ABSTRACT
Multiple agrometeorological disaster (MAD) occurs simultaneously in maize production. In order to ascertain the occurrence regularity and characteristics of MAD of maize in Liaoning Pro-vince, we defined and classified MAD, identified MAD of 50 meteorological stations in the maize growing season of Liaoning Province from 1961 to 2017, and examined the effects of MAD on maize yield in typical years. The results showed that the occurrence range of MAD was higher in most years from 1961 to 2017 than that of single agrometeorological disaster (SAD), and that the occurrence frequency of MAD was higher in most areas than that of SAD. The major MAD in Liaoning Province was drought in multiple periods (M1-D), followed by the combination of drought and delayed cold damage (M2-DC). The occurrence range of M1-D showed an upward trend from 1961 to 2017, whereas other MAD types showed a downward trend. After analyzing the occurrence of MAD in the typical years of maize yield reduction, we found that the occurrence frequency of M1-D and M2-DC was higher.
Subject(s)
Disasters , Zea mays , China , Climate Change , DroughtsABSTRACT
The evaporative demand drought index (EDDI) is a multi-scale drought index developed from the atmospheric evaporation demand (E0). EDDI is independent of precipitation and suitable to different underlying surfaces, which can well capture water stress signals at different time scales. Based on the meteorological observation data at 52 stations in Liaoning Province from 1961 to 2018, we estimated daily E0, calculated EDDI at six time scales (annual, growing season, spring, summer, autumn and winter), and further identified the interannual variability of drought occurrence in Liaoning Province for the past 58 years. The results showed that EDDI had obvious interannual variation, with two high concentration periods in multiple time scales. In the 1960s, when there were many years and serious drought in Liaoning Province, high EDDI values were concentrated at the five time scales (annual, growing season, spring, autumn and winter). 2014-2018 was another relatively concentrated period of EDDI high value at all time scales except winter. In 1981-1982, the values of EDDI were high at the time scales of the annual, growth season, summer and autumn. The periods of 1963-1965 (except summer), 1972-1973 (growth season, summer), 1989-1990 (annual, growth season, spring and winter), 1997-1998 (annual, growth season and summer), 2004-2005 (spring and winter) and 2013-2014 (annual, growth season and autumn) occurred abrupt alternation from dry to wet or from wet to dry. In 1985-1987, 1993-1995 and 2005-2013, Liaoning Province had obvious dry gaps.
Subject(s)
Climate Change , Droughts , China , SeasonsABSTRACT
For deeply understanding water consumption characteristics and disaster-causing mechanism of spring maize under drought stress, continuous no-water complementing for 40 days and subsequent rewatering treatments were conducted in jointing (T1) and tasseling (T2) stages of spring maize 'Danyu 39'. In the meantime, leaf and root water potential, main variables associated with photosynthesis including net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conduc-tance (gs), intercellular CO2 concentration(Ci) and stem flow rate (SF) were dynamically observed and the characteristics of their responses to drought and subsequent rehydration were investigated. The results indicated that leaf and root water potential, both presenting logarithm relationships with soil water content, decreased due to suffering from drought stress in different growth stages and the response of the former lagged behind that of the latter. At the same time, the response of leaf (root) water potential to drought stress in tasseling stage was earlier (later) than in jointing stage. For the response of rewatering, leaf water potential for the treatment T1(T2) was (not) able to recover to a certain extent, and could not reach the normal condition, while water potential of root was more responsive and closer to the normal level than that of leaf for the treatment T1. Furthermore, Pn and Tr responded more quickly to the treatment T2 than to the treatment T1. For subsequent rewatering after the treatment T1(T2), both Pn and Tr restored rapidly (slowly) with the former exceeding (returning) and the later being (not) able to reach normal level. Meanwhile, the response of Tr was faster than that of Pn to the treatment T1 and they responded simultaneously to the treatment T2. The response of gs agreed with Pn to drought stress. Change trend of Ci for the treatment T1(T2) was consistent (opposite) with that of Pn. In addition, SFs for various drought treatments and their daily maximums decreased and appeared ahead of time to different extents, respectively. At the same time, the response of SF to drought stress was more sensitive for the treatment T2 than for T1 and on a clear day than on a cloudy day, but the sensibility of SF declined after drought reached a certain level. Besides, SFs for both the treatment T1 and T2 increased as a result of rewatering after drought and the increase for the treatment T1 was larger than that for the treatment T2.
