12份扁蓿豆种质苗期耐盐性综合评价

Comprehensive evaluation of salt tolerance in 12 germplasm resources of Medicago ruthenica at seedling stage

利用不同浓度NaCl(0,100,200,300mmol·L-1)溶液处理12份扁蓿豆(Medicago ruthenica)种质种子,通过砂培法研究其苗期的耐盐性。结果表明,随着NaCl浓度的增加,供试12份扁蓿豆种质的绝对株高、单株地上生物量和叶片相对含水量逐渐降低,可溶性糖含量不断上升。与对照相比,景泰种质绝对株高平均降幅最大,为16.4%;镇原种质绝对株高、单株地上生物量下降较慢,分别为30.6%、35.0%;100～300mmol·L-1 NaCl处理下陇西种质叶片相对含水量降幅均最大,分别为6.2%、21.5%、30.3%;300mmol·L-1 NaCl浓度处理景泰种质可溶性糖含量上升最快,达4.4倍。与对照相比,各材料根总长、根表面积及根体积在300mmol·L-1 NaCl处理下均呈不同程度的下降,其中天水种质下降最快,陇西下降最慢;200和300mmol·L-1浓度处理下各材料叶绿素含量均小于低浓度处理和对照,且后者显著低于对照(P<0.05)。各扁蓿豆种质净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)随盐浓度的上升总体呈下降趋势,胞间CO2浓度(Ci)除陇西、临夏、宁县、土默特扁蓿豆种质随盐浓度的增加上升外,其余8份种质均先升后降。NaCl胁迫使各扁蓿豆种质光合作用受到不同程度的抑制。应用隶属函数法综合评价得出,参试种质种子苗期耐盐性强弱依次为景泰>永昌>土默特>宁县>天水>天祝>夏河>临夏>榆中>自选8号>陇西>镇原。

Twelve germplasms of Medicago ruthenica were treated with different concentrations of NaCl(0,100,200,300 mmol·L-1),and their salt tolerance at seedling stage was studied by sand culture.The results showed that,with an increase in NaCl concentration,the absolute plant height,aboveground biomass per plant,and leaf relative water content of the 12 populations of M.ruthenica gradually decreased while the soluble sugar content increased continuously.Compared with the control(CK),the mean decline in absolute plant height of Jingtai germplasm was 16.4%.The absolute height and aboveground biomass per plant of Zhenyuan germplasm decreased slowly by 30.6%and 35.0%,respectively.Under 100,200,and 300 mmol·L-1 treatments,the highest decline in leaf relative water content was observed in Longxi germplasm(6.2%,21.5%,and 30.3%,respectively).The increase in soluble sugar content of Jingtai germplasm was the fastest at 300 mmol·L-1 treatment and was up to 4.4 times the soluble sugar content of control.Compared with CK,the root total length,root surface area,and root volume decreased to a different degree on treatment with 300 mmol·L-1 NaCl in all the germplasm materials,of which the decline in Tianshui germplasm was the fastest and that in Longxi was the slowest.Additionally,the chlorophyll contents of all the materials treated with 200 mmol·L-1 NaCl and 300 mmol·L-1 NaCl were lower than those of the materials treated with lower NaCl concentrations,and the latter was significantly lower than that of CK(P<0.05).The net photosynthetic rate(P n),transpiration rate(T r),and stomatal conductance(G s)of all M.ruthenica populations decreased with an increase in salt concentration.The intercellular CO 2 concentration(C i)of Longxi,Linxia,Ningxian,and Tumete germplasm increased with an increase in salt concentration;C i of the remaining eight germplasms increased initially but decreased afterward.Photosynthesis in all the populations of M.ruthenica was inhibited differently under NaCl stress.Salt tolerance of the tested germplasm resources at seedling stage was comprehensive evaluated by the membership function method and ranked as Jingtai>Yongchang>Tumote>Ningxian>Tianshui>Tianzhu>Xiahe>Linxia>Yuzhong>No.8 Zixuan>Longxi>Zhenyuan.