| Maize is an important cereal crops in the world and one of the main food crops in China.As the demand for maize increases,increasing density has become a key measure for high yield of maize.However,the problem of stalk lodging has limited the further improvement of yield and quality of maize.The stalk strength,as a quantifiable index in the evaluation of maize lodging resistance,is widely used in breeding of lodging resistance varieties and germplasm identification.Formation of maize stalk strength is not only related to the external environmental conditions,but also closely related to its own genetic factors.Lignin,as the main structural compound of the secondary cell wall of the stalk,provides an important material source for the formation of maize stalk strength.The purpose of this experiment was to explore the effect of lignin accumulation on the formation of stalk strength at the base internode in maize hybrids and their parents.Be analyzing and comparing the internal relations between morphological characteristics,dry matter accumulation,lignin accumulation,activities of lignin synthesis related enzymes and the stalk strength（RPS）at base internode in maize hybrid and their parents.The main results are as follows:1.Analysis of stalk characteristics of base internodes in maize.With stronger lodging resistance of hybrid（F1）the dry weight per unit length（DWUL）,the diameter increased significantly,and the diameter was higher than that of its parents.The DWUL shows that the female parent is higher than the hybrids than the male parent.The DWUL of female parent with higher stalk strength hybrid（F1）are higher.Therefore,when cultivating lodging-resistant maize varieties,a combination with higher DWUL female parent should be targeted.2.The relationship between RPS and lignin accumulation in maize stalk.The peaks of RPS in hybrids appeared during the blister stage,and the formation of RPS started from the jointing stage to the blister stage.The hybrids（F1）with higher RPS had higher lignin accumulation rate and longer synthesis duration.The rapid lignin accumulation period was from jointing stage（V9）to tasseling stage（VT）in the third internodes of different hybrids（F1）and their parents,indicating that this period was the key period for lignin accumulation.The hybrids with higher RPS also had stronger RPS in their parents,and the rapid formation period of RPS is relatively long.The RPS and accumulation of lignin showed the mid-parent heterosis.The variation trend of the lignin accumulation of the hybrids was more similar to that of the female parent.The maize hybrid（F1）with higher the lignin accumulation had higher lignin accumulation in its parent.The hybrids and their parents showed a significant positive correlation between RPS and lignin accumulation.The higher accumulation of lignin on the basal internode will obviously enhance the RPS,thereby improving the lodging resistance of the maize stalk.Therefore,in the breeding process of lodging-resistant varieties,the parents with faster lignin accumulation in the stalk should be selected,which can help to improve the stalk strength of hybrids（F1）and enhance the lodging resistance.3.The relationship between the lignin accumulation and their synthesis-related enzymes in maize stalk.The enzymes activities of the large trumpet stage（V12-V15）of different lodging-resistant maize hybrids（F1）and lignin accumulation in the tasseling stage（VT）showed a significant or extremely significant relationship,indicating that the enzymes activities related to lignin synthesis during the large trumpet stage higher were beneficial to promote the rapid accumulation of lignin.The hybrids（F1）that its parents had higher mid-parent value of enzymes activities related to lignin synthesis had more lignin accumulation and higher stalk strength.Therefore,in the early stage of maize growth,effective measures were taken to promote the activities of enzymes related to lignin synthesis of maize stem at the trumpet stage,which can accelerate the rapid of lignin accumulation,and improve the lodging resistance. |
