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Cangzhou Academy of Agricultural and Forestry Sciences, Cangzhou 061001, China

1 Introduction

Wheat is a grain crop requiring much water. Studies have shown that reasonable irrigation period and irrigation times are important guarantees for the high and stable yield of wheat. Reasonable water deficit exercise during the proper growing period of wheat is favorable for increasing the stress resistance and water utilization efficiency of wheat, while water deficit adjustment and irrigation at improper growth stage will lead to a significant decline in wheat yield[1-2]. From the period after sowing to the period before jointing, the water consumption accounts for 35%-40% of the water consumption during the whole growth period, and the daily water consumption is about 6 m3/ha. The period from jointing to heading is the critical period of wheat growth. In this period, water deficit will lead to yield decline, and the water consumption in 25-30 days accounts for 20%-25% of the total water consumption, and the daily water consumption is about 33.0-51.0 m3/ha. In the period from heading to maturity, the daily water consumption is larger, the water consumption in 35-40 days accounts for 26%-42% of total water consumption. Especially in the heading stage, the daily water consumption is up to 60 m3/ha. This shows that the main growth stages of wheat are basically consistent with the change process of water demand. Zhang Jinghui[3], Pei Wenshouetal.[4-5]studied the water demand and winter wheat water-saving and high-yield cultivation techniques, and found that the average water demand per kg of wheat during the whole growth period is 0.723 m3[6-10]. There have been many reports of combined application of nitrogen fertilizer and impact on late wheat under limited water irrigation conditions[11-14].

Cangzhou City, located in Heilonggang River valley, Hebei Province, is a main wheat producing area in Hebei Province. Subject to poor natural conditions, the wheat yield is low, the average yield is about 5 4700 kg/ha, it has a high potential of yield increase. It is also a typical funnel area in North China. The exploitation of groundwater is excessive, water resources are seriously deficient. Excessive groundwater exploitation has caused severe ecological problems[15]. According to the latest statistics, the annual average precipitation in Cangzhou City is 551.1 mm, and the average water resource volume is 12 333 million m3, including 596.14 million m3surface water, 692.39 million m3underground water, and repeated calculation is 55.23 million m3. Calculated according to the population (6.847 5 million) of Cangzhou City in 2005 and the area of 0.807 million ha of cultivated land at the end of the 2005, the per capita amount of water resources in the city was 180 m3and the average per mu of water resources was 102 m3, which is 6.8% and 5.9% of the national average value respectively, and 43.0% and 40.8% of that of the average value of Hebei Province[16-17]. Therefore, China set forth specific measures of banning the exploitation of groundwater in North China. As Cangzhou wheat production belongs to well-irrigation production, the banning of exploitation will inevitably affect the wheat production, we must actively respond. In this experiment, we studied and analyzed the effects of irrigation times of 19 wheat cultivars on the wheat production.

2 Materialsandmethods

2.1SamplematerialsWe selected 18 wheat cultivars from the National Wheat Industry Technology System and set the local wheat variety Nongda 399 as the control.

2.2Experimentdesign

2.2.1Overview of the experiment. The experiment was carried out at the Xian County seed farm in Comprehensive Experimental Station of Cangzhou (116°11′59″ E and 38°11′33″ N). This experimental site has uniform soil fertility and flat terrain. The seed was sown on October 16, 2015. The experiment was carried out by the large area comparison method, the area was 7.5 ha, and no repetition was set. The seeding rate was 150 kg/ha, the row spacing was 16 cm, and protection zone was set outside the planting area. In the spring irrigation 2 experiment, the irrigation 1 was implemented at the jointing stage (April 1), the irrigation 2 was implemented at the flowering stage (May 10). In the spring irrigation 1 experiment, the irrigation 1 was implemented at the jointing stage (April 1). In the irrigation 0 experiment, no irrigation was implemented. On April 1, combining the irrigation, 225 kg/ha urea was applied. On June 12, wheat was harvested.

2.2.2Experimental varieties and field planting diagram. Nonghaha 2BX-9 Wheat Seed Drill was applied, to ensure uniform sowing of every wheat cultivar. After fixing the site, observation road was made, to make the field landscape become excellent. The field planting diagram is illustrated in Fig.1.

