Effects Of Soil Moisture On Potato Starch Formation And Yield

Moisture is an important factor affecting the growth of potato, soil moisture content directlyaffects potato tuber enlargement, accumulation of starch and yield formation. In this research,low starch variety Kexin.19and high starch variety Kexin22were selected as test materials. Potexperiments were carried out in the rain proof canopy, continually control moisture during tuberformation period. Set three soil moisture treatments,55%,70%(CK),85%of maxmun fieldcapacity, and studied on different starch content at different soil moisture conditions. Test resultsare as follows:Soil moisture of55%treatments reduced plant height, stem diameter and the number ofbranches. The treatment of85%soil moisture reduced the stem diameter of two varieties,increased plant height and the number of branches of Kexin22.Soil moisture of55%treatments inhibited fresh weight and dry matter of plant. Soilmoisture of85%treatment shorten the duration of maximum biomass of low starch varietyKexin19, decreased fresh weight and dry matter of stems and leaves in advance. Whereas, thestem and leaves of high starch variety Kexin22grew strong relatively, and the decreasing offresh weight, dry matter of stems and leaves began much later than Kexin19.The conditions of soil moisture of55%and85%limited tuber growth, reduced the tuber drymatter content and the starch yield. During mature period, treatment of soil moisture of55%ledto22.29%(Kexin19),20.92%(Kexin22) reduction of single plant starch yields. Treatment ofsoil moisture at85%led to10.99%(Kexin19),11.38%(Kexin22) reduction of single plantstarch yields. High starch variety Kexin22had low tuber yield, but starch yield was higher thanthe low starch variety Kexin19. During late growth stage,the soil moisture of55%treatment hadthe highest amylose content, the treatment that soil moisture of55%have the lowest.Both soil moisture of55%and soil moisture of85%treatments reduced single plant yieldand tuber dry matter content. Under the55%soil moisture conditions, there were15.94%and18.93%reduction in yield of Kexin19and Kexin22respectively. Under the85%soil moistureconditions, there were8.94%and7.13%reduction in yield of Kexin19and Kexin22respectively.55%soil moisture treatment decreased the tuber number per plant, reduced the rateof medium and large tubers.85%soil moisture treatment reduced the tuber number per plant, increased the rate of medium and large tubers.During the tuber expansion period, above-ground parts of the plants and tubers grew at thesame time, low or excessive soil moistures go against starch accumulation and formation of yield.Late growth stage of potato, proper control of moisture could maintain plants robust relativelyand improved starch and tuber yields.