PFTDM, more number of high density grain (HDG) and higher grain yield.

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· Indian 1. Plant Physiol., Vol XXXVI, No.4 pp. 215-219 (December,J 993)

PHYSIOLOGICAL BASIS OF HIGHER PRODUCTIVITY IN RICE

i •

N.M. CHAU· AND S.C. BHARGAVA

..

Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi- 110012

Received on 19 Dec., 1992

SUMMARY

Grain yi~ld was positively correlated with post-flowering total dry matter production (PFTDM), grain number/m1

, sink size and leaf area duration during grain filling while it was negatively correlated

with leaf area index (LAI) and TDM at flowering. In high yielding cultivars namely, Jaya and Pusa­ 743 large sink sae was due to higher number of grains/m1

, increased panicle weight, more number of

spikelets on primary branches and higher number of primary branches. Larger sink size triggered enhanced canopy photosynthesis which resulted in better PFTDM, more number of high density grain (HDG) and higher grain yield.

INTRODUCTION

IRRI (1989) proposed that the physiological and morphological traits required to realise yield potential should be examined across tropical, subtropical and tem­ perate regions. Venkateswarlu and Vergara (1989) sug­ gested that enhanced production of assimilates during post flowering appears to be the lim~~ation to higher yield potential. They further proposed yield potential could be increased by increasing the single spikelet weight and/or enhancing the proportion of high density grain (HDG) having higher weight. Yoshida (1972) showed that in­ crease in yield potential ofa variety is not associated with increase in leaf photoysnthetic rate (Pn). Similar view was expressed by Murty et al. (1992). They reported that the cultivars having high Pn rate had low LAI resulting in low canopy photosynthesis (Pn x LAl); on the other hand, cultivars with moderate Pn and high LAl recorded high canopy photosynthesis, dry matter production and high yield.

Apart from high PFTOM and high canopy photosyn­ thesis during grain filling, larger sink size (number of spikelets/panicle) has also been suggested as one of the parameters for attaining increased yields Nishiyama

(1989); Park and Cho (1989); Tuan (1989); Guangnan and Jiling (1989), and IRRl (1989). Comparison of potential and actual yield by Chau (1992) also revealed that an estimated 36% increase in grain yield is feasible under Northern Indian condition by increasing the num­ ber ofHDG/panicle. The present investigation highlights the physiological and morphological parameters required to realise high yield potential under North Indian condi­ tion.

MATERIALS AND METHODS

Eight high yielding cultivars of two duration groups namely early: Pusa 2-21, Rasi, Pusa - 744, and medium: Pusa-169, Pusa-743, Pusa-205, Pusa-429 and Jaya were grown under field condition during the rainy seasons of

1990 and 1991. Twenty five days old seedlings were transplanted at lOx 20 cm spacing. One day before transplanting 50 kg P;P/ha as superphosphate and 50 kg ~Olha as murate of potash were applied as basal dose. Nitrogen at 100 kg Nlha was given as urea in three splits : 113 N at 10 days after transplanting (OAT), 113N at 25 OAT and 113 N at 40 OAT. Experiment was laid in randomised complete block design with three replica­ tions. The observations were recorded on 4 plants/repli­

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216 N.M. CHAU AND S.C. BHARGAVA

cation for the traits viz. (I) leaf area index (LAI), (2) post flowering total dry matter (PFTDM), (3) leaf photosyn­ thetic rate (pn) (mg C0 m,2sec ,I), (4) stomatal conduc­

2

tance (Cs) (cm sec 'I), Pn and Cs were measured on flag leaf using LICOR-6200 portable photosynthetic system, (5) grain yield and (6) yield attributes were taken as described by Yoshida et al. (1972). The grains were fractionated into different grades : poor (1.00 to 1.06 specific gravity, average 1.06 to 1.14, good 1.14 to 1.20 and high density grain (submerged) at 1.2 by specific gravity method. (Venkateswarlu et al.1986). Potential yield was calculated by multiplying the total spikelets produced per unit area and 1000 grain weight of HOG analysis among different traits and grain yield was also attempted.

