Analysis On Hydrotropism Of Roots And Drought Resistance In Seedling Stage Of 12 Silage Maize Varieties

Silage maize has a high energy content and good absorption rate in ruminants.It contains abundant non structural carbohydrates,which are beneficial for digestion and growth of ruminants.At the same time,the lignin content is low,providing more easily digestible nutrients.In addition,due to the high yield per unit area of silage corn,the dry matter yield during harvest is also relatively high,making its cost-effectiveness more prominent.Therefore,silage corn has become an important source of feed for the beef and dairy industries.Drought is the main environmental pressure that seriously affects the growth,development,and yield of maize.Hydrotropism response refers to the biological characteristics of plant root tips that sense the gradient of water potential in the growth environment and grow towards areas with high water potential,which is crucial for plants to effectively obtain soil water.Improving the water absorption efficiency of plant roots is an effective measure to enhance plant drought resistance.The analysis and evaluation of hydrotropism and drought resistance of different silage maize varieties have important guiding significance for silage maize cultivation in arid and semi-arid areas.In this study,a stable hydrotropism induction system was used to evaluate the hydrotropism of 12 silage maize varieties,and the subordinate function method and principal component analysis were used to evaluate the drought resistance of 12 silage maize varieties in the seedling stage in the greenhouse by pot experiment.The effects of uneven water distribution on the growth status and root system of silage maize seedlings were studied by unilateral watering partial drought treatment experiment.The main results and conclusions are as follows:1.Using the hydrotropism induction system of maize roots,12 silage maize varieties were evaluated by four indicators: hydrotropism curvature of maize primary roots,growth speed,the time required to trigger hydrotropism and the time required to contact water sources after triggering.The results showed that the hydrotropism of different silage maize varieties was significantly different.Among them,the varieties with strong hydrotropism are Yu 23,Heyu36 and Dajingjiu 26,and the varieties with weak hydrotropism are Datang 136.The results of correlation analysis showed that the time needed to trigger hydrotropism was significantly negatively correlated with root growth rate and hydrotropism curvature,indicating that the more sensitive the variety to water gradient,the faster the root growth rate and the greater the hydrotropism curvature angle.2.The membership function method was used to comprehensively evaluate the morphological and physiological indicators of 12 varieties,including aboveground dry weight,malondialdehyde content,and relative leaf water content.According to the D-value,the drought resistance was ranked from highest to lowest as follows: Zhengsiyu 2>Ningyu688>Heyu 36>Zhongyu 335>Datang 8>Datang 12>Yu 23>Datang 136>Yayu 8>Dajingjiu26>Datang 20>Jingke 932.Principal component analysis showed that the drought resistance of the 12 maize varieties during the seedling stage was as follows: Zhengsiyu 2>Heyu36>Datang 8>Zhongyu 335>Datang 12>Ningyu 688>Datang 20>Datang 136>Yayu8>Dajingjiu 26>Jingke 932>Yu 23.Zhengsiyu 2 and Heyu 36 are strong drought resistant varieties.3.A partial drought experiment with unilateral watering was conducted to analyze the aboveground and root morphology,structure,and water use efficiency of 12 varieties of silage corn.The results showed that the aboveground dry weight,plant height,and stem diameter of Datang 8 were least affected by drought.Zhengsiyu 2,Heyu 36,and Ningyu 688 have the highest water use efficiency,while the root morphology and structure are less affected by drought stress,with deeper soil penetration depth and more developed roots.This indicates that these three varieties can maintain a certain yield under water stress,which is of great significance in production.Overall,the varieties with strong drought resistance selected in this study are Zhengsiyu2,Heyu 36,Zhongyu 335,Ningyu 688,Datang 8,and Datang 12.Among them,Zhengsiyu 2,Heyu 36,Zhongyu 335,Ningyu 688,and Datang 12 experienced more rapid underground root growth under drought stress.Zhengsiyu 2,Heyu 36,and Ningyu 688 had the highest water use efficiency,while Datang 8 had the least impact on the aboveground part,Heyu 36 has strong hydrotropism.