Towards the selection of phosphorus efficient rice varieties Lalith Suriyagoda 1,2, Vishna Weerarathne 1, Dinarathne Sirisena 3, Matthias Wissuwa 4 1 Faculty of Agriculture, University of Peradeniya, Peradeniya, Sri Lanka 2 School of Plant Biology and Institute of Agriculture, The University of Western Australia, 35 Stirling Hwy, Crawley, Perth, WA 6009, Australia 3 Rice Research and Development Institute, Bathalagoda, Ibbagamuwa, Sri Lanka 4 Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba , Japan

Soil P range (mg kg -1 ) Cropping System (Olsen-P) Rice-Rice (% fields) Rice-Vegetable (% fields) Vegetable-Vegetable (% fields) <5 9 5 – – – – – < 2968 Distribution of soil P levels in different cropping systems in Sri Lanka (Wijewardena, 1990) At present rice crops in Sri Lanka do not show P deficiency Sri Lanka does not own high quality P reserves Department of Agriculture has reduced the P application rate to rice recently

Identify P deficiency sensitive growth and development characteristics Screen the local and selected exotic germplasms to find P efficient rice varieties Objectives

Initial soil conditions P sensitive growth characteristics in rice MeasurementValue pH 7.4 Available (Olsen) P (mg kg -1 ) 13.8 Total P (mg kg -1 )338 Exchangeable K (mg kg -1 ) 84.7

DW (g hill -1 ) Growth Above ground DW Grain yield Total P uptake Tissue [P] Plant height vv

Variation in plant height Weeks After Planting Plant height (cm) P(+)P(-) Initial plant responses to declining soil P status were; reduction in plant height, total above ground DW, total P uptake, and tissue [P] but not the grain yield

Screening rice varieties for P efficiency … Plant materials: 44 recommended rice varieties in Sri Lanka, and 36 IRRI set Harvest: at 6 weeks after planting (both roots and shoots) Measurements: Growth (DW), tissue P and K concentrations

Character Unfertilised site (for 30 years!) Fertilised site pH6.56 Total N (mg g -1 ) Exchangeable K (mg kg -1 ) Total P (mg kg -1 ) Available (Olsen) P (mg kg -1 ) OM (%) 22.2 In unfertilised site both local and IRRI lines were grown In fertilised site only the local varieties were grown Only for local varieties

At303 At307 Bg300 Bg305 Bg369 Bw363 Bw451 At402 Bg357 Bg358 Bg366 Bg11-11 Bg400-1 Bg450 Bw367 DW (g plant -1 ) under unfertilised condition (Olsen P 1.6 mg kg -1 ) DW (g plant -1 ) under fertilised condition (Olsen P 11.8 mg kg -1 ) Growth of local rice varieties under low and high soil fertility

Total P uptake (mg plant -1 ) Plant DW (g) Total K uptake (mg plant -1 ) Local (44 varieties) At303 Bg300 Bg305 Bg357 Bg400-1 GUAN YIN TSAN DJ123 IRRI set (36 lines) At303 Bg300 Bg305 Bg400-1 Bw451 Growth, P and K nutrition at unfertilised site

P concentration (mg kg -1 ) K concentration (mg kg -1 ) Unfertilised site Fertilized site Grain P and K concentrations Local (44 varieties) IRRI set (36 lines)

At303 Bg300 Bg305 Bg369 Root DW (g plant -1 ) Shoot DW (g plant -1 ) Local (44 varieties) IRRI set (36 lines) A wide variability in the growth and P nutrition was observed for local rice varieties under low-fertile soil conditions, In general, local rice varieties performed better than the IRRI set, Certain local rice varieties showed promise to be used in future breeding experiments

Acknowledgement International Foundation for Science, Sweden National Research Council, Sri Lanka National Science Foundation, Sri Lanka SPS2014 Organisers, Thank you