RICE GROWTH AND DEVELOPMENT or Are you breaking the world rice yield record? Jim Hill UC Davis

So what is the world record? Or should we ask--is the world record really the world record?

So what is the world record? 1.80 cwt cwt cwt cwt

CountryAve YieldRecord Yield (cwt) (cwt) India na 204 China California (M-202) 133 (exp) Reported Record Yields

Outline  Yield Components  panicles/area  spikelets/panicle  % filled grains  grain weight  Growth Stages and Yield  vegetative growth seedling tillering  reproductive growth panicle initiation flowering  grain ripening  Harvest Index

Definitions Spikelet = future grain or seed Panicle = the head or all the grains on a tiller

The Yield Components panicles/ area  Established Seedlings  Tillers per seedling

The Yield Components x panicles/ area spikelets/ Panicle

The Yield Components xx panicles/ area spikelets/ panicle % filled spikelets

The Yield Components xxx panicles/ area spikelets/ panicle % filled spikelets grain weight

The Yield Components xxx panicles/ area spikelets/ panicle % filled spikelets grain weight = yield

Example: Your crop has 60 panicles per square foot and each has 70 kernels. The kernel weight is 30 grams/1000 grains, there is 10% blanking, what is the yield? Yield Component Analysis Conversion Factors: 1 lb = 454 grams 1 a = 43,560 ft 2 Abbreviations: grams = g Pound = lb Square foot = ft 2 Step 1: 60 panicle/ft 2 x 70 kernel/panicle x 90% filled spikelets = 3780 kernels/ft 2 Step 2: 30 g/1000 kernels x 3780 kernel/ft 2  454 g/lb = 0.25 lb/ft 2 Step 3: 0.25 lb/ft 2 x 43,560 ft 2 /acre = 10,880 lb/acre

Example: Your crop has 60 panicles per square foot and each has 70 kernels. The kernel weight is 30 grams/1000 grains, there is 30% blanking, what is the yield? Step 1: 60 panicle/ft 2 x 70 kernel/panicle x 70% filled spikelets = 2940 kernels/ft 2 Step 2: 30 g/1000 kernels x 2940 kernel/ft 2  454 g/lb = 0.19 lb/ft 2 Step 3: 0.19 lb/ft 2 x 43,560 ft 2 /acre = 8,280 lb/acre Yield Component Analysis

Seeding Rates and Seed Density Seed Rate Density 1 Range 2 (lb/a) (seed/ft 2 ) (seed/ft 2 ) (S-102 to Kosh>44%) typical of field run calrose varieties 2 range across California varieties based on seed weight tillers

Yield Components Plant Panicle Seeding RateStand Density (lb/acre) (sq ft) (sq ft) Tillers per plant 30 lb/a = 5 60 lb/a = lb/a = lb/a = 1.7 tillers

Yield Components Plant Panicle Spikelets Seeding RateStand Density per Panicle (lb/acre) (sq ft) (sq ft) (no.) spikelets

Yield Components Plant Panicle Spikelets Filled Seeding RateStand Density Per Panicle Spikelet (lb/acre) (sq ft) (sq ft) (no.) (%) Normally about 12% Blanking % filled spikelets

Yield Components Plant Panicle Spikelets Filled Grain Seeding RateStand Density Per Panicle Spikelet Weight (lb/acre) (sq ft) (sq ft) (no.) (%) (mg) grain weight

Yield Components Plant Panicle Spikelets Filled Grain Seeding RateStand Density Per Panicle Spikelet Weight Yield (lb/acre) (sq ft) (sq ft) (no.) (%) (mg) (lbs/acre) yield

Yield Components Plant Panicle Spikelets Filled Grain Seeding RateStand Density Per Panicle Spikelet Weight Yield (lb/acre) (sq ft) (sq ft) (no.) (%) (mg) (lbs/acre) yield Step 1: 7 plants/ft 2 x 5 tillers/plant = 35 panicles/ft 2 Step 2: 35 (60) panicle/ft 2 x 90 (70) kernel/panicle x 90% filled spikelets = 2835 (3780) kernels/ft 2 Step 2: 30 g/1000 kernels x 2835 (3780) kernel/ft 2  454 g/lb = (0.25) lb/ft 2 Step 3: (0.25) lb/ft 2 x 43,560 ft 2 /acre = 8,160 (10,880) lb/acre

Outline  Yield Components  panicles/area  spikelets/panicle  % filled grains  grain weight  Growth Stages and Yield  vegetative growth seedling tillering  reproductive growth panicle initiation flowering  grain ripening  Harvest Index

Growth Stages of Rice VegetativeReproductiveRipening

Growth Stages of Rice [ Vegetative ][---Reproductive----]

Seedling Stage HeterotrophicAutotrophic [ Vegetative ]

Growth Stages of Rice [ Vegetative ][---Reproductive----] [----Tillering----]

Tiller Initiation Approximately DAS All maturities

Tiller Initiation

Growth Stages of Rice Tillering ends at or before PI [ Vegetative ][---Reproductive----]

MaturityAve Days toAve Days CultivarGroup(County)50% headingto PIPI Range M-104VEButte Sac SJ M-202EarlyButte Sac SJ Glenn M-205Early-MidButte Colusa Yuba Glenn M-206EarlyButte Sutter SJ Colusa Yuba Average Date to 50% Heading, Estimated Time to PI and Variation in PI Range over 9 years from

Growth Stages of Rice--Reproductive Panicle is visible When stem cut about 7 days after PI but…. Spikelets per panicle are already formed

Cold Temperature Induced Floret Sterility

Collar alignment of the flag leaf and the previous leaf is an indicator of the cold sensitive period for pollen formation Left—before sensitive Middle—sensitive Right—after sensitive How many spikelets get filled is deter- mined at this stage

Of all the yield components, seed weight is under the tightest genetic control and LEAST influenced by environment. You can lower seed weight easily, but you can’t increase it! Plant Panicle Spikelets Filled Grain Seeding RateStand Density Per Panicle Spikelet Weight (lb/acre) (sq ft) (sq ft) (no.) (%) (mg) This is why decisions on drain times and north winds at grain filling can mess with you!

Outline  Yield Components  panicles/area  spikelets/panicle  % filled grains  grain weight  Growth Stages and Yield  vegetative growth seedling tillering  reproductive growth panicle initiation flowering  grain ripening  Harvest Index

Harvest Index (HI) HI = (GW)/(GW + SW) where: HI = Harvest Index GW = Grain Weight SW = Straw Weight Example 1: A tall variety produces 6000 lbs of grain 7000 lbs of straw HI = 6000/( ) = 0.46 Example 2: A semidwarf variety produces 8000 lbs of grain 7500 lbs of straw HI = 8000/( ) = 0.52

Harvest Index (HI) HI = (GW)/(GW + SW) where: HI = Harvest Index GW = Grain Weight SW = Straw Weight Example 1: A tall variety produces 6000 lbs of grain 7000 lbs of straw HI = 6000/( ) = 0.46 Example 2: Let’s assume the HI =.52 for a short variety and calculate the amount of straw = 6000/(6000+ SW) SW = 5540 lbs

What yield component can be influenced most by good management? 1.Spikelets/panicle 2.Panicles/ft 2 3.Seed weight 4.% filled grains

What yield component is influenced least by management practices? 1.Spikelets/panicle 2.Panicles/ft 2 3.Seed weight 4.% filled grains

xxx panicles/ area spikelets/ panicle % filled spikelets grain weight = yield Thank you