施磷对苜蓿抗蓟马的影响

Effects of phosphorus application on alfalfa resistance to thrips(Thripidae)

为了明确施磷是否能有效提高苜蓿对蓟马的耐害性,以感蓟马苜蓿品种甘农3号和抗蓟马苜蓿品种甘农9号为材料,设0,6,12,18(P_2O_5)g/m^2等4个磷水平,在大田蓟马为害高峰期,评价和测定了不同磷水平处理下苜蓿的受害指数、植株磷含量和农艺性状。结果表明,随着磷水平的升高,甘农3号和甘农9号植株的磷含量增加,受害指数均明显降低,株高、产量及叶片含水量增加,茎叶比下降;植株磷含量、叶片的含水量均与苜蓿的受害指数呈负相关关系,但第2茬植株磷含量与苜蓿的受害指数相关性不显著(P>0.05),茎叶比与苜蓿的受害指数呈显著正相关关系(P<0.05)。相同磷水平处理下,第1茬甘农9号的受害指数均显著低于甘农3号(P<0.05);第2茬在12(P_2O_5)g/m^2和18(P_2O_5)g/m^2处理下,甘农9号的受害指数与甘农3号差异不显著(P>0.05);施磷后甘农3号的受害指数均低于未施磷甘农9号的受害指数。磷元素可通过提高苜蓿生长性能来提高苜蓿对蓟马的耐害性;在大田条件下,通过施磷管理来提高感虫苜蓿品种对蓟马的耐害性是一种有效的措施;12(P_2O_5)g/m^2是本试验中最经济有效的施肥量。

To investigate whether phosphorus improve tolerance to thrips effectively, two alfalfa varieties were chosen for the study, Gannong No. 9 （resistant to thrips） and Gannong No. 3 （susceptible to thrips）. The dam age index, phosphorus content in plants and agronomic traits were evaluated and measured at different phos phorus （P205） levels （0, 6, 12, 18 g/m2） treatment during the thrips damaging peak in field. The results showed that the damage index of Gannong No. 3 and Gannong No. 9 decreased with the phosphorus levels in creasing, in addition, phosphorus content of plants increased, and yield, height and leaf water content in creased significantly, the stem-leaf ratio reduced. Correlation analysis indicated that the phosphorus content of plants and leaf water content correlated negative significantly with the damage index of alfalfa, but the phos phorus content of plants had no correlation with the damage index in second cutting, while the stem-leaf ratio correlated positively with the damage index. The damage index of Gannong No. 3 were higher than Gannong No. 9 at the same phosphorus level, but no obvious difference with Gannong No. 9 at the phosphorus （P205） levels （12,18 g/m2） treatment in second cutting. Gannong No. 3 damage index with phosphorus treatment were lower than Gannong No. 9 ＇s without phosphorus application. The phosphorus can enhance the resistance of alfalfa to thrips effectively by improving the growth performance. Therefore, the phosphorus management was an effective measure on enhancing the tolerance of alfalfa to thrips in field. The most economic fertilizer was 12（P205） g/m2 in this experiment.