Developmental variation in ovaries and kernels in a multi-kernelled rice variety- Jugal

The rice fruit or spikelet contains only one kernel. A handful traditional cultivars are available with more than one ovaries/kernels per spikelet. Jugal, a traditional rice cultivar from West Bengal, India possess multiple ovaries before flowering and multiples kernels per spikelet. In this endeavour, the single grained-spikelet varied from 0.00 to 46.26% per panicle. Single pistillated-spikelet was first reported on 8th day before flowering and it was 2.63%. The number of spikelet bearing single ovary/kernel gradually increased till the panicle emergence and then till physiological maturity of grains. Maximum single kernelled-spikelet was recorded on 30th day after panicle emergence (46.26%). The double ovary/kernelled-spikelet per panicle varied from 53.74% to 95.39%. High percentage of double pistillated-spikelet per panicle was recorded before heading and it was more than 90% or very near to 90%. Gradually the double pistillated-spikelet per panicle decreased with the advancement of developmental course of the panicle and continued to decrease till grain maturity. Lowest percentage (53.74%) of double kernelled-spikelet per panicle was observed on 30th day after panicle emergence and it almost remained static till harvest of the crop. Triple pistillated-spikelet was 4.33% per on 10th day before panicle emergence. On 9th day before panicle emergence it was 2.33% and on 8th day before panicle it was 1.00% only and subsequently, no triple pistillated-spikelet was observed till grain maturity. However, randomly one/two triple kernelled-spikelet was also reported. It would be useful if all the spikelets were doubled kernelled. The shape of kernels obtained from doubled kernelled-spikelets were slender, which has high demand among the urban and sub-urban consumers.


Introduction
Rice is known to be the starchy cereal responsible for feeding two-thirds of the world landraces not only maintain genetic diversity but also can exceed many modern varieties in 46 special characters and for cultivation in difficult soils. 47 Apart from the agronomically distinguishable characters which are preferred by the 48 consumers and the farmers, some cultivars exhibit special traits which can be useful for 49 further breeding or cultivation purposes or characterization for its distinctive features. The 50 special traits exhibited are multiple spikelet developed from a single pedicel (e.g.

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Khejurchari), multiple carpels per ovary, multiple stigmas per gynoecium, and multiple 52 kernels (2-3 mostly) per spikelet [1,2]. 53 Rice is usually considered to be a crop yielding single grain, i.e., one spikelet will 54 bear one kernel. However, the traditional variety of rice from West Bengal-the Jugal reveals 55 that the cultivar bears multi-kernelled spikelets and it bears 2-3 kernels per spikelet. Taking   Weight of ovary/kernel 72 Average weight of ovary was studied on alternate days and started from 7 th day before 73 panicle emergence. The same spikelets which were used for study of number of ovaries per 74 spikelet were also used for recording observation on weight of ovary/kernel. As the size of 75 the ovaries in the initial stage was very small, 100-ovaries were used for recording weight 76 and after flowering 50-kernels were used for recording weight.

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Developmental course of ovaries/kernels 85 The single grained-spikelet varied from 0.00 to 46.26% per panicle (Fig 1). It was thought-86 provoking that there was no single pistillated-spikelet per panicle from panicle initiation to 9 th 87 day before panicle emergence. Single pistillated-spikelet was first reported on 8 th day before 88 flowering and it was 2.63% (Fig 2A). The number of spikelet bearing single ovary/kernel 89 gradually increased till the panicle emergence and then till maturity of the grain. Maximum    The double ovary/kernelled-spikelet per panicle varied from 53.74% to 95.39% ( Fig   102   1). High percentage of double pistillated-spikelet per panicle was recorded before emergence 103 or heading and it was more than 90% or very near to 90% (Fig 2B). Gradually the double Triple pistillated-spikelet was observed only during initial stage of panicle formation.

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In this endeavour, 4.33% of total spikelets per panicle was observed on 10 th day before 110 panicle emergence. On 9 th day it was 2.33% and on 8 th day it was 1.00% only and 111 subsequently, no triple pistillated-spikelet was observed till grain maturity (Fig 1). However, 112 randomly one/two triple kernelled-spikelet was reported which was not recorded in the Fig 1. 113

Distribution of multi-kernelled spikelets in panicle 114
The distribution of multi-kernelled spikelets at harvestable maturity was not uniform in the  (Table 2), however the test 7 131 weight at physiological maturity was 33.50 g (Fig 3). The decrease in test weight at 132 harvestable maturity was due to reduction in kernel moisture content at harvestable maturity.  The quantitative and qualitative characters data were presented in Some of the unique characteristics of the cultivar were purple coleoptile colour, dark 157 purple stigma (Fig 5), occasional presence of multiple stigma on single ovary (Fig 5), purple 158 coloured long awn, frequently presence of multiple ovaries ( Fig 2&4) and multiple kernels 159 per spikelet (Fig 2&4), red aleurone layer. The cultivar was highly photoperiod sensitive, it 160 can be grown only during Kharif season.

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The grain characters were presented in Table 2. Straw coloured lemma and palea.

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In case of three kernelled spikelets, always one kernel was much smaller than other two (Fig   224   6i). Middle kernel was flat at both sides, other two kernels were flat on the inner sides. degeneration of ovary has been reported (Fig 6a-h). The exact cause of degeneration of the 249 ovary was not studied. created scarcity of space in the spikelet as the space inside a spikelet is limited (Fig 6h)  Weight of 1000 fully developed grains (g) High (30 g) 47.
Decorticated grain aroma Absent