Effects Of Row Spacing,Nitrogen Application And Harvest Time On Seed Production Of Festuca Sinensis And Festuca Rubra

Festuca sinensis and Festuca rubra are high-quality cultivated forages.Recently,they have been widely used in grassland construction and ecological management projects in Qinghai-Tibet alpine pastoral areas because of their strong resistance,rich leaves,good palatability and high nutritional value.However,the insufficient yield of such seeds has become a bottleneck restricting the restoration of grassland vegetation in Qinghai-Tibet region.The improvement of seed yield of native grass and supply of sufficient high-quality grass seeds are important for grassland ecological restoration in the Qinghai-Tibet Plateau.From 2020 to 2022,we conducted three years field trail to evaluate row spacing effects on Festuca sinensis and Festuca rubra seed produciton,and nitrogen effects on Festuca sinensis seed yield of in Menyuan,Qinghai province.Besides,seed development of Festuca sinensis and Festuca rubra were also determined in Menyuan,Qinghai province and Yuzhong,Gansu province.Four levels of row spacings（20,30,50 and 70 cm）were used in row spacing experiment.Four nitrogen levels(0,80,130,180 kg·hm^-2)and four nitrogen times（regreening stage,initial flowering stage,regreening stage+initial flowering period,autumn harvest+regreening stage）were set up in nitrogen experiment.After the full flowering stage,samples were taken every 6 days in Menyuan and every 3 days in Yuzhong to explore the effects of different site on seed development of Festuca sinensis and Festuca rubra.The main results are as follows:（1）The seed yield of F.sinensis and F.rubra decreased with the increase of row spacing,and the average seed yield was the highest in 20 cm row spacing treatment,which were 1007.1 kg·hm^-2and 825.9 kg·hm^-2,respectively.However,the variation of seed yield under row spacing of less than 30 cm should be further tested.The inflorescence number/m²of F.sinensis and F.rubra decreased with the increase of row spacing,Other yield components were ether increased significantly with increase of row spacing（P<0.05）or the difference was not significant with the increase of row spacing.Inflorescence number per/m²was the key factor for obtain of high seed yield.（2）Seed yield of F.sinensis increased with the increase of nitrogen application rate.When 130 kg·hm^-2nitrogen（RF130）was applied at the regreening stage and the early flowering stage,the average actual seed yield was the highest,which was2456.3 kg·hm^-2.Seed yield components such as inflorescence number/m²also increased with the increase of nitrogen application rate.The agronomic efficiency of nitrogen fertilizer and partial factor productivity of nitrogen fertilizer decreased with the increase of nitrogen application rate.The harvest index increased first and then decreased with the increase of nitrogen application rate.When the nitrogen application rate was 130 kg·hm^-2,the seed yield of F.sinensis was the best in the treatment of nitrogen application at the regreening and early flowering stages（RF）.（3）The seed yield of two kinds of Festuca was higher in Menyuan than in Yuzhong,but the seed yield of F.sinensis was higher than that of F.rubra.The seed quality of F.sinensis in Menyuan was better than that in Yuzhong,while that of F.rubra was similar in the two places.The best seed harvest time of F.sinensis and F.rubra was 36 to 42 days after flowering stage in Menyuan,and 24 to 27 days after flowering stage in Yuzhong.Each of the growth period of F.rubra and F.sinensis in Menyuan was later than that in Yuzhong.All growth period of F.rubra.was later than that of F.sinensis.In summary,the highest seed yields of F.rubra and F.sinensis in Menyuan were obtained at a row spacing of 20 cm.The variation of seed yield under row spacing of less than 20 cm should be further tested.The optimum nitrogen application combination for F.sinensis was 130 kg·hm^-2nitrogen（RF130）which is applied half and half at the regreening and early flowering stages,respectively.F.sinensis is more suitable for seed production in Menyuan,while F.rubra can be used for seed production in Menyuan and Yuzhong.