不同铝水平胁迫对橡胶树幼苗若干生理指标的影响

研究不同铝水平胁迫(0、50、100、200、400 mmol/L)对橡胶树幼苗过氧化物酶(POD)、超氧化物歧化酶(SOD)、丙二醛(MDA)、叶绿素含量、叶片相对电导率及幼苗地上部与地下部铝含量变化的影响。结果表明,铝胁迫均使橡胶树幼苗生理指标产生一定的变化。在200 mmol/L和400 mmol/L铝水平下橡胶苗叶片POD活性和SOD活性先上升后下降至胁迫前甚至为0;MDA含量则大量增加,而且越来越高;叶绿素总量、叶绿素a和叶绿素b随胁迫时间的推移呈下降趋势,且铝浓度越大下降趋势越明显;相对电导率随胁迫时间的推移均呈现上升趋势,介于60%~100%之间,超过细胞质膜死亡的阈值;橡胶苗地下部铝含量分别约为地上部铝含量的3倍、2倍、1.3倍。不同铝水平胁迫处理中,随着铝浓度越高、胁迫时间越长对橡胶树幼苗生理指标的影响越大。其中在200 mmol/L铝水平下叶片相对电导率大于50%,达到叶片细胞膜透性阈值,MDA则大量增加,SOD和POD急速上升后下降,叶绿素含量极少。因而认为橡胶树幼苗的最高铝耐受浓度为200 mmol/L,地下部铝含量的耐受量为6.2 mg/g,地上部的耐受量为2.9 mg/g。     

大豆连作对植株营养水平、叶绿素含量、光合速率及其产物影响的研究

研究了大豆连作条件下植株体内营养水平和叶绿素含量、光合速率及其产物的差异。结果表明 ,由于连作造成根际土壤障碍和植株生长发育障碍 ,导致体内硝态N、速效P、速效K含量显著降低 ,使叶片叶绿素含量、光合速率、体内可溶性糖、氨基酸总量极显著下降 ,影响大豆叶片的光合性能和有机物的积累 ,从而导致减产。随着连作年代的延长呈现渐低趋势 ,表现为正茬 >迎茬 >重茬。     

地膜覆盖栽培对春小麦叶片衰老特性的影响

为了揭示春小麦在地膜栽培条件下是否早衰的问题,采用管栽模拟试验的方法,研究了地膜覆盖和露地栽培条件下春小麦叶片的叶绿素、蛋白质、叶片丙二醛(M DA)含量和细胞质膜相对透性的变化。结果表明,采用地膜覆盖栽培方法,在春小麦生长前期能明显提高叶片叶绿素和蛋白质的含量(日均增加量分别比露地春小麦高31.49%和7.94%),但后期又会加速其降解速率;M DA含量和细胞质膜相对透性均表现为覆膜处理高于露地处理(日均增加量分别比露地春小麦高71.96%~11.78%和2.42%~9.57%)。说明覆膜栽培可使春小麦提前进入正常衰老阶段,但由于其增温、保湿等效应,使春小麦生长量增加,穗粒数和穗粒重比露地春小麦提高22.95%和27.68%,表现出良好的增产效应。     

大气CO2浓度升高对茶树光合生理特性的影响

通过对不同大气CO2浓度水平下的茶树观测试验,研究了大气CO2增长对茶树新梢叶片净光合速率、蒸腾气孔导度、水分利用效率、叶绿素含量和营养元素含量等光合生理特性的影响。结果表明,在大气CO2浓度为550、750μmol·mol-1时,比正常大气CO2水平下茶树叶片日平均净光合速率提高17.9%和25.8%,并缓解和消除了光合午休现象;茶树叶片气孔导度降低7.6%和13.0%,蒸腾速度稍有下降,水分利用效率提高21.6%和35.8%;同时使茶树新梢叶绿素a、叶绿素b、叶绿素总量和类胡萝卜素含量分别提高12.8%～18.4%、14.0%～22.0%、13.1%～19.4%和17.2%～20.1%,但叶绿素a与叶绿素b的比值有所降低。大气CO2浓度的升高使新梢营养元素N、K、Ca含量有不同程度降低,而Mg、Fe、Zn、Mn、Cu含量有所增加。     

