| The field experiment was carried out in 2011~2012 and 2012~2013 wheat growth seasons. The research was carried out with wheat cultivar Jimai 22. Four soil layers(0~20, 0~40, 0~60 and 0~140cm) weredesigned to make the supplemental irrigation at jointing stage and anthesis stage. Four levels of soil relative water content in each soil layer weredesigned, 65% at jointing and 65% at anthesis(W1), 70% at jointing and 70% at anthesis(W2), 75% at jointing and 75% at anthesis(W3), and 80% at jointing and 80% at anthesis(W4), taking no irrigation(W0)during the whole growth season as the control.In order to study the effect of supplemental irrigation based on measuring soil moisture in thedifferent soil layers on photosynthetic characteristics and yield of wheat, the main results as follow:1 Under the same soil layer, effect of supple mental irrigation based on measuring soil moisture indifferent target soil relative water content on photosynthetic characteristics and grain yield of wheat1.1 Effect ofdifferent treatments on water consumption characteristics of wheatUnderd4, the Soil water consumption accounted for the proportion of the total water consumption of wheat which under jointing and anthesis stage soil relative water content were 75% that was significantly increased than which under jointing and anthesis stage soil relative water content were 80%, which was benefit for emptying soil volume.Underd2, anthesis to maturity water consumption amount,diurnal water consumption amount and water consumption percentage which under jointing and anthesis soil relative water content were 75% that were significantly higher than which taking no irri gation and under jointing and anthesis soil relative water content were 65% and 70%, which was benefit for emptying soil volume at a nthesis to maturity. Jointing and anthesis soil relative water content increased to 80%, those indicators had no significantly increase.1.2 Effect ofdifferent treatments on carbon metabolism of wheatIn 2011~2012 and 2012~2013 wheat growth seasons, photosynthetic rate(Pn), the maximal quantum yield of PSII(Fv/Fm), actual efficiency of PSII(ΦPSII), photosynthetic electron transport rate(ETR) and chlorophyll content of flag leaves at the middle and later of filling which under jointing and anthesis soil relative water content were 75% that were significantly higher than which taking no irrigation and under jointing and anthesis soil relative water content were 65% and 70%. Jointing and anthesis soil relative water content increased to 80%, those indicators had no significantly increase.Dry matter accumulation amount, grain accumulation amount at maturity and AA which under jointing and anthesis soil relative water content were 75% that were significantly higher than which taking no irrigation and under jointing and anthesis soil relative water content were 65% and 70%. Jointing and anthesis soil relative water content increase d to 80%, those indicators had no significantly increase.Underd2, starch content and amylose content of grain at maturity which under jointing and anthesis soil relative water content were 75% that were significantly increased than which taking no irrigation and under jointing and anthesis soil relative water content were 65% and 70%. Jointing and anthesis soil relative water content increased to 80%, those indicators had no significantly increase.1.3 Effect ofdifferent treatments on grain yield and water use efficiencyIn 2011~2012 wheat growth seasons, underd2,d3 andd4, grain yield and water use efficiency which under jointing and anthesis soil relative water content were 75% that were significantly increased than which taking no irrigation and under jointing and anthesis soil relative water content were 65% and 70%. Jointing and anthesis soil relative water content increased to 80%, those indicators had no significantly increase.In 2012~2013 wheat growth seasons, underd1,d2 andd4, grain yield which under jointing and anthesis soil relative water content were 75% that was significantly increased than which taking no irrigation and under jointing and anthesis soil relative water content were 65% and 70%. Jointing and anthesis soil relative water content increased to 80%, grain yield and water use efficiency had no significantly increase.Which Jointing and anthesis soil relative water content were 75% was the most appropriate irrigation treatment for recommendation by considering grain yield, water use efficiency and irrigation benefit.2 Under the same target soil relative water content, effect of supple mental irrigation based on measuring soil moisture in the different soil layers on photosynthetic characteristics and grain yield of wheat2.1 Effect ofdifferent treatments on water consumption characteristics of wheat Under W2 and W3, the Soil water consumption accounted for the proportion of the total water consumption of wheat under supplemental irrigation in 0~40cm soil layer significantly increased than that under supplemental irrigation in 0~60cm soil layer, which was benefit for emptying soil volume.Under W3, water consumption percentage of wheat under supplemental irrigation in 0~40cm soil layer significantly increased than that under supplemental irrigation in 0~20cm soil layer, which was benefit for emptying soil volume. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, the indicator had no significantly increase.2.2 Effect ofdifferent treatments on carbon metabolism of wheatUnder W3, w hen making supplemental irrigation in 0~40cm soil layer, the oval chloroplasts of flag leaves with intact membrane closely arranged along the cell membrane atday 22 after anthesis. Clear grana lamellaes arranged along the long axis of chloroplasts. And clear stroma lamellaes connected grana lamellaes. The obviousdamages of chloroplas ultramicrostructure were observed when making supplemental irrigation in 0~20cm soil layer, And the chloroplas ultramicrostructure was caused more seriousdamage when no irrigationduring the whole growth period. The round chloroplasts of flag leaves withdamaged membrane arrangeddisordered and cell wall had a breakdown. The chloroplas ultramicrostructure had no significantdifference between supplemental irrigation in 0~60cm soil layer and 0~40cm soil layer. When making supplemental irrigation in 0~140cm soil layer, there weredamages of chloroplas ultramicrostructure were observed. Chloroplasts membrane was intact, membranes of cells wasdamaged and there were gaps among grana lamellaes.There were significantly positive correlation among the numbers of chloroplast, chloroplast grana, grana lamellae of mesophyll cell of flag leaves and chlorophyll conten t(r=0.99**,0.99**,0.96**). The numbers of chloroplast, chloroplast grana and grana lamellae of mesophyll cell under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer and no irrigationduring the whole growth period, and which was why there was high chlorophyll content under supplemental irrigation in 0~40cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, the numbers of chloroplast, chloroplast grana and grana lamellae of mesophyll cell had no significantly increase and so as to chlorophyll content.Under W3, the maximal quantum yield of PSII(Fv/Fm), actual efficiency of PSII(ΦPSII) and photosynthetic electron transport rate(ETR) of flag leaves of wheat under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, Fv/Fm, ΦPSII and ETR had no significantly increase.Under W3, atday 22 after anthesis, stomatal frequency of FB and FV of flag under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, stomatal frequency had significantlydecline. At anthesis andday 22 after anthesis, length and width of stomatal aperture and stomatal apparatussize of flag leaves under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, those indicators had no significantly increase. Correlation analysis showed that increasing the length and width of stomatal aperture and stomatal apparatussize of flag leaves can significantly increase Pn and Gs of flag leaves.Dry matter accumulation amount, grain accumulation amount at maturity and AA under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, those indicators had no significantly increase.Starch content of grain at maturity under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, the indicator had no significantly increase.2.3 Effect ofdifferent treatments on grain yield and water use efficiencyIn 2011~2012 and 2012~2013 wheat growth seasons, grain yield and water use efficiency under supplemental irrigation in 0~40cm soil layer significantly increased than those under supplemental irrigation in 0~20cm soil layer. When making supplemental irrigation in 0~60cm and 0~140cm soil layer, those indicators had no significantly increase. Supplemental irrigation based on soil moisture measurement based on 0~40cm soil layer was the most appropriate irrigation treatment for recommendation by considering grain yield and water use efficiency of wheat. |
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