Indian J. PI.llt Physiol•• Vol. XXVIII No.2 pp. 1S7-163 (June 1985)
EFFECT OF DIFFERENT DATES OF SOWING ON PANICLE INITIATION AND FLOWERING IN SORGHUM·
K. PANDU SASTRYl and K. KRISHNA MURTHY'
Department of Agronomy, CoUege of Agriculture, University of Agricultural Sciences, Hebbal, Bangalore-560 024
SUMMARY
Four genotypes of Sorghum (2077-B Early, 2077-B, C8-3S41 and
CS-3S41) were sown throughout the year (January. 1978 through December, 1979) on red sandy loam soils of Bangalore, under irrigated condition to study the flowering behaviour. During the reproductive phase i.e., from panicJe initiation (PI) to flowering. different stages in panicle development were observed and named as branch initiation phase. spikelet differentiation phase and inflorescence elongation phase. Days taken to 50 percent flowering decreased with the advancement in sowing date from January to August and then increased with further delay. Changes in days to flowering were found mainly due to panicle initiation and also to some extend due to panicle development. Correlation studies
revealed a negative relationship of ~phasic development with minimum
temperature and positive relationship of phasic development with sunshine hours per day.
INTRODUCTION
Little is known of panicle inititation and panicle development in sorghum apart from some basic studies made by Lee et al. (1974). This paper describes an ex.periment conducted at Agronomy Department, University of Agricultural Sciences, Bangalore to study the effect of date of sowing on panicle initiation and development.
MATERIALS AND METHODS
Experiment was conducted in field of Main Research Station of the University of Agricultural Sciences, Hebbal, Bangalore during January, 1978
*A part of Ph.D. dissertation by senior author.
Present Addresses: I. Scientist, Central Institute of Medicinal and Aromatic Plants, Regional Centre, Kodaikanal-624 103
] 58 K. PANDU SASTRY AND K. KRfSHNAMURTHY
through December, 1979 under irrigated condition. The experimental site was a red sandy loam soil of moderate fertility (Nitrogen-421 kg/ha; PllOS -31 kg/ha; K20 -276 kg/ha). Four genotypes viz., 2077-B, 2077-B Early (2077-BE), CS
3541, CS-3541 Late (CS-3541 L) were shown montbly (first week of every month, January to December) in a split plot design with three replications. The main plots were sowing dates and subplots were genotypes. The gross and net plot sizes were2.4X3.Omand1.8x2.7m, respectively. The spacing was 30x15cm.and the dose of fertilizer was 120N, 75 PZ0 5 and 25 K20, kg/ha. Half the dose of
nitrogen, full of P205 and K20, were applied at the time of sowing and the rest of nitrogen was applied thirty days after sowing. There was no major incidence of pests and diseases.
Sampling techniques : A composite sample of five plants was collected for each genotype once in every three days starting from 20 days after sowing. The collected plants were dissected and the growing tips were transferred to sampling tubes containing Carnoy's B fixative for instant killing and fixing. The samples were observed under dissection microscope (stereozoom, x to)
and the stage of development was identified as followed by Lee et al., 1974.
RESULTS
Days to panicle initiation (PI) : In all sowings, 2077·B was found to be late in attaining PI stage followed by C3-3541L and 2077-BE (Fig. I). On an average for two years, days to PI decreased with advancement in sowing dates from January to September in 2077-BE and CS-3541, from January to
August in 2077-B and from January to July in CS-3541L.
Branch Initiation Phase (BIP) : The Branch initiation phase (PI to onset of spikelet initiation) i Dcreased from January to April sowings in 2077-Band CS-3541, and from January to May sowings in 2077-BE and 3541L. In case of 2077-BE, this phase remained constant in June to December sowing (except July and December). In CS-3541, it decreased in May to July sowings, and in CS-3541L this phase increased from June to December sowings (except September). Through the variation was high this phase did not follow any particular trend (Fig. 1).
PANICLE INITIATION IN SORGHUM 159
PeriOd from initiotion to stigma initiation
2
26
14
22 20
18
20
15
Period b~tween poniclt and ,pikelet initiation (81P)
45~
40
JS
lC
25
~--~~~~~~~-~~~~-1>'-~W~~~~r-I~~
J
~~~~~~$~~~rsowtNG fJi"lNihS
Fig. 1. Phasic development of panicle from initiation to flowering in tbe genotypes of sorghum as influenced
by drift in sowing dates duriag 1978 and 1919
(pooled data)
1-2077 BE ( - ) 2-2077 B ( x - x ) 3-CS 3541 (e-e) 4-CS 3541 L ( 0 - 0 )
Duration of the period between panicle iBitiatioD (PI) and Stigma initation iD spike lets (STI)
160 1(. PANDU SASTRY AND 1(. KRISHNA MURTHY
Days to 50% Dowering: In all sowings, 2077-B took significatly more number of days to 50% flowering, followed by CS-3541L, CS-3541 and 2077-BE. The number of days taken to 50% flowering decreased progressively from January to July sowings in 2077-B and 2077-BE and from January to August sowings in CS-3541 and CS-3541L. It increased in leters sowings {Fig.
O.
DISCUSSION
Flowering bebaviour doe to 'fariation in sowing date
The number of days taken to 50% flowering decreased by eleven days with advancement in sowing from January to August. The differential flowering was mainly due to differences in panicle initiation since days to PI decreased by seven days in January to September. Similarly, in sorghums decrease in days to PI with advancement in sowings has been reported by Kassam ane Andrews. (1975) and delayed PI in summer months by Millineton et al. (1977).