几种杀虫剂对小麦旗叶光合及叶绿素荧光特性的影响

为给小麦优质高效安全生产中科学使用杀虫剂提供理论和技术依据,以弱筋小麦扬麦13、强筋小麦烟农19为材料,在开花末期分别喷施推荐、3倍、6倍剂量的阿维菌素、毒死蜱、吡虫啉、乐果4种杀虫剂,研究其对小麦旗叶光合及叶绿素荧光特性的影响.结果表明,杀虫剂处理会改变小麦旗叶的SPAD值、光合速率及叶绿素荧光特性,且剂量越高影响越明显;不同类型杀虫剂对小麦光合速率及荧光特性的影响程度不同,影响较大的杀虫剂是吡虫啉和乐果,其次是毒死蜱,最后是阿维菌素;不同小麦品种对杀虫剂的耐受性不同,弱筋小麦扬麦13比强筋小麦烟农19的耐受性强.杀虫剂处理主要是通过降低叶片叶绿素含量、光系统Ⅱ的实际光化学效率(ΦPSⅡ)和光化学荧光淬灭系教(qP),引起单叶光合速率下降,最终导致小麦产量降低.     

低温驯化及封冻阶段不同冬小麦品种叶绿素荧光参数的比较

为了解小麦品种的抗寒机制,对抗寒品种东农冬麦1号和对照品种济麦22在低温驯化及封冻阶段植株的叶绿素荧光参数进行测定和分析.结果表明,低温驯化阶段对照品种济麦22新叶的最大荧光产量(Fm)、PSⅡ最大量子产量(Fv/Fm)、实际量子产量(yield)、光化学淬灭(qP)显著高于东农冬麦1号,低温驯化结束后济麦22的这些参数迅速降低,显著低于东农冬麦1号新叶相应的值;调查期内东农冬麦1号新叶的初始荧光(Fo)变化稳定,降幅为26.2%,济麦22新叶Fo的降幅为52.8%;两品种老叶的荧光参数值变化趋势接近一致,低温驯化结束后东农冬麦1号老叶的Fm、qN、qP值显著高于济麦22老叶相应的值.在生产上可以利用叶绿素荧光参数对品种抗寒性进行鉴定,鉴定时期为低温驯化期结束、封冻期开始时,鉴定的部位应为植株新叶.     

浸提法测定玉米叶绿素含量的改进

以玉米叶片为试材,研究了8种不同有机溶剂浸提液提取叶绿素的效率及低温冷冻对叶绿素提取的影响。试验中采用叶绿素仪先预叶片;冷冻—高温快速浸提试验,采用先称取样品,后冷冻方式。结果表明:室温(25℃)下,浸提法要优于研磨法,混合液浸提叶绿素比单独用丙酮或乙醇浸提快,其中丙酮∶乙醇=2∶1的浸提液浸提速度快而稳,是试验中最佳的叶绿素提取方法。最佳浸提时间在浸提16h时。叶片冷冻处理后,快速浸提能够缩短叶绿素浸提时间。由于受光照、高温的影响,测定值普遍较低。     

硅对严重干旱胁迫下黄瓜幼苗叶绿素荧光参数的影响

研究了硅对严重干旱胁迫下黄瓜幼苗叶绿素荧光参数的影响。结果表明:黄瓜幼苗在严重干旱胁迫6 d后,Fo升高,Fm,Fv,Fv/Fm,Fv/Fo及NPQ均下降,施硅使各荧光参数均呈现相反的变化趋势。说明土壤施硅可缓解严重干旱胁迫对黄瓜幼苗光合机构的损伤与破坏,提高抗旱性能。     

Integrated Management of Organic Manures and Chemical Fertilizers for Enhancing Paddy Yield and the Nutrient Content of Rice Cultivars

The integrated nutrient management with organic manure and chemical fertilizers can improve rice (Oryza sativa L.) production, soil health, and fertility. Hence, this study aimed to evaluate the combined effects of organic manures and chemical fertilizers on the yield and nutrient content of wetland rice under field conditions. It was conducted in northern Iran in two consecutive years, 2015 and 2016 as a factorial experiment based on a randomized complete blocks design (RCBD) with three replications. Two local rice cultivars, Tarom Hashemi and Tarom Mahalli, were chosen as the first factor; mineral fertilizers in four levels: 100% recommended nitrogen-phosphorus-potassium (NPK), 75% recommended nitrogen with 100% phosphