Effect Of Irrigation Frequency And Potasssium Fertilization Rate On Population Dry Matter Production And Grain Yield Formation Of Winter Wheat

In order to clarify the effects of irrigation frequency and potassium fertilization on population dry matter production and grain yield formation, two field experiments was carried out during 2006-2007 in Gaocheng County and 2007-2008 in Baoding with locally commercial winter wheat cultivar Henong 822 and Shixin 616 respectively. The experiments during two winter wheat growing seasons was designed as split plot arrangement, with irrigation times as main plots (including 0, 1, 2 and 3 times, expressed as W0, W1, W2 and W3 respectively), and potassium application amounts as split plots (including K2O 0, 112.5 and 225 kg/ha respectively). The main results were summarized as follows:1. Irrigation frequency and potassium fertilization affected more or less the indexes of population quality, such as the population culm number, dry matter accumulation and LAI. The variances of population culm number before overwinter and at double ridge stage between the two growing seasons were statistically different, but the variances of population culm number between the two growing seasons were similar statistically. The population culms of W2 at mid-late phenostages were the highest among the four irrigation levels, with that of W3 slightly decreased. The dry matter accumulation increased with the increase of irrigation times and potassium amounts, with that of W0K0 always lowest, and that of W3K2 highest. The difference of dry matter accumulation among the four irrigation levels was different at various phenostages, with that of W0 always lower, and that of W3 higher than those of other levels statistically. Comparison among the three potassium levels, only the difference of booting spike between K0 and K1 was insignificant. The other growing stages were statistically different among the three potassium levels each other. The LAI increased with the increase of potassium amounts under the four irrigation levels at various growing stages between the two growing seasons. During 2006-2007, the LAI of different potassium levels were statistically different among the four irrigation levels each other. During 2007-2008, the indexes of LAI among the three potassium levels were similar statistically, only at some growing stages and irrigation levels were statistically.2. Irrigation frequency and potassium fertilization affected more or less the indexes of grain yield and yield components. During 2006-2007, the difference of grain yield and yield components among the four irrigation levels was different at various growing stages. Although the grain yield of W3 was higher than W2, the yield components of W3 were really not optimum, the difference of W3 and W2 was insignificant. During 2007-2008, The highest grain yield was obtained for W2, and higher than those of other levels statistically, as a result of the iteration of the three yield components. Comparison among the three potassium levels, only the difference of grains per spike between K0 and K1 was insignificant during 2006-2007. The other two yield components and grain yield were statistically different among the three potassium levels each other in the two growing seasons.3. Proper potassium fertilization can prolong the functional period of flag leaf, and increase chlorophyll content further. As compared with K0, chlorophyll content of K1 and K2 decreased more slowly, and remained at a high level 35 days after anthesis further. The interaction of irrigation frequency and potassium fertilization amounts on chlorophyll content of flag leaf was statistically significant. Photosynthetic rate of flag leaf increased with the increase of potassium application, under more times in irrigation. Under W0 condition, the photosynthetic rate of flag leaf in the three potassium levels all reached a peak at booting stage, and then decline after booting stage. Under W1 condition, the photosynthetic rate of K0 reached a peak at booting stage, but the photosynthetic rate of K1 and K2 reached a peak at anthesis. Under W2 and W3conditions, the photosynthetic rate of flag leaf in the three potassium levels all reached a peak at anthesis, and for a longer duration.4. The dynamics of potassium accumulation in the whole growing stages showed a single peak, with the largest amount at anthesis. On the phasic absorption of potassium, the highest uptake of potassium was at double ridge to stem elongation, about 43%. The interaction of irrigation frequency and potassium fertilization amounts on potassium absorption rate was statistically significant. During 2006-2007, under W0 and W1 conditions, the highest uptake of potassium on K0 and K1 was at double ridge to stem elongation, but the others were at stem elongation to anthesis. During 2007-2008, the highest uptake of potassium on all treatments were at stem elongation to anthesis.5. The water productive efficiency increased with the increase of irrigation times. As a result of the more precipitation during 2007-2008, the water consumption increased. The differences of the water productive efficiency about the two growing seasons decreased with the increase of irrigation times, the largest for W0K0 , and the lowest for W3K2. Therefore, the interaction of the two growing seasons on water productive efficiency was statistically significant. The water productive efficiency of 2006-2007 was higher than 2007-2008. The differences of the water productive efficiency about the two growing seasons decreased with the increase of irrigation times, the largest for W0K0 , and the lowest for W3K2.It is necessary to satisfy the high yield requirement of winter wheat for water by irrigating twice at stem elongation and heading-anthesis at the base of suitable presowing soil moisture, and for potassium by fertilizing K2O 225 kg/ha with suitable coordination of nitrogen and phosphorus fertilization.