Responses Of Seed Germination To Temperature And Water For Typical Native Plants In The Loess Hilly Region

The hill-gullied Loess Plateau region is one of the most ecologically fragile areas in China.The key to the management of this area is vegetation restoration.The key to successful plant regeneration lies in the germination ability of seeds.Seed germination is affected by many factors,of which temperature and moisture are the main factors.Biological soil crusts are widely distributed in hill-gullied Loess Plateau region,and changing the soil moisture has become another important factor affecting seed germination.In this paper,the fourteen common species in the hill-gullied Loess Plateau region were chosen as experimental materials:Artemisia scoparia?Artemisia giraldii?Artemisia sacrorum?Stipa grandis?Stipa bungeana?Dracocephalum moldavica?Periploca sepium?Bothriochloa ischaemum?Setaria viridis?Patrinia scabiosaefolia?Potentilla tanacetifolia?Linum usitatissimum?Lespedeza davurica?Sophora davidii.Temperature and moisture thresholds for seed germination of test plants were studied through laboratory experiments,and the most suitable temperature and moisture combinations for seed germination were discussed.Explore the effects of biological soil crust types and sowing positions on the germination of plant seeds under humid and drought conditions.The aim is to gain a deeper understanding of the ecological characteristics of seed germination in the study area,and a more scientific understanding of the slow spontaneous recovery of plants in the study area under the background of climate change,to provide a basis for the successful establishment of values for these species in the study area.The main findings are as follows:1.The study on the effect of accumulated temperature model on the seed germination and temperature threshold of fourteen test species showed that the germination of different species has different responses to temperature,and the temperature threshold and temperature time value of seed germination in the same habitat are still different.Among the tested species,the optimal germination temperature and the widest germination temperature threshold of P.sepium were the highest,and the optimal germination temperature of S.bungeana is the lowest,and the germination temperature range is the narrowest.2.The predicted results of the germination process show that the seed germination rate of the species has an extremely significant correlation with the corresponding temperature and time value(p<0.01).When the germination rate reaches the maximum value,the temperature and time required for seed germination are different depending on the species,The temperature and time required for the germination of Artemisia scoparia seeds is the smallest,and the germination is the fastest,followed by A.sacrorum and A.giraldii,and S.bungeana has the largest temperature and time value and the slowest germination.3.Research on the effects of water potential model on the seed germination and water potential threshold of the tested seeds shows that the cumulative germination rate and germination rate of the tested plant seeds are extremely significantly positively correlated with water stress(p<0.01),and different species have a positive effect on water stress.The responses were different.Among the tested plants,the S.davidii and L.usitatissimum were the most resistant to drought;mild drought stress promoted the germination of the seeds of L.usitatissimum,L.davurica and S.davidii.4.Research on the effects of PEG simulated water stress on seed germination under different temperature conditions shows that:(1)When the temperature is constant,the seed germination rate of each species decreases with the decrease of PEG solution osmotic potential,and the germination time lag gradually increases and the germination duration gradually increases.Short;(2)The seeds of the tested species show different germination characteristics under different water temperature conditions;(3)Seed size affects seed germination.Small seeds have a faster germination rate,shorter germination time lag,and higher germination rate than large seeds.The characteristics of short germination duration;(4)The germination potential and germination index of seeds are affected by temperature and moisture.There are differences among species.5.Research on the germination of test species through biological crusts showed that:(1)The seed germination rate of different species is significantly related to crust types and seed placement positions(p<0.05).Moss crusts can retain longer than lichen crusts.Water allows more species to survive and the germination rate is higher;(2)The influence of biological soil crusts on the germination rate of seeds is related to the morphological characteristics of the seeds,Large seeds have a higher germination rate and stronger ability to emerge from the soil.