A method for the identification and evaluation of stay-green wheat variety

摘要

Leaf senescence is synchronized with grain-filling in wheat. Delayed leaf senescence, or stay-green, can improve wheat yield. In this study, a method has been proposed to identify and evaluate the stay-green wheat. First, chlorophyll content of flag leaf was measured by SPAD-502 meter at three-day intervals from seven days after anthesis to physiological maturity. Meanwhile, green leaf area duration was visually recorded using 0-9 scale. Secondly, a mathematical model was simulated according to the above phenotypic dates. Thirdly, the senescence characteristic parameters were calculated, including the time from anthesis to (i) senescence start (T-s), (ii) complete senescence (T-o), and (iii) maximum rate of senescence (T-MRS), as well as the maximum rate of senescence. Finally, wheat varieties were divided into three stay-green types by hierarchical cluster analysis, including stay-green, early senescence and intermediate type. Based on this approach, a functional stay-green variety, Tainong 18 was screened. Tainong 18 with a delayed T-s and normal rate of senescence (RS) was similar to dSnR of type A under normal irrigation. However, it had earlier T-s and very small RS, and was similar to type B under drought stress. It can be used as a parent of crossing combinations in future wheat breeding, due to a longer photosynthetic activity and high yield potential.