Sichuan Plateau. The prediction was made for the future changes in the suitable area of T. matsutake by analyzing the relationship between climate factors and dynamic distribution. The results showed that the area under curve (AUC) values of both the model training set and validation set were greater than 0.90, indicating that the model prediction results were extremely accurate. The environmental variables affecting the potential distribution of T. matsutake were mainly the lowest temperature in the coldest month, the coldest season precipitation, annual temperature difference and soil type, with accumulative contribution of 90.3%. The niche parameters of suitable distribution areas of T. matsutake were as follows: the lowest temperature in the coldest month was -18.5--5.4 ℃, the coldest season precipitation was less than 15.7 mm, the annual temperature difference was 39.5-45 ℃, and soil type was semi-leached soil, including dry red soil, cinnamon soil, gray cinnamon soil, black soil and grey forest soil. The suitable areas of T. matsutake were distributed in the southwest, south, central and east of the plateau at an altitude range of 1900-3600 m. The highly suita-ble areas were mainly distributed in some towns of Yajiang, Xiangcheng, Kangding, Jiulong, Daocheng, Litang, Batang, Danba, Maerkang, Xiaojin, Jinchuan, Lixian, Maoxian, etc. The moderately and lowly suitable areas were located in some towns of Derong, Daofu, Xinlong, Luhuo, Baiyu, Luding, Rangtang, Wenchuan, Heishui, Jiuzhaigou. The highly suitable areas were discontinuously distributed according to the direction of rivers and mountains. The moderately suitable areas were connected with the highly suitable areas, while the lowly suitable areas were the extension of the highly and moderately suitable areas. Future climate change would be beneficial to the growth of T. matsutake on the western Sichuan Plateau, while the climate-suitable areas would show an overall increasing trend. Suitable areas in the low-altitude Minjiang River Basin would be more affected by climate change than those located in high-altitude areas.

Construction and application of meteorological index for Apis cearna cearna activity in nor-thern mountainous area of Sichuan Basin, China.

We analyzed the climate ecological suitability of Apis cerana cerana in the northern mountain area of Sichuan Basin, based on the meteorological data of two meteorological stations, the production and the ecological characteristics and activity of A. cerana cerana. Taking temperature, moisture, light, wind and weather conditions as impact indices and referring to life meteorological index, we constructed a hierarchical calculation method for activity meteorological index and annual evaluation of A. cerana cerana in northern mountainous area of Sichuan Basin. Results showed that the main meteorological factors affecting A. cerana cearna activity in the study were temperature, relative humidity, sunshine hour, wind power and daytime cumulative duration of precipitation. Among those factors, temperature and daytime cumulative duration of precipitation were the main ones. The meteorological index of A. cerana cerana activity was constructed through the combination of different values of these five index factors, with which the grading evaluation being carried out. When the index was greater than 12, the weather condition was good and suitable for A. cerana cearna activity. When the index was 7-12, the weather condition was general, which was sub-suitable for A. cerana cearna activity. When the index was 1-7, the weather condition was poor, the activity of A. cerana cearna would significantly decrease. When the index was less than or equal to 1, the weather condition was bad and would not be suitable for A. cerana cearna to be active or in the overwintering period. We used this index to evaluate the climate of Zhongshan bee farm. Results showed that the average comprehensive meteorological index was 129.3 (score 60.4) for many years (April to October), the overall meteorological condition was good. The yield of "local honey" was significantly correlated with the annual comprehensive meteorological index. The accuracy rate of annual meteorological evaluation was 90%.

Association between mental health and community support in lockdown communities during the COVID-19 pandemic: Evidence from rural China.

Governments worldwide have taken unprecedented social distancing and community lockdown measures to halt the COVID-19 epidemic, leaving millions of people restrained in locked-down communities and their mental well-being at risk. This study examines Chinese rural residents' mental health risk under emergency lockdown during the COVID-19 pandemic. It investigates how the environmental, socioeconomic, and behavioral dimensions of community support affect mental health in this emergency context. We also explore whether community support's effectiveness depends on the strictness of lockdown measures implemented and the level of individual perceived COVID-19 infection risk. We collect self-reported mental health risk, community support, and demographics information through a cross-sectional survey of 3892 Chinese rural residents living in small towns and villages. Ordinary least square regressions are employed to estimate the psychological effects of community support. The results suggest that the COVID-19 epidemic and lockdown policies negatively affect psychological well-being, especially for rural females. The capacity for community production has the largest impact on reducing mental health risks, followed by the stability of basic medical services, community cohesion, housing condition, the stability of communications and transportation supply, and the eco-environment. The effectiveness of different community support dimensions depends on the level of lockdown policy implemented and the levels of one's perceived risk of COVID-19 infection. Our study stresses the psychological significance of a healthy living environment, resilient infrastructure and public service system, and community production capacity during the lockdown in rural towns and villages.

