Although this study examines the same effect of alternate wetting and drying (AWD) on rice sheath blight, causal agent Thanatephorus cucumeris, there are differences between the 2015 and 2016 seasons that make them two separate experiments that cannot be analysed as one. These changes are a result of the findings in 2015 and were made in an effort to improve the experiment.

The differences are:

See the following lists for complete details of the study.

Schedule

IRRI Dry Season (2)

2015 Schedule of Major Activities

Activity Date Days After
Transplanting 		Days After
Inoculation
Transplanting 2015-01-09 0
Inoculation 2015-01-29 20 0
First Assessment 2015-02-12 34 14
Second Assessment 2015-02-20 42 22
Third Assessment 2015-03-05 55 35
Fourth Assessment 2015-03-19 69 49
Fifth Assessment 2015-04-01 82 62

2016 Schedule of Major Activities

Activity Date Days After
Transplanting 		Days After
Inoculation
Transplanting 2016-01-20
to
2016-01-22 		0
Inoculation 2016-03-01 41 0
First assessment 2016-03-15 55 14
Second assessment 2016-03-29 69 28
Third assessment 2016-04-13 84 43
Fourth assessment 2016-04-29 100 59

Methodology

Experimental Design: Split-plot

  • Main plot : Water management (2)

    • W1 – Alternate Wetting and Drying (AWD)

    • W2 – Puddled (Farmers’ Practice)

  • Sub-plot : Nitrogen management (5)

    • 2015

      • N0 – 0 kg/ha

      • N1 – 100 kg/ha

      • N2 – 120 kg/ha

    • 2016

      • N3 – 60 kg/ha

      • N4 - 180 kg/ha

Plot layout

  • Replication: Four (4)

  • Plot Sizes (2015)

    • Main plot size: 12m x 12m (144 sq m)

    • Sub-plot size: 5m x 5m (25 sq m)

    • Replication size: 12m x 24m (288 sq m)

    • Buffer: 1m per sub plot

    • Experiment size: 1,152 sq m

  • Plot Sizes (2016)

    • Main plot size

    • Block 2007: 21m x 20.5m (412.5 sq m)

    • Block 2008: 20.25m x 21.6m (437.4 sq m)

    • Sub-plot size

    • Block 2007: 21m x 10.25m (215.25 sq m)

    • Block 2008: 20.25m x 10.8m (218.7 sq m)

    • Replication size:

    • Block 2007: 42m x 20.5m (861 sq m)

    • Block 2008: 40.5m x 21.6m (874.8 sq m)

    • Buffer: 0.5m per sub plot

    • Experiment size: 3471.6 sq m

Inoculation methods

  • Inoculation methods (2015)

    • 20 bottles (1 bottle = 151g) of inoculum were spread over each plot (4m x 11m)

  • Inoculation methods (2016)

    • 10 bottles (1 bottle = 151g) of inoculum were spread over one sampling area (1m x 1m) in each plot

Disease Rating Scale

Disease was rated using an ordinal scale for field evaluation of sheath blight (S Savary & N Castilla).

  • Rating Scale - Severity (%)

    • 0 - 0,

    • 1 - 1%,

    • 2 - 5%,

    • 3 - 15%,

    • 4 - 50%,

    • 5 - >50%

Nitrogen Management Rates

Nitrogen
treatment 		Year Total N
(kg/ha) 		Application Amount (kg/ha)
Basal Tillering Panicle
Intitiation
N0 2015 0 0 0 0
N100 2015 100 60 20 20
N120 2015 120 60 30 30
N60 2016 60 30 30 0
N180 2016 180 60 60 60

File Contents

Zeros are recorded as empty values.

2015 Column Headings and Column Contents

  • TRT - Treatment ID

  • REP - Replicate

  • WMGT - Water management

    • PDL - Puddle
    • AWD - Alternate Wetting and Drying

  • SMPL - Sample ID

  • NRTE - Nitrogen rate (kilograms per hectareO)

  • HILL - Hill (there were nine per A/B sample)

  • HGHT - Height of the tallest tiller

  • NTIL - Number of tillers in the hill

  • NTShB - Number of tillers with sheath blight

  • TIL1:TIL4 - Tiller number

  • SHB1:SHB4 - Sheath sheath blight lesion rating for corresponding tiller number

  • GL1:GL4 - Number of green leaves for each corresponding tiller number. Green leaves have >50% green tissue

  • DL1:DL4 - Number of dead leaves for each corresponding tiller number. Dead leaves have >50% dead tissue

  • SLA1-4:SLF1-4 - Leaf sheath blight lesion rating for corresponding tiller numbers

2016 Column Headings and Contents

  • DATE - Date observation was made

  • REP - Replicate

  • WMGT - Water management

    • PDL - Puddle
    • AWD - Alternate Wetting and Drying

  • NRTE - Nitrogen rate (kilograms per hectareO)

  • SMPL - Sample ID

  • HILL - Hill (there were nine per A/B sample)

  • NTIL - Number of tillers in the hill

  • NTShB - Number of tillers with sheath blight lesions in the hill

  • NSHShB - Sheath sheath blight lesion rating

  • TIL - Tiller number, 1 to 4

  • GL - Number of green leaves per tiller. Green leaves have >50% green tissue

  • DL - Number of dead leaves per tiller. Dead leaves have >50% dead tissue

  • ShBL1:ShBL6 - Leaf sheath blight lesion rating, 1 to 6