Response Of Water Consumption Process To Rice Yield Formation In Black Soil Region

In order to study the response mechanism of water consumption process on rice growth physiological indexes,yield formation and water use efficiency in cold black soil region,the rice water consumption test was carried out in the rice irrigation experiment center of Qingan County,Heilongjiang Province in 2017 and 2018.The test method adopts U₇?7⁶?uniform design to clarify the water consumption characteristics of rice in cold black soil region and its effects on rice growth physiological characteristics,yield and water use efficiency,the optimum water production function model of rice in the experimental area was optimized,and the limited water was allocated in the whole growth period.The main results are as follows.?1?According to the analysis of water consumption during the growth period of rice,it was found that the water consumption during the growth period of rice in 2017 and 2018 generally increased first and then decreased.The average water consumption and water consumption coefficient of the treatment at the jointing and booting stage were the highest;the water consumption intensity in rice growth period increased first and then decreased,and reached the maximum value at heading and flowering stage;the water consumption modulus coefficient at tillering stage was the highest,and the change range after the heading and flowering period was relatively flat.The water consumption in the daytime and the nighttime of rice treatment showed a trend of “low-high-low”.The average water consumption during the heading and flowering period reached the maximum.The proportion of daily water consumption in rice was gradually increased with the advance of rice growth period;in 2017,the water consumption characteristics of rice in the middle and early stages of the tillering were inverted “V” curve,the peak water consumption was from 12:00¹3:00;the “M” curve appeared at the late tillering stage to the milky stage,and the water consumption peak From 11:00¹2:00 and 13:00¹4:00,The first peak of water consumption in milking stage was 10:00¹1:00 in advance.Relative humidity was the main factor affecting water consumption in the early stage of rice growth,while air temperature played a dominant role in regulating water consumption in the middle and late stage of rice growth.The change range of water content was the most obvious.?2?The results of relationship between rice growth characteristics and water consumption process showed that ET₃ had the greatest impact on leaf dry matter weight at the late tillering stage;ET₄ and ET₅ had the greatest effects on stem sheath and ear dry matter weight,ET₂ and ET₃ had the greatest positive and negative effects on root dry matter weight,respectively;ET₂ had the greatest impact on the root wound flow,and the effect of ET₁ on root injury flow was the smallest;ET₁ and ET₆ had no significant effects on rice panicle formation rate;ET₂-ET₅ had significant effects on rice panicle formation rate,and the order of effect was ET₄,ET₅,ET₃,ET₂;the positive correlation between ET₃ and leaf area index reached significant level;the response of leaf photosynthetic potential to ET₄ was the greatest.ET₃ was significantly positively correlated with the effective leaf area rate,ET₄ was positively correlated with the effective leaf area rate and the efficient leaf area rate,ET₅ was positively correlated with the maximum dry matter accumulation and population growth rate at different stages,ET₁,ET₃ and ET₆ had no significant effects on the output rate of stem and sheath substances,ET₂,ET₄ and ET₅ had significant effects on the output rate of stem and sheath substances.ET₅,ET₂ and ET₄ had no significant effects on the transformation rate of stem and sheath substances,but water consumption had a significant effect on the transformation rate of stem and sheath substances in other periods,the order from large to small was ET₅,ET₆,ET₃,ET₂;The effect of ET₃ on the transformation rate of stem and sheath substances was negative.?3?The results of relationship between physiological characteristics and water consumption process of rice showed that the effects of water consumption on stomatal conductance and transpiration rate in the middle stage of tillering,jointing and booting stage,and heading and flowering stage were positive effects,and the water consumption in the e arly stage of tillering had a certain negative effect on leaf transpiration rate.The effect of water consumption on the intercellular CO₂ concentration and net photosynthetic rate was not significant in the early stage,and the water consumption in the middle of tillering to the flowering stage was ET₅,ET₂,ET₄,ET₃;ET₂,ET₅,ET₄,ET₃.ET₃ had a significant negative effect on both net photosynthetic rate and intercellular CO₂ concentration.There was a linear relationship between leaf stomatal conductanc e,transpiration rate,chlorophyll content and net photosynthetic rate.The intercellular CO₂ concentration and net photosynthetic rate showed a quadratic function curve.The response of leaf chlorophyll content to ET₄ and ET₅ reached a very significant level.?4?The results of the response relationship between rice yield and its components and water consumption process showed that the yield reduction ratio of different water treatments was between 6.10% and 21.38% compared with CK treatments;the negative correlation between ET₄,ET₅ and rice economic coefficient was significant;Jensen,Blank,Stewart and Singh models were selected to verify the regional water production function,and the Jensen model was identified as the best model of water production function in Heping irrigation area.The water sensitivity index was higher in the middle stage of tillering,at the jointing stage and at the heading stage.The water consumption in these three periods had a more significant effect on the yield;The optimi zed yield of each treatment was higher than the actual yield;ET₄ and ET₅ had significant positive effects on the effective panicle number,seed setting rate,grain number per spike and 1000-grain weight.?5?The results of the relationship between water use efficiency and water consumption process showed that the direct effect of stage water consumption on WUE and the total contribution to R² were arranged in the same order: ET₅,ET₂,ET₄,ET₃,ET₆ and ET₁;water consumption at late tillering stage and milky stage had a direct negative effect on WUE,and the variables with larger determinants of stage water consumption on WUE were ET₅,ET₄*ET₅,ET₂*ET₅,ET₂,ET₄;Water use efficiency of biomass at heading and flowering stage?SWUE₅?was significantly positively correlated with rice yield and WUE.The effects of water consumption from early tillering to flowering stage on SWUE₅ were as follows: ET₅,ET₄,ET₃,ET₁,ET₂;leaf water use efficiency at heading and flowering stage?LWUE₅?was the highest,while the negative correlation between ET₁ and LWUE₅ was not significant.The positive correlation between ET₂-ET₅ and LWUE₅ ranked from large to small as ET₅,ET₄,ET₂,ET₃,and the correlation between ET₄,ET₅ and LWUE₅ reached significant level.