Analysis On The Mechanism Of Wheat Yield Difference In Hubei Province And Research On Approaches To Narrow Yield Gap

Hubei Province is an important part of the wheat area in the middle and lower reaches of the Yangtze River and one of the main wheat producing areas in China.Currently,the wheat production level in Hubei Province only reaches 67% of the highyielding provinces in the middle and lower reaches of the Yangtze River,and the average yield still needs further improvement.Reducing yield gaps is an effective way to comprehensively improve regional production.The objectives are to clarify the differences in yield levels and formation mechanisms between regions and within regions in Hubei Province,and to explore the main limiting factors of yield gaps are of great significance for achieving comprehensive improvement in regional wheat production.This study employs research methods such as household surveys,field experiments,and crop model simulations to reveal key factors causing yield gaps between different planting systems in Hubei Province from multiple perspectives,including climate change,soil properties,cultivation management,and social factors.The study aims to provide a theoretical basis and technical support for reducing the yield gaps and increasing total grain production in Hubei Province.The main conclusions are as follows:(1)There are yield gaps between regions and within regions in wheat production levels among farmers in Hubei Province.Through the comprehensive analysis of 791 survey data from wheat farmers in Hubei Province,it was found that the yield gaps mainly exist between regions and within regions.The average wheat yield in the Jianghan Plain area is significantly lower than that in the northern Hubei region,with a yield gap of 1125 kg/hm2.Soil fertility and meteorological disasters are the main factors causing yield gaps between regions.Specifically,the northern Hubei region has poor soil fertility,and wheat in the late growth stage is prone to drought and high-temperature stress.In contrast,waterlogging occurs more frequently in the Jianghan Plain area,leading to severe soil erosion.When waterlogging occurs,the probability of low-yielding farmers(yield < 4500 kg/hm2)in the Jianghan Plain area increases by 8.6 times,and when soil erosion is severe,the probability of low-yielding farmers increases by 4.8 times.Frequent meteorological disasters result in a 20.7% higher proportion of low-yielding farmers in the Jianghan Plain area compared to the northern Hubei region.In addition,there are yield gaps between different planting systems within the same region,with rainfed wheat having an average yield 134-575 kg/hm2 higher than that of wheat following rice.Differences in cultivation management practices are the main factors causing yield gaps between wheat planting systems.Considering the current average nitrogen fertilizer application of wheat following rice is 9.8 kg/hm2 higher than rainfed wheat,there is an urgent need to optimize nitrogen fertilizer management for wheat following rice.(2)Optimizing nitrogen fertilizer management can effectively reduce yield gaps between planting systems.Based on three years of field nitrogen fertilizer management experiments,the key physiological mechanisms leading to yield gaps between planting systems were analyzed.Under two wheat planting systems,three nitrogen levels and five nitrogen-to-base fertilization ratios were set to explore the regulatory effects of optimizing nitrogen fertilizer management on narrowing yield gaps between planting systems.The results showed that there were significant differences in soil environment and growth development between rainfed wheat and wheat following rice.Compared to rainfed wheat,the soil environment of wheat following rice had higher bulk density,poorer water retention capacity,and permeability.In terms of chemical properties,the available nitrogen content and nitrogen availability in the plow layer soil were lower in wheat following rice.Due to the influence of soil environment,under traditional nitrogen fertilizer application,the root system of wheat following rice mainly concentrated in the0-20 cm layer,resulting in fewer tillers,shorter plant height,lower dry matter accumulation,and lower harvest index compared to rainfed wheat.Optimizing nitrogen fertilizer management can effectively alleviate the loss of available nitrogen in wheat following rice soil,increase the root distribution in the 20-40 cm layer,promote root penetration,and improve the growth and development of wheat following rice.Optimizing nitrogen fertilizer management can stabilize interannual yield variations and reduce yield gaps between planting systems,with better optimization effects observed in the nitrogen-to-base fertilization ratio treatment than in changing nitrogen application rates.Considering wheat yield and nitrogen utilization efficiency,split nitrogen application is more suitable for wheat following rice.(3)Solar radiation is the main factor causing spatial heterogeneity in wheat potential yield between regions across climatic factors.Based on previous field experiment data and meteorological information,the spatialtemporal characteristics of wheat potential yield in Hubei Province were analyzed using the APSIM-Wheat model.The yield gaps between regions(northern Hubei and Jianghan Plain)and the key mechanisms causing yield differences due to meteorological factors were quantified.The potential yield of wheat in Hubei Province ranged from 5068.9 to7895.3 kg/hm2.The distribution of potential yield and climate resources during the wheat growing season showed distinct latitudinal patterns.The potential yield and total solar radiation exhibited a decreasing trend from north to south,while the average temperature and total precipitation showed an increasing trend from north to south.The main climate factors causing spatial differences in wheat potential yield in Hubei Province were solar radiation(contributing an average of 48.6%)and precipitation(contributing an average of 23.1%).Due to the effects of solar radiation and temperature,compared to Xiangyang,wheat in Jingzhou had a shorter period of vegetative growth(from sowing to jointing stage)and a lower average daily growth rate from jointing to maturity,which was the main reason for the lower biomass and potential yield of wheat in Jingzhou compared to Xiangyang.The wheat production potential in Hubei Province has declined at an average rate of 422.0 kg/hm2 every 10 years from 1985 to 2021,with the highest decline rate observed in the Jianghan Plain area.Increased precipitation is the main factor contributing to the decline in potential yield in this region.In conclusion,the yield gaps between different regions in Hubei Province are caused by differences in solar radiation and precipitation,with increased precipitation being the main factor contributing to the decline in potential yield.The yield gaps between planting systems within the region are mainly influenced by soil environment and cultivation management practices.Optimizing nitrogen fertilizer management can effectively reduce the yield gaps between rainfed wheat and wheat following rice,with better effects observed in split nitrogen application.The research results are of vital significance for developing cultivation techniques targeted at disaster prevention and mitigation,and breeding climate-resilient varieties,with the aim of narrowing the yield gaps between regions and planting systems.