| Wheat as one of the most important staple crops (Triticum aestivum L.), it is urgent toresolve the contradiction between supply and demand for it and develop its potency toimprove the yield in the limited cultivated land. At this time, it will provide the theoreticalbasis for implementing effective cultivation measures and exerting the potential of increasingyield through explore the physiological mechanism of big–headed wheat deeply. Aexperiment in field and laboratory conditions is conducted to investigate the yield traits, leafphotosynthetic rates, chlorophyll fluorescence parameters, chlorophyll ralative value (SPAD)and leaf area indexes (LAI) between eight big-headed wheat new lines (present in2009Shaanxi Provincial Wheat Variety Pretest and2010Wheat Variety Regional Test) and Xinong979(CK). Study the differences of specific leaf area (SLA), leaf dry matter content (LDMC)and leaf nutrient content during different growth and development stages, then discuss thenitrogen accumulation and distribution of different organs. Research on the correlationsbetween the yields and main agronomic traits of eight new high-yield big-headed wheat linesand the yield differences of the lines.Main results are as follows:(1) The eight new lines presented higher kernel numbers per spike, kernel weights and1000kernel weights than the control but lower spike numbers per unit area than the latter; thebig-headed varieties2036,2037,2038,2040presented remarkably higher yields than thecontrol. The average Pn of the new lines did not significantly differed from that of the control,and the Fv/Fm, ФPSⅡ,qP, and Fv’/Fm’ of the former were higher than those of the latter; theleaf chlorophyll relative value of the lines2037,2040,2039,2038and2036were17.5%,19.1%,15.3%,13.9%and7.9%higher than those of the control and their LAI of the formerlines were significantly higher than that of the latter and slowly declined in the late growthperiod.(2) The average SLA and LDMC of big-headed wheat is less than Xinong979. Thebig-headed wheat leaf nutrient content was in the following order: N> K> P. The averagenitrogen accumulation capacity of the big-headed lines was higher than the control at maturity.The order of separate organs nitrogen accumulation and distribution ratios was: grain> stemand sheath> spike grass> flag leaf> fall second leaf> remain leaves.The average transferrate and contribution rate of the big-headed lines were lower than Xinong979. SLA and LDMC of flag leaf were negatively correlated at heading stage. SLA was no significantpositive correlated with N content, but highly significant negative with P, K.(3) The eight new wheat lines were remarkably lower than Xinong979in spike numberper unit area but significantly higher than Xinong979in the other agronomic traits; theaverage yield of new lines was higher than the control. The yields of the lines were moreclosely correlated with their spikes numbers per unit area and kernel weights; the yields of thelines were closely related to their fifth internodes and the internodes next to their spikes; andthe aboveground biomasses of the new lines had negative effects on their yields. The newlines could get their spike numbers per unit area increased, thereby getting their yield traitsoptimized. |
