Effects Of Supplemental Irrigation On Tiller Occurrence And Spike Formation And Yield In Different Spike-type Wheat Cultivars

In order to ascertain the physiological mechanism of tiller occurrence and spike formation,and the grain yield per plant of main stem and tillers in different positions and its photosynthetic physiological mechanism of medium and large spike-type wheat cultivars,the field experiment was carried from 2019-2020 in experimental farm of Shandong Agricultural University and from 2020-2021 in modern agricultural park of Shandong Agricultural University,in Tai’an City,Shandong Province.The experiment adopted the split plot design.The main area was cultivar treatment,and two cultivars were tested:the medium-spike cultivar Jimai 22（J22）and the Shannong 23（S23）.The sub-area was supplemental irrigation,and three different soil moisture treatments were set:no irrigation during whole growth period（W0）,water-saving supplemental irrigation（W70,the relative water content of the soil layer of 0～40 cm was supplemented to 70%at seeding,jointing and anthesis stage）,sufficient supplemental irrigation（W90,the relative water content of the soil layer of 0～40 cm was supplemented to 70%at seeding,jointing and anthesis stage）.Total six treatments and three repetitions.The effects of different supplemental irrigation on tiller occurrence and spike formation,and photosynthetic characteristics and grain yield of main stem and tillers in different positions in two spike-type wheat cultivars were studied.The main results are as follow:1 Effect of supplemental irrigation on the occurrence and spike formation of tillers in different positions and its physiological basis in different spike-type wheat cultivars.The tiller node area at wintering and trans zeatin content,and net photosynthetic rate,transpiration rate and stomatal conductance of the uppermost unfloding leaves in main stem at wintering and turn-green stage of two wheat cultivars under water-saving supplemental irrigation treatment were all higher than no irrigation treatment,which promoted tillers occurrence.Under water-saving supplemental irrigation,the stem number per plant of two wheat cultivars in tillerⅡ,Ⅲ,Ⅰ_PandⅣat wintering stage,tillerⅢ,Ⅰ_P,Ⅳand other tillers at jointing stage and of Shannong 23 in tillerⅡat jointing stage increased,the total stem number per plant of Jimai 22 and Shannong 23 were 1.35 and 1.16 higher than no irrigation at wintering stage,and 1.07 and 1.67 higher than no irrigation treatment at jointing stage.Under water-saving supplemental irrigation,the net photosynthetic rate,transpiration rate and stomatal conductance of the uppermost unfolding leaves at jointing stage,dry matter weight and distribution amount of ¹³C assimilates of two spike-type wheat cultivars of main stem and tillers in different positions at 7 days after labeling and maturity were higher than those under no irrigation treatment,The formation spike number per plant of tillerⅡandⅢof Jimai 22and tillerⅠandⅡof Shannong 23 increased significantly,and the total spike number per plant of Jimai 22 and Shannong 23 under water-saving supplemental irrigation were 0.36 and 0.41higher than no irrigation.Compared with sufficient supplemental irrigation,the total stem number per plant and total number of population stems under water-saving supplemental irrigation of two spike-type wheat cultivars were significantly decreased.While the formation spike number of tillerⅡof Jimai 22 and tillerⅠof Shannong 23 were significantly decreased,no significantly difference were found in spike number per plant between water-saving and sufficient supplemental irrigation.Under the same supplemental irrigation treatment,the total stem number per plant,total number of population stems and total spike number per plant of Jimai 22 were significantly higher than Shannong 23.2 Effect of supplemental irrigation on photosynthetic characteristics and grain yield per plant of main stem and tillers in different positions in different spike-type wheat cultivarsThe SPAD value,net photosynthetic rate,sucrose content,sucrose phosphate synthase activity of main stem and tillers in different positions of two spike-type wheat cultivars under water-saving supplemental irrigation were significantly higher than those under no irrigation,the grain weight per spike and grain yield per plant under water-saving supplemental irrigation were significantly higher than those under no irrigation.Compared with sufficient supplemental irrigation,the above parameters of flag leaf and the grain yield of main stem of Jimai 22 had no significantly difference with water-saving supplemental irrigation and tillerⅠandⅡwas significantly increased,tillerⅢwas decreased,the above parameters of flag leaf and the grain yield of main stem of Shannong 23 had no significantly difference with water-saving supplemental irrigation and tillerⅠwas significantly increased,the grain yield of tillerⅢwas decreased.The grain yield per plant of Jimai 22 and Shannong 23 under water-saving supplemental irrigation had no significantly difference with sufficient supplemental irrigation.3 Effect of supplemental irrigation on grain yield,water use efficiency and irrigation water use efficiency in different spike-type wheat cultivarsThe grain yield per hectare of Jimai 22 and Shannong 23 under water-saving supplemental irrigation was 35.00%and 44.27%higher than those under no irrigation,respectively,and the WUE was 9.30%and 8.55%.The grain yield per hectare under sufficient supplemental irrigation of two spike-type wheat cultivars had no significance with water-saving supplemental irrigation,the water consumption amount and irrigation amount increased,and water use efficiency and irrigation water use efficiency decreased,significantly.Under the same supplemental irrigation treatment,the grain yield per hectare,water use efficiency and irrigation water use efficiency of Jimai 22 were significantly lower than those of Shannong 23.