RESULTS AND DISCUSSION

Results indicate that grain yield was not correlated with TOM at flowering or TOM produced before flower­ ing. On the other hand, grain yield was positively corre­ lated with PFTOM (r 0.85**). Murty (1985) reported that high yielding varieties accumulated 40-50% ofTDM after flowering. In the present investigation, the percent PFTDM in high yielding cultivars such as Jaya and Pusa - 743 was 56.1 and 52.39 respectively, whereas in low yielding cultivar, Pusa-169 the percent PFTDM was only 34.63 (Table I). Thus, it may be inferred that greater the

Table I : Post flowering dry matter production (PFTDM) (gIm2) and percent total dry matter production before and after flowering in different rice cultivars

Cultivars PFIDM %IDMbefore % IDMafter flowering flowering

1990

Rasi 983 42.13 51.21

Pusa 2-21 1141 42.59 51.41

Pusa-144 1029 41.30 58.10

Pusa-143 1232 41.61 52.39

Pusa-169 659 65.31 34.63

Pusa-205 151 60.51 39.49

PFTDM, higher the grain yield (Table IV). At flowering, LAI was generally higher in medium duration cultivars than that in short duration cultivars. A negative relation­ ship between LAI at flowering and grain yield was observed in the present study. Dingkuhn et al. (1991) also observed a negative relationship between LAI at flower­ . ing and grain yield.

High

yielding cultivars like Pusa2­ 21, Pusa 744 and Jaya possessed relatively low LAI i.e. 4.19, 4.91 and 5.83 respectively, while low-yielding cultivars namely Pusa-429 and Pusa-205 possessed rela­ tively higher LAI values of 6.42 and 6.70 respectively (Table 11). Chau and Deshmukh (1989) under Delhi conditions reported that a LAl at flowering of about 4.6 to 6.0 was sufficient to produce grain yield of 6 tons/ha. Hence, it may be concluded that an optimum LAI at flowering under North Indian conditions ought to be in the range of 4.5 to 6.0. On the other hand, leaf area duration during grain filling was positively correlated with grain yield (r

=

0.65*) (Table VI).

Table II : Leaf area index (LAI) at successive growth stages during grain filling

Cultivars Flowering IODAF 20DAF 30DAF

~

1990

Rasi 3.80 4.89 4.10 0.65

PlIsa-2-21 4.19 5.14 2.11 n.20

Pusa-144 4.91 6.31 4.34 1.81

Pusa-143 6.29 6.15 3.11 l.31

Pusa-169 5.38 5.01 1.13 0.09

Pusa-205 6.10 5.03 2.84 0.54

Jaya 5.83 4.81 4.53 1.28

Pusa-429 6.42 5.24 3.15 1.28

CD at 5%P 1.42 NS 0.65 0.28

1991

Rasi 6.15 4.25 4.26 1.08

Pusa-2-21 5.18 6.23 2.43 0.15

Pusa-143 6.13 5.31 1.91 0.12

Pusa-169 6.12 5.55 1.82 O.1l3

Jaya 1.44 6.92 4.13 (J.n

CD at 5% P 0.14 NS 0.85 0.18

Jaya 1340 43.90

Pusa-429 964 54.91

CD at 5% P 319 15.20

1991

Rasi 551 61.69

Pusa-2-21 651 60.63

Pusa-143 519 61.41

Pusa-169 622 61.11

Jaya 640 68.15

CD at5%P NS 5.32

56.10 NS = Non significant 45.03 DAF=Days after flowering

12.62

The canopy photosynthesis (Pn x LAI) at flowering 38.31

was higher in high yielding cultivars namely Jaya, Pusa 39.31

38.59 2-21, Pusa-743 than in low yielding cultivars namely, 32.22 Pusa-169 (Table III). Canopy photosynthesis at flower­ 32.23 ing was better in Jaya than Pusa-169 and also better in NS Pusa 2-21 than Rasi. Low canopy photosynthesis in Pusa­

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217 PRODUCTiVITY IN RICE

Table III : Leaf photosynthetic rate (pn) (mg CO2, dm-2 canopy photosynthesis, dry matter production undhigh

br1) stomatal conouctance (CS) (cm, sec -1) and canopy yield, on the other hand, high Pil cultivars had low LAI

photosynthesis (gm-2 br1) (Kharit:l991) resulting in low canopy photosynthesis.

Cultivars

Rasi Pusa-2-21

Pn Cs

(flowering)

24.62 1.31 32.80 1.73

Canopy photosyn thesis (flowering) 16.62 18.95 Pn

(15 OAF)

14Al

16.56

Cs

0.80 1.86

Grain yield was positively correlated with sink size (r

=

0.66*) (Table VII). Large sink size (Table IV) in high yielding cultivars Jaya and Pusa-743 was due to high number ofgrains/m2 , heavier panicle weight, more spike-lets on primary (SpPB) ~ranches, high number ofprimary

Pusa-743 27.73 1.30 17.00 15.36 1.63 branches (PB) and high ratio of SpPB : SpSB (spikelets

Pusa-169 22.30 Jaya 23A6

CD at 5% P 5.26 1.28 1.36 NS 13.64 19A5 3.71 13.56 14.17 OAI 0.56 0.84 0.32

on secondary branches) (Table V), percent HDG/panicle was positively correlated with SpPB, SpPB : SpSB, postflowering TDM and grain yield (r =0.86**). HDGI

NS

=

Non significant

m! was highly correlated with grain yield (r = 0.92**)

• OAF

=

Days after flowering

(Table VII).

