The Identification And Feed Value Of Wuyujing3 Mutants With Brittle Stem Characters

Brittle mutants have brittle stems,leaves,internodes and other organs.Such performance has been reported in Arabidopsis,corn,tomatoes,rice(Oryza sativa L.)and other plants.Additionally,compared with wild type,the brittle culm mutants have reduced content of cellulose or lignin and fragile structure in cell walls,vulnerable for breaking when mechanically pressed.Thus,they are valuable materials for breeding grain-feed amphibious rice.We can either harvest the grains as food,or promote the straws to be a new kind of feed resources.However,the studies of feed nutrition value of brittle rice straw are seldom reported.So the agronomic traits of them and their characteristics of digestion which are more excellent than traditional rice straw are ignored.In this study,Wuyujing3 and its two brittle mutants are materials.The plant morphology,chemistry of stem and anatomical features has been identified.Nitrogen fertilizer and harvest time have been conducted,too.The main findings are as follow:(1)Agronomic traits analysis showed that,there were significant differences in the plant morphology,chemical composition of stems,stem anatomical characteristics and other aspects between the brittle culm mutants and the wild-type.In plant morphology,compared to wild type,the D12W230 shows brittleness in stem,leaf,sheath and spike and grows shorter,producing approximately 8.0t/hm2-10.1 t/hm2.The length of second internode increases by 3.44%,the gravity significantly decreased by 9.78%,and stem diameter reduced by 6.88%.The D12W231 performs brittleness in stem,leaf,sheath and spike,too.There is no significant change in the height of D12W231,and the yield of it is about 9.0t/hm2-10.6 t/hm2.Its second internode grows higher by 7.73%,the gravity slightly decreases by 2.32%,and not any significant changes in stem diameter and thickness of stem wall.In the chemical composition of stems,the content of cellulose of D12W230 decreases by 11.23%while the content of lignin of it increases by 7.68%.Both the content of cellulose and lignin of D12W231 respectively decrease by 12.34%and 10.22%.In the anatomical feature of stem,the increase of wall thickness is especially apparent in epidermal sclerenchyma of the D12W230.The increased cell lumen and loosely arranged cells are also observed.The reduction of wall thickness was especially apparent in cortical fibers of the D12W231,and cells are arranged loosely,too.Both of them show changeable plant morphology,cell wall components,cells wall structure and wall thickness of epidermal sclerenchyma.However,the differences between them are significant.The basal internodes are short and thin of D12W230,the content of lignin increases thus the hardness of it grows higher.The basal internodes are long and thin of D12W231,and the components of cell wall are decreased thus the brittleness is changed.(2)Mechanical behavior analysis results show that,mutants with brittleness perform decline in breaking load,bending moment of the whole plant and bending moment at breaking,so that the mechanical strength of the stem reduce significantly.In the aspect of breaking load,the mutation resulted in reduction of 15.7%-37.5%in D12W230 compared to the wild type,while reduction of 35.6%-45.9%happened in D12W231.In the aspect of bending moment of the whole plant,although the length from broken point to panicle top of D12W230 remained unaffected,the fresh weight from broken point to panicle top significantly reduces 11.3%-15.7%,together with the bending moment at breaking,then the mechanical strength is weaken.Although the length from broken point to panicle top of D12W231 goes up by 5.89%-9.33%,the fresh weight from broken point to panicle top significantly reduces 10.16%-12.45%,thus then the mechanical strength is weaken,too.In the aspect of bending moment at breaking,reduction in modulus section and bending stress results in reductions of 8.42%-10.33%in the bending moment at breaking.Similar performance is observed in D12W231.Because of the decline of breaking load,bending moment of the whole plant and bending moment at breaking,changes occur in either D12W230 or D12W231.(3)Nitrogen application has effect on feed value,it suggests that increasing nitrogen fertilizer enhances content and accumulation of crude protein,nitrogen free extract and crude ash,reduces content and accumulation of crude fiber.In the aspect of crude fiber,reductions of accumulation of NDF,ADF,C,ADL,especially of ADL,are appeared in the two mutants.D12W230 and D12W231 are respectively reduced by 3.4%-6.9%,1.1%-10.3%,3.8%-11.5%,6.73%-9.88%and 4.69%-7.82%,2.02%-9.76%,4.28%-7.11%,5.6%-9.27%.In the aspect of crude protein,nitrogen fertilizer promotes the content of crude protein of D12W230 by 13.46%-15.71%,and that of D12W231 is improved by 10.28%-11.13%.In the aspect of nitrogen free extract,nitrogen fertilizer promotes the content of nitrogen free extract of D12W230 and D12W231 by 5.5%-19.2%and 4.8%-14.0%,respectively.In the aspect of crude ash,it appreciably raises the content of crude ash of D12W230 and D12W231,too.Balanced application between basal fertilizer and spike fertilizer(N5-5),promotes the content and accumulation of crude protein to the highest.The basal fertilizer proportion is higher(N10-0),the more the content and accumulation of nitrogen free extract,and the less the content and accumulation of crude fiber.(4)The results of different harvest time indicate that,it can influence the feed value significantly.In the aspect of crude fiber,from heading to maturity,accumulations of NDF,ADF,HC,C and ADL of D12W230 are increased respectively by 4.41%-10.3%,3.48%-6.5%,3.32%-4.17%,5.26%-10.3%,4.99%-12.13%,while that of D12W231 are increased respectively by 3.83%-10.11%,2.78%-7.61%,3.42%-4.3%,3.45%-7.89%,3.46%-7.89%.In the aspect of crude protein,content of crude protein of D12W230 and D12W231 are respectively decreased by 2.17%-6.29%and 3.1%-6.6%.In the aspect of nitrogen free extract,the accumulation of nitrogen free extract of D12W230 and D12W231 are respectively increased by 3.41%-5.63%and 2.85%-5.93%.In the aspect of crude ash,its accumulations of D12W230 and D12W231 are appreciably raised by 2.24%-5.6%and 2.46%-4.33%.These results indicate that,from heading to maturity,contents and accumulations of crude fiber,nitrogen free extract and crude ash have an increasing trend,while an decreasing tendency in crude protein.It also shows that,panicle is the main organs to be harvested,and maturity is the best harvest period.But to avoid the presence of competitive relationship with other rice during the harvest period,the rice brittle culm mutants should be appropriate harvested in advance.In short,D12W230 and D12W231,which are brittle culm mutants,have excellent feed nutritional quality.We can adopt the way of balancing the application between basal fertilizer and spike fertilizer,and harvest them ahead of maturity.