Breeding achievement of k in rice

1. W e l c o m e

2. Breeding for K in Rice
PALB 6191
PALB 6192

4. Why potassium???...
• Modern high-yielding rice varieties absorb
potassium in greater quantities .
• In farmers’ fields across Asia, total K uptake
rates of a crop yielding 5 t/ha are in the
range of 100 kg/ha, of which more than 80%
are concentrated in the straw at maturity.
(Dobermann and Fraihurst, 2000).
• For yields greater than 8 ton/ha, total K
uptake may even exceed 200 kg/ha.

5. • Figure: shows that potassium is continuously taken up by the rice plant
at a rate described by a sigmoidal curve, which gets to its maximum
value during flowering. The potassium is firstly used for building the
leaves biomass, then for the culms and later for the grains.

6. Potassium (K) nutrition in rice promotes:
Tillering
Panicle development
Spikelet fertility
Nutrient uptake of nitrogen and phosphorus
Leaf area and leaf longevity
Disease resistance
Root elongation and thickness
Culm (stem) thickness and strength
Rice plant tolerance to diseases and pests
Rice plant resistance to lodging

8. Effect of potassium on grain filling in rice.

9. Increased root volume
Increasing efficiency of potassium uptake from
the soil and translocation in plants
Increasing mobility of potassium in soil
Molecular breeding of new varieties with
greater potassium efficiency
Strategies for improving potassium use efficiency
in plants are:

10. Rice :
• Up to four transporters from the HKT family
are permeable to K+ (corratgé-faillie et al.,
2010).
• The Shaker and HKT transport systems, and at
least part of the HAK and KEA systems, are
located at the cell membrane.
• The TPK channels appear to play an essential
role in K+ transport across the vacuolar
membrane.

11. Mechanisms of membrane energization and potassium
transport across the plasma membrane.

12. Research papers

13. A rice quantitative trait locus for salt tolerance
encodes a potassium transporter
 In rice a QTL, SKC1 maintained K+ homeostasis in the
salt-tolerant variety under salt stress.
 To understand the molecular basis of this QTL, they
isolated the SKC1 gene by map-based cloning and found
that it encoded a member of HKT-type transporters.
 SKC1 is preferentially expressed in the parenchyma cells
surrounding the xylem vessels.
 Physiological analysis suggested that SKC1 is involved in
regulating K+ homeostasis under salt stress, providing a
potential tool for improving salt tolerance in crops.

14. Potassium nutrition of rice (Oryza sativa L.) varieties
under NaCl salinity
Abstract:
A salt-tolerant (Pokkali) and a salt-sensitive
(IR28) variety of rice was grown in a phytotron to
investigate the effect of K application on salt
tolerance. K application significantly increased
potential activity, % of filled spikelets, yield and K
concentration in straw. At the same time it also
significantly reduced Na and mg concentrations
and improved the K/Na, K/Mg and K/Ca
ratios.IR28 responded better to K application
than Pokkali.
J.S.BOHRA & DOERFFLING

15. Rice Resistance to Sheath Blight Mediated
by Potassium
 Two cultivars BR-IRGA 409 and Labelle were grown in
nutrient solution containing 0, 50 and 100 ppm of K.
 The foliar K concentration on leaf sheaths tissue
increased by 61.48 and 116.05% in cultivars BR-IRGA
409 and Labelle, respectively, as the K rates
increased from 0 to 100 mm.
 Sheath Blight relative lesion length was decreased
by 29.2 and 21.3% for cultivars BR-IRGA 409 and
Labelle, respectively, as the K rates in the nutrient
solution increased.

16. Thank you