Thus the differences· in PI seems to be more important in determining the days to fiowering, since in Sorghum once the panicle is initiated the time for anthesis is fixed (Qumby and Karper, 1947). Days to PI is negatively correlated with minimum temperature and positively related with bright sunshine hours per day (Table I). Days to panicle initiation increased with decrease in minimum temperature and increase in sunshine hours per day and vice versae in all sowings. These findings are in accordance with those of Miller et al. (1968) and Caddel and Weibel (1971).
Though, there is a difference of eleven days in fiowering between August and January sowings, the differences in PI accounts for only six days. Thus there is about five days unexplained difference in flowering. This might be due to differences in panicle development and elongation.
The total period of panicle development (from PI to STI) was more by two days in January (24. 2 days) compared to August (22.2 days). This difference of two days was due to spikelet differentiation phase but not due to branch initiation phase. There was a difference of three days in the period between stigma initiation and flowering (elongation period), which was 18.2 days in January and 15.2 days in August sowings. Hence, six days difference in PI, two days difference ill panicle development and three days difference in elongation accounted for eleven days difference in flowering between January and August.
Similarly~ delayed flowering by about ten days in December was also due to
Table I : Co-efficient values of correlation between phasic development periods and meteriological parameters Parental lines Character 51. lO77-BE 2077-B CS-354I CS-3541 Pooled No. Early Late 1. Number of days taken to PI VII. Maximum temperature Vs. Minimum temperature Vs. Sunshine hours/day 2. Days to stigma initiation spikelets VII. Maximum temperature Va. Minimum temperature Va. Sunshine hours/day 0.120 -0.360
0.640** 0.027 -0.582* 0.739**
0.91
-.(),467* 0.699**
0.939·
-0.531-*
0.806"
-0.105 -0295 o.s68
0.121
-0.485 0.646*
0.028
-0.455· 0.656*
0.735- -0'485* 0.729** 0.092 -0.299* 0.642** 0.511* -0.446* 0.713*
"G > z .... (") I:'" til
...
Z...
~ .... ~...
~
3.
Duration
between
stiama
initiation
...
Zand
flowering Vs.
Maximum temperature Vs. Minimum temperature VI. Sunshine hours/day
-0.294 -0.127 -0.129 -0.468* -0.508** -0.164 -0.456 -0.460· -0.162 -0.459* -0.382· -0.275 -0.275* -0.486- 0.201
~
Qc=
=
Ie4. Number of days taken to 50% ftowering. Vs. Maximum temperature Vs. Minimum temperature Vs. Sunshine bours/day
-0.020 -0.538-· -0.619" -0.053 -0,028
3.667
-0.053 -0.449 0.584·* -0.087 -0.629-· 0.605-· -0569·· -0.569 0.617
*Significant ··Significaut at at P-O.OS P-o.o1
-01
162 K. PANDU SASTRY AND K. KRJSHNAMURTHY
The slow panicle development and inflorescence elongation in January and October to December sowings might be due to lower minimum temperature and more sunshine hours per day (Fig 2). The correlation studies also substantiated this idea. (Table I). The total period of panicle development was significantly and negatively correlated with minimum temperature, while it had a significant positive relationship with bright sunshine hours per day. Elongation period was significntly and negatively correlated with minimum temperature only, Similarly, delay in panicle initiation, deveplopment and elongation are associated with cold temperatures in rice (Satake et al., 1969; Vergara et al., 1970; Carnahan et al., 1972),
,,3
15
-
...
«»..
::J
-
d0
... 25
"
0. ::r
E
0"
C-
..
...
~
Z
30
25
• I I I I ,
J
FMAMJ JASOND
Fig. 2. Mean monthly maximum temperature ( 0 - - 0), minimum
temperature (e--e) and sun shine ( x - - x ) hours per
PANICLE INITIATION IN SORGHUM 163
REFERENCES
Caddel, J.L. and Weibel. D.E. (1971). Effect of photoperiod and temperature on development
of sorghum. Crop Sci., 63 : 799·803.
Caranahan, H.L., Erickson, 1.R. and Masterbrock, J.l. (1972). Tolerance of rice to cool
temperatures-U.S.A. In "rice Breeding". Int. Rice Res. Inst., Manila, Phillipines. p.535-540.
Griffiths, D.J. (1961). The influence of day length on ear emergence and setting in oats. J. agric. Sci., (camb)., 57 : 279.288.
Kassam,.A.H. and Andrews, D.l. (1975). Effect of sowing date on growth development. and
yield of photosensitive sorghum at Samaru, North Nigeria Exp/. Agric., 11 : 227-240.
Lee, Kit-Wah Lomm:tSon, R.C. and Bastin, 1.0. (1974). Developmental studies on the·
panicle initiation in sorghum. Crop Sci.• 14 : 80-84.
Miller, F.R., lames, O.K. and Cruzado, H.l. (1968). Effect of tropical photoperiods on the
growth of sorghum when grown in 12 monthly plantings. Agnon J., 60 : 499·502.
Millington, A.I., Whitting, MI.K., WiHiams, W.T. and Boundy, C.A.P. (1977). The effect
of sowing date on the growth and yield of three sorghum cultivars in the Ord. River Valley. I. Agronomic aspects. Aust. J. agrie. Sci., 28 : 369·379.
Quinby, I.R. and Karper, R.E. (19n). The effect of short photoperiod on sorghum varieties
and first generation hybrids. J. Agrie. Res., 7S : 295.
Satake, T. Nishimura, I. Ito, V. and Hayase, H. (1969). Male sterili ty caused by cooling treatment at the meiotic stage in rice plants. 1. Methods of growing rice plants and inducing sterility in the phytotron. Proce. Crop Sci. Jpn., 38 : 603·609.
Vergara, B.S. Chu, T.M. and Visperas, R.M. (1970). Effect of temperature on the anthesis
