Modelling the effects of physiological and morphological characters on oil palm growth and productivity
HENSON, Ian EugeneThe model OPRODSIM is a mechanistic simulation model of oil palm growth and yield, the output of which depends crucially on the values assigned to various physiological and morphological characters. In this article, the effects of manipulating these values are explored and related to what is known concerning the magnitude of their natural variation.
The main physiological and morphological variables in crop growth simulation models include leaf photosynthetic characteristics such as the initial light-use (quantum) efficiency (a) and the photosynthetic rate at light saturation (AMAX), the canopy structural features affecting the capture of radiation, summarized in terms of the radiation extinction coefficient (k), the partitioning of assimilates between the various organs, and morphological attributes, which either influence or are the outcome of, underlying physiological processes. In relation to its morphology, the specific leaf area (m2 kg-1 dry weight)of the fronds of oil palm is of interest as this may affect the efficiency of light capture in relation to dry matter allocation. Other aspects of palm growth considered in the model are frond expansion rate, frond production rate (determined as the emergence rate which influences not only the allocation of dry matter to fronds but also the production of inflorescences that are located in the frond axils), the rate of increase in height of the trunk (which has practical implications in terms of ease of harvesting of bunches), the rate of root biomass turnover (possibly a source of wasteful assimilate use) andthe bunch development time (time from anthesis to ripening), which affects standing biomass and maintenance respiration requirements. Assimilate storage and frond turnover are also briefly discussed.
The effects of varying each of these parameters is examined and a sensitivity analysis undertaken where appropriate, to determine the relative importance of each. The results are compared with those of previous studies.
ABSTRAK
Model OPRODSIM ialah satu model simulasi mekanistik tumbesaran dan hasil sawit, di mana outputnya sangat bergantung pada nilai yang diberi kepada pelbagai ciri-ciri fisiologi dan morfologi. Dalam artikel ini, kesan manipulasi nilai ini ditinjau dan dikaitkan dengan apa yang diketahui mengenai kesan perbezaan semula jadi.
Ciri-ciri utama fisiologi dan morfologi dalam simulasi tumbesaran pokok termasuk ciri-ciri daun fotosintesis seperti kecekapan jumlah penggunaan cahaya awal (a) dan kadar ketepuan cahaya fotosintesis (AMAX), sifat struktur kanopi yang mempengaruhi penangkapan sinaran cahaya, diringkaskan dalam bentuk pekali kepupusan sinaran cahaya (k), pembahagian bahan serapan antara pelbagai organ, dan sifat morfologi sama ada mempengaruhi atau sebagai kesan proses fisiologi asas. Berkenaan dengan morfologi, luas daun spesifik (m2 kg-1berat kering) pelepah sawit sangat menarik kerana boleh memberi kesan kepada kecekapan penangkapan cahaya dalam hubungan pembahagian bahan kering. Aspek lain dalam tumbesaran sawit yang diberi pertimbangan dalam model ini ialah kadar pengembangan pelepah, kadar pengeluaran pelepah (ditentukan sebagai kadar pengeluaran di mana bukan sahaja mempengaruhi pembahagian bahan kering kepada pelepah tetapi juga pengeluaran jambak bunga yang terletak di celah pelepah), kadar pertambahan ketinggian batang (di mana akan memberi kesan penuaian tandan), kadar pengeluaran akar (kemungkinan sumber pembaziran kegunaan bahan serapan) dan masa pembentukan tandan (masa dari bunga mengorak sehingga masak), di mana memberi kesan biojisim tegak dan keperluan pernafasan).
Kesan pelbagai parameter ini diteliti dan analisis sensitiviti dijalankan di mana sesuai untuk menentukan kepentingan setiap satu parameter secara relatif. Keputusannya dibandingkan dengan kajian sebelum ini
Tags: OIL PALM-Growth, OIL PALM-Yield, MPOB PUBLICATIONS, OIL PALM-Production
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