The Growth and Development of Sarawak Rice Towards Photoperiod

Putri Ainaa Afiqah, Hossen (2023) The Growth and Development of Sarawak Rice Towards Photoperiod. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

A series of controlled environment treatments were conducted on Sarawak traditional rice, notably Bario Sederhana and Biris landraces, aimed to quantify the development and growth performance when sown at five photoperiod regimes (8, 9, 10, 11 and 12 hours). This study revealed that both landraces had a short basic vegetative phase, as crop sensitivity to photoperiod commenced after the appearance of fourth leaf for Bario Sederhana (P<0.001) and third leaf (P<0.001) for Biris. For Bario Sederhana landrace, phyllochron varied with different photoperiod regimes, except for rice plants that were sown at 11 and 12 hours photoperiod. Under these photoperiods, Bario Sederhana took a longer time to produce each successive main stem leaf at 12 hours photoperiod (215 oCd/leaf, 8.5 day/leaf) compared with 11 hours photoperiod (135 oCd/leaf, 5.6 day/leaf). Similar trend was seen in Biris landrace where the landrace sown at 12 hours photoperiod took an extended duration (213 oCd/leaf, 8.4 day/leaf) to produce a new leaf than Biris sown at 11 hours photoperiod (117 oCd/leaf, 4.9 day/leaf). Bario Sederhana produced a maximum number of 9.3 leaves on the mainstem with thermal time requirement between 1513-2903 oCd and 64-122 calendar days to reach flag leaf development. In contrast, Biris failed to produce flag leaf under 8, 10, and 11 hours photoperiod and did not develop further. Nevertheless, Biris took 3667-3831 oCd (152-160 days) to produce a maximum of 7.9 main stem leaves under both 9 and 12 hours photoperiod. The reproductive development towards photoperiod showed a delayed pattern in time to heading, anthesis and maturity for Bario Sederhana under lengthening photoperiod from 10 to 12 hours. For example, under 10 hours photoperiod the crop required 1680 oCd (~71 days) from emergence to heading but took an extended duration of 3147 oCd (~133 days) when it was sown at 12 hours photoperiod. Similarly, Biris took a longer time to heading (P<0.05) at 12 hours photoperiod (4067 oCd, 169 days) compared with 9 hours photoperiod (3800 oCd, 158 days). The prolonged time taken for reproductive development modified by photoperiod resulted in higher yield components. This is because the extended time from heading to maturity means longer duration of grain filling. In both landraces, the longest photoperiod of 12 hours gave the highest percentage of filled spikelets, consequently the heaviest grain weight per panicle (1.4 g for Bario Sederhana, 3.5 g for Biris). Hence, under optimum photoperiod and proper farm management practices, the cultivation of the two Sarawak rice landraces will improve the socio-economics of local farmers.

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