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Distribution and Interrelationship of Differentiated, Degenerated and Surviving Spikelets on Panicle Branches in Rice (oryza Sativa)

Tahmid Hossain Ansari
Principal Scientific Officer
Bangladesh Rice Research Institute, Gazipur 1701

Tetsushi Yoshida
Professor
Faculty of Agriculture, Kochi Universiry, Japan.

Yoshinori Yamamoto
Professor
Faculty of Agriculture, Kochi Universiry, Japan.

Akira Miyazaki
Associate Professor
Faculty of Agriculture, Kochi Universiry, Japan.

Abstract/ Executive Summary:

Distribution pattern of differentiated, degenerated and surviving spikelets and interrelationship of spikelets on the basis of their position on rachis branches in a panicle of both japonica and indica cultivars were studied elaborately. Distribution of differentiated spikelets on primary branches (PBs) and secondary branches (SBs) followed I: 1 ratio in the japonica cultivars and 1:2 or more than 2 in the indica ones irrespective of plant type revealed the genetic factor had the more influence on the observed distribution pattern in both japonica and indica cultivars. The percentage of degenerated spike lets to the differentiated ones on PBs was a little higher in the japonica (4.2-83%) than in the indica (0.5-6.6%) cultivars. The degenerated percentage of differentiated spikelets on SBs varied more widely in the indica (11.9-56.2%) than in the japonica (26.1-48.2%) cultivars, although average was almost the same (37.7% in the japonica and 38.9% in the indica cultivars). Correlation coefficients showed that the increase of differentiated spikelets on PBs strongly increase the number of surviving spikelet per panicle or on PBs per panicle in both the cultivar groups. But this was not significantly increase the number of degenerated spikelets on PBs but showed possibility of increase the number of degenerated spikelets on SBs per panicle in both cultivar groups. The number of increasing differentiated spikelets on SBs substantially increased, the numbers of both surviving and degenerated spikelets on SBs per panicle and showed weak negative (in japonica) and positive (in indica) significant correlation with the percentage of degenerated spikelets on SBs. The number of surviving PBs was highly correlated with the surviving spikelets on PBs per panicle. Therefore, above results imply that the increase of differentiated spikelets on PBs of both cultivar groups and on SBs in the japonica group could sustain the survival of spikelets with higher number of differentiated PBs per panicle.

Keywords: Rice cultivar, Degenerated spikelet, Differentiated and Surviving spikelet, Panicle branch

Location: Kochi University, Japan.

Start Date: 00-06-1999

End Date: 00-10-2000

Program Area: Variety and Species

Commodity: Rice

Objectives:

To characterize the distribution pattern of differentiated, degenerated and surviving spikelets with their interrelationship in a panicle among cultivars belonging to different ecospecies.

Methodology:

Two experiments were conducted in the farm of Kochi University, Japan, during June-October in 1999 and 2000. Twenty-two cultivars in 1999 and 13 cultivars in 2000 were used in this study under different cultivar groups or ecospecies of different origins ie japonica and indica (including japonica-indica hybrid) cultivars with different plant types. Among them, intermediate indica (lMI) and semi-dwarf indica (SDI) cultivars in indica were modern high yielding. Presents the cultivars approached in both the experiments. Seedlings were raised following the conventional method of the Faculty F arm except the seeding rate at 100 g per box. Seedlings with 3.5-4th leaf stage were transplanted manually at 30- x 15-cm plant spacing with two seedlings per hill on 5 June 1999 and 2 June 2000 respectively. Cultivars were arranged following randomized complete block (RCB) design with two replications each. Before final puddling, fertilizers for N, P 205 and K₂O were applied at the rate of 100 kg/ha from a slow (controlled) release compound fertilizer (Kumiai-hifuku Nyoso iri-fukugo 14-14-14,140 d-E80). Additional 20 kg N/ha was also applied from ammonium chloride to promote the transplanted seedling establishment. Water management, control of weeds, pests and diseases were followed according to the conventional agronomic practices. At heading, two hills of average number of tillers were selected from the twenty hills counted before sampling. These were collected from every plot in each cultivar for determining the differentiated, degenerated and surviving spikelets. Sampling was done when most of the panicles in a hill headed out and 1/2-3/4^th portion of the panicles exerted from the leaf sheath. Samples were dried in an oven first at 95ºC for 2 hours and subsequently at 65ºC for 48 hours and then preserved in polyethylene bag. All the panicles in each hill were examined under the stereo binocular microscope to count the degenerated and surviving spikelets with recording their position on primary rachis branch (PB) and secondary rachis branch (SB). The sum of the number of surviving and degenerated spikelets was taken as the number of differentiated spikelets. The percentage of degenerated spikelets is the number of degenerated spikelets divided by the number of differentiated spikelets×100. The Percentage of surviving spikelets was calculated as the percentage of differentiated spikelets (100%) minus the percentage of degenerated spikelets. Mean comparison was done following the Duncan’s Multiple Range Test (DMRT).Both year data was used for correlation analysis separately for japonica and indica. The distribution of spikelet components and branches was described based on the experiment conducted in the year 1999 as both year results showed similar trend.

Source of Information: Bangladesh Rice Journal, Vol: 17 (1&2), pp: 43-53, Jan-Dec 2013

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Therefore, the effective way to increase the number of surviving spikelets in indica should be based on the increase of spikelets on PBs having lower degeneration, because the increase of spikelets on SBs resulted in the parallel increase of the degeneration percentage of these spikelets. On the other hand, in the japonica cultivars, a possibility to increase the surviving spikelets depending on the increase of differentiated spikelets on SBs to some extent was suggested due to the negative tendency of the relation between the differentiated spikelets and the degenerated percentage of these spikelets. However, the difference observed in the association between the number of differentiated spikelets on SBs and the degenerated percentage of these spikelets in this study might be related with the different range in the number of spikelets on SBs in the japonica and indica cultivars used in the experiments. So, further study should be carried out to examine the interrelations among the numbers of differentiated, degenerated and surviving spikelets as well as the degenerated percentage of spikelets under the condition of about the same range in number of spikelets per panicle and on SBs in both japonica and indica cultivars.

Knowledge Management: Journal