The Effects Of Plant Growth Regulators On Machine-transplanted Japonica During The Recovery

Rice,the most important food crop worldwide,is a staple food crop for more than 50%of the world's population.An increase in rice production of 1.2%per year is required to meet the growing demand for food due to population growth and economic development in the next decade.Rice is also one of the major food crops in China,being a staple food for more than 65%of its national population.Therefore,improve rice production plays an important role in the food security of China.With the transfer of the rural labor force and the improvement and promotion of agricultural machinery and agronomic practices,the importance of rice planting mechanization has become increasingly prominent.Machine-transplanted rice is the main way of mechanization of rice cultivation.However,machine transplantation confers a serious transplanting shock upon seedlings and results in longer recover stage,which causes significantly negative impact on growth of low-position tillers and yield of machine-transplanted rice.Therefore,relieving the transplanting shock of machine-transplanted rice,shortening the recovery stage and promoting the growth of low tillers are important to improve the yield of machine-transplanted rice.A barrel experiment was conducted to examine the effect of foliar application of Hexanoic acid 2-?diethylamino?ethyl ester?DA-6?and Triacontanol?TRIA?on machine-transplanted rice during recovery stage,and yield at maturity.The main results are as followed:1 The effects of DA-6 and TRIA on the seedlings morphological index during the recovery after transplantingThe influence of the exogenous TRIA was significant on green leaves,stem diameter and dry weight after transplanting.However,an effect of exogenous TRIA on root regeneration after transplanting was not observed;The application of DA-6 significantly increased the numbler of green leveas and roots,dry weight and R/S,and of the three treamtents,the 20mg/L was best.2 The effects of DA-6 and TRIA on the physiological characteristics of rice seedlings during the recovery after transplantingAfter transplanting,the exogenous application of TRIA significantly improved the chlorophyll content and sucrose content compared to the control after transplanting;the spray of DA-6 markedly improved the photosynthetic rate,chlorophyll content and sucrose content after transplanting,compared to the control.3 The effects of DA-6 and TRIA on MDA?H₂O₂ and antioxidant system of rice seedlings during the recovery after transplantingThe exogenous application of TRIA significantly decreased H₂O₂ and MDA content during recovery after transplanting,and improved CAT?POD?APX and GR;And the results show that CAT and POD have different sensitivities toward adversity after transplanting,which impairs the activity of CAT and activates POD.Thus,we speculate that POD plays an important role in scavenging H₂O₂ during recovery stage after transplanting.The applicationg of DA-6 markedly decreased the MDA and H₂O₂ content,and improved the activity of antioxidase.After tansplanting,the exogenous application of TRIA and DA-6 improved ASA,GSH,ASA/DHA and GSH/GSSH in the rice seedlings.4.The effects of DA-6 and TRIA on the yield components of rice at maturityThe application of TRIA and DA-6 had a significant effect on the panicles and grain filling at maturity;A dose of 10 ?M TRIA was the most efficient in reducing the negative effects of transplant shock,increasing the panicles and grain yield per hill by 17.80%and 16.49%,respectively;the 20 mg/L of DA-6 was the best,and increased grain yield per hill by 23.96%,respectively,compared to the control.