Effects of soil moisture on photosynthetic characteristics of different specialized end-uses winter wheat at their later growth stages and on their yields

In this study, pot experiments with various cultivars of specialized end-uses winter wheat were carried out at Henan Agricultural University Research Station during 2001-2003. The results showed that as for cultivar Yumai 34, the values of its chlorophyll meter(SPAD), PSII activity (Fv/Fo) and maximal PSII light energy transformation efficiency (Fv/Fm) were the highest when soil moisture content was at 60% of field capacity (FC), but the photochemical quenching coefficient (qP), non-photochemical quenching coefficient (qN), apparent photosynthetic electron transport rate (ETR) and the ratio of PSII photochemical quantum yield (φ2) were all increased at 80% of FC. For high-yielding cultivar Yumai 49, its SPAD, qP, qN and ETR were higher at 80% of FC, but Fv/Fo, Fv/Fm and φ2 were less affected by FC. For cultivar Yumai 50, the values of its photosynthetic characteristics were the highest at 80% of FC, except that the qN value was the lowest. The yield and the relative content of grain protein of cultivar Yumai 34 were also increased at 60% of FC. Furthermore, there was a significant difference among grain yields. The relative contents of grain protein of cultivars Yumai 49 and 50 were improved at 40% of FC, while the highest yields were obtained at 80% of FC. There were significant differences in the grain yields of Yumai 49 and 50 among different soil moisture treatments.