| The regulations of spring wheat (TriticumaestivumL)response to precipitation changing andtemperature increasing were studied in this thesis based on field experiments and a long sequenceagro-meteorological datain semi-arid rainfed farming regions. Meanwhile, the impact of climatechanging on growing, developing and layout of main crops in Gansu Province were analyzed.The main results were as followed:Emergence rate of spring wheat increased significantly with temperature increasing in thesemi-arid regions. The stages of vegetative growing and reproductive growing of spring wheatdecreased significantly with the precipitationdecreasing. The stages of springwheat were putforward with the global climate warming, and stages of cotton, except the stage of cessationgrowing. The periods of wintering stage-green stage, milky ripe stage-maturity stage and wholegrowing stage of spring wheat were shorten. The periods of sowing stage-five-leaf stage, five-leafstage-budding stage, spinning stage-cessation growing stage and whole growing stage of cottonwere prolonged.Effects of temperature increasing and precipitation changing on height of spring wheat werenot significant at the jointing stage, but were significant at the filling stage. The cooperationeffects of precipitation decreasing and temperature increasingon aboveground dry matter ofspring wheat were negative, and precipitation increasing could alleviate this negative effect. Theunderground dry matter of spring wheat increased and then decreased with temperatureincreasing.The Pn of spring wheat leaves increased when temperature increased about1degree, but not2-3degree. Meanwhile, hot and drought conditions were not good for photosynthesis duringthejointing stage.The interactions of temperature increasing and precipitation decreasing restrainedthe photosynthesis of spring wheat during late stages. And also temperature increasing restrainedthe photosynthesis, but precipitation increasing increased photosynthesis. The stomataon leaveswas main factor for the decline photosynthetic of spring wheat during jointing stage, but not thestomata after the filling stage. The water use efficiency (WUE) of spring wheat decreased withthe temperature increasing during the jointing stage, and effects was obvious as the precipitationdecreasing, but not obvious when precipitation increasing or unchanging. WUE decreased withthe temperatureincreasingwhen precipitation decreased about20%. WUE increased at first and then decreased with the temperatureincreasingwhen precipitation increasing or unchanging. Andinflection point temperatures were1℃and2℃, respectively.The potential maximal photochemical efficiency (Fv/Fm), the actual photochemicalquantum efficiency (ΦPSII), photochemical quenching (qP) and electron transport rate (ETR)decreased in logarithmic function withthe temperature increasing. And effects were obvious asthe precipitation decreasing. NPQ increased at first and then decreased with thetemperatureincreasing, and the inflection point temperature was2℃. Precipitation had notsignificantly effects on fluorescence parameters. So it can be concluded that response of wheat tothe precipitationwas not sensitive as the precipitationdecreased about20%duringthe temperaturechanged about0-3°C.With the temperature increasing, the proline (Pro) contentand soluble protein contentofspring wheat leaves increased, but the soluble sugar contentdecreased. At the sametemperature,the Procontentincreased with the precipitation increasing, but the soluble sugarcontentand soluble protein content decreased. The SOD activity of spring wheat leaves decreasedwith the temperature increasing under the conditions of precipitationincreasing or unchanging.The SOD activity of spring wheat leaves increased at first and then decreased with thetemperature increasing under the conditions of precipitationincreasing, and the inflection pointtemperature was1℃, but SOD activity decreased all times. The malondialdeyde (MDA) contentand the relative permeability of the plasma membrane (RC) of spring wheat increased withthetemperature increasing.The cooperation effects of precipitation decreasing and temperature increasingabout3℃ondecrease of number of grain of spring wheat were significant. And effects of precipitationdecreasing on grain weight of spring wheat were important under condition of the temperatureincreasing. The rate of sterility spike of spring wheat increased with the temperature increasing inquadratic. And rate of sterility spike of spring wheat was45%under conditions of theprecipitation decreasing and the temperature increased at3°C, leading to grain yields of springwheatdecreased with the temperature increasing. Compared with control, decreases of grainyields were-12.13%,-24.72%and-42.70%, respectively, in temperature increased about1°C,1°C and3°C under the precipitation decreasing about20%. While decreases were-8.37%,-15.10%an-21.82%, respectively, under the precipitation unchanging, and were-8.95%, -15.50%and-22.19%, respectively, under the precipitation increasing about20%. Correlationbetween thegrain yield of winter wheat and the minimum temperature in winter was positive(R=0.67, P=0.023), but correlation between thegrain yield of winter wheat and the maximumtemperature in June was negative during the periods of the green stage-booting stage and themilky ripe stage–maturity stage.The relations between grain weight of winter wheat and themaximum temperature in June was y=-0.336X2+15.848X-152.66(R2=0.4015). The grain weightof winter wheat started to decrease as the maximum temperature in June is more than24℃. Themaximum temperature in June was the main factor which constrained grain forming during theperiods of the milky ripe stage-maturity stage. The accumulated temperature in winter willdecrease about74℃and death rate of the winter wheat will be2.4%in10years.Theprecipitation was the key factor which affected grain yields of winter wheat. And decrease ofgrain yields was42.00kg ha-1with precipitation reduce about10mmduring the wheat growingseasons.The relations between the yields of cotton and the average minimum temperature beforeflowering and in October were positive. The flower production before frost had a significantrelation with the minimum temperature in October.With minimum temperature increasing inOctober, the growing stage of cotton was prolonged, and dry matter and the flower production ofcottonwere increased.With the temperature increasing, the starch content of spring wheat decreased, but the grainprotein contentof spring wheat increased. The number of aphids decreased with temperatureincreasing under conditions of precipitation decreasing. The number of aphids increased at firstand then decreased with temperature increasing under conditions of precipitation increasing orunchanging. The rate of rust of spring wheat increased with the temperature increasing.With climate warming, the suitable areas for spring wheat planting are becoming small inarid and semiarid regions, and are becoming big in humid and semi-humid regions. The mostsuitable and unsuitable areas of winter wheat are became small, and the areas of suitable, lesssuitable and cultivable are becoming big.The decrease of the most suitable, most suitable andunsuitable areas were35%,3%and2%, respectively, for potato production, and the increase oftheless suitable and cultivable areas were18.5%and18.5%, respectively. The area of the mostsuitable areas is becoming big, but the suitable area is becomingsmallfor maize productionin Hexioasis irrigation region and in the middlebasin of the yellow river irrigation region. The less suitable areas is becoming small in Hexi oasis irrigationregion and is becoming big in themiddlebasin of the yellow river irrigation region. The cultivable area is unchangeablein Hexioasis irrigationregionand in becoming small in the middlebasin of the yellow river irrigationregion. And the unsuitable areas are becoming smallin both regions. The most suitable and lessareas is becoming big, but the suitable and cultivable areas are becoming small, and theunsuitable area is unchangeable for maize production in the rainfed farming inHedong regions. |
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