| The experiment was carried out in Institute of Water-saving Agricultural in Arid Areas of China, Northwest A&F University from June in 2014 to June in 2015 under a rain shelter. It included two experiments. Experiment 1: Choosing ‘Zhengdan-958’ as the test object, three irrigation amounts(i.e., W1, W2, and W3; or 120%, 100%, and 80% ETc) and three frequencies(D1, D2, and D3; 3d, 6d and 9d intervals) were applied to the study. Experiment 2:Choosing ‘Xinong-979’ as the test object, three irrigation threshold treatments(i.e., W1, W2,and W3; or 60%, 70%, and 80% θF) and two fertilization treatments(N, P2O5, K2 O.kg-1 dry soil)(F1: 0.15, 0.12, 0.15; F2: 0.3, 0.24, 0.3) were applied to the study. The research investigated the effects of water and fertilizer application on growth, yield, water and nutrient use efficiency, nutrient accumulation and soil nutrient distribution of wheat and maize.Results showed that:(1)With the development of maize growth period, plant height, stem diameter and leaf area presented a rising trend, and reached the maximum in mature period. Plant height, stem diameter, leaf area and dry matter of maize in mature period were influenced significantly by irrigation amount, and they increased with the increase of irrigation amount, showing as W1>W2>W3. Irrigation frequency reached a significant level on plant height and reached a higher significant level on stem diameter, leaf area and dry matter for maize in mature period.They presented a downward trend with the increase of irrigation frequency, showing as D1<D2<D3.(2)Irrigation amount and frequency influenced maize yield significantly. maize yield increased with the increase of irrigation amount, and decreased with the increase of irrigation frequency, while the maximum, 83.25 g, was obtained in W1D3 treatment.In addition to ear length, bald ear length and row number, Ear coarse, kernel number per row and hundred-grain weight also increased with the increase of irrigation water and the decrease of irrigation frequency, appearing the same change regularity as yield. The fitting relationship between maize dry matter and yield presented a linear relationship, while R2 was 0.969. It indicated that dry matter played an important role to increase yield.(3)Water use efficiency(WUE) and irrigation water use efficiency(IWUE) showed a increasing trend firstly and then declined with the increase of irrigation water, and all showeda decreasing trend with the increase of irrigation frequency. The maximum of WUE and IWUE were processed in W2D3 treatment, showing as 1.84 kg/m3 and 1.62 kg/m3 respectively.Water use efficiency of W2D3 treatment increased by 4.26% than W1D3 treatment, but yield reduced by 13.25%. Under the experimental condition, W1D3 treatment was the suitable experimental layout.(4)Irrigation amount and frequency affected nutrient accumulation of maize in mature period significantly. Amount of nutrients(nitrogen, phosphorus and potassium) absorption increased significantly with the increase of irrigation water, and declined significantly with the increase of irrigation frequency. Nutrients(nitrogen, phosphorus and potassium) use efficiency showed as P>N>K. Increasing irrigation amount, nitrogen, phosphorus and potassium use efficiency all decreased, while increasing irrigation frequency, they all showed a rising trend. Nutrients(nitrogen, phosphorus and potassium) uptake efficiency showed as K>N>P. Nitrogen, phosphorus and potassium uptake efficiency and partial fertilizer productivity(PFP) increased with the increase of irrigation water, and decreased with the increase of irrigation frequency. The maximum value of PFP appeared in W1D3 treatment with2.56 kg/kg while the minimum value was obtained in W3D1 with 1.60 kg/kg.(5)Irrigation amount and frequency had different effects on distribution of soil NO3-N in mature period while the fertilizers of all treatments were consistent. In addition to soil layer of14 cm in W2D3 treatment, soil NO3-N content of all treatments increased with the increase of soil depth under the same level of irrigation amount. They all reached the maximum value at soil layer of 35 cm. Soil vertical section NO3-N accumulation increased with increasing irrigation frequency, and decreased with the increase of irrigation amount.(6)With the development of wheat growth period, plant height and leaf area increased firstly and then declined. The peak of plant height appeared in filling period while leaf area was obtained in flowering period. Plant height, leaf area and above ground dry matter of all growth periods increased with the increase of irrigation threshold and the decrease of fertilization, and the maximum values all appeared in W3F1 treatment. With the development of wheat growth period, chlorophyll contents of wheat showed a increasing trend at first, then decreased. Content of chlorophyll a, chlorophyll b and chlorophyll content had a peak in flowering period, while carotene content appeared in filling stage. Chlorophyll contents of wheat increased with the increase of irrigation threshold and fertilization, obtaining the maximum in W3F2 treatment.(7)Wheat yield increased significantly with the increase of irrigation threshold, and decreased significantly with the increase of fertilization, showing as W1<W2<W3, F1>F2.Yield of W3F1 treatment was the largest with 88.98 g, while the minimum was obtained inW1F2 treatment with only 51.64 g. Changes of spike numbers and hundred-grain weight were similar to wheat yield,and the fitting relationship of spike numbers and yield,hundred-grain weight and yield all presented a linear relationship. R2 were 0.917 and 0.973 respectively, and fittings were good. The fitting relationship between wheat above ground dry matter and yield also had a linear fitting relationship, and R2 was 0.978. It showed that dry matter quality had an important effect to increase wheat yield.(8)Irrigation threshold and fertilization had significant impact on water use efficiency(WUE) and irrigation water use efficiency(IWUE). With the increase of irrigation threshold,WUE and IWUE increased firstly and then decreased. With the increase of fertilization, all showed a trend of decline. The maximum value of WUE appeared in W2F1 treatment with1.94 kg/m3, followed by W3F1 treatment with 1.93 kg/m3. There were no significant difference between the two treatments, but wheat yield of W3F1 treatment increased by 10.33% than W2F1 treatment. IWUE in W2F1 treatment reached the maximum value of 1.91 kg/m3,followed by W3F1 treatment with 1.90 kg/m3. Based on the analysis of yield and water use efficiency, W3F1 treatment was suitable under this experimental condition.(9)Nitrogen, phosphorus and potassium accumulation in wheat plant increased with the advancement of growth period, and reached the maximum in mature period. Nitrogen,phosphorus and potassium accumulation migrated gradually from wheat stems and leaves to ears, and nutrient accumulation of wheat ears was the largest in ripening period. Irrigation threshold and fertilization affected nitrogen, phosphorus and potassium accumulation in above ground dry matter significantly, and increased with the increase of irrigation threshold and the reduce of fertilization in all growth periods. Nutrient(nitrogen, phosphorus and potassium)use efficiency showed as P>K>N. Under the same fertilization, phosphorus and potassium use efficiency had a downward trend while nitrogen use efficiency showed a increasing trend firstly and then decreased with the increase of irrigation threshold. Increasing fertilization,nitrogen, phosphorus and potassium use efficiency all presented a downward trend. Nutrient(nitrogen, phosphorus and potassium) uptake efficiency showed as N>K>P. Nitrogen,phosphorus and potassium uptake efficiency and partial fertilizer productivity(PFP) increased with the increase of irrigation threshold, and decreased with the increase of fertilization. They all reached the maximum in W3F1 treatment. The maximum value of PFP was 4.17 kg/kg while the minimum appeared in W1F2 treatment with only 1.21 kg/kg. There was significant difference between the two treatments. |
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