稻草硅化和溶解特性对稻草纤维降解率及其利用的影响

 对早、中、晚季７个水稻品种稻草的硅化特点、稻草硅的溶解特性与纤维各组成成分瘤胃降解率的关系以及尿素处理稻草的去硅化效果进行了研究。早、中、晚季稻草总硅含量相近，早稻稻草硅溶解率和纤维素含量分别显著高于中稻（１８．９％和９．１％）和晚稻（２６％和１１．２％），可溶性硅和纤维素的降解率也比中、晚稻稻草分别高７０．０％和１７．５％、４７．８％和２３．７％，稻草降解率和体外消化产生的挥发性脂肪酸比中、晚稻稻草分别提高１４．５％和１９．０％、１２．９％和１４．８％。稻草各形态部位的硅的溶解率、纤维素含量和体外消化产生的挥发性脂肪酸均为叶＜鞘＜茎。稻草的可溶性硅与纤维素含量呈显著协相关（ｒ＝０．８６），而可溶性硅和纤维素与稻草潜在降解率（ａ＋ｂ）的协相关分别为ｒ＝０．９０，ｒ＝０．８４。因此，稻草硅的溶解特性是影响稻草潜在降解率的主要因素，而不是稻草的总硅含量。用尿素处理稻草，能使稻草降解率、降解速率、潜在降解率分别提高１０．８％、２７．９％、１０．１％。

Effects of Rice Straw Silicification and Characters of Extraction Biogenic Silicon on the Degradation of Fibrous Components in Straw

Seven varieties of the early-, middle-and late maturing rice were collected from Huazhong Agricultural University in Hubei. A study was carried for rice straw in the aspects of the characters of straw silicification and extraction biogenic silicon(EBSi), the relationship between characters of EBSi and kinetic characteristics of degradation of fibrous components in fistulated cows, as well as the effect of urea treatment on rice straw desilicification. Although total silicon content(ADISi) in rice straw was similar, the efficiency of extraction biogenic silicon(EEBSi) and cellulose content in early rice straw were significantly higher than that in middle(18. 9% and 9. 1 0~) and late one(26.100 and 11. 2~o). The degradabilities of EBSi and cellulose in early rice straw were higher than that in middle by 70. ~ and 17. 50~ and in late by 47. 8 00 and 23. 7 00 respectively. The in sacco degradability and in vitro VFA production of early rice straw were also higher than that of middle for 14. 5 and 19. OOo and late for 12. 9 and 14. 8% Comparing the morphological fractions of rice straw, EEBSi, cellulose content, and in vitro VFA production were differing as the order of blade < sheath < stem. A significant correlation was found between the contents of EBSi and cellulose(r=0. 86), the two contents were, however, remarkably correlated with the potential straw degradability(a b) by r=0. 90 and r=0. 84 respectively. Therefore, EBSi in rice straw was a main factor affecting the potential degradability of rice straw, rather than the ADISi of straw. Urea treat- ment improved rice straw degradability, degradation rate and potential degradability by 10. 8%, 27. 9%, and 10. 1 % respectively.