12345678910111213141516171819Prote?ctionzoneKe?nong2011Xing?mai13Han115276HengS29Cang?mai028Anmai1Luo?mai7Ke?yuan088BinBY34Taike?mai33Yan?nong172Liao?mai18Yong1917Lin091Yao?mai16Shi10?4393Ji?mai23Zhong?mai4072Nong?da399Prote?ctionzone2Irrig?ationObservationroad1Irrig?ationObservationroad0Irrig?ation

Fig.1Fieldplantingdiagramfortreatedwheatcultivars

2.3Experimentmethods

2.3.1Stem-tiller situation. By means of the fixing site survey, we measured the number of stems, tiller number per plant of representative row No. 1 in the seeding stage, wintering stage, re-greening stage, jointing stage, and maturity stage, and converted to the average per unit area.

2.3.2Determination of leaf area. During the grain filling stage, we measured the flag leaf area using the ruler and selected 10 plants continuously.

2.3.3Indoor seed evaluation. We evaluated the spike length, number of spikelet, and panicle type of harvested samples, and measured the volume weight of sampled dried wheat.

2.3.4Yield components. At the maturity stage, we surveyed the number of grains and the number of spikes per ha; in each plot, we selected typical 6.7 m2to harvest and threshed separately, dried and calculated the yield and converted into the yield per ha; in the dried wheat, we randomly selected samples and measured the 1 000-grain weight.

2.4DataanalysisWe processed data and carried out analysis using Excel and DPS7.05 software.

3 Resultsandanalyses

3.1AnalysisofyieldresultsFrom Table 1, it can be seen that the yield of irrigation 1 increased by 5.26%-39.19% (average increase of 16.03%) compared with that of irrigation 0, while the yield of irrigation 2 increased by -8.97%-34.72% (average increase of 11.33%) compared with that of irrigation 1. The average yield of irrigation 1 increased by 68.07 kg compared with that of irrigation 0, while the average yield of irrigation 2 increased by 60.00 kg compared with that of irrigation 1. Irrigation exerted a very significant effect on the increase of wheat yield. Every decrease of one time of irrigation times, there will be loss of yield about 60.00 kg.

Table1Resultsofeffectsofirrigationtimesonyieldofwheatcultivars

CultivarNo．CultivarnameYield∥kg/haIrrigation0Irrigation1Irrigation2Increaseofirrigation1overirrigation0∥%Increaseofirrigation2overirrigation1∥%Averagedifferencebetweenirrigation1andirrigation0∥kg1Kenong20117100．407700．408400．458．459．09650．0252Xingmai136700．357900．358100．4517．912．53700．0503Han1152768100．459100．5010250．5512．3512．641075．0504HengS297400．408400．459200．4013．519．52900．0005Cangmai0287100．408200．359300．4515．4913．421100．025

(To be continued)

(Continued)

CultivarNo．CultivarnameYield∥kg/haIrrigation0Irrigation1Irrigation2Increaseofirrigation1overirrigation0∥%Increaseofirrigation2overirrigation1∥%Averagedifferencebetweenirrigation1andirrigation0∥kg6Anmai16100．357600．357800．4524．592．63850．0507Luomai77800．459100．5010100．5516．6710．991150．0508Keyuan0887100．408700．458300．4022．53-4．60600．0009BinBY346500．407800．457100．4020．00-8．97300．00010Taikemai336600．307400．409100．5012．1222．971250．10011Yannong1727400．4010300．5010400．5539．190．971500．07512Liaomai186200．256800．408650．509．6827．211225．12513Yong19177500．458900．408800．5018．66-1．12650．02514Lin0918000．408900．409300．4511．254．49650．02515Yaomai168200．359300．4510350．4513．4211．291075．05016Shi10-43936800．407200．309700．505．8834．721450．05017Jimai237700．408700．4510250．5512．9917．821275．07518Zhongmai40726500．408100．4510300．5024．6127．161900．05019Nongda3997600．358000．409800．555．2622．501100．100

3.2EffectsofirrigationonwheatpopulationsituationandthespikerateThrough the field survey of population situation of wheat cultivars, the growth conditions were basically consistent from the period after sowing to the period before re-greening between wheat cultivars. The highest number of stems reflected the difference between cultivars and the correlation coefficient with yield was not significant. The spike rate of wheat reflects the changes from the highest number of stems to effective number of spikes. From Table 2, it can be seen that the irrigation 0 and irrigation 1 were negatively correlated with the yield, the irrigation 2 was positively correlated with the yield, showing the significant influence of irrigation on the spike rate.