[Effects of high temperature on photosynthetic physiological characteristics of strawberry seedlings in greenhouse and construction of stress level.] / é«˜æ¸©å¯¹æ¸©å®¤è‰èŽ“å ‰åˆç”Ÿç†ç‰¹æ€§çš„å½±å“åŠèƒè¿«ç­‰çº§æž„å»º.

Strawberry variety 'Benihoppe' was used as the experimental material. The temperature treatments were set at 32 ℃/22 ℃, 35 ℃/25 ℃, 38 ℃/28 ℃ and 41 ℃/31 ℃ (daily maximum temperature/daily minimum temperature), and the stress days lasted for 2, 5, 8 and 11 d, with 28 ℃/18 ℃ as the control. We measured the photosynthetic characteristics, chlorophyll fluorescence characteristics, reactive oxygen species, protective enzyme activity and membrane lipid peroxidation of strawberry under different high temperature treatments. The key indices were extracted by principal component analysis. The high temperature stress index (Z) was defined to divide the high temperature stress grade. The results showed that 1) with the aggravation of high temperature stress and the extension of stress time, chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoid (Car), light saturation point (LSP), maximum net photosynthetic rate (Pmax), apparent quantum efficiency (AQE) and maximum photochemical efficiency (Fv/Fm) decreased, while light compensation point (LCP) and dark respiration rate (Rd) increased. 2) High temperature hindered the energy transfer of thylakoid in PSⅡ center (ΔWOK＞0), and accelerated the reduction rate of PSⅠ terminal electron receptor pool. On the 11th day of the stress, except that under 32 ℃, all other oxygen evolution complexes (OEC) were inactivated. 3) The content of reactive oxygen species (H2O2 Content and O2-· production rate) and malondialdehyde (MDA) increased with the stress days under different high temperature treatments. 4) The protective enzyme activities and soluble protein content increased first and then decreased with stress duration. 5) Based on principal component analysis (PCA) and combined with the difficulty of index acquisition, Chl a, Pmax, Fv/Fm and MDA were extracted as the key indices, and Z value was calculated. Five high temperature stress grades were divided which were normal (0

[Climatic ecological suitability and potential distribution for Boletus edulis in mountainous areas of Western Sichuan Plateau, China]. / 川西高原山地美味牛肝菌气候生态适宜性及潜在分布.

The ecological climate suitability of Boletus edulis was systematically analyzed in mountainous areas of the Western Sichuan Plateau using DEM, land cover data and meteorological data from 52 weather stations in Sichuan Province and four weather stations in other provinces. Factors such as temperature, precipitation and vegetation cover were selected as the regionalization index to analyze the potential spatial distribution of B. edulis in Western Sichuan Plateau by GIS technology. The results showed that the northern boundary of potential distribution area for B. edulis was near 32° N, the upper and lower limits of the altitude were about 800 m and 3000 m. The total distribution area was 2863000 hm2, accounting for about 9.7% of the whole study area. The Panxi area at south of 29° N was the main distribution area, accounting for about 90% of all potential distribution areas. Among the main distribution area, the suitable area was about 20%, and the remaining is the secondary suitable area. The suitable area was mainly distributed in the Anning River basin at the elevation of 1000 m to 2600 m in East of the Yalong River in the Panxi area. The secondary suitable area was mainly located in forest area extending upward and downward from suitable area at an altitude of about 3000 m and 800 m, respectively. The unsuitability areas were the alpine regions at altitude above 3000 m and the dry-hot valley regions at altitude below 800 m.

[Spatio-temporal variation of NPP from 1999 to 2015 in Zoige grassland wetland, China]. / 1999­2015年若尔盖草原湿地净初级生产力时空变化.

