Shihong WANG, Dingyin CHU, Qiuzhi LI, Huihui YIN, Haitao LI, Tong LI, Jianhua ZHAO,Zhongxu YANG

Luxi Comprehensive Experimental Station of National Cotton Industry Technology System/Liaocheng Academy of Agricultural Sciences, Liaocheng 252000, China

Western Shandong was an important cotton-producing regions of the Yellow River Basin,and the cotton plant areas were more than 100 thousand hm2. In recent years, the larger change of climate in different years,especially abnormal weather was often happened in July and August which were the critical period in the cotton growth,and the larger change of precipitation in different years,which was uneven distribution and excessive or too concentrated precipitation in some years,so it brought serious adverse effect to the growth of cotton. Rainy and less illumination weather seriously affected the growth of the cotton in the middle and later periods, and resulted in a large number of abscission and boll rot of cotton buds and bolls, which seriously affected the cotton yield. The change of meteorological factors had become the major factor affected the yield fluctuations of cotton in different years[1-6].

The influence of meteorological factors changes on corn, wheat and other crops had been more study and application. Sun hongyong et al.[7]found that the average temperature in late June, sunshine hours in mid-July and early September were the key meteorological factors that affected corn yield fluctuations.Zhang jiwang et al.[8]indicated that weak light stress declined the dry matter accumulation of corn and decreased yields. Cao yanfang et al.[9]thought the influence of climate change on yield and quality was more by studying the relationship of the climate change and population structure of wheat, the population quality and yield and quality.Many researchers agreed that the yield and quality of wheat increased in different years with the obviously aggravating drought[10-12]. There were many researches about the influence of meteorological factors on cotton yield. The consensus was that cotton yield and the average annual temperature were positively correlated.Higher temperature was conducive to the formation ofcotton yield, but excessive rainfall in the middle and later periods and few sunshine hour would cause a large number of abscission of cotton buds and bolls and directly impact on cotton yield[2-6,13-15].In this study,the fluctuated changes of meteorological factors and cotton production of western Shandong in different years were surveyed.Field trial about the influence of climate change between five years on cotton yields was did in order to determine the main meteorological factors that affected the cotton yield in that area, and provide a basis for the formulation of cultivation techniques and the selection of variety type in cotton production.

Materials and Methods

Testing time and areas

The experiment was did in Liaocheng of academy of agricultural science and technology demonstration park of Shandong Province from 2009 to 2013.

Experimental variety

The experiment selected ‘Lumianyan 28’ which was national authorized variety(2006)as test materials.

Test methods

Experiment design The test ground was clay soil and the soil fertility was moderate. Conventional fertilizer and furrow application of 105 kg of urea,90 kg of potassium sulfate and 150 kg of DAP per hectare before sowing. The first top application was before or after June 25th, and applied 150 kg of urea,90 kg of potassium sulfate per hectare.The second top application was before or after July 15th, and applied 195 kg per hectare. The cultivation density was 49 500 plant/hm2, and the region area was 667 m2. Repeated three times,and randomly arranged.

Data processing and collecting In annual test,mulching sowing was carried out on April 26th, final seedling on May 30th.Five points was randomly selected in each region, and continuous 10 plants in each point were selected to regularly survey the number of fruit branches,the total number of fruit sections, the number of abscission, boll number per plant and four bolls distribution. The number of stiff and rot bolls should be recorded.

In the first picking,the cotton bolls of 50 plants were all picked and calculated the average boll weight.Lint percentage of seed cotton collected from 50 cotton plants was measured. After the boll opening, seed cotton yield before frost (before Oct.30th)and seed cotton yield after frost(Oct.30th-Nov.10th)in each cotton region were picked three or four times. Every time the cottons were dried and weighed, in order to calculate the earliness. Then cotton ginning according to the region,and cottonseed samples were send to Ministry of Agriculture Cotton Quality Supervision and Testing Center for testing.

Weather data was the surface observational data of Liaocheng meteorological bureau.Statistical analysis was completed by SPSS software.

Results and Analysis

Overview of the meteorological factors in different years

The results showed that the main meteorological factors changes were different during the growth period of cotton in different years. The accumulated temperature change was not significant in growth period,and the coefficient of variation of sunshine hour was 7.4%. The precipitation change was significant in different years and the coefficient of variation of precipitation was up to 18.4%. So sunshine hour and precipitation were important meteorological factors that restricted the change of cotton yield in different years(Table 1).

During 2009 to 2013, western Shandong region went through normal years, dry years and wet years, which basically represented the characteristics of climate change in this region.Among them, 2012 belonged to normal years, precipitation distribution was more evenly during the growth period, and the illumination was adequate, which was the bumper year of the region.2010 and 2013 belonged to typical wet years, the precipitation reached up to 648.9 mm and 740.7 mm respectively, which was an increase of 21.5%and 38.7%above that of the corresponding period of 2012.2011 belonged to dry years, the precipitation was only 479.6 mm and the sunshine hour was 830.1 h,which was an increase of 85.6% and 89.8%above that of the corresponding period of 2012.

Table 1 The main meteorological factors in the growth period of cotton in during 2009 to 2013

The distribution of the meteorological factors in different years

Temperature Cottons were thermophilic crops, which required higher temperature conditions in the growth and development process[16-17].In 2009 to 2013, the average temperature change of each ten days during the growth periods of cotton showed slow rise in the earlier stage,the daily temperature was highest in July and August, and slow decline in September.The average temperature change of each ten days was obvious in different years,which the coefficient of variation was larger in early May and middle of September, 11% , 13.5% , 8.9% respectively.It showed that higher average daily temperature in July and August was beneficial to mutual coordination of vegetative growth and reproductive growth of cotton and enrich cotton bolls(Fig.1).

