Abstract:
Objectives We constructed different types of radiation use efficient populations through the plant densities of wheat, and compared their N accumulation and transport characteristics before anthesis and the N accumulation after anthesis, to provide a theoretical base for improving wheat yield through efficient radiation use efficiency (RUE).
Methods Field trials were conducted in Suixi and Mengcheng counties of Anhui Province in 2018−2019, the cultivar “An 1302” with strong tillering ability and “Wankenmai 0622” with weak tillering ability were employed as the test materials. Four plant densities: 180×104 plants/hm2 (D1), 240×104 plants/hm2 (D2), 300×104 plants/hm2 (D3), and 360×104 plants/hm2 (D4) were set up for the investigation of yield, and the interception rate, amount, and photosynthetic conversion efficiency of active radiation at milk-ripening stage. According to these data, the wheat population was divided into high, moderate and low radiation use efficient types, denoted as H-, M-, and L-RUE, respectively. The N accumulation and translocation during anthesis stage, and the N accumulation and leaf area index at milk-ripening stage were compared among the three population types.
Results Cultivar, density and their interaction significantly affected the RUE and grain yield. The RUE and grain yield of H-RUE population were 1.4% and 9.7 t/hm2, which were higher than those of M- and L-RUE by 5% and 14%, 1% and 5%, respectively. The interception rate at anthesis and milk-ripe stages, and the interception amount of available radiation from anthesis to milk-ripe stages were not significantly different among the three population types, but the photosynthetic conversion efficiency of H-RUE was 2.34 g/MJ, which was higher than that of M- and L-RUE population. The H-RUE population had a higher leaf area index at anthesis (7.24) and milk-ripe stages (4.53), and higher N accumulation in stem & leaf sheath (63.9 kg/hm2), leaves (79.5 kg/hm2), and per unit leaf area (143.78 μg/cm2) at anthesis, compared to the other population types. In addition, H-RUE population and the individual stem had similar translocation rate of N at pre-anthesis stage with the M- and L-RUE populations and the individual stems, but had significantly higher N translocation amount due to their higher N accumulation amount. The leaf area index of H-RUE population was significantly higher than the M- and L-RUE populations at anthesis and milk-ripening stage as well.
Conclusions The wheat population with high radiation use efficiency could accumulate more N in stems & leaf sheaths, and leaves, and has higher N accumulation amount per unit leaf area before anthesis stage, in spite of higher translocation amount of N, the N accumulation in the vegetative organs is higher than those in the moderate and low radiation use efficiency populations, so the population maintains high leaf area index at anthesis and milk-ripening stage, which is inductive to the radiation conversion and the formation of yield.