Rapeseed (Brassica napus L.) is the second most widely grown premium oilseed crop globally, mainly for its vegetable oil and protein meal.  One of the main goals of breeders is producing high-yield rapeseed cultivars with sustainable production to meet the requirements of the fast-growing population.  Besides the pod number, seeds per silique (SS), and thousand-seed weight (TSW), the ovule number (ON) is a decisive yield determining factor of individual plants and the final seed yield.  In recent years, tremendous efforts have been made to dissect the genetic and molecular basis of these complex traits, but relatively few genes or loci controlling these traits have been reported thus far.  This review highlights the updated information on the hormonal and molecular basis of ON and development in model plants (Arabidopsis thaliana).  It also presents what is known about the hormonal, molecular, and genetic mechanism of ovule development and number, and bridges our understanding between the model plant species (A. thaliana) and cultivated species (B. napus).  This report will open new pathways for primary and applied research in plant biology and benefit rapeseed breeding programs.  This synopsis will stimulate research interest to further understand ovule number determination, its role in yield improvement, and its possible utilization in breeding programs. 

The rice cultivars carrying dep1 (dense and erect panicle 1) have the potential to achieve both high grain yield and high nitrogen use efficiency (NUE).  However, few studies have focused on the agronomic and physiological performance of those cultivars associated with high yield and high NUE under field conditions.  Therefore, we evaluated the yield performance and NUE of two near-isogenic lines (NILs) carrying DEP1 (NIL-DEP1) and dep1-1 (NIL-dep1) genes under the Nanjing 6 background at 0 and 120 kg N ha^–1.  Grain yield and NUE for grain production (NUEg) were 25.5 and 21.9% higher in NIL-dep1 compared to NIL-DEP1 averaged across N treatments and planting years, respectively.  The yield advantage of NIL-dep1 over NIL-DEP1 was mainly due to larger sink size (i.e., higher total spikelet number), grain-filling percentage, total dry matter production, and harvest index.  N utilization rather than N uptake contributed to the high yield of NIL-dep1.  Significantly higher NUEg in NIL-dep1 was associated with higher N and dry matter translocation efficiency, lower leaf and stem N concentration at maturity, and higher glutamine synthetase (GS) activity in leaves.  In conclusion, dep1 improved grain yield and NUE by increasing N and dry matter transport due to higher leaf GS activity under field conditions during the grain-filling period.

Coordinating light and nitrogen (N) distribution within a canopy is crucial to improve rice yield and resource use efficiency.  However, little attention has been paid to light and N distribution in response to planting density and N rate, and its relationships with grain yield, radiation use efficiency (RUE), and N use efficiency for grain production (NUEg) in rice.  Here, a two-year field experiment was conducted with two hybrid varieties under three N levels, 0 (N1), 90 (N2) and 180 kg ha^-1 (N3), and two planting densities, 22.2 (D1) and 33.3 hills m^-2 (D2).  On average, a 3.4% higher yield and 4.4% higher NUEg were observed under N2D2 compared with N3D1.  The extinction coefficient for N (K_N) and light (K_L) and their ratio (K_N/K_L) at the heading stage were significantly affected by the N rate, planting density, and their interaction.  K_N decreased with the increase of N input or planting density.  Compared with N1, K_N decreased by 43.5 and 58.8% under N2 and N3, respectively, and K_N under D2 decreased by 16.0% compared with D1.  Higher K_L and K_N/K_L values were observed under a low N rate, while the opposite trend was shown under a high N rate.  Moreover, increasing planting density resulted in a decrease in K_L and K_N/K_L values.  Compared with N3D1, N2D2 had higher K_L and K_N, and thus comparable K_N/K_L.  Correlation analysis further revealed that K_L was negatively correlated with RUE, while K_N and K_N/K_L were positively correlated with NUEg.  Therefore, increasing planting density under reduced N input could ensure rice yield while improving resource use efficiency via regulating canopy light and N distribution.