钼对甘蔗氮代谢的影响

本试验选用巴西固氮甘蔗品种B 1和B 8为供试材料,在温室条件下桶栽砂培甘蔗施以含不同钼水平的营养液(0m g/L、0.01m g/L、0.02m g/L、0.04m g/L),在不同时期测定甘蔗叶片中硝酸还原酶、G S酶活性及硝态氮、氨态氮含量。试验结果表明,在大棚含氮条件下,三个钼处理都提高了两个甘蔗品种的硝酸还原酶活性而降低了硝态氮含量。0.01m g/L钼处理在拔节期后提高了B 1叶片的G S酶活性,而在幼苗期提高了B 8叶片的G S酶活性,降低了氨态氮含量,促进了氮代谢。在大棚无氮条件下,三个钼处理在拔节期后都提高了两个甘蔗品种的NR酶活性,降低硝态氮含量;提高了B 1的G S酶活性,降低氨态氮含量;在分蘖期也提高了B 8叶片的G S酶活性而降低了其氨态氮含量。因而在大棚里,无论是含氮或无氮条件下,在不同时期不同钼处理对甘蔗氮代谢和氨同化过程的作用也不同,但是相对以较低水平钼处理较能提高两个甘蔗品种的硝酸还原酶活性而降低硝态氮含量;提高了B 1与B 8的G S酶活性,降低氨态氮含量,促进了甘蔗的氮代谢和氨同化。

Effects of molybdenum on nitrogen metabolism of sugarcane

Two Brazilian nitrogen fixing sugarcane varieties B1 and B8 were employed as the plant materials.They were cultured with nutrition solution that contained different levels of Mo i.e. 0mg/L, 0.01mg/L, 0.02mg/L and 0.04mg/L, respectively, in pot trial with sand in greenhouse. the activities of nitrate reductase (NR)and glutamine synthetase (GS), and the contents of NO3--N and NH4+-N were measured at different stages. The results showed that under nitrogenous conditions in the greenhouse, all the Mo treatments increased the activity of NR and decreased the NO3--N content compared with the control for both B1 and B8. As a result, the treatment with 0.01mg/L Mo increased the activity of GS in B1 after initial elongation stages and that in B8 at young seedling stage, and it also decreased the NH4+-N content to improve the nitrogen metabolism. Under non-nitrogenous conditions, after initial elongation stage, the activity of NR was increased and the NO3--N content was decreased in both sugarcane varieties treated with different levels of Mo. Furthermore, the activity of GS was higher than the control of B1 and the NH4+-N content was lower in leaves of B8 at tillering stage. Obviously, the effect of different Mo treatment on the process of nitrogen metabolism and ammonia assimilation at different stages was different under nitrogenous or nonnitrogenous condition, but the lower concentration of Mo could increase the activities of NR and GS absolutely, decrease the contents of NO3--N and NH4+-N in leaf of the two sugarcane varieties, and improve the nitrogen metabolism and ammonia assimilation.