以二倍体野生一粒小麦(Triticum boeoticum)、栽培一粒小麦(T. monococcum)、节节麦(Aegilops tauschii)和黑麦(Secale cereale)、四倍体野生二粒小麦(T. dicoccoides)、栽培二粒小麦(T. dicoccum)、硬粒小麦(T. durum)、六倍体普通小麦(T. aestivum)‘扬麦9号’和‘扬麦158’及八倍体小黑麦(Triticale)为材料,采用盆栽试验研究了不同小麦进化材料生育后期旗叶光合特性的演变及产量的差异。结果表明,与六倍体普通小麦和八倍体小黑麦相比,二倍体和四倍体材料在开花前具有较高的光合速率(P_n)、气孔导度(G_s)、最大光能转换效率(F_v/F_m)和实际光化学效率(Φ_PSⅡ)。开花以后,二倍体和四倍体材料受非气孔因素的影响,光合能力下降较快;除黑麦外,旗叶光合速率在开花10 d后都低于普通小麦和小黑麦,胞间CO₂浓度(C_i)迅速增加,F_v/F_m、Φ_PSⅡ和叶绿素含量快速下降。二倍体和四倍体材料开花前单株总叶面积速,功能期短;单株穗数也较多,但穗粒数、千粒重、产量和收获指数却显著低于普通小麦。因此,小麦长期进化过程中,普通小麦花后较高的光合能力及较长的光合持续期是提高千粒重,进而提高产量的重要生理基础。

Aims Understanding genetic differences in photosynthetic capacity of different wheat materials evolved from diploid to hexaploid and octoploid is important for breeding and cultivation management, but the physiological basis for late-growth photosynthetic characteristics and grain yield of different wheat evolutionary materials is unclear. This study investigates evolutionary patterns in photosynthetic and fluorescent parameters by examining grain yield during late growth period in different wheat evolutionary materials.

Methods Pot experiment used ten wheat materials: four diploid species (Triticale boeoticum, T. monococcum, Aegilops squarrosa and Secale cereale), three tetraploid species (T. dicoccoides, T. dicoccum and T. durum), two hexaploid cultivars (`Yangmai 158' and `Yangmai 9') and one octoploid species (Triticale). Each pot contained 7.5 kg of sieved soil containing 14.8 g·kg^-1 organic matter, 1.2 g·kg^-1 total N, 82.3 mg·kg^-1 available N, 30.9 mg·kg^-1 available P and 126.7 mg·kg^-1 available K. Before sowing, 0.9 g N, 0.9 g K₂O and 0.36 g P₂O₅ were applied to each pot and topdressing of 0.3 g N was added at jointing stage. Fourteen seeds were sowed and thinned to seven plants in each pot at five-leaf stage. The experiment was arranged in a completely randomized design with ten replications per treatment.

Important findings The photosynthetic rates (P_n) of diploids and tetraploids were higher than that of hexaploids before anthesis, because diploids and tetraploids had higher stomatal conductance (G_s), maximum photochemical efficiency (F_v/F_m) and actual light transformation efficiency (Φ_PSⅡ). However, the P_n of diploids and tetraploids declined faster and became lower than those of hexaploids beginning 5 days after anthesis, except in S. cereale. Moreover, F_v/F_m, Φ_PSⅡ and chlorophyll content (SPAD value) of diploids and tetraploids declined faster, while intercellular CO₂ concentration (C_i) increased, which resulted in non-stomatal inhibition to P_n. Furthermore, the leaf area per plant of hexaploids and the octoploid declined slower after anthesis, as compared with diploids and tetraploids, although diploids and tetraploids had higher leaf area before anthesis. Mean number of spikes per plant of diploids and tetraploids was higher, but the kernels per spike, 1 000 kernels weight and grain yield were lower than those of hexaploids and the octoploid, indicating grain yield was related to the increased kernels per spike and 1 000 kernels weight. This study indicate that improved photosynthetic capacity and duration after anthesis are important physiological bases for enhancing grain yield from increased grain weight during evolution from diploid to current normal wheat.