Physiology unit

Drought as major abiotic constraint in rice production

INTRODUCTION

Rice is the seed of the monocot plants Oryza sativa

(Asian rice) or Oryza glaberrima (African rice).

As a cereal grain, it is the most important staple food

for a large part of the world's human population,

especially in Asia and the West Indies.

It is the grain with the third-highest worldwide

production, after maize (corn) and wheat, according

to data for 2009

The drought challenges

O. Glaberimma field

O. Sativa field

Healthy seedsHealthy seedlings

Healthy crop

Producing good rice yield

High grain yield

Diverse rice varieties

Diverse milled rice grain

Diverse rough grain

Outline:

Diverse dishes

Yep !

Drought stress occurrence &rice responses

What is drought ?

1. Drought is a deficiency in precipitation over an extended period, usually a

season or more, resulting in a water shortage causing adverse impacts on

vegetation, animals, and/or people.

2. A prolonged period of abnormally low rainfall, leading to a shortage of water

Low land drought Upland drought

Rain

EvaporationTranspiration

Runoff

Drainage

Infiltration=> Water available

1

2

3a

3b

4

5

Distribution of water derives from precipitations

Lost =2- Runoff3a- Evaporation4- Transpiration5- Drainage

Available water depend on:•Type and depth of sol•La balance between gain and lost

= main source of water

Ability of soil to hold water

Drought prone area

Weather stationTensiometerDiviner 2000

How to monitor drought environments

9

7

5

3

1

Scale: 1 to 5 Scale: 1 to 9

Visual drought symptoms of drought

(Leaf rolling)

Leaf photosynthesis meter

Infrared thermometer

Leaf area meter

SPAD Meter

Quantification of drought stress

Intermittent Drought

13-Jul 2-Aug 22-Aug 11-Sep 1-Oct 21-Oct 10-Nov

S (W

ater

leve

l - c

m)

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

15Transplanting

Flowering

Maturity

Early Drought

13-Jul 2-Aug 22-Aug 11-Sep 1-Oct 21-Oct 10-Nov

S (W

ater

leve

l - cm

)

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

15Transplanting

FloweringMaturity

Intermittent drought

Early drought

13-Jul 2-Aug 22-Aug 11-Sep 1-Oct 21-Oct 10-Nov

S (W

ater

leve

l - cm

)

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

15

Flowering

Transplanting

Maturity

Late drought

Terminal drought

Growth stages of rice plant & type of drought

Reduction of grain yield

Effect of drought on rice grain yield vs growth stages

Plot leveling

Planting Data collection

Field observation

Some field activities

17

Drought screening facility in our main experimental station: Ikenne (Ogun state)

18

Upland field at Ikenne

Rice fields under at Ikenne

Rice field under ROS Ikenne

Drought screening facility at Ikenne

Flat land

Conclusions

Good knowledge of the target environment is essential in droughtbreeding: what type of stress is more frequent?

Yield stability under drought scenarios and crop water productivity(ratio of yield achieved per water used) should be the target

Drought screening systems should be uniform, repeatable anddifferentiate genotypes

Field and irrigation management are critical for drought screeningScreening procedure are function of targets, needs and means.

Each breeding program should adapt procedures to won environmentand conditions.

Trait-based improvement needs careful choice and requires integrationof breeding and other disciplines

Thank you so much

Merci beaucoup