Differences Of Water Requirement And Water Stress Response Characteristics For Representive Winter Wheat Cultivars Released In Different Decades

Variation of water use characteristics, agronomic characters traits and a few physio-ecologicalindexes of six respective winter wheat cultivars, widely cultivated along the Yellow River in centralHenan Province since the1950s, were investigated. Response characteristics of crop growth, waterrequirement, gas exchange and chlorophyll fluorescence kinetics parameters to water stress of six winterwheat cultivars were also analysed. The experiment was conducted in the irrigation experiment stationsof Guangli Irrigation District (35°40′N,112°55′E) in2010~2011. The results were as follows.1. Plant height of winter wheat was decreased scalariformly with varietal development. Leaf areaindex of winter wheat after the1970s was lower than that before the1970s. However, there was noobvious difference between the dry matter accumulation for winter wheat with the development of times.The1000-grain weight and grain yield of winter wheat were improved with varietal development.Compared with the varieties of the1950s, the1000-grain weight and grain yield of the modern cultivarsincreased by55%~69%and46%~78%, respectively. Increase of the1000-grain weight is the mostprominent factor for yield increase.2. Photosynthetic rate (Pn) and transpiration rate (Tr) of the modern cultivars was higher than that ofthe old varieties. Difference of Pn between winter wheat varieties was not significant at jointing stage;the photosynthetic capacity of the old varieties was similar to the near/modern varieties during the rapidvegetative growth stage of vegetative growth. The chlorophyll content of winter wheat cultivars wereincreased linearly with varietal development. Values of the initial fluorescence (Fo), maximumfluorescence (Fm) and variable fluorescence (Fv) of the modern cultivars were whole higher than that ofthe old varieties.3. The amount and the intensity of water consumption in winter wheat presented a regular variationduring the whole growth stage. Before returning green, the daily water consumption intensity of winterwheat was smaller, while after returning green, the daily water consumption was highest and increasedwith the irrigation amount. The crop water consumption of winter wheat cultivars released in differentdecades was basically similar regardless of the differences in crop water consumption of winter wheatcultivars. The average water consumption of the low-water, mediate-water and high-water treatment was289.40mm,357.64mm and402.70mm, respectively. Early varieties, such as “Xinong6028” and“Fengchan3”, consumed soil moisture too early and too quickly, easy cause severe drought late, is notconducive to the grain filling and yield formation under water deficit conditions. While the modernvarieties can make better use of soil moisture, and their water consumption model more in line with thewater-saving and efficient irrigation of winter wheat.4. Pn, Tr, leaf water potential and Gs of winter wheat was decreased with water deficit. The jointingand flowering stages were the water deficit sensitive period for winter wheat. The intercellular CO2concentration was increased with water stress after anthesi, indicating the non-stomatal factors was the main limiting factor of photosynthesis capacity. The PS II potential activity center was damaged withwater stress at grain filling, the primary conversion of photosynthetic restrained, the electronic transferprocess affected, and the against light inhibitory ability of winter wheat reduced.5. Leaf water use efficiency of winter wheat was increased with water stress at jointing stage underfiled conditions, but there were opposition results in the pot. Compared to the cultivars released infifties-sixties of the last century, grain yield and WUE of the modern winter wheat cultivars increased by53%(low-water treatment),78%(mediate-water treatment),46.6%(high-water treatment) and45.6%(low-water treatment),63.4%(mediate-water treatment),57.8%(high-water treatment), respectively.Under the condition of crop water consumption keeping stable, the increase of grain yield of winterwheat is the dominant factor of the improvement of WUE.