Net primary productivity (NPP) is one of the core components of the grassland wetland ecosystem carbon balance and climate change. Based on data of vegetation index, meteorology (precipitation and temperature), and vegetation type, we used the CASA (Carnegie-Ames-Stanford Approach) model to estimate NPP of the Zoige grassland wetland from 1999 to 2015. The spatial and temporal patterns of NPP in the Zoige grassland wetland ecological function area and its relationship with precipitation and temperature were examined. The results showed that the measured values of NPP were close to the simulated values, with the root mean square error being 120.3 g C·m-2 and a R2 of 0.78. The annual mean and the growth season (April-September) mean of NPP of the study area were 329.0 and 229.4 g C·m-2·a-1, respectively, with obvious inter-annual fluctuations, with a weak trend of decline (2.3, 1.6 g C·m-2·a-1). The inter-annual fluctuations of NPP in different vegetation types were basically consistent with the overall fluctuations of NPP of the whole study area. The slope of NPP in annual and growing seasons was from -21.3 to 18.7, -31.5 to 23.1 g C·m-2·a-1. The area with significant increase (mainly distributed in forest coverage area and wetland ecological compensation area) only accouned for 0.3% and 0.7% of the total area, and the area with significant decline (mainly distributed in areas where human activities were concentrated) only accounted for 1.4% and 6.4% of the total area, respectively. The carbon sequestration capacity of different vegetation types was different, among which the forest was the strongest, the grassland was the second, and the wetland vegetation was the weakest. Precipitation was the dominant climatic factor affecting NPP in grassland wetland.

Predictions of potential geographical distribution of Diaphorina citri (Kuwayama) in China under climate change scenarios.

Climate change significantly affects geographic distribution of plants pests and diseases worldwide. Understanding the influence of future climate change on the suitable areas of Diaphorina citri (Kuwayama) in our country and taking timely countermeasures are crucial for improving the effectiveness of control of pest. Based on the occurrence points of D. citri and the selected environmental variables, the potential suitable areas of this pest under climate change scenarios in China were predicted by using MaxEnt and GIS tools. Our results showed that the higly suitable area were mainly located in Guangxi, Guangdong, Fujian, Southern Zhejiang, Southern Jiangxi, Eastern Hunan, Southwestern Guizhou, and the area was 43.7 × 104 km2. Areas of moderate and low suitability were centered on areas of high suitability and radiate to the North successively, with an area of 59.28 × 104 km2 and 93.46 × 104 km2 respectively. From current to 2070 s, the areas of the highly suitable areas will increase, and the geometric center of the highly and total suitable areas will move to north under three climate change scenarios.

[Potential distribution and suitability regionalization of kiwifruit canker disease in Sichuan Province, China]. / å››å·çœçŒ•çŒ´æ¡ƒæºƒç–¡ç— æ½œåœ¨åˆ†å¸ƒé¢„æµ‹åŠé€‚ç”ŸåŒºåŸŸåˆ’åˆ†.

To detect the suitability of kiwifruit bacterial canker in Sichuan, a MaxEnt model based on distribution information and environmental variables was used to predict its potential distribution area and to analyze the impact of major environmental variables. The receiver operating characteristic curve was used to evaluate the accuracy of the model simulation. The average area under curve of 10 replicates was 0.914, which indicated that the predictive results were reliable. The highly sui-table distribution areas of kiwifruit bacterial canker were Chengdu, Deyang, Mianyang, Guangyuan, Bazhong, Dazhou, and Ya'an. All the 21 cities of Sichuan were classified as moderately suitable areas. The main environmental factors affecting the potential distribution of kiwifruit bacterial canker as determined by Jackknife method were minimum temperature of coldest month (-6.8-7.5 ℃), mean temperature of warmest Quarter (15.6-32.3 ℃), mean temperature of driest quarter (-0.8-21 ℃), annual precipitation (709-950.9 mm), and standard variation of temperature seasonality (4.7-9.6 ℃). Our results are impotant for early monitoring, early warning, and developing control measures for kiwifruit bacterial canker.

Predicting the potential distribution of the Asian citrus psyllid, Diaphorina citri (Kuwayama), in China using the MaxEnt model.