Table IV : Grain yield, its components and sink size in different rice cultivars

;;, Cultivars Grain Yield (tlha) Panicle No.lm2 Grain No.1 panicle Grain No./m2

(x I Ol)

Total spikeletsl m2 (xIOl)

1990

% ster ility 1000 grain

wt. (g)

HI (%) Sink size (glm2) Tiller No. per panicle i" Rasi Pusa-2-21 Pusa-744 Pusa-743 Pusa-169 Pusa-205 Jaya Pusa-429 CD at 5%

5.89 7AO 7.10 6.52 5.92 6.33 6.93 5.98 0.23 458 404 479 304 408 346 375 342 87 74.0 88.5 75.0 79.0 60.0 79.0 86.0 76.0 NS 33.89 35.75 35.92 24.01 24A8 27.37 32.25 25.99 1.75 40.39 37.81 40.57 30.85 33.70 31.55 35.19 29.12 2.85 5AO 15A2 11.39 22.16 27.33 13.39 8.37 10.76 NS 19.12 19.54 21.79 27.59 23.15 21.15 24A3 20.68 NS 50 53 52 46 48 46 45 47 5.7 1099 1292 1245 1398 1060 1176 1613 855 NS 9.16 0.08 9.58 6.08 8.16 6.91 7.50 6.83 {lA5

1991

Rasi Pusa-2-21 Pusa-743 Pusa-169 Jaya 5.31 5.27 5.12 4.97 5.62 393 352 278 367 296 62.5 80.5 56.0 72.0 83.0 24.56 28.33 25.56 26A2 24.56 25.84 31.22 28.00 27.67 27.56 5.6 9.3 13.4 38.1 10.6 20.75 19.73 28.11 24.01 24.39 44 57 48 49 46 967 1070 1195 1237 1290 15.72 14.08 11.12 (4.68 11.84.

CDat5% P NS 32 7.8 NS 4.12 7.8 1.41 1.7 83.5 2.59

NS

=

Non significant

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218 N.M. CHAU AND S.c. BHARGAVA

Table V : Morphological characteristics of panicle of different rice culti vars

Cultivars PB SB PB: SB SpPB SpSB SpPB:

(No) (No) (No) (No) SpSB

Rasi 11.3 27.0 0.42 67.3 77.3 0.87 Pusa-2-21 11.3 36.6 0.30 63.3 124.6 0.50 Pusa-744 8.7 23.3 0.37 42.3 69.3 0.61 Pusa-743 12.0 34.0 0.35 65.3 81.0 0.80 Pusa-169 11.0 30.0 0.37 62.0 92.0 0.67 Pusa-205 9.6 26.3 0.36 52.7 83.7 0.62 Jaya 15.3 32.3 0.47 90.0 116.3 0.77 Pusa-429 13.3 25.3 0.52 88.7 78.0 1.63 CD at 5% P 1.62 7.49 0.08 14.81 85.74 O.l

P.B.

=

Primary branch S.B.

=

Secondary branch

SpPB

=

Spikelet on primary branch SpSB

=

Spikelet on secondary branch

Table VI : Correlation coefficient (r) between grain yield and other characters

Characters grain yield

1.000-graill weight 0.06 Spikelets/panicle 0.38 Post-flowering IDM 0.63** Percent sterility -0.015 Spikelets/m2 0.40* Panicle weight 0.38 Grains/m2 0.63** Panicles/m2 0.16 Harvest index 0.52**

Sink size 0.66**

LA! at flowering -0.21 IDM at flowering -0.41* lMD at final harvest 0.24

LAD 0.65**

Grain filling duration 0.26 Grain filling rate 0.06

*

=

Significant at 1% **

=

Significant at 5%

important role. Among sink size components, high num­ ber of SpPB and high number of PB are desirable charac­ ters as most HDG are located on primary branches. In brief following morphological and phYSiological charac­ ters need to be' marked while screening available gennplasm for utilization in breeding programme:

