Starch and prolamin composition and content are important indexes for determining the processing and nutritional quality of wheat (Triticum aestivum L.) grains. Several transcription factors (TFs) regulate gene expression during starch and protein biosynthesis in wheat. Storage protein activator (TaSPA), a member of the basic leucine zipper (bZIP) family, has been reported to activate glutenin genes and is correlated to starch synthesis related genes. In this study, we generated TaSPA-B overexpressing (OE) transgenic wheat lines. Compared with wild-type (WT) plants, the starch content was slightly reduced and starch granules exhibited a more polarized distribution in the TaSPA-B OE lines. Moreover, glutenin and ω- gliadin contents were significantly reduced, with lower expression levels of related genes (e.g., By15, Dx2, and ω-1,2 gliadin gene). RNA-seq analysis identified 2023 differentially expressed genes (DEGs). The low expression of some DEGs (e.g., SUSase, ADPase, Pho1, Waxy, SBE, SSI, and SS II a) might explain the reduction of starch contents. Some TFs involved in glutenin and starch synthesis might be regulated by TaSPA-B, for example, TaPBF was reduced in TaSPA-B OE-3 lines. In addition, dual-luciferase reporter assay indicated that both TaSPA-B and TaPBF could transactivate the promoter of ω-1,2 gliadin gene. These results suggest that TaSPA-B regulates a complex gene network and plays an important role in starch and protein biosynthesis in wheat.

The goal of this study is to identify the optimum NPK fertilization to maximize yield and productivity under local environmental constraints. To address this concern, a field experiment was conducted at Agronomy Research Farm, The University of Agriculture, Peshawar, during the rabi seasons of 2019–2020 and 2020–2021 in a randomized complete block design (RCBD) with three replications. Treatments consisted of five Chinese wheat hybrids (18A-1, JM-1215, JM-1683, JM-1216, H-1) and one Australian hybrid (WS-1) with two local checks (Wadan-17 and Pirsabak-15) and two NPK levels, i.e., basal dose (120-90-60 NPK kg ha⁻¹) and 25% higher than basal dose (150-112-75 NPK kg ha⁻¹). The results of the two years’ experimentation exhibited that wheat hybrid WS-1 produced higher tillers (444 and 423 m⁻²), leaf area (32.7 and 30.7 cm²), leaf area index (5.0 and 5.4), plant height (105.3 and 103.1 cm), spike length (21.9 and 21.5 cm), spikes (329 and 322 m⁻²), grains spike⁻¹ (59 and 58), thousand grain weight (62.2 and 62.2 g) and biological yield (9769 and 9906 kg ha⁻¹) as compared to local check varieties. Wheat hybrids WS-1, JM-1683, H-1 and 18A1 produced 31%, 27%, 26% and 26% higher grain yield than local check Pirsabak-15, respectively, while a higher harvest index (61 and 59%) was noted for JM-1683 in both years. Application of NPK at the rate of 150-112-75 kg ha⁻¹ increased emergence (87 m⁻²), tillers (421 and 407 m⁻²), leaf area (23 and 20.5 cm²), leaf area index (3.3), plant height (98.2 and 96.9 cm), spike length (15.9 and 16.3 cm), spikes (317 and 314 m⁻²), grains spike⁻¹ (43), thousand grain weight (56.5 and 56.3 g), biological yield (9057 and 9163 kg ha⁻¹) and grain yield (3702 and 3778 kg ha⁻¹) compared to the lower level of NPK (120-90-60 kg ha⁻¹). It is concluded that Chinese wheat hybrid JM-1683 and Australian hybrid WS-1 responded better to the higher level of NPK (150-112-75 kg ha⁻¹) in terms of grain yield and its components and are therefore recommended for the agro-climatic condition of the Peshawar valley.

Hybrid wheat is considered to be one of the main ways to greatly improve the wheat yield in the future, and population construction is an important factor affecting their yield heterosis formation. In order to clarify the effect of population regulation of hybrid wheat on source–sink systems, the two-line hybrid wheat variety Jingmai 6 was used to carry out relevant research in this experiment. The leaf area index (LAI) of Jingmai 6 showed an increasing trend, while the tiller-spike rate exhibited a downward trend with the increase of planting density. The total accumulation of dry matter at maturity increased with the increase of planting density, among which the relative proportion of dry matter pre-anthesis gradually increased, while that after anthesis gradually decreased. The sink capacity and spikes number of hybrid wheat were positively correlated with the grain yield. There was higher sink capacity, spike to leaf ratio and grain to leaf ratio under A2 and A3 conditions. With the increase of planting density, the hybrid wheat yield showed a unimodal curve, and A3 had the highest grain yield. Combined with the change trend of dry matter accumulation before and after anthesis, it was proved that suitable planting density was the key to obtaining high yield of hybrid wheat.