Subject(s)
Droughts , Photosynthesis , Zea mays/growth & development , Plant Leaves , Plant Roots , Stress, Physiological , WaterABSTRACT
To investigate the influences of continuous decline of soil water content during different growth stages on the growth, development and yield of maize, artificial water control experiment with a rainout shelter were conducted, and the dynamic variations of several physiological and ecological indices of maize were analyzed, including plant height, leaf area index (LAI), photosynthesis characteristics, aboveground biomass, and yield. The experimental factors considered in this field experiment were the starting time and duration of water control. Rainfall was sheltered from jointing with duration of 20 (T1) and 27 days (T2) and from heading with duration of 20 (T3) and 27 days (T4) for each starting time. In total, there were 5 treatments in this field experiment, including the treatment of control check (CK). The results indicated that LAI was reduced by conti-nuous drought with leaves rolling, tresses and early aging of lower leaves, thus biomass accumulation and grain yield were reduced. At the end of each treatment of continuous drought, LAI was reduced to 74.9%, 68.2%, 60.5% and 48.3% of the CK LAI for the T1 to T4 treatments, respectively. After experiencing continuous water control, the maximum photosynthetic rate (Pn max) of leaf decreased gradually, with Pn max decreased to 23% of the CK Pn max for the treatment T1 and T3, and to less than 10% of the CK Pn max for the treatment T2 and T4 at the end of each treatment. Two weeks after re-watering, Pn max recovered to around 90% of the CK Pn max. Compared with CK, grain yield decreased by 18.5% and 24.0% for the T1 and T2 treatments, and by 46.1% and 45.8% for the T3 and T4 treatments, respectively. Continuous drought brought about more serious effects during heading period than during jointing period on aboveground biomass and yield components. The drought condition of soil could be represented by drought degree (D), which was linearly correlated with maize yield loss and could be used to predict the yield loss.
Subject(s)
Droughts , Zea mays , Biomass , Photosynthesis , Plant Leaves , Soil , WaterABSTRACT
The anomaly of mean temperature summation from May to September (ΔT5-9) was commonly used to assess delayed cold damage of rice in Northeast China, but whether the change of statistics years for climatic mean value (ΣT5-9) would affect the, evaluation results of Liaoning rice under cold damage needed to be further studied. By using the meteorological industry standard of the People's Republic of China "technical standard on rice cold damage evaluation" (QX/T 182- 2013) and the supplemental indices (ΔT5-9), the index (ΣT5-9) was calculated in four periods 1961-1990 (S1), 1971-2000 (S2), 1981-2010 (S3) and 1961-2010 (S4), and the spatial and temporal changes of cold damage in Liaoning Province were analyzed based on the ratio between cold damage stations and total stations (IOC) and the occurrence frequency. The results showed that the heat condition (Σ T5-9) in rice growing season increased obviously and the spatial and temporal changes were significant from 1961 to 2010. The original meteorological index of rice cold damage was improved by using quadratic polynomial model. The identification results were similar between S2 and S4. The variation coefficient of IOC in S3 was lower than that of the other three. Compared with the typical rice yield reduction years, the evaluation results accorded better with the actual situation in evaluating the rice delayed cold damage in Liaoning during study period by using the S3 climate mean value. The results could provide evidence for accurately evaluating the variation of rice cold damage in spatial and temporal distribution in Liaoning Province under the background of global climate change.
Subject(s)
Climate Change , Cold Temperature , Oryza/physiology , China , Hot Temperature , SeasonsABSTRACT
Maize water suitability (MWS) model was developed at growth stage scale. Frequency and severity of drought were evaluated by combining MWS estimates and agricultural meteorological drought indexes. The MWS at each growth stage was calculated by using maize observational data and conventional meteorological data at 52 sites in Liaoning during the period from 1981 to 2010. Based on the climatic trend and abrupt change analysis, spatiotemporal dynamics of MWS were investigated. Meanwhile, occurrence of agricultural drought and its severity were also estimated. The results showed that the variation of MWS largely differed at different growth stages. Climatic abrupt change happened in 1994, 1996 and 1999 at the stages of emergence to seven leaves (II), jointing to tasseling (IV) and physiological maturity to maturity (VI). During the past 30 years, MWS showed an obvious increasing trend at the stages of sowing to emergence(I) , seven leaves to jointing(III), IV and tasseling to physiological maturity(V), while it showed a decreasing trend at the stages of II and VI, and that at VI stage was statistically significant. In addition, the climatic trend of MWS showed apparently spatial variability. The frequencies of drought at different severities varied with maize growth stages. Areas of high variability of MWS were located in the Northwest and South of Liaoning at the stages of I , II , III and VI, where were also the regions of high frequency of mid- and severe-drought. At the stages of IV and V, the frequency of drought was low and only light- and mid-drought occurred in few areas. In conclusion, the regional mean MWS could be capable to reasonably assess the agricultural drought in Liaoning at the regional scale.