3.3EffectsofirrigationontheflagleafareaThe survey of flag leaf area of wheat cultivars at the grain filling stage showed that the leaf area of irrigation 0 was the smallest (18.15 cm2on average), the leaf area of irrigation 1 was 20.34 cm2, and the leaf area of irrigation 2 was 24.05 cm2. The leaf area difference S1was 2.19 cm2, and S2was 3.71 cm2. This indicated that the irrigation times affect the size of the flag leaf, and eventually affecting the flag leaf photosynthesis and the yield.

Table2Correlationcoefficientbetweenthehighestnumberofstems,spikerate,andtheyieldofeachtreatment

ItemIrrigationtimesCorrelationcoefficientHighestnumberofstems0r=0．47431r=0．33112r=0．0464Spikerate0r=-0．36111r=-0．06812r=0．0610P(0．05)=0．455

Table3Effectsofirrigationontheflagleafarea

CultivarNo．CultivarnameFlagleafarea∥cm2Irrigation0Irrigation1Irrigation2DifferenceofleafareaS1S21Kenong201117．7516．5123．54-1．247．032Xingmai1319．4615．7024．30-3．768．603Han11527615．3319．5425．364．215．824HengS2919．3424．9127．315．572．405Cangmai02823．0626．3925．973．33-0．426Anmai117．7620．1022．482．342．387Luomai718．5119．9223．111．413．198Keyuan08817．3319．4627．632．138．179BinBY3418．2620．0324．341．774．3110Taikemai3320．8524．3223．663．47-0．6611Yannong17212．9816．7819．243．802．4612Liaomai1821．3322．3524．371．022．0213Yong191718．6620．7623．452．102．6914Lin09117．4521．1523．423．702．2715Yaomai1618．2716．5224．08-1．757．5616Shi10-439316．2518．3222．562．074．2417Jimai2314．8919．5523．414．663．8618Zhongmai407217．0920．3222．193．231．8719Nongda39920．2123．7426．543．532．80

Note: S1is the leaf area of irrigation 1 deducting that of irrigation 0, while S2is the leaf area of irrigation 2 deducting that of irrigation 1.

3.4EffectsofirrigationtimesonindoorseedevaluationindicatorsThrough the field survey and seed evaluation, we found that the irrigation times had significant influence on the plant height of wheat (the plant height of irrigated wheat was about 8-20 cm higher that without irrigation). This was most prominent in wheat cultivars Keyuan 088, Yaomai 16, and Jimai 23, showing that these three cultivars were very sensitive to water.

Through the measurement of the spike length, rate of infertile spikelet and volume weight, we found that with the increase in the irrigation times, the volume weight of most cultivars declined, the spike length increased, and the rate of infertile spikelet slightly declined. Results are listed in Table 4.

Table4Effectsofirrigationtimesonspikelength,volumeweight,andinfertilespikelet

CultivarnameIrrigation0Spikelength∥cmVolumeweight∥g/LRateofinfertilespikelets∥%Irrigation1Spikelength∥cmVolumeweight∥g/LRateofinfertilespikelets∥%Irrigation2Spikelength∥cmVolumeweight∥g/LRateofinfertilespikelets∥%Kenong20117．28128．338．080417．787．581325．00Xingmai136．380726．257．078620．007．580616．00Han1152767．481621．118．781512．229．281110．00HengS297．882415．567．681222．227．883115．56Cangmai0288．680116．678．480019．448．381522．22Anmai17．080313．338．380816．007．880817．50Luomai77．878125．008．878210．008．678216．67Keyuan0885．880510．716．579311．116．881118．89BinBY347．078532．507．278515．567．281010．00Taikemai336．281028．576．880515．637．0792．09．38Yannong1728．082110．007．882618．757．880821．11Liaomai189．779916．6710．080511．0010．08067．78Yong19177．581013．897．380010．007．38108．33Lin0916．579116．677．28006．677．578313．89Yaomai167．282522．508．480114．008．581026．67Shi10?43937．080513．898．679523．647．780315．00Jimai236．582512．507．580021．887．082413．89Zhongmai40727．880818．758．580421．887．67978．89Nongda399ck7．079212．507．578911．007．680519．00

