본 연구는 수수 × 수단그라스 바이오에탄올 생산을 위한 적정 수확 시기 및 수확 후 재생과정에서 요구되는 적정 질소 시비 수준을 파악하기 위해 수행되었다. 포장 실험은 2017부터 2018년까지 실시했으며, 시험구 배치는 난괴법(RCBD)으로 여름 수확 후 질소 추비 수준을 달리하여(0, 50, 100, 150 kg N/ha; 0N, 50N, 100N, 150N) 처리하였다. 재생과정에서 canopy height은 2017년 여름 수확 후(DAT, day after summer harvest treatment) DAT23에서 DAT48로 경과함에 따라 약 3.0배, 2018년 DAT26에서 DAT48로 경과함에 따라 약 2.9배 신장하였다. 엽록소 함량은 재생과정 초기 질소 무처리구와 질소처리구간 유의한 차이가 나타났으나, DAT48 이후 처리 간 차이는 없었다. 여름 수확은 2017년 파종 후 61일 뒤, 2018년 파종 후 83일 뒤 각각 이루어졌으며 건물수량은 8.6Mg/ha, 11.0Mg/ha로 차이를 보였다. 생육시기별 2차 수확의 건물수량은 2017년의 경우 생육이 진전됨에 따라 꾸준히 증가하였으며, 2018년에는 DAT76까지 증가하였다. 2017년 DAT107에서 무처리구(9.0Mg/ha)에 비해 질소 처리구(12.3Mg/ha)에서 1.4배 높았으며, 무처리의 수량이 낮았던 2018년 DAT113에서는 무처리구(2.3Mg/ha)에 비해 질소 처리구 (5.6Mg/ha)로 2.5배 높았다. 수확물의 바이오에탄올 품질을 나타내는 바이오에탄올 수율(TEP)는 생육 후기 cellulose와 hemicellulose 비율 감소로 일부 줄어들었으나, 전체적인 TEP변화는 생육시기나 추비수준과 관계없이 5% 이내로 큰 차이는 없었다. 총 바이오에탄올 수량(total TEY)은 2017년 DAT107에서 7,944L/ha, 2018년 DAT76에서 7,163L/ha로 추정되었다. 따라서 TEY를 높이려면 수확물의 단위면적당 건물중을 증가시키는 재배방법이 필요하다. 여름 수확 후 충분한 재생을 위해서 필요한 질소 추비 수준은 100kg N/ha 이상이었으며, 2차 수확은 여름 수확 실시 후 2개월 이상 경과 한 이후 실시해야 한다.

To elucidate the physiological responses of rice plants to the essential mineral silicon (Si), we assessed the effects of treatments with Si, nitrogen (NH4NO3; ammonium nitrate), and calcium (CaCl2; calcium chloride), independently or in combination on mineral uptake rates and levels of the hormones abscisic acid (ABA), gibberellin (GA1) and jasmonic acid (JA). We found that nitrogen and calcium uptake was inhibited by Si application. However, solo application of nitrogen or calcium did not affect Si uptake. Compared to the untreated plants, the application of Si, NH4NO3 or CaCl2 increased the endogenous hormone levels in treated plants. In particular, the concentrations of GA1 and JA increased significantly after the application of Si or NH4NO3. The level of GA1 observed after a treatment (solo or combine) with Si, and NH4NO3 was higher than that of the control. By contrast, independent application of CaCl2 or a combined treatment with Si and CaCl2 did not alter GA1 levels. The highest level of GA1 was present in plants given a combination treatment of Si and NH4NO3. This effect was observed at all time points (6 h, 12 h and 24 h). Endogenous JA contents were higher in all treatments than the control. In particular, a combination treatment with Si and NH4NO3 significantly increased the JA levels in plants compared to other treatments at all time points. A small increase in JA levels was observed after 6 h in plants given the CaCl2 treatment. However, JA levels did not differ between plants given a CaCl2 treatment and controls after 12 h or 24 h of exposure. We conclude that treatment with CaCl2 alone does not affect endogenous JA levels in the short term. Endogenous ABA contents did not show any differences among the various treatments.

Agricultural productivity is subjected to enormous environmental constraints, particularly to salinity and drought due to their higher magnitude of adverse impacts and worldwide distribution. Silicon (Si) was found to play a favorable role in salinity and drought stress alleviation of soybean cultivar Daewonkong. All growth attributes insignificantly improved with Si nutrition. The endogenous bioactive GA1 and GA4 content increased with the application of elevated Si level both under normal and stressful condition. JA contents sharply increased with NaCl and PEG application but decreses with Si added to salt and drought stress treatments. SA level increased with NaCl and PEG and was further enhanced with Si in the salt treated plants, but reduced with the combined application of Si and PEG. The endogenous bioactive GA1 and GA4, JA and ABA content of soybean leaves were analyzed through chromatograph/mass spectrometer (GC/MS) in selected ion monitoring (SIM) mode, while SA content was quantified with HPLC.

The adverse effects of salinity and drought on soybean cultivar Hwangkeumkong were also investigated. Endogenous bioactive gibberellins GA1 and GA4, jasmonic acid (JA), abscisic acid (ABA) and salicylic acid (SA) content and pertinent changes in response to basic and double NaCl (70 mM & 140 mM) and PEG (8% & 16%) were examined. We found that plant growth and yield components significantly reduced with the application of NaCl and PEG during pre-flowering and post-flowering growth periods. The endogenous bioactive GA1 and GA4content decreased under elevated salt and drought stress. However, an insignificant increase in GA4level was noted with 8% PEG, applied during post-flowering growth stage. JA levels significantly increased with NaCl and PEG applications, but declined with elevated PEG applied during post-flowering period. SA level drastically reduced with NaCl, while insignificantly reduced with PEG. Endogenous ABA contents of leaves increased with elevated NaCl and PEG application. The endogenous bioactive GA1 and GA4, JA and ABA content of soybean leaves were analyzed through chromatograph/ mass spectrometer (GC/MS) in selected ion monitoring (SIM) mode, while SAcontent was quantified with HPLC.