| As one of China's main food crops,rice cultivation accounts for 28% of the country's grain planting area.The Northeast Black Soil Region,as an important rice production base in China,plays a vital role in ensuring national food security.At present,rice planting in the black soil region of Northeast China is still dominated by traditional transplanting mode,with large water consumption and low water use efficiency,which causes serious waste of water resources.Moreover,rice of traditional transplanting mode has problems such as easy lodging and difficult harvesting at the maturity stage,which further limits the increase in yield.Therefore,it is of great significance to seek a high-efficiency water-saving rice planting model suitable for the northeast black soil region to promote the sustainable development of agricultural soil and water resources in the black soil region of Northeast China and to ensure the national food security.Based on this,this experiment takes rice as the object,adopts the method of measuring pit micro-zone test,setting three kinds of planting modes of direct seeding in dry land of rice under drip irrigation(DH),direct seeding in dry land of rice under flood irrigation(MH)and traditional rice transplanting under basin irrigation(CK),and using CK as a control to explore the effects of rice growth dynamic index,physiological index,water dynamic index,stalk resistance index,water consumption,yield and its constituent factors,water use efficiency,etc.under different planting patterns.And comprehensive evaluation of different planting patterns is carried out to select the optimal planting mode for high-efficiency water-saving,preferably suitable for northeast black soil area.It can also provide new solutions and ways for rice lodging that has a bad effect for yield and quality in the northeast black soil region.The trials were conducted at the Rice Irrigation Test Center in Heping County,Heilongjiang Province,in 2017 and 2018,respectively.The following test results were obtained:(1)The DH and MH have not changed the growth law of rice compared with CK.Compared with CK,the DH and MH had different degrees of reduction in plant height,stem diameter,leaf dry weight,sheath dry weight,stem dry weight,but there had been an increase in root dry weight and root-shoot ratio.Among them,at the maturity stage,compared with CK,the plant height of DH and MH were decreased by 8.94%~9.35% and 8.28%~8.40%,respectively,and the stem diameter decreased by 7.27%~7.87% and 5.86%~6.38%,respectively.The dry weight of leaves of DH and MH at the whole growth period were decreased by 3.70%~10.26% and 2.22%~8.20%,respectively.The dry weight of the sheath of DH and MH were decreased by 2.20%~10.87% and 0.98%~6.52%,respectively.The dry weight of stems were decreased by 1.79%~6.06% and 2.17%~4.65%,respectively.The dry weight of the panicle were decreased by 3.33%~14.29% and 2.67%~12.04%,respectively.While the dry weight of the root were increased by-9.84%~16.93% and-4.92%~16.72%,respectively,and the root-shoot ratio were increased by 0.84%~27.10% and 1.02%~26.41%,respectively.(2)The photosynthesis rate,transpiration rate and stomatal conductance of the three treatments were firstly increased and then decreased with the growth process.The photosynthetic rate and transpiration rate peaked at the heading and flowering stage,and were the smallest at the early stage of tillering.The overall fluctuation of intercellular CO2 concentration in the three treatments was not dramatic.The specific performance showed that the photosynthesis rate of DH and MH was higher than that of CK by-22.15%~13.69% and 21.41%~22.43%,respectively,and the transpiration rate of DH and MH was decreased by-3.06%~53.01% and-7.42%~44.00%,respectively,and stomatal conductance of DH and MH was decreased by-14.73%~39.71% and-17.15%~27.85%,respectively,and the intercellular CO2 concentration of the three treatments was maintained at 220?mol·mol-1~330?mol·mol-1.(3)The moisture content of leaves,sheaths,stems,ears and crowns of the three treatments was continuously decreased with the growth process.The moisture content of the leaves,sheaths and stems of DH and MH was lower than that of CK,and DH was the lowest.And DH and MH were reduced by 1.27%~7.68%,0.82%~7.76%,4.11%~5.20% and 0.35%~3.65%,-0.44%~5.98%,2.11%~3.97%,respectively.The moisture content of the panicle of DH and MH are both higher than that of CK by 1.00%~25.79% and-2.48%~19.15%,respectively(except for the milk maturity period of MH).The moisture content of the root of DH and MH was higher than that of CK at the end of tillering by 0.42%~5.47% and 0.14%~4.53%,respectively,which was the highest in DH.The DH and MH had lower injury intensity at the early growth stage,but they began to increase significantly compared with the CK from the heading flowering stage,and DH and MH were increased by 4.11%~19.77% and 0.75%~16.00%,respectively.(4)The internode moisture content of stems of the three treatments at milk maturity and yellow maturity period showed a "S" curve trend with the increase of height,which was the largest in CK,and the smallest in DH.For the internode length and the unit length inter-section weight of the stem,the internode length of each section of DH was the lowest,but unit length inter-section weight of the stem of DH reached the maximum,and the unit length inter-section weight of the S3~S5 internodes was significantly higher than that of CK by 91.29%~275.76% and 72.73%~279.36%.The DH significantly improved the bending resistance,breaking moment and bending stress of the stem,reduced the bending moment,section modulus and lodging index,and the lowest lodging index at the S5 internode.The lodging resistance of DH was significantly improved.The internode length,internode moisture content,bending moment,section modulus and lodging index of the three treatments showed a very significant positive correlation(P<0.01).Lodging index can be characterized and predicted by the stem moisture content.The unit length inter-section weight,bending resistance,breaking moment,bending stress and lodging index were significantly negatively correlated(P<0.05).(5)The water consumption of DH and MH was significantly lower than that of CK,which decreased by 19.67%~75.60% and 13.70%~56.03%,respectively,and the water consumption was reached the highest at the jointing and booting stage.The DH and MH did not cause a significant decline in yield,which was only 2.44%~4.92% and 0.80%~4.13% lower than that of CK,and the difference among the three treatments was not significant.At the same time,the 1000-grain weight and seed setting rate of DH and MH were not significantly decreased,and the panicle length and panicle number was decreased significantly,and the effective panicle number was increased significantly,but WUEl and WUEy of DH and MH were significantly higher than CK.The increase of WUEl in DH was-13.21%~103.69%,and WUEy in DH was increased by 2.62~2.66 times.The WUEl in MH was increased by-14.92%~45.07%,and WUEy in MH was increased by 1.61~1.63 times.(6)AHP-fuzzy comprehensive evaluation model was used to comprehensively evaluate different rice planting patterns.The comprehensive evaluation results were DH(0.3359)>CK(0.3324)>MH(0.3317),which was sorted according to the evaluation grades of excellent,good and bad.The results were DH,CK and MH.Therefore,the optimal rice planting mode suitable for the northeast black soil region is the direct seeding in dry land of rice under drip irrigation. |
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