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Wheat Information Service
Number 75: 54-56 (1992)


Phosphorus utilization by induced high temperature tolerant wheat

A. P. Gupta¹, R. S. Malik¹, and R. K. Behl<sup>2

1</sup> Department of Soil Science Haryana Agricultural University, Hisar, India
² Department of Plant Breeding, Haryana Agricultural University


Introduction

During last two decades, the productivity of wheat crop has been doubled. This increase was mostly due to the introduction of high yielding varieties, increase in fertilizer consumption and increase in irrigation facility. The high cost of fertilizers is still limiting the farmers to apply balanced doses of fertilizers to exploit the full potentials of different wheat varieties. The availability of native nutrients from the soils depend upon temperature and moisture. The high yielding semi-dwarf wheat varieties generally complete their grand growth periods when the temperature of soil is low. Contrarily, the high temperature tolerant wheat mutants suitable for early sown after the cessation of monsoon rains are exposed to high temperature coupled with adequate soil moisture during early growth stages (Behl et al 1986). High temperature coupled with moisture could mobilize higher native P and thus resulting in reduction of phosphatic fertilizer application. The present study was undertaken on the utilization of applied P by radiation induced mutants of wheat (WH 147, C 306).


Materials and methods

Surface soil for the present study was collected from Research Area of Soil Science Department. The field was classified as "Typic Ustochrept". The physico-chemical properties of the soil were: pH (1 : 2) 7.3, EC (1 : 2) 0.19 dSm^-1, sandy loam in texture, organic C 0.43%, available P 11 mg kg^-1. Earthen pots of 25 cm diameter lined with polyethylene were filled with 4 kg air dried, crushed (2 mm) soil. Basal dose of N (40 mg kg^-1), P (30 mg kg^-1), K (25 mg kg^-1), Zn (5 mg kg^-1), Fe (5 mg kg^-1), Mn (5 mg kg^-1) and Cu (2.5 mg kg^-1) were applied in each pot. Phosphorus was tagged with ³²P @0.25 mCi g^-1 P. All these nutrients were applied through their analytical grade salts and mixed thoroughly with soil before filling the pots.

Ten seed of wheat varieties, WH 147, C 306 and their mutants were sown in each pot. Four plants in each pot were maintained after complete germination. Demineralized water was applied for irrigating the pots as and when required. All the pots were placed after randomization keeping three repeats for each treatment. The crop was harvested 40 days after sowing. Plant samples were washed, dried (65 + or - 2^oC), weighed and ground in a stainless steel grinder. Plant samples were digested in H₂S0₄ and HCl0₄ in the ratio of 5 : 1.

Phosphorus in the plant digests was estimated by phosphomolybdovanadate yellow color method of Koenig and Johnson (1942). Radio-essay of plant digests was done on 1209. Recbeta scintillation counter using PPO- POPOP as scintilattors. Fertilizer P in plant and fertilizer use efficiency was calculated as suggested by Mackenzie and Dean (1948). The data was subjected to statistical test of significance using single factor completely randomized design.

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