Search

As a key enzyme for nitrogen assimilation in plant, glutamine synthetase (TaGS) is encoded by 12 genes in common wheat (Triticum aestivum L.), namely TaGS1;1-6A/6B/6D, TaGS1;2-4A/4B/4D, TaGS1;3-4A/4B/4D, and TaGS2-2A/2B/2D. Transcripts of TaGS genes were obtained using the single molecular sequencing technology, and the results showed that TaGS1;1-6A had one alternative splicing (AS) version of transcripts and TaGS1;1-6B had two AS versions. Compared with the TaGS encoded by normal transcript, TaGS1;1-6A-1 lacked part of the Gln_synt_N domain, and TaGS1;1-6B-3 lacked the Gln_synth_gly_rich_ site domain; TaGS1;1-6B-4 was a new AS event, and encoded a truncated GS without Gln_synth_gly_rich_site and Gln_synth_ cat_dom domain. The relative expression level of TaGS alternative splicing transcripts of wheat cultivars with different nitrogen use efficiencies showed that the relative expression level of TaGS1;1-6A-1 in leaves of YM49 (N-efficient) was significantly higher than that of XN509 (N-inefficient), and increased with the increase of nitrogen supply. In roots, the relative expression of TaGS1;1-6A-1 increased with the increase of nitrogen supply in YM49, but decreased in XN509. TaGS1;1-6B-3 showed a similar expression trend in YM49 and XN509, and high concentration of NO3- promoted the expression of TaGS1;1-6B-3 in leaves while inhibited in roots. High concentration of NH4+ inhibited the expression of TaGS1;1-6B-3 in leaves, but had little effect in roots. TaGS1;1-6B-4 was mainly expressed under low nitrogen condition, and its expression in roots of YM49 was not affected by NH4+ supply. Understanding the AS transcript versions of TaGS genes is helpful to illustrate the functions of TaGS isozymes in nitrogen metabolism of wheat. [ABSTRACT FROM AUTHOR]

To provide theoretical support the full use of water and fertilizer resources for wheat, we explored the effects of irrigation on wheat yield, plant and soil nutrient distribution during flowering period and its relationship with root characteristics. We set up two treatments by using the 2 m deep soil column cultivation method with irrigation during flowering (T 1 ) and no irrigation during flowering (T 2 ), with the drought-resistant and high-yield cultivar Luomai 28 (LM28) and the high photosynthetic efficiency cultivar Bainong 207 (BN207) as materials. We measured contents of nitrogen, phosphorus and potassium in plants and soils, as well as the characteristics of soil roots. The results showed that ammonium, available phosphorus, and available potassium were mainly distributed in 0-80 cm soil layer, and that nitrate was mainly distributed in soil layer below 80 cm during wheat harvest. Irrigation at anthesis stage promoted wheat to absorb ammonium, available phosphorus and available potassium from the upper layer of soil and nitrate nitrogen from the lower layer but did not aggravate the deep leaching of nitrate. The root of wheat mainly concentrated in 0-60 cm soil layer and decreased with increasing soil depth. Dry matter accumulation, total nitrogen and total phosphorus were mainly distributed in wheat grains at maturity, while total potassium was mainly distributed in stems. Irrigation at anthesis stage significantly increased the 100-grain weight of wheat, and consequently the yield. Root morphology was negatively correlated with soil nitrate in 0-40 cm soil layer, positively correlated with soil ammonium in 80-100 cm soil layer and soil available phosphorus in 0-100 cm soil layer. Irrigation at anthesis stage promoted the full absorption of soil nutrients by roots at late filling stage, delayed the senescence of flag leaves after flowering, prolonged the functional period of transporting nutrients from vegetative organs to reproductive organs, leading nutrients in vegetative organs more fully transported to grains, increasing grain weight and yield.

To clarify the effects of row spacing and sowing rate on the vertical distribution of canopy PAR, biomass, and grain yield in winter wheat, a field experiment was conducted without increa-sing water and fertilizer input. There were two row spacing modes, R 1 (equal spacing, 20 cm+20 cm) and R 2 (wide and narrow row spacing, 12 cm+12 cm+12 cm+24 cm), and three sowing rates, D 1 (low, 120 kg·hm -2 ), D 2 (medium, 157.5 kg·hm -2 ), D 3 (high, 195 kg·hm -2 ). The canopy photosynthetically active radiation (PAR) interception and utilization rate in different heights, population photosynthetic capacity, biomass, and grain yield were measured during the main growth stages of winter wheat. The results showed that both total PAR interception and upper layer PAR interception of winter wheat canopy under R 1 treatment were significantly higher than those in R 2 treatment, but those of the middle layer and lower layer were higher in R 2 than in R 1 , and with significant difference in the middle layer. From flowering to maturity, the photosynthetic potential (LAD), population photosynthetic rate (CAP), PAR conversion rate, and utilization rate in R 2 were all significantly higher than those in R 1 under the same sowing rate, with the highest value under R 2 D 2 treatment. With the increasing sowing rate, the population biomass (BA) and leaf biomass (BL) at different layers increased, but the individual biomass (BP) showed an opposite trend. Under the same sowing rate, BA, BL and BP in R 2 were higher than that in R 1 after the flowering stage. Among them, BA and BP had significant difference in row spacing treatments at the maturity stage, with significant difference between the two row spacing treatments being observed in BL of the middle and lower layers under D 2 and D 3 sowing rates. The spike number, grain number per spike, 1000-kernel weight, and grain yield of winter wheat among different treatments were the highest in R 2 D 3 , R 2 D 1 , R 2 D 1 , and R 2 D 2 , respectively. The 1000-kernel weight, grain number per spike and grain yield in R 2 treatment were significantly higher than R 1 . In summary, the PAR interception in the middle and lower layers of winter wheat canopy was improved by changing row spacing, with positive consequence on the photosynthetic capacity of individual plant and population, PAR utilization and transformation efficiency, which finally increased biomass and grain yield. Therefore, optimizing the field structure and shaping the ideal population photosynthetic structure should pay more attention during the high-yield cultivation of winter wheat. Making full use of light resources per unit land area and excavating the photosynthetic production potential of crops were also critical to achieve high yield and efficiency. In this experiment, the population photosynthetic capacity, photosynthetic effective radiation utilization rate, and yield were the highest under the treatment of R 2 D 2 .

In the winter-wheat and summer-maize multiple cropping system in lime concretion black soil of Huanghuaihai Plain, the effects of three tilling methods (conventional tillage, rotary tillage, subsoiling tillage) in wheat season coupling with three nitrogen treatments (120 kg·hm -2 , 225 kg·hm -2 , 330 kg·hm -2 ) before maize sowing on the activities of microorganisms and enzymes re-lated nitrogen transformation, and inorganic nitrogen content in the rhizosphere soil during the main growth stages of maize, as well as the yield were investigated. The results showed that the rotary tillage had the highest ammonification intensity, and the more nitrogen was put in, the higher were the activities of microorganisms and enzymes related to soil nitrogen transformation. The activities of nitrification, denitrification and urease of subsoiling tillage was significantly higher than those of conventional and rotary tillage. Furthermore, in subsoiling tillage treatment, increasing nitrogen fertili-zer could promote soil nitrogen transformation while excessive nitrogen input inhibited soil nitrogen transformation, though the latter had higher yield and soil inorganic nitrogen content. The treatment of subsoiling tillage coupling with 225 kg·hm -2 nitrogen, was best for soil nitrogen transformation while the treatment of subsoiling tillage coupling with 330 kg·hm -2 nitrogen, had the highest corn yield.