4 Conclusionsanddiscussions

According to the requirements of state for limiting the exploitation of underground water in North China, Hebei Province set forth the goal of gradually realizing zero-exploitation of agricultural water in excessively exploited areas. Cangzhou is the main implementation area. Its production mode, farming system and application technologies will have fundamental changes. The wheat industry of Cangzhou City should be based on guaranteeing the total yield, formulate the target of limiting irrigation, select drought resistant and high yield wheat varieties, and rely on high technology to explore the potential of biological water saving, to realize the high yield and high efficiency of wheat production under the condition of limiting irrigation[18]. Zhang Yongpingetal.[19]studied the stomatal characteristics of different green organs of wheat under different water supply conditions. The results showed that the photosynthetic rate of leaves declined under drought conditions, while the photosynthetic rate of non-leaf organs remained relatively stable, which could relatively increase the water utilization efficiency. Guo Xiaowei[20]studied the effects of different water treatments on the flowering and seed setting of winter wheat, and found that in severe drought conditions, drought-resistant varieties have strong ability of flowering and seed setting.

This experimental study provides a support for limiting irrigation water in the limited exploitation area. In October 29-30, there was a process of little precipitation. Wheat realized planting with adequate moisture. After sowing, the average temperature was relatively high, it was suitable for wheat germination. In November, the sunshine time was seriously insufficient. At the end of November, rainfall occurred in the whole country, the snow fell ahead of previous years. Just because of sharp temperature drop, some areas suffered the extreme low temperature, which exerted a great impact on the growth of winter wheat (varying degrees of frost damaged occurred to the winter wheat). In the early March of this year, winter wheat started re-greening. On the whole, the re-greening was normal and wheat seedlings grew well. Although the temperature in late January was 4.6℃ lower than that in normal years, and there was the extreme minimum temperature of -20.1℃ (January 23), there was very good moisture content in the early stage of precipitation and there were very few dead seedling due to frost damage, which made winter wheat live through the winter safely. However, since the experiment was just one year field experiment, and the rainfall of this year was 147.1 mm, 5.5% less than normal years, it would have a certain influence on the experimental results.

Cangzhou is typical funnel area in North China. The exploitation of groundwater is excessive, water resources are seriously deficient. Excessive groundwater exploitation has caused ecological problems, thus, it is required to limit the groundwater exploitation. In this experiment, the average yield of irrigation 1 increased by 68.07 kg compared with that of irrigation 0, while the average yield of irrigation 2 increased by 60.00 kg compared with that of irrigation 1. Irrigation exerted a very significant effect on the increase of wheat yield. Every decrease of one time of irrigation times, there will be loss of yield about 60.00 kg. Through the field survey and seed evaluation, we found that the irrigation times had significant influence on the plant height of wheat (the plant height of irrigated wheat was about 8-20 cm higher that without irrigation). This was most prominent in wheat cultivars Keyuan 088, Yaomai 16, and Jimai 23, showing that these three cultivars were very sensitive to water. Through the measurement of the spike length, rate of infertile spikelet and volume weight, we found that with the increase in the irrigation times, the volume weight of most cultivars declined, the spike length increased, and the rate of infertile spikelet slightly declined.

[1] FANG Q, MA L, YU Q,etal. Irrigation strategies to improve the water use efficiency of wheat-maize double cropping systems in North China Plain[J]. Agricultural Water Management,2010,97(8): 1165-1174.

[2] KARROU M, OWEIS T. Water and land productivities of wheat and food legumes with deficit supplemental irrigation in a Mediterranean environment[J]. Agricultural Water Management, 2012(107): 94-103.

