Study On Effects Of Selenium On Cotton Agronomic And Economic Characters

To seek the cotton varieties with strong selenium enrichment capacity,and probe into the influence of exogenous selenium on the agronomic trait and quality character of cotton,so as to lay a foundation for the application of selenium in cotton cultivation.Five cotton varieties are chosen as the experiment materials for the application of five kinds of exogenous selenium fertilizer,and each kind of selenium source is provided with 2 different concentration;the experiment is carried out by randomized blocks design,and the functional leaves in boll-setting period when the trait expression of cotton is fullest are taken as the samples to determine the selenium content,and investigate the plant height,stalk node interval,shedding rate and other traits;the plant laboratory test is conducted to determine the seed cotton yield,lint yield,boll number per plant,single boll weight,lint percentage,lint index,seed index and other yield traits,and HVI1000 is used to detect the fiber quality traits,such as fiber length,micron value,specific strength,elongation,uniformity and etc.The results of analysis and determination of selenium content in the functional leaves of cotton show that in the cotton varieties under experiment,GY5,EK13 and XLZ 38 could better utilize the exogenous selenium.Cotton varieties and exogenous selenium interacted in a complex manner.Cotton leaves across different processing combinations varied in selenium content.The Ekang 13-sodium selenite combination excelled in enriched selenium by cotton leaves,as demonstrated by a selenium content of0.3227mg/kg,much higher than other combinations.The selenium content in EK13-sodium selenite cotton is highest,namely,0.3227 mg/kg,which is significantly higher than that in other groups.For the enrichment of selenium at different concentration in cotton leaves,the differences among most combinations are not significant,of which only sodium selenite at10 mg/kg has the optimal enrichment effect in cotton leaves.It shows that there are some differences among the enrichment of different selenium sources at different concentration in the leaves of different cotton varieties.When the comparison was limited to individual varieties,only Ekang 13 showed significantly higher selenium content in leaves when processed with sodium selenite than with other exogenous selenium.The other four varieties displayed largely similar selenium content in leaves when processed with different sources of selenium.Using the same source of selenium to process different cotton varieties produced different results.selenium content in cotton leaves of different varieties processed with AB fertilizer was largely at the same level;Ekang 13 cotton leaves processed with sodium selenite contained much more selenium than leavesof the other four varieties also processed with sodium selenite,while these four varieties were basically at the same level in this regard;after being processed with FXB,GY5 and TM-1 showed significantly different selenium content in their leaves,which was not seen in other varieties;Ekang 13,GY5,and TM-1 differed significantly in selenium content in leaves after being processed by selenomethionine;after being processed with selenite mineral powders,GY5 leaves contained much more selenium than DP410 B and TM-1 leaves.Different exogenous selenium varied in enriched selenium in cotton leaves.The analysis of plant height,stalk node interval,and shedding rate results obtained through field investigation shows that the plant height,stalk node interval,and shedding rate of all cotton varieties processed with different selenium sources at different concentration show certain variations,but the differences have not reached the significant level yet.All cotton varieties processed with different sources of selenium at different concentrations varied in plant height,but not to a significant degree.Plant heights of the tested cotton varieties increased to a certain extent when sodium selenite or selenomethionine was applied,decreased when FXB was applied,and recorded mixed results when AB fertilizer or selenomethionine was applied.Despite changes of the plant height of cotton varieties processed with different sources of selenium,none of these changes were statistically significant.All cotton varieties processed with different sources of selenium at different concentrations varied in main stem pitch,but not to a significant degree.Main stem pitches of the tested cotton varieties increased to a certain extent when AB fertilizer,selenomethionine,or selenite mineral powder was applied,decreased when FXB was applied,and recorded mixed results when sodium selenite was applied.Despite changes of the main stem pitch of cotton varieties processed with different exogenous selenium,none of these changes were statistically significant.After processing cotton varieties with different sources of selenium,all varieties except DP410 B recorded significantly reduced boll shedding than the cotton varieties in the control group.However,concentration levels of selenium did not make a significant difference in to which extent boll shedding was reduced.DP410 B also showed reduced boll shedding when processed with different concentrations of selenium,but to a less extent than other varieties,with all of these reductions falling under the significant or extremely significant level.To use exogenous selenium in improving plant height,shortening main steam pitch,and reducing boll shedding,both the type of selenium and cotton variety must be considered.The results of laboratory test upon the yield and yield components show that,the seed cotton yield and lint yield after sodium selenite processing is significantly higher than that processed with other four kinds ofselenium sources,while the yield after the processing of AB fertilizer,Fuxibao,Selenomethionine,and selenium ore powders shows no significant difference.In the yield component,the analysis results of boll number per plant and traits show that the application of sodium selenite is more significant than other selenium sources;there is no significant difference in other three yield components,namely,single bell weight,lint percentage and seed index after processed by different selenium sources.For the lint index,the processing effects among sodium selenite,selenomethionine and selenium ore powders are significantly different,while the differences among other processing are not significant.Sodium selenite can affect the seed cotton yield and lint yield through affecting the boll number per plant.After the same cotton variety is applied with different exogenous selenium,the seed cotton yield,lint yield and boll number per plant show significant differences,which is genotype dependent,so it shows that the yield-increase function of selenium in cotton is complex and it is necessary to screen the exogenous selenium suitable for commercial varieties in practical application.There is no significant difference in the lint percentage of same cotton variety after processed with different selenium sources.Selenium processing will not affect the lint percentage of any variety.There are some differences in the lint index and seed index of the same cotton variety after processed with different selenium sources,and there is also certain genotype dependency.HVI1000 fiber quality testing results show that the application of different exogenous selenium will result in different fiber length,of which the root application of selenium ore powders has the greatest effect on fiber length,while the leaf application of exogenous selenium-sodium selenite has the greatest effect on fiber length.The processing with different exogenous selenium will make the macron value show certain differences.Selenium ore powders have the best processing performance on macron value,which is significantly different from the processing with other exogenous selenium.The processing performance of selenium ore powders on fiber ratio strength,elongation,and fiber uniformity is most excellent among different exogenous selenium,but the differences among different exogenous selenium have not reached a significant level.The results of comparative study on the application of exogenous selenium and no application show that the effect of exogenous selenium on cotton fiber quality is rather complex,and it is essential to choose suitable exogenous selenium and appropriate selenium enrichment cotton varieties,and pay attention to the concentration of selenium,because high concentration will lower the fiber quality of cotton to a certain extent.After the application of five kinds of different exogenous selenium to the five varieties of cotton,the cotton varieties with effective selenium enrichment are selected through the analysis of the selenium content in cotton leaves andthe important agronomic and economic traits of cotton,and the influences of different exogenous selenium on the cotton yield trait and fiber quality trait of different varieties are determined,thus providing a test basis for the application of selenium in cotton.