施钾对甘薯根系生长和产量的影响及其生理机制

为探讨施钾调控甘薯根系生长的生理机制,设K0(K_2O:0 kg hm~(-2))、K1(K_2O:75 kg hm~(-2))、K2(K_2O:150 kg hm~(-2))和K3(K_2O:225 kg hm~(-2))4个处理,调查施钾对甘薯生长前期和薯块膨大期根系生长、13C分配量、碳代谢酶活性、光合特性、叶绿素荧光特性、以及产量和产量构成的影响。结果表明,与CK相比,施钾处理2个生长时期光电子传递速率(ETR)提高12.7%~63.6%,净光合速率(Pn)提高7.2%~26.4%,施钾通过提高光合特性加速光合产物积累,为根系生长提供物质基础。同时,施钾有利于光合产物由地上部向地下部运转,地下部13C分配量提高10.6%~66.2%(P0.05)。其次,施钾处理提高了块根中蔗糖合酶、磷酸蔗糖合酶、腺苷二磷酸葡萄糖焦磷酸化酶活性,加速了块根中碳的同化,利于光合产物在块根中的积聚,促进甘薯根系分化与生长。生长前期,施钾处理总根长提高13.6%~22.8%,根平均直径提高11.3%~51.9%,显著提高了不定根向毛细根和块根分化量(P0.05),有利于有效薯块的早期形成,保证有效的单株结薯数。薯块膨大期,施钾处理提高块根生物量,有利于薯块的膨大,提高平均薯块重,最终显著增产。与CK相比,2014年K1、K2和K3处理分别增产15.8%、24.3%和44.7%,2015年分别增产7.9%、13.4%和22.8%。

Effect of Potassium Application on Root Grow and Yield of Sweet Potato and Its Physiological Mechanism

The objective of this study was to investigate the physiological mechanism of potassium application on root growth and yield improvement in sweet potato. Two year field experiment was conducted with three potassium levels (0 kg ha–1, 75 kg ha–1, 150 kg ha–1, and 225 kg ha–1) to study the effects of potassium on root growth, 13C distribution, metabolic enzyme activity, photosynthetic characteristics and yield of sweet potato. Compared with CK, potassium treatments increased ETR 12.7% to 63.6%, Pn by 7.2% to 26.4%. Potassium application improved photosynthetic characteristics and accelerated the accumulation of photosynthate, providing material basis for root growth. While, potassium application was beneficial to the photosynthate products from shoots to roots, root 13C distribution amount increased by 10.6% to 66.2% (P<0.05). Then, potassium application by increasing sucrose synthase, sucrose phosphate synthase and adenosine diphosphate glucose pyrophosphorylase activities to accelerate the assimilation of carbon in roots, to improve the photosyntheate accumulation in roots, and to promote root differentiation and growth in sweet potato. In early growing stage, potassium application increased total root length by 13.6% to 22.8%, the average diameter of root increased by 11.3% to 51.9%, and significantly increased the differentiation from adventitious roots to fibrous roots and tuberous roots (P<0.05), which is beneficial to the early formation of effective tuber, ensureing the effective number of tubers per plant. Potassium treatments increased the root biomass and average tuber weight. Compared with CK, the potassium treatments increased yield by 5.8%, 24.3%, and 44.7% in 2014, and by 7.9%, 13.4%, and 22.8% in 2015.