Effects of Altitude on Photosynthetic Characteristics and Grain Filling of Coix lacryma-jobi L.

Huang Sheng; Liu Min; Xia Yuanqian; Cheng Yi; Liu Dailing; Song Bi

doi:10.14083/j.issn.1001-4942.2025.08.008

Abstract：To provide the theoretical basis and technical guidance for high-yield cultivation of Coix lacry-ma-jobi in mountainous area,the effects of different altitudes on its photosynthetic characteristics and grain fill-ing were studied in this experiment.A single factor randomized block design was adopted with three attitudes(1 100,1 300 and 1 500 m)and four Coix lacryma-jobi varieties including Xingren Xiaobaike(A),Wenyi 2(B),Anguocoix(C)and Shizong Xiaoheike(D).The experiment was conducted in the main producing area of C.lacryma-jobi in Xingren,Guizhou Province.The effects of different altitudes on photosynthetic character-istics,grain filling characteristics and yield of each C.lacryma-jobi variety were studied.The results were as follows.(1)The photosynthetic indexes of C.lacryma-jobi under different altitudes showed 1 300 m treat-ment＞1 500 m treatment＞1 100 m treatment.The net photosynthetic rate(Pn),intercellular CO2 concentra-tion(Ci),transpiration rate(Tr),minimum fluorescence yield(Fo),maximum fluorescence yield(Fm),actual photosynthetic quantum yield[Y(Ⅱ)]and electron transport rate(ETR)of C.lacryma-jobi leaves at 1 300 m altitude were 29.71％,41.32％,51.87％,17.65％,20.00％,4.08％and 17.74％higher than those at 1 100 m altitude,respectively.The Tr and Fm were the most significantly affected by altitude changes.A-mong the four C.lacryma-jobi varieties,the photosynthetic indexes showed as A＞D＞B＞C.(2)The dry matter accumulation when the grain filling rate was the largest(Wmax),the average grain filling rate(Va)and the maximum grain filling rate(Vmax)increased first and then decreased with the increase of altitude,and those were the highest at 1 300 m altitude,which increased by 7.15％,9.09％and 16.67％respectively compared with 1 100 m altitude.The dry matter weight of grains at 42 days after anthesis at 1 300 m altitude was 10.85％higher than that at 1 100 m altitude.The filling characteristics of A and D varieties were better than those of the other varieties.(3)The effective panicle number,1 000-grain weight and yield of C.lacryma-jobi were the highest at 1 300 m altitude,which increased by 3.90％,2.58％and 49.31％respectively compared with 1 100 m altitude and reached significant level.Among the four varieties,the yield of A was the highest as 5 832.5 kg/hm2,which was significantly higher than that of C with the increase amplitude as 79.31％.(4)Correlation analysis showed that the yield was significantly positively correlated with Pn,Ci,Tr,Fo,Fm,Fv/Fm,Y(Ⅱ),ETR,Wmax,Va and Vmax.It could be seen that the photosynthetic characteristics of Xingren Xi-aobaike planted at 1 300 m altitude were stronger,which would be conducive to grain filling and easier to ob-tain high yield.