[3] ZHANG JH. The characteristics of wheat water demand and high-yield cultivation techniques[J].Hebei Agriculture, 2013(1): 11-12. (in Chinese).

[4] SONG CJ, WANG ZH, ZHENG XR,etal. Determination of water consumption characteristics and crop coefficient of spring wheat under drip irrigation condition in Northern Xinjiang[J]. Acta Agriculturae Boreali-occidentalis Sinica, 2013,22(3):58-63. (in Chinese).

[5] PEI WS, PANG WX, WANG SX. Analysis of wheat water demand in the hilly area of West Anhui Province[J]. Agricultural Technology Service, 2015, 32(7): 108-109. (in Chinese).

[6] YANG YH, WU JC, HE F,etal. Effects of water and fertilizer application strategies on winter wheat photosynthetic characteristics, yield and water use[J]. Journal of Henan Agricultural Sciences, 2015, 44(5): 67-71. (in Chinese).

[7] SUN LZ, YU LN, ZHAO HM,etal. An experimental study on the effect of nitrogen and phosphorus on the yield of wheat under water-saving condition[J]. China Agricultural Information, 2016(1): 66-67, 69. (in Chinese).

[8] ZHANG Q. The application of agronomic water-saving technology in the development of agronomy[J]. Modern Agriculture, 2016(9):50. (in Chinese).

[9] YAN P, CHEN YQ, SUI P. Status and trends of researches on agriculture water issues in North China Plain：Based on bibliometric methods[J]. Journal of China Agricultural University, 2016, 21(9): 206-214. (in Chinese).

[10] GUO FZ, GUO LY, HUANG XJ,etal. Effects of different water treatments on agronomic characters of wheat[J]. Bulletin of Agricultural Science and Technology, 2015(5): 130-133. (in Chinese).

[11] ZHOU JH, WANG KW, TONG GX,etal. The application effect of stress resistance inducer on wheat under water limit irrigation[J]. Beijing Agriculture, 2008(6): 25-27. (in Chinese).

[12] HAO BZ, ZHANG YH, JIANG LN,etal. Effect of topdressing amount of nitrogen on photosynthetic characteristics and assimilates transportation in winter wheat under limited irrigation[J]. Journal of Triticeae Crops, 2010, 30(5): 863-869. (in Chinese).

[13] YAO ZJ, YANG YF, CHEN RY. Effects of limited irrigation and nitrogen application times on photosynthetic characteristics of flag leaves and yield traits of wheat[J]. Journal of Anhui Agricultural Sciences, 2011,39(13):7650-7652. (in Chinese).

[14] WANG P, WANG QX, LU LQ,etal. Effect of irrigation operation on 1000-grain weight and yield of winter wheat[J]. Acta Agriculturae Boreali-Sinica, 2001,16(3): 80-85. (in Chinese).

[15] JIANG WL. Study on water resource safety strategy for China in the 21th century[J]. Advances in Water Science, 2005(5): 23-26. (in Chinese).

[16] GUO YQ, DUAN XH. Problems and countermeasures in the utilization of water resources in Cangzhou[J]. Journal of Hebei Engineering and Technical College Quarterly, 2007(4): 18-20. (in Chinese).

[17] CHEN ZK. Research on the development trend and rational allocation of water resources in Northeast China[M]. Beijing: Science Press, 2007. (in Chinese).

[18] CAI FR, WANG YP, YAN YZ,etal. The water saving,high yield and high efficiency technique of wheat in Cangzhou area[J]. China Seed Industry, 2011(1):31-32. (in Chinese).

[19] ZHANG YP, WANG ZM, WU YC,etal. Stomatal characteristics of different green organs in wheat under different irrigation regimes[J]. Acta Agronomica Sinica, 2006, 32(1): 70-75. (in Chinese).

[20] GUO XW, ZHAO CJ, KANG SJ. Effects of water treatments on the configuration, physiological characteristics and yield of winter wheat[J].Acta Agriculturae Boreali-Sinica, 2000,15(4):40-44. (in Chinese).