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INFLUENCE OF NITROGEN RATE ON DRY MATTER PRODUCTION, NITROGEN UPTAKE AND YIELD IN HIGH YIELDING CULTURES OF RICE G.

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NITROGEN UPTAKE AND YIELD IN HIGH YIELDING CULTURES OF RICE

G. SAHu and K. S. MuRTY

Central Rice Research Institute, Cuttack

Received on October 8, 1974

SUMMARY

The productive efficiency of six high yielding nee cultures, Bala, Cauvery (very early), Hamsa, Padma (early), Jaya and CR. 10-4128 (mid-season) was tested during dry season at 80 and 160 kg Njhec. The response to nitrogen varied from 5-14 kg of grain per additional kg of N and it was mostly due to an increase in the panicle number. Jaya showed the maximum response. The dry matter production and N uptake were low up to primordial stage and rapid thereafter in early varieties; whereas the reverse trend was noticed in mid-season types. The dry matter at harvest showed direct association with yield. The productivity for unit leaf area index as well as harvest index was high in Bala; whereas Ja;•a recorded the highest yieldjhec because of high 1000 grain wt, high dry matter production and N uptake even during the ripening stage.

INTRODUCTION

The grain yield in rice is determined by the total dry matter produced during the growing season and paritition of the dry material to the panicle or grain (Yoshida, 1972). The total dry wt in the grain or yield is reflected in the number of grains/unit area i.e. the product of panicle number, grain number per panicle and 1000 grain wt (Matsushima, 1966). The productivity depends on the optimum values of the above attri-butes. The objective of the present investigation was to assess the response to high rate of nitrogen and study the relationship between yield and various growth components m some of the popular high yielding rice varieties (HYV) of different maturity periods.

MATERIALS AND l\fETHODS

Field experiments were conducted at the Central Rice Research Institute, Cuttack in an alluvial clay loam soil having pH=6.4; O.M. =0.57; N =0.06 during the dry season (Jan-May, 1970). Six high yielding varieties of rice, Bala, Cauve1y, (very early, 100-105 d),

Hamsa, Padma (early, 115-120 d), Jaya and CR. 10-4128 (mid-season, 130-135 d) were transplanted at 15

x

15 em spacings under 80 and 160 kg nitrogenjhec. TheN was appli-ed in 3 splits

n-

basal+i- mid-tillering+i- at PI). Phosphorus (P) and potassium (K) were incorporated at 42 and 22 kgjhec, respectively at planting. The experiment was laid out in

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Samples were collected for dry matter determination at primordial, flowering, mid-harvest i.e. 15 days after flowering (15 DAF) and mid-harvest stages from 20 hills and parti-tioned into leaf, stem and panicle dependig on the growth stage. The percentage of N in different plant parts and the N uptake at the progressive growth stages were assessed. The grain yield and yield components were recorded at harvest.

The response for N was calculated as the increase in yield per unit increase in N rate, i.e. (Y2-Y1)/80, where Y2 and Y1 were yields at 160 and 80 kg N/hec, respectively. The

harvest index (HI) was determined as grain yield/total dry matter yield at harvest X 100. The leaf area index(LAI) was calculated as leaf area for 1m2 of land area. The

correl-ation coefficients between yield and growth components were calculated and partitioned into direct and indirect effects by following Dewey and Lu (1959).

RESULTS

Grain J'ield and yield components:

TheN responsiveness or increase in yield per unit increase in applied N (from 80 to 160 kg Nfhec) varied from 4. 7 to 14.4. Jaya showed the maximum response and it was mostly associated with increase in panicle number. The grain number/panicle and 1000 grain wt were least influenced with N rate. The early varieties produced more panicles/ m2 than the mid-season types but grain number/panicle was comparatively low in these

cultivars.

