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Significance Maintaining diploid-like pairing behavior is essential for a polyploid to establish as a new species. The Pairing homeologous 1 ( Ph1 ) gene, regulating such behavior in polyploid wheat, was identified in 1958, but its molecular function remained elusive. The present communication reports identification of the candidate Ph1 ( C-Ph1 ) gene that is expressed exclusively during meiotic metaphase I, whose silencing resulted in formation of multivalents like the Ph1 gene mutations. Although the C-Ph1 gene has three homoeologous copies, the 5B copy has diverged in sequence from the other two copies. Heterologous gene silencing of the Arabidopsis homologue of the C-Ph1 gene also confirmed its function. Molecular characterization of this gene will make it possible to develop precise alien introgression strategies.

Spike architecture influences grain yield in wheat. We report the map-based cloning of a gene determining the number of spikelet nodes per spike in common wheat. The cloned gene is named TaCOL-B5 and encodes a CONSTANS-like protein that is orthologous to COL5 in plant species. Constitutive overexpression of the dominant TaCol-B5 allele but without the region encoding B-boxes in a common wheat cultivar increases the number of spikelet nodes per spike and produces more tillers and spikes, thereby enhancing grain yield in transgenic plants under field conditions. Allelic variation in TaCOL-B5 results in amino acid substitutions leading to differential protein phosphorylation by the protein kinase Ta K4. The TaCol-B5 allele is present in emmer wheat but is rare in a global collection of modern wheat cultivars.

Knowledge‐intensive approaches have been proposed to manage the variability in indigenous nutrient supplies (IS) in irrigated rice (Oryza sativa L.) systems. On‐farm experiments were conducted at 155 locations in seven domains of Asia to quantify the variability of soil properties, grain yield, and nutrient uptake in N, P, and K omission plots (0‐N, 0‐P, and 0‐K, respectively). Except for pH, coefficients of variation of soil properties within a domain ranged from 17 to 43%. Similar ranges were measured for grain yield and plant nutrient uptake in nutrient omission plots, which served as crop‐based estimates of indigenous N, P, and K supply. Soil properties showed little association with plant nutrient uptake or grain yield in nutrient omission plots. Mean grain yields in nutrient omission plots increased in the order 0‐N (3.9 Mg ha−1) < 0‐K (5.1 Mg ha−1) ≤ 0‐P (5.2 Mg ha−1). Soils, climate, and crop management caused large variability of IS among irrigated rice domains, years, growing seasons, and fields within a domain. Grain yield and nutrient uptake in omission plots were mostly higher in high‐yielding than in low‐yielding climatic seasons. No changes in indigenous N supply occurred for periods of 4 to 6 yr in the same seasons. Grain yields in nutrient omission plots were strongly correlated with each other and also with the yield in the fertilized farmers' fields. Fertilizer recommendations should be fine‐tuned to spatial domains with relatively uniform agroecological characteristics, cropping practices, and socioeconomic conditions. Within such domains, season‐specific management of the IS variability can include field‐specific approaches.