Subject(s)
Agriculture , Droughts , Zea mays , China , Climate Change , Ecosystem , Models, Theoretical , Spatio-Temporal Analysis , WaterABSTRACT
Through the measurement of the spectral reflectance of large areas Chinese pine (Pinus tabulaeformis Carr. ) canopy in western Liaoning Province, this paper analyzed the difference of the spectral reflectance of the canopies with different damaged rates of needle leaf. In visible band, the characteristics of the spectral reflectance of P. tabulaeformis canopies with healthy and damaged needle leaf were in accordance with the spectral characteristics of green plants, but the position of red valley was not obvious when the damaged rate of needle leaf was higher than 60%. In near-infrared band, with the decrease of the damaged rate of needle leaf, the canopy spectral reflectance increased at 780-1350 nm, but decreased at 1450-1800 and 1950-2350 nm. With the increase of the damaged rate, the position of red-edge inflection moved to the short-wave direction. There were significant correlations between the damaged rate of needle leaf and the red edge feature variables and some vegetation indices. The model based on DVI (1470, 860) could be more reliable for predicting the damaged rate of needle leaf in P. tabulaeformis canopy in western Liaoning Province.
Subject(s)
Pinus/growth & development , Pinus/parasitology , Plant Leaves/parasitology , China , Plant Diseases/prevention & control , Remote Sensing Technology , Spectrum AnalysisABSTRACT
Taking 3 maize cultivars (Danyu 39, Yuandan 29, and Longdan 13) as test materials, a field experiment was conducted to study their growth characteristics and responses to air temperature under the conditions of early, medium and late sowing. For the three cultivars, the days from sowing to seedling emergence under early, medium and late sowing were averagely 13, 11 and 8 d, respectively, and the seedling emergence rate was the fastest when the mean air temperature was about 18 degrees C. Higher or lower air temperature would decrease the seedling emergence rate. The test cultivars had less difference in the days from seedling to jointing, which was slightly affected by air temperature. Compared with Danyu 39 and Yuandan 29, the late-maturing Longdan 13 had an increased growth rate from jointing to mature stage, and thus, the days for mature shortened markedly. For all the three maize cultivars, the days from jointing to mature tended to decrease with increasing air temperature. The dry matter accumulation rate in whole growth period, grain yield, and 100-seed mass were in the order of Danyu 39 > Yuandan 29 > Longdan 13.
Subject(s)
Biomass , Seedlings/growth & development , Temperature , Zea mays/growth & development , Agriculture/methods , China , Ecosystem , Zea mays/classificationABSTRACT
By monitoring hyperspectral characteristics of spring maize from jointing to silking stage under different drought stress in Jinzhou of Liaoning, China, its spectral characteristics of visible light, red edge region and near infrared were researched, and the correlation of spectral reflectivity of different wavelength with soil moisture was analyzed. The results show that during the jointing to siking stage, the spectral reflectivity of 350-710 nm has significant negative correlation to soil moisture of 0 and 20 cm depth, but the spectral reflectivity of 710-1 300 nm has positive correlation to soil moisture of 0, 20, 40 and 60 cm, and the significant correlation is at 40 cm depth. The spectral reflectivity of red edge region (680-760 nm) which is relatively sensitive and stable, can better reflect the growth status of the plant, and the reflectivity variation per unit wavelength in this region increased at first and then decreased. The trend of polynomial regression curve of red edge parameters and soil moisture of different depth (0-60 cm) is similar, which shows that soil moisture of 0 and 20 cm increased at first and then decreased, but that of 40 cm and 60cm was opposite.
Subject(s)
Droughts , Remote Sensing Technology/methods , Spectrum Analysis/methods , Stress, Physiological , Zea mays/growth & development , China , Regression Analysis , Seasons , Soil/chemistry , Water/analysis , Zea mays/physiologyABSTRACT
Taking spring maize variety Danyu-39 as test object, an experiment was conducted in a large-scale agricultural water controlling experimental field to study the impacts of drought stress at three key growth stages, i. e. , 3-leaf-jointing, jointing-silking, and silking-milk ripe, on the growth and development and grain yield of spring maize in Northeast China. Two treatments were installed, including moderate drought stress (MS) and re-watering to suitable water (CK). Compared with CK, the MS at 3-leaf-jointing stage postponed the whole growth period of Danyu-39 by 13 d, and the plant height and leaf area at jointing stage were decreased by 29.8% and 41.2%, respectively. After re-watering, the plant height and grain yield recovered obviously, and the differences in ear characteristics and final yield were insignificant. The MS at jointing-silking stage shortened the whole growth period by 7 d, the plant height and leaf area at silking stage were decreased by 18.6% and 14.1%, respectively, the ear length, grain number per ear, ear dry mass, and grain mass per ear decreased by 6.9%, 19.1%, 28.1%, and 29.4%, respectively, and the blank stem rate increased by 13.3%. When the maize suffered from moderate drought stress at silking-milk ripe stage, the whole growth period was shortened by 15 d, the plant height and leaf area at milk ripe stage were decreased by 2.3% and 37.3%, respectively, the ear length, grain number per ear, ear dry mass, and grain mass per ear decreased by 9.2%, 24.1%, 30.8%, and 27.9%, respectively, and the blank stem rate increased by 24.5%. After re-watering at the latter two stages, the recovery of plant height was little, and the grain yield decreased significantly.
