Study On Physiological Characteristics And Change Of Yield And Quality In Spring Wheat Under Low Seeding Density Cultivation

In order to explore the feasibility of low seeding density cultivation on spring wheat in Hei longjiang province and the influences on characters of physiology under low seeding density cultivation, eight spring wheat cultivars (lines) grown in great area in Hei longjiang province which had selected through cultivars characters last year were selected for the experiment. We designed three experimental treatments:Al conventional treatment, had 6 million basic seedings per hectare;A2, A3low seeding density treatment, each had 4.5 and 3.0 million basic seeding per hectare, then compacted in seeding stage and applied fertilization for three leaves stage, fertilization for head sprouting. Photosynthetic physiological characters , spikes characters, quality characters, yield and yield components were stuied by field experiment. The result were summarized as follows:Photosynthetic rate of flag leaf improved under low seeding density cultivation, Change curves of photosynthetic rate of flag leaf among different wheats were same (A3>A2>A1 ), under low seeding density cultivation, max photosynthetic rate of Dongnong 125, Longmai20, Longmai29, LongfulO, Kefeng6 were about 20(umolCO₂.m^-2.s^-1), and photosynthetic rate of Dongnong 125, Longmai20, Longmai29 were high in the maturity, which had high photosynthetic character of flag leaf in latter period, could produce more photosynthetic outcome. Change tredency of Chl(a+b) and Chl(a/b) of flag leaf were different, Max Chl(a+b)of Dongnong 122, Longmai29, LongfulO were in A3 treatment, Max Chl(a+b)of photosynthetic rate of Dongnong 125, Dongnong97-4056, Kefeng6 were in A2 treatment, Chl(a/b)of Dongnong 125, Longmai26, Dongnong97-4056, Kefeng6 in A3 treatment delined quikly, bigger Chl(a+b) and less Chl(a/b) of flag leaf had high photosynthetic character of flag leaf in latter period, could produce more photosynthetic outcome. SLW of flag leaf improved differently under low seeding density cultivation, SLW of Dongnong 122, Longmai26, Longmai20, Longmai29 under low seeding density treatment were higher than conventional treatment, max SLW of Dongnong97-4056 was about in 28 days after full expansion, which accumulated much dry matter in flag leaf in latter period, and produced high yield. Nitrogen content of flag leaf and grain changed in the form of intersect under three treatments, change tredency of nitrogen content was same but not obvious, flag leaf nitrogen content of Dongnong 122, Longmai29 was higher under A3, A2 treatments than other treatments separately, grain nitrogen content of Dongnong 125, Dongnong97-4056, Longmai29 was higher under low seeding density treatment than conventional treatment.Under low seeding density cultivation, functional period of flag leaf was long , senescence velocity of flag leaf was low, large matter accumulated per leaf area provided nitrition in grainfilling period, change tredency of LA of single plant of different wheats was A3>A2>A1 and LAI of different wheats was A1>A2>A3 ?Low seeding density cultivation improved harvesting spike number (83 spikes), number of spike kernel (8.33 kernels), spike kernel weight (0.38g), thousand kernel weight (3.99g), total number of spikelet (1.48), number of valide spikelet (2.09), delined number of invalide spikelet (1.05) , Different cultivars adapted themselves to low seeding density differently, which yield increased more and less differently. Dongnong97-4056> Longmai29 under A3 treatment derived highest yield, so they were the cultivars favorable for low seeding density cultivation, Dongnongl22, Longmai26 under A2 treatment obtained highest yield, they were the cultivars fit for low seeding density cultivation, other cultivars were capable of low seeding density cultivation.Grain protein content of Longmai29 and Kefeng6 increased significantly (A3>A2>A1) ,but protein content of other cultivars changed little, in the process quality characters few cultivars was significant, characters of most cultivars were not significant, relation of protein yield and grain yield was positive correlation significantly under low seeding cultivation, relation of protein content and number of spike kernel, content of wet gluten and spike kernel weight, sedimentation value and thousand kernel weight were positive correlation all, these quality characters and yield were negative correlation all, contradiction of yield and quality existed under low seeding cultivation.Relation between yield and protein content of bigger spike and more kernels cultivars ------Longmai26 and Longmai29 harmonized very well, then kernel weight cultivars------Dongnongl22,Longmai20 and more spikes cultivars------Kefeng6, it proved that yield and qulity were able toimprove together by means of harmonizing inner process under low seeding density or improving cultivars, so ultimate aim of cutting down cost, high yield, good quality, beneficial results on spring wheat in Leilongjiang province would come true.