Jaya recorded the highest yield of 7. 7 and 8.9 t/hec at 80 and !60 kg N respectively, followed by CR. 10-4128. The high yield in Jaya was associated with high 1000 grain wt (28.7 g) and optimum grain numberjpancile, while in CR. 10-4128, the grain number/ panicle (127) contributed mostly to grain wt. Bala and Cauvery which were very early

Table I. Effect qf N rate on yield, LA! and HI in high yielding rice cultures during dry season (

N

1 =80 and N2

=

160 kg Nfhec)

Culture/ N Yield Panicles/ Grain 1000 grain. LAI

Variety rate (kgjhec) m• no,pan wt (g) Fig

Bala Nt 6235 431 67.3 20.0 5.2

Nz 6923 512 72.5 20.4 7.4

Cauvery Nt 5718 529 53.8 22.9 8.2

N, 6092 636 49.1 23.2 10.3

Hams a Nt 5361 356 66.2 22.7 7.9

N. 5982 476 75.3 23.5 11.5

Padma Nt 5440 512 78.9 21.2 9.4

No 5862 556 81.4 20.6 11.4

Jay a Nt 7719 387 81.2 28.5 9.5

N. 8873 436 79.1 28.9 12.4

CR. 10·4128 Nt 7514 356 130.4 21.1 8.8

No 8158 436 124.3 20.8 12.5

Mean Nt 6331 429 79.6 22.7 8.2

N. 6983 509 80.3 2.9 10.9

N,fN1X100 110 120 101 101 134

CD (0.05)

Varietv 121 41 15.3 0.8 1.5

N-levei 215 18 NS NS 1.3

VxN NS NS NS NS NS

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produced higher grain yield than Hamsa and Padma which were later in duration, indi-cating the potential high yielding cultures even among the short duration cultivars (Table I).

Growth components:

Dry matter production ( DMP) .-The dry matter at flowering and harvest was higher (15-20%) at 160 than at 80 kg Nfhec. The increase was more apparent in early types than in mid-season cultures. The DMP both at flowering and harvest increased with the duration of the variety. However, considerable variation in this trait existed even in the same duration group, i.e. Cauvery, Hamsa and Jaya were more efficient than Bala, Padma and CR. 10-4128 from the three groups, respectively (Fig. 1).

00

Eml

stelll 0 L.ea.f B Panicle

16

BaJA Cauvery HU~Sa Padma Jaya. CR.I0-412~

Fm. 1. Dry matter production and N uptake in high yielding rice varieties at primordial (P), flowering (F) and harvest (H) stages under 80 (N,) and 160 (N2) kg N/hec.

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The HI was lower at higher N rate especially in early types. These types invari-ably showed higher HI than the medium ones. The HI was higher in CR. 10-±128 than in ]a)'a indicating the variability of this trait even in the same duration group.

Leaf area index (LA!).-The LAI at flowering was enhanced by about 34-% at higher

N rate especially in Bala, Hamsa and CR. 10-4128. LAI was low in Bala, (5.2 to 7.4), but the grain yield per unit LAI was the highest in this variety indicating better efficiency of the leaf in carbon assimilation. The LAI was more or less similar in rest of the varieties showing, thereby, that this character was not always associated with the flowering dura-tion of the cultivar (Table I).

Nuptake.-The Nj~ increased in the plant (stem and leaf) by 15%-20% at high N rate, especially at PI stage. The early types consistently showed higher percentage of N at all the growth stages. The N% of leaf declined steeply with age in early types. The variation in N% of culm and panicle at different growth stages was not appreciable in the mid-season types (Fig. 2).

I

z

PF H P F H f ' F H P F H P F H P F H

&Ia Cauvery Ha.msa Pa.dma. lava. Cf\.10-~128 FIG. 2 Percentage of nitrogen in leaf, stem and panicle at different stages.

The N uptake increased by 2•3% and 33% at flowering and harvest, respectively at high N rate and the increase was more apparent in early types. As in DMP, theN uptake at primordial stage was low (44%) in early types whereas in mid-season cultures it varied from 70-80% of the total N absorbed by harvest. There was even loss of absorbed N after flowering in Cauvery, Hamsa and CR. 10-4128 (Fig. I).

Association of characters with yield.-The association between yield and some of the

growth components indicated that DMP, both at flowering and harvest, was highly cor-related with yield (r=0.90 to 0.94). According to path analysis also, the direct effect of dry matter at harvest on yield was positive and significant (P= 1.07) and the significance of other characters as indicated below was only due to the indirect influence through

dry matter.

Character

Dry matter at flowering Dry matter at harvest LAI at flowering

Association with Jield

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LAI at mid-harvest N uptake at flowering N uptake at harvest ** Significant

DISCUSSIO::<!

