干旱胁迫下钾肥对甘薯产量形成及钾素分配利用的影响

摘要

旨在研究干旱胁迫下钾肥对甘薯不同时期生长发育、产量和钾素分配利用的影响,以食用型甘薯品种‘泰中6号’为材料,以硫酸钾(K2SO4)为供试肥料,水分处理设正常灌水(W1)和干旱处理(W0),分别为土壤最大持水量的60％～70％和30％～40％;钾肥(K2O)施用量分别为0 g/m2 (K0)、12 g/m2 (K1)、24 g/m2(K2)和36 g/m2(K3)4个水平,测定茎叶生长指标、光合势、块根膨大速率、干物质质量分数、产量和钾素质量分数等.结果表明,施钾可以促进甘薯茎叶生长和产量提高,随着施钾量的增加,正常灌水下,甘薯茎叶生长指标、结薯数和产量在K2和K3处理均高于K1;而干旱胁迫下K2和K1处理均高于K3.正常灌水下甘薯光合势和块根膨大速率随施钾量的增加而增大,最大为K3处理,干旱胁迫下最大为K2处理.干旱胁迫下甘薯植株地上部器官中钾质量分数均高于正常灌水,块根中相反,且甘薯钾肥利用率显著低于正常灌水.干旱胁迫下施钾有利于甘薯茎叶生长,增强单株光合势,同时,植株茎叶钾素质量分数增大,渗透调节能力增强,从而提高甘薯的抗旱性;施钾增大干物质向块根的分配,提高块根产量,而且干旱胁迫下甘薯的适宜施钾量低于正常灌水.%The experiment was conducted to investigate the effects of different potassium rate on growth and development,storage root yield and potassium distribution under drought stress,which will provide theoretical basis for drought resistance and high yield cultivation of sweet potato.Sweet potato cultivar ‘Taizhong No.6’ was used as tested variety,and the water treatments included normal water supply (W1,soil with water content of 60％-70％) and drought stress (W0,soil with water content of 30 ％-40 ％).The K fertilizer treatments included K0 (K2 O,0 g/m2),K1 (K2 O,12 g/m2),K2(K2O,24 g/m2) and K3(K2O,36 g/m2),growth and development,leaf photosynthetic potential,storage root increasing velocity,dry matter content,yield and potassium mass fraction were determined.The result showed that application of potassium improved the stem and leaf growth and storage root yield,and there were significant differences in the effect of potassium application under both conditions.Under normal-watered condition,the stem and leaf growth index,tuber number and storage root yield of K2 and K3 were both higher than that of K1;but under drought stress,K2 and K1 were both higher than K3.Under normal-watered condition,photosynthetic potential of leaf and bulking rate of storage root increased with the increase of potassium application,,and the best treatment was K3,while the best one was K2 under drought stress.The potassium mass fraction of overground organs under drought stress was higher than that of normal-watered condition,but the storage root was opposite.The potassium utilization efficiency of the sweet potato under drought stress was lower than that of normal-watered condition.The application of potassium under drought stress was benefit to growth of the stem and leaf,and improvement of leaf photosynthetic potential.Meanwhile,the potassium mass fraction of the stem and leaf were increased,and osmotic adjustment ability was improved,both of them improved the drought resistance of the sweet potato.The application of potassium under drought stress increased dry matter distribution rate of storage root,which improved root yield.And the optimum potassium rate under drought stress was lower than that under well-watered condition.