BACKGROUND: Citrus huanglongbing (HLB) is a destructive disease of citrus and a major threat to the citrus industry around the world. This disease accounts for substantial economic losses in China every year. Diaphorina citri Kuwayama is one of the major vectors by which citrus HLB is spread under natural conditions in China. Research is needed to identify the geographic distribution of D. citri and its major areas of occurrence and to formulate measures for early warning, monitoring, and control of this pest and citrus HLB. METHODS: In this study, the ecological niche modelling software MaxEnt (maximum entropy model) was combined with ArcGIS (a geographic information system) to predict the potential geographic distribution of D. citri in China. Key environmental factors and the appropriate ranges of their values were also investigated. RESULTS: Our results show that the training data provided a good forecast (AUCmean = 0.988). The highly suitable areas for D. citri in China are mainly concentrated to the south of the Yangtze River, and the total area is 139.83 × 104 km2. The area of the moderately suitable areas is 27.71 × 104 km2, with a narrower distribution than that of the highly suitable area. The important environmental factors affecting the distribution of D. citri were min temperature of coldest month, mean temperature of coldest quarter, precipitation of wettest quarter, mean temperature of warmest quarter, precipitation of warmest quarter, max temperature of warmest month, and temperature seasonality. These results provide a valuable theoretical basis for risk assessments and control of D. citri. DISCUSSION: The predicted results showed that there were highly suitable areas for D. citri in Chongqing, Hubei, Anhui, and Jiangsu. Therefore, the possibility exists for the further spread of D. citri in China in the future. Extreme temperature variables, especially the min temperature of the coldest month, play an important role in the distribution of D. citri and are most closely related to the distribution of D. citri.

Modeling and mapping the current and future distribution of Pseudomonas syringae pv. actinidiae under climate change in China.

OBJECTIVE: Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to the kiwifruit industry throughout the world and accounts for substantial economic losses in China. The aim of the present study was to test and explore the possibility of using MaxEnt (maximum entropy models) to predict and analyze the future large-scale distribution of Psa in China. METHOD: Based on the current environmental factors, three future climate scenarios, which were suggested by the fifth IPCC report, and the current distribution sites of Psa, MaxEnt combined with ArcGIS was applied to predict the potential suitable areas and the changing trend of Psa in China. The jackknife test and correlation analysis were used to choose dominant climatic factors. The receiver operating characteristic curve (ROC) drawn by MaxEnt was used to evaluate the accuracy of the simulation. RESULT: The results showed that under current climatic conditions, the area from latitude 25° to 36°N and from longitude 101° to 122°E is the primary potential suitable area of Psa in China. The highly suitable area (with suitability between 66 and 100) was mainly concentrated in Northeast Sichuan, South Shaanxi, most of Chongqing, West Hubei and Southwest Gansu and occupied 4.94% of land in China. Under different future emission scenarios, both the areas and the centers of the suitable areas all showed differences compared with the current situation. Four climatic variables, i.e., maximum April temperature (19%), mean temperature of the coldest quarter (14%), precipitation in May (11.5%) and minimum temperature in October (10.8%), had the largest impact on the distribution of Psa. CONCLUSION: The MaxEnt model is potentially useful for forecasting the future adaptive distribution of Psa under climate change, and it provides important guidance for comprehensive management.

[Risk assessment and regionalization of maize drought disasters in Sichuan Basin, Southeast China].

Based on the information of maize yield, phonological period, and related weather data, four models (those of climatic drought risk, crop drought risk, yield loss risk, and drought resistant capability) applicable for the assessment of maize drought risk in Sichuan Basin and the corresponding index systems were established, and a comprehensive model for assessing the maize drought disasters in the Basin was constructed, with the comprehensive index for the risk regionalization of the maize drought disasters determined. The values of the indices for assessing the maize drought risk in the Basin differed obviously with different regions, but showed similarity in some areas. The Sichuan Basin was divided into three regions, with high, medium and low maize drought risk, respectively. The region with high risk was mainly in the most areas of northwest basin, the middle basin, and parts of the south basin of Sichuan, the region with medium risk was in the north basin and some parts of the south basin, and the region with low risk was in the northeast and southwest basin, and parts of the southeast basin.

[Photosynthetic characteristics and dry matter accumulation of hybrid rice varieties under different light conditions].

The study on the photosynthetic characteristics and dry matter accumulation of twelve hybrid rice varieties in the eco-environments with low- and high light intensity showed that the adaptation abiility of the varieties to eco-environment was mainly (depended on the varieties themselves, and there existed greater (differenees among them. The differences in net photosynthetic rate (Pn) and chlorophyll content (Chl) were more significant among the varieties than between the eco-environments. The grain yield had significant positive correlations with Pn and total dry matter mass (TDM), the determination coefficient R2 being 0.584 and 0.590, respectively, but no significant correlations with the export percentage of the matter in stem-sheath (EPMSS) and the transformation percentage of the matter in stem-sheath (TPMSS). In the eco-environment with high light intensity, the leaf thickness and dry matter accumulation increased, while the EPMSS and TPMSS decreased. Under enough sunlight condition, the high proportion of matter in grain yield was mainly come from the photosynthesis at late growth stages; while under insufficient sunlight condition, it was mainly originated from the early growth stages photosynthesis.