Increased post-flowering TDM (50% of total

Table VII : correlation coefficient between rate of tilling and panicle characters with different parameters

Characters Rate of SpPB SpSB SpPB filling SpSB

Percent Hoo 0.66** 0.72** 0.22 0.57**

HOO/tn2 0.61** 0.68** 0.32 0.45*

PFIDM 0.61** 0.43** 0.44* 0.06 Spikelets on P.B. 0.93** 1.00 0.37 0.71 ** Spikelets on S.B. 0.52** 0.71 ** 1.00 0.41 SpPB: SpSB 0.58** 0.54** 0.36 1.00 Total spikelets

per panicle 0.32 0.14 0.33 -0.13 1,000 grain

weight 0.20 0.13 0.08 0.04 Rate filling 1.00 0.93** 0.43** 0.58** Percent sterility -0.22 -0.27 0.06 -0.31. Harvest index -0.41 * 0.49* 0.16 -0.53** Sink Size 0.18 0.06 0.52** -0.40* Grain yield 0.06 0.93** 0.53** 0.58** * = Significant at 1 %

**

=

Significant at 5%

TDM at final harvest)

LAI in the range of 4.5 to 6

Increased canopy photosynthesis during gr.Lin filling

Increased sink size reflected by higher number of SpPB and PB (15-17)

Increased ratio ofPB : SB, higher percentage of HDG/panicle, increased panicle weight (4.3 -4.6 glpanicle) and bolder grains (24-27 gllOOO grain)

REFERENCES

Cbau, N.M. and Deshmukh, P.S. (1989). Net assimilation rate during grain filling and grain yield in relation to nitrogen application. New Botanist. 16: 261-266.

Chau, N.M. (1992). Physiological basis of high yielding rice with special reference to grain filling. Ph. D. thesis, Indian Agricul­

tural Research Institute, New Delhi.

Dingkuhn. M.; Sehnier H.F.; De Datta S.K .. Dorffing K. and Javellana C. (1991). Relationship between ripening-phase productivity and crop duration, canopy photosynthesis and senescence in transplanted and direct-seeded lowland rice.

Field. Crops Res, 26: 327-345.

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219 PRODUCTIVITY IN RICE

IRRI, (1989) Physiological aspects for increasing production. In

Progress in Irrigated Rice Research, IRRI, Los Banos, Phillippines, pp 362-363.

Murty, KS. (1985). Physiological Studies on rice. In Rice Research in India. lCAR, New Delhi. pp 154-202.

Murty, KS. Dey, S.K and Jachuck, P.I., (1992). Physiological traits of certain restorers in hybrid rice breeding, IRRN, 17 (I), 7.

Nishiyama, I. (1989). High yielding ~ultivars in Japan. In Progress in Irrigated Rice Research, IRRI. Los Banos, Phillippines, p. 75.

Park, S.H. and Cho, S.Y. (1989). High yielding rice cultivars in South Korea, In Progress in Irrigated Rice Research, IRRI. Los Banos, Phillippines. P. 75.

Tuan, D. 1. (1989). High-yielding rice varieties in Vietnam. In

Progress in Irrigated Rice Research, IRRI, Los Ballos, Phillippines, n. 77.

Vellkateswarlu, B., Vergara, B.S., Paras, F.T. and Visperas, RM.

( I 986). Enhancing grain yield potentials ill rice by increasing the number of high density grains. Phillippines. J. Crop Sci.

11 (3): 145-152;

Venkateswarlu, B. and Vergara, B.S. (1989). Improving the yidding ability of rice. In Progress ill Irrigated Rice Research, IRRJ,

Los Banos, Phillippilles. P. 74

Figure

Table II : Leaf area index (LAI) at successive growth stages during grain filling

Table II :

Leaf area index (LAI) at successive growth stages during grain filling p.2
Table I : Post flowering dry matter production (PFTDM) (gIm2) and percent total dry matter production before and after flowering in different rice cultivars

Table I :

Post flowering dry matter production (PFTDM) (gIm2) and percent total dry matter production before and after flowering in different rice cultivars p.2
Table III : Leaf photosynthetic rate (pn) (mg CO2, dm-2 br1stomatal conouctance (CS) (cm, sec and canopy

Table III :

Leaf photosynthetic rate (pn) (mg CO2, dm-2 br1stomatal conouctance (CS) (cm, sec and canopy p.3
Table VI : Correlation coefficient (r) between grain yield and other characters

Table VI :

Correlation coefficient (r) between grain yield and other characters p.4

References