0.66 0.84** 0.82**

The response to high rate of N (160 kg N fhec) over that of80 kg N/hec was mostly associated with increased panicle number. The grain number/panicle and 1000 grain wt were not influenced by N rate. Similar observations were reported by Srivastava and Singh (1971), Nair and George (1973) and Pillai and George (1973). The increase in yield was not proportionate with the increase in LAI, DMP or N uptake at high N rate due to lower impaired translocation of assimilated products from straw to panicle leading to lower HI (Oshima, 1962; Murayama, 1967; Murty, 1969).

Among the growth components, dry matter at harvest showed direct association with yield whereas, LAI and N uptake influenced yield indirectly through DMP. The association of grain yield with total dry matter yield was earlier reported by Murata (1971) and Murata and Togari (1972). However, Yoshida (1972) observed asymptotic relationship between yield and DMP due to reduction in HI at higher dry matter yield. The present study also indicated lower HI in mid-season types which produced the high-est dry matter.

The N uptake was almost complete by flowering in both early and mid-season types and there was even loss of absorbed N from the plant during ripening stage in some cul-tivars, e.g. Cauvery, Hamsa and CR. 10-4128. Such losses were reported earlier by Tanaka and Navasero (1964).

The early varieties showed lower growth rate initially and later the growth in terms of DMP was rapid. However, the total DMP and yield were low in these types due to shorter growth period. Bala, in spite of the shorter duration and less DMP, gave higher yield than the rest of the early cultures because of high HI. The HI was also associated with efficient DMP after flowering in this variety. Among the 6 cultures, ]aJa recorded the highest yield and the characters associated with such productive efficiency were opti-mum tillering (104 panfm2), high 1000 grain wt (28.7), moderate grain number/panicle (80), high DMP at flowering (1.24 kgfm2) and during ripening and ability to absorb N even after flowering stage. Some of these physiological traits might serve as indices for selection and breeding of better productive types with stable yields.

AcKNOWLEDGEMENTs

The authors are grateful to Dr. S.Y. Padmanabhan, Director, Central Rice Res-earch Institute, Cuttack for his constant encouragement in the course of investigation.

REFERENCES

Dewey, D.R. and Lu, K.H. (1959). A correlation and path coefficient analysis of components of crested wheat grass seed production. Agron. J, 51: 515-18.

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Murata, Y. (19il). Limitations to the productivity of rice. Presented at the Symp. on Crop Productivity, 12th Pacific Sci. Congr., August 1971.

- - - and Togari, Y. (1072). Analysis of the effect of climatic factors upon the productivity of rice at different localities in japan. Proc. Crop Sci. Soc. Japan, 41 : 372-81.

Murayama, N. (1967). Nitrogen nutrition of rice plant. Jap. Agric. Res. Q., 2: 1-5.

Murty, K.S. (1969). Effect oftop dressing nitrogen at heading time on carbon assimilation of rice plant during the ripening period. Indian J. Pl. Physiol., 12: 202-10.

Nair, P.K.R. and George, C.M. (1973). Studies on differential response of rice varieties to nitrogen. Agri. Res. J. Kerala, 11: 17-22.

Oshima, M. (1962). Studies on the nitrogen nutrition of plant. III. Effect of nitrogen nutrition on the trans-location of photosynthetic products. J. Sci. Soil and Manure, Japan, 33:21-24.

Pillai, G.R. and George, C.M. (1973). Studies on the performance of rice var. IR-8 under varying levels of nitrogen and spacing. Agri. Res. J. Kerala, 11: 38-42.

Srivastava, K.N. and Singh, K.S.P. (1971). Performances of tall and dwarf rice varieties under varying levels of nitrogen. Ind. J. Agro., 16: 394-95.

Tanaka, A. and Navasero, S.A. (1964). Lo;,s of nitrogen from the rice plant through rain or dew. Soil. Sci. and Plant Nutr., 10: 36-39.

Figure

Table I. Effect qf N rate on yield, LA! and HI in high yielding rice cultures during dry season ( N1 =80 and N2= 160 kg Nfhec)
FIG. 2 Percentage of nitrogen in leaf, stem and panicle at different stages.

References

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