Sunshine hours Illumination was one of the important conditions for the formation of cotton yield.Adequate illumination in favor of photosynthesis,and establishing material foundation for the formation of cotton yield[18-19]. In 2009 to 2013, sunshine hours during the growth period of cotton showed higher in May and June, obvious decline in July and August and slow rise in September.It showed that rainy and less illumination weather in July andAugust easily led to abscission and boll rot, which was not conducive to the formation of yield. While the increase of sunshine hours in September in favor of less boll rot rate and expulsion rate, which was contributed to the formation of yield(Fig.2).

Precipitation Precipitation was the main meteorological factors affected cotton production. In the process of growth, cotton needed to consume a lot of water[20].In 2009 to 2013,precipitation during the growth periods of cotton showed less in May and June,sharp increase in July and August and decline in September. The relative concentration of precipitation was in July and August, which the proportion of precipitation accounted for 57% -88.3% of that in the whole growing period. Among them, the precipitation of 2012 and 2013 were excessive during the blooming period, which could easily led abscission of cotton boll and decline of the number of bolls, ultimately affected the yield(Fig.3).

The response of yield to meteorological factors change in different years

The change of cotton growth and yield traits during the growth period of cotton in different years The growth traits during the growth period of cotton in different years showed that the change of fruit section number of single plant was not significant, and the range was 44.7 to 50.2.The expulsion rate changed significantly, which reached up to 62.4% and 58.4% in 2013 and 2010 respectively. The boll rot rate was also changed significantly,which was significantly lower than other years in 2012 and 2013. The boll number of single plant was not significant, and the range was 20 to 24(Table 2).

The yield traits during the growth period of cotton in different years showed that the change of seed cotton yield was significant.Among them,the seed cotton yield was lowest in 2010,which was 3 558 kg/hm2. The seed cotton yield was highest in 2012,which was 4 170 kg/hm2. The lint yield change was significant, and the proper order of lint yield in different years was 2012(1 676 kg/hm2),2009(1 586 kg/hm2), 2011 (1 550 kg/hm2), 2013(1 481kg/hm2)and2010 (1466kg/hm2).The change of lint percent in different years was significant,among them the highest rate was 42.3% in 2011 and the lowest rate was 40.2% in 2012(Table 3).

The influence of meteorological factor changes on the growth and yield traits Due to the change of accumulated temperature during the growth period of cotton in different years was not significant (Table 1),sunshine hours and precipitation were important meteorological factors that restricted the cotton yield change in different years. Combining the meteorological characteristics of too much or too concentrated precipitation in some years in this region, the sunshine hours, precipitation, fertility traits and yield traits were carried out multiplefactor partial correlation analysis. The results showed that sunshine hours and fruit section of single plant,expulsion number,expulsion rate,rotten boll number and boll rot rate were negatively correlated, sunshine hour and cotton boll number of single plant were positively correlated, which all not reached significant level (Table 4).Precipitation and fruit section of single plant, expulsion number, expulsion rate and boll rot rate were positivelycorrelated, among them precipitation and fruit section of single plant reached significant positive correlation,precipitation and cotton boll number of single plant were negatively correlated.The results showed that adequate illumination reduce abscission of cotton bolls and rotten boll number, increase single plant cotton boll number,in favor of improve yield. To much or too concentrated precipitation in later period of growth, which easily led to a large number of abscission,rotten bell,and seriously affected the cotton yield.

The results showed that sunshine hours and seed cotton yield,seed cotton yield before frost, and lint yield were positively correlated, and not reach significant level. Precipitation and seed cotton yield, seed cotton yield before frost, and lint yield were negatively correlated, and all reached significant level.It means that precipitation was the key meteorological conditions affecting cotton production,while precipitation had a positive correlation with lint yield. The reason might be the moisture demand of fiber was much more than seeds, much rainfall helped to improve lint percent.

Table 2 The growth traits of cotton in different years

Table 3 The yield traits of cotton in different years

Table 4 The related analysis of growth traits and meteorological factors of cotton in different years

Table 5 The related analysis of yield traits and meteorological factors of cotton in different years

Conclusion and Discussion

Sunshine hours and precipitation were important meteorological factors that restricted the change of cotton yield in different years. This study showed that sunshine hours and seed cotton yield, seed cotton yield before frost,lint yield were positively correlated.The reason was that good illumination in favor of photosynthesis of cotton, reducing abscission of cotton buds and bolls, reducing boll rot and improving the bolls per plant, which helped to improve cotton yield.Precipitation and seed cotton yield,seed cotton yield before frost, and lint yield were negatively correlated, and all reached significant level. This study showed that too much rainfall led to increase of cotton abscission, decline of the number of bolls and decline of yield.The reason was that too much or too concentrated precipitation in some years in western Shandong brought serious adverse effect to the growth of cotton. Rainy and less illumination weather seriously affected the growth of cotton in the middle and later periods, and resulted in a large number of abscission and boll rot of cotton buds and bolls.

In conclusion, the cotton yield was closely related to meteorological conditions.In the middle and later periods of cotton growth, more rainfall and less illumination weather led the rapid elongation of the stem of cotton plants, loose plant types, tall cotton plants, serious field closing, increased abscission of cotton buds and bolls and increased boll rot, meanwhile easy to form a non-peach cotton plant,which seriously affected the cotton yield. In the rainfall and less illumination weather conditions,the field management should be done as follow:firstly, water should be discharged af-ter cotton field flooding; secondly, the methods of light hold the cotton plant,the implementation of incorporative ridges or chemical fungicides should be used to prevent boll rot;thirdly,took the"water hurt fertilizer subsidy"measures and the method of push strains and scattered wet, in order to ensure the nutritional needs of boll development, and prevent premature aging;fourth,the prevention of Miridae,planthopper and other pests; last, pruning and shaping.

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