- 學位論文
有機態氮肥對水稻光合作用、產量與產量構成成分的影響
Effect of Organic Nitrogen on Leaf Photosynthesis, Yield and Yield Components of Rice (Oryza sativa L.)
摘要
氮素可促進光合作用生產較多的乾物質，也是水稻產量最重要且需求量較大的礦物營養之ㄧ。本論文研究的目的在探討施用有機態氮肥對水稻光合作用、產量與產量構成成分的影響。提供給農民瞭解施用有機態氮肥可以提高光合作用效率以改善水稻產量的能。在塑膠溫室的試驗採用完全逢機設計，在田間的試驗採用逢機完全區集設計，四種有機質肥料(O1: 家畜糞堆肥; O2: 家禽糞堆肥; O3: 蔗渣堆肥; O4: 牛糞堆肥)，組合四個氮素等級(0, 50, 100, and 150 kg N per hectare)。 由小盆栽試驗結果顯示，光合作用氧氣釋放速率隨著施氮量增加達到對照處理的51％，O1堆肥處理有更高的光合作用氧氣釋放速率。於57 DAT時盆栽土壤氮素被水稻吸收最多的是O1堆肥處理，其次是O2 > O3 > O4。在大盆栽試驗結果顯示，於幼穗形成始期光合作用氧氣釋放速率較高，之後的抽穗期、糊熟期光合作用氧氣釋放速率降低。糊熟期 的光合作用氧氣釋放速率隨著施氮量增加達到對照處理的27％。施用有機態氮肥的植株於糊熟期可維持較高的葉片氮素含量與光合作用速率，比化學肥料處理者分別高出12 與10%，以致生產較多的乾物質。葉片氮素含量與光合作用速率有顯著的線性關係，於抽穗期與糊熟期分別為R2 = 0.79 與R2 = 0.76。由這些結果得知，適當地施用有機質肥料可增加礦物營養的有效性，進而提高水稻光合作用速率。 小盆栽試驗的株高、分蘗數、葉綠素與生物質量顯著受到由於增施氮肥導致增加Rubisco與光合作用的影響，水稻農藝性狀充分反映不同有機質肥料的礦物營養含量與有效性。田間的試驗結果顯示，增施氮肥至100 kg N ha-1 可藉由增加穗數與積儲而穫得高的產量，增施氮肥可增加分蘗數而穫得高的乾物質量，但減少光合產物的分配效率，收穫指數隨著氮肥增施而減少；對照處理(0.49) > 低量(0.46) = 中量 (0.46) > 高量 (0.44)。隨著生長時期葉綠素含量對於氮肥施用量更為敏感。穀粒產量與穗數、穗重有極顯著相關，分別為r = 0.70 與0.99。大盆栽試驗結果顯示，於移植後112天，增施氮肥的處理可增加葉綠素含量與株高分別達15與14%。於糊熟期葉片氮素含量與光合作用速率、葉綠素含量、穀粒重有顯著的正相關分別為r = 0.87、0.95與0.97。即使每株的穗數相當，施用有機態氮肥的產量比化學肥料處理更高出20%。主要是由於有機質肥料於成熟期間仍然可釋放礦物營養持續稻株光合作用活性，提高充實飽滿穀粒的比例而導致高產。因此適當地施用有機態氮肥可以使稻作生產者穫得經濟利潤。
並列摘要
Nitrogen (N) is the most important nutrient and comparatively large amounts are required by rice plants (Oryza sativa L.) to produce more dry matter through photosynthesis process. Photosynthesis is the primary source of dry matter production for total biomass and grain yield of rice plants. This has motivated for physiological study of the photosynthesis with special focus on N from organic fertilizers, which has slow and continuous ions releasing property. The objectives of this study were to investigate photosynthesis activity, yield and yield components as affected by different N levels and to increase farmers’ awareness of improving rice yield potential with photosynthesis efficiency. Experiments were conducted in plastic house (small and big pot) with complete randomized design. Another field level with randomized complete block design was conducted in between small and big pot experiment period. Four different types of organic fertilizers (i.e., O1: Cattle pig dropping; O2: Poultry manure-II; O3: Sugarcane bagasse; O4: Cattle manure) were used in combination with one control (without any organic fertilizer or amendment) and three different N levels (50, 100, and 150 kg N per hectare). The result of small pot experiment indicated that photosynthetic oxygen evolution rate of N treated plants was increased by an average of 51% as compared to control. A significantly higher leaf photosynthetic rate was observed in O1 organic fertilizer compared to that of the other treatments. Total N content of pot soil after rice harvested on 57 DAT showed the order of N uptake by rice plant was O1 > O2 > O3 > O4. In the big pot experiment, oxygen evolution rate of all treatments was comparatively higher in panicle initiation stage and decreased through heading to dough stages. Application of N increased photosynthesis by an average of 27% in dough stage compare to control. Plants treated with organic-N maintained higher total leaf N and photosynthetic rate by an average of 12% and 10% respectively when compared with chemical-N at dough stage. A close linear relationship was observed between total leaf nitrogen and photosynthetic rate at heading (R2 = 0.79) and dough stage (R2 = 0.76). These results can be used as guidance of appropriate organic fertilizer application to increase nutrient availability and to get full benefit of photosynthesis. Under small pot experiment, plant height, tiller number, SPAD reading and biomass accumulation were significantly influenced as N supply increased which might be due to increased photosynthesis rate and Rubisco activity. Responses of agronomic characteristics were associated with nutrient concentrations and its availability in different organic fertilizers. Field experiment has shown that there was high grain yield as level of N supply increased up to certain limit (100 kg N ha-1) through enhanced sink size by increasing both panicle number and spikelet number per panicle. The increase in number of tillers per hill with N application resulted in higher dry matter production. Harvesting index (H.I.) was decreased with increasing N application rate in sequential order of C (0.49) > L (0.46) = M (0.46) > H (0.44). SPAD reading became more and more sensitive to nitrogen rates following growth stages. Grain weight was significantly correlated with panicle number (r = 0.70) and panicle weight (r = 0.99). Big pot experimental results showed that N application increased SPAD reading by an average of 15%, and plant height by an average of 14% on 112 DAT when compared to control treatment. Similarly, Number of tillers produced was significantly different in order of C < L < Cf < M < H. Positive correlations were found between total leaf N content with photosynthetic oxygen evolution rate (r = 0.87), chlorophyll content (r = 0.95) and grain weight (r = 0.97) at dough stage. Plant under organic-N application produced 20% more yield than that of chemical-N, even though the panicle number per hill was similar. The high percentage of filled grain was the reason associated with higher grain yield which benefited from the slow release of nutrients and extended photosynthesis activity during ripening. So, careful attention to nitrogen fertilization could be necessary for rice grower to obtain economic profit from optimum organic-N application.