There should be no nutrient deficiency and toxicity symptoms from tillering to early panicle initiation and flowering stages that may impair the growth, development and yield of rice.

At flowering stage:

• achieve at least 210 panicles/m2 in rainfed lowland
• 300 panicles/m2 in irrigated lowland for transplanted rice
• 270 panicles/m2 in rainfed lowland
• 350 panicles/m2 in irrigated lowland for direct wet seeded rice.

To asses panicle density:

• randomly select 3 sampling sites in a diagonal line across the field (the sampling sites should be at least 1 m from the edge of the field)
• count the number of panicles using a 1 m x 1 m quadrat
• add the number of panicles and divide the total by 3 to get the average number of panicles/m2.

Know and manage the nutrient requirement of your crop based on the available information, nutrient assessment and decision-support tools.

Manage the Nitrogen needs of your crop based on the leaf color chart (LCC).

• If the LCC reading is below 4 for transplanted rice and below 3 for direct wet-seeded rice, apply N fertilizer (1.5 bags urea per hectare in the dry season and 1 bag urea per hectare in the wet season) from tillering to early flowering stages

• Minus-One Element Technique (MOET)--conduct the MOET test 30 days before transplanting or direct wet seeding and assess the nutrient status based on plant nutrient deficiency symptoms and growth response
• Soil Test Kit (STK).

Aside from nutrient deficiency, consider mineral toxicity in deciding on the nutrients to apply. You can use other soil fertility assessment methods in assessing the nutrient status of the soil.