The Effect of Organ Temperature on Total Yield of Transplanted and Direct-Seeded Rice (Oryza sativa L.)

Abstract

The canopy temperature of rice is an important index that directly reflects the growth and physiological state of rice, and affects the yield of rice plants to a great extent. The correlation between the temperatures of different rice organs and canopy in different growth stages and the grain yield is complex. The stability and universality of these correlations must be verified. We conducted a pot experiment using two rice varieties and two temperature treatments (high temperature treatment was carried out at the beginning of heading stage for 10 days). We measured rice organ temperature during seven stages of growth using a high-precision infrared thermal imager. Results showed that the optimal observation period for the rice canopy temperature was 13:00. Although the rice variety did not significantly impact the canopy or organ temperature (p > 0.05), the different organs and canopy exhibited significantly different temperatures (p < 0.05). The correlations between the leaf, stem, panicle, canopy-air temperature differences and seed setting rate, theoretical and actual yields were the strongest during the milk stage. Among them, the correlation coefficient between ΔT s and theoretical and actual yields was the highest, the relationship between theoretical yield (Y) and ΔT s (X) was Y = −5.6965X + 27.778, R 2 = 0.9155. Compared with ΔT l , ΔT p and ΔT c , ΔT s was closely related to the main traits of plants. ΔT s could better reflect the growth characteristics of rice than ΔT c , such as dry matter accumulation (r = −0.931), SPAD (r = 0.699), N concentration (r = 0.714), transpiration rate (r = −0.722). In conclusion, stem temperature was more important indicator than canopy temperature. Stem temperature is a better screening index for rice breeding and cultivation management in the future. KEYWORDSPlanting method; canopy temperature; organ temperature; grain yield Nomenclature DT l Leaf-air temperature differences DT s Stem-air temperature differences DT p Panicle-air temperature differences DT c Canopy-air temperature differences This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.