Effects Of Supplemental Lighting Time At Night On The Growth And Development After Heading Stage Of Wheat

Lighting is an important environmental factor in the process of plant growth and development.At present,the use of artificial light source had become one of the important ways to improve crop quality and yield.Using a winter wheat cultivar Yu Nong 186 as the material in order to explore the effects of different supplemental lighting time at night on photosynthetic characters,endogenous plant hormones content,grain filling characteristics,grain quality and yield.The experiment included 5 treatments: Natural lighting time,without non-woven fabrics covering and no supplemental lighting(CK1);Natural lighting time,with non-woven fabrics covering but no supplemental lighting(CK2);After the wheat heading stage adding 2 hours lighting by using artificial light source at night(T1),with non-woven fabrics covering;After the wheat heading stage adding 4 hours lighting by using artificial light source at night(T2),with non-woven fabrics covering;After the wheat heading stage adding 6 hours lighting by using artificial light source at night(T3),with non-woven fabrics covering.The main results are as follows:1.Supplemental lighting time could significantly increase the grain weight and yield,but it had no significant influence on spike numbers and spike grain numbers.The grain weight of T3 treatment(6 h)was increased by 11.04%,the yield of T3 treatment(6 h)was 14.07% higher than that of CK1,which reached 7 720.33 kg?hm-2.Supplemental lighting time also could significantly increase the grain starch content.But the total protein content of grain decreased at the treatment of supplemental lighting time at night,and the content of albumin,globulin,gliadin and glutenin also all decreased at the treatments of supplemental lighting time at night.2.Supplemental lighting time at night could increase the dry matter accumulation and improve the contribution to grains after anthesis.Supplemental lighting time at night can decreased the dry matter translocation amount before anthesis,dry matter translocation ratio after anthesis,and contribution of assimilates translocated from vegetative organs to grains.Among all the treatments,the effects of supplemental lighting time of 6 h treatment(T3)were the most significant.The contribution of assimilates translocated from vegetative organs to grains of 6 h treatment was 24.58% and 23.76% lower than that of CK1 and CK2,the contribution of assimilates produced after anthesis to grains of 6 h treatment was 31.21% and 28.20% higher than that of CK1 and CK2.3.Supplemental lighting time could significantly increase the maximum grain filling rate,the average grain filling rate and maximum grain weight,the treatments also could shorten the time of reaching the maximum filling rate.Compared with CK1 and CK2,the maximum grain filling rate of T3 treatment(6 h)increased by 0.314 mg/d and 0.295 mg/d,the average grain filling rate increased by 0.096 mg/d and 0.168 mg/d.Grain filling duration and rate during early,middle and late phases were influenced by supplemental lighting time at night.Supplemental lighting time at night could improve the average grain filling rate during early,middle and late phases.Among all the treatments,the effects of supplemental lighting time of 6 h treatment(T3)was the most significant.4.Supplemental lighting time at night could affect the endogenous plant hormones content in flag leaves.Compared with CK1 and CK2,the content of GA3,IAA and ZR were significantly increased by the treatments of supplemental lighting at night,but they had little influence on ABA.At the 20 days after heading,compared with the CK1 and CK2,the IAA content of flag leaves of T3 treatment(6 h)increased by 52.68% and 53.99%,the content of ZR increased by 29.39% and 31.96%,the content of GA3 increased by 35.36% and 32.59%.The treatments of supplemental lighting at night had little effects on the content of ABA,but the treatments also increased the ABA content,at the 20 days after heading,the ABA content of T3 treatment(6 h)were 12.53% and 13.33% higher than that of CK1 and CK2.5.The supplemental lighting time at night could influence the photosynthetic characters of wheat leaves.Compared with the control treatments,the treatments of supplemental lighting time at night could improve the area of leaves,increase the chlorophyll content and photosynthetic rate of flag leaves,the effects of supplemental lighting time of 6h treatment(T3)were the most significant.At the 21 days after heading,the area of leaves of T3 treatment(6 h)increased by 11.52% compared with CK1 and increased by 10.21% compared with CK2.At the 14 days after heading,the chlorophyll content of flag leaves of T3 treatment were 13.49% and 15.16% higher than that of CK1 and CK2,and the photosynthetic rate of flag leaves increased by 22.85% and 24.72% compared with CK1 and CK2.The effects of supplemental lighting time at night on chlorophyll fluorescence parameters of flag leaves showed that,compared with the control treatments,supplemental lighting time at night could improve the Fv/Fm and PIABS,decrease the DIo/RC,but the effects of supplemental lighting time on F0 were not significant.Among all the treatments,the effects of supplemental lighting time of 6 h treatment(T3)were the most significant.Supplemental lighting time at night also affected the light-response curve of photosynthesis of flag leaves.The maximum photosynthetic rate and dark respiration rate were increased by supplemental lighting time at night,the maximum photosynthetic rate of T3 treatment were 33.7% and 33.10% higher than that of CK1 and CK2,and the dark respiration rate of flag leaves increased by 34.94% and 34.17% compared with CK1 and CK2.The Photosynthetic rate,stomatal conductance,intercellular CO2 concentration and transpiration rate of flag leaves were affected by supplemental lighting time,and the effects of 6 h treatment(T3)were the most significant.The results indicated that proper supplemental lighting time(6 h)was beneficial to the growth of leaves.Supplemental lighting time at night could enhance the photosynthetic characteristics,and achieve more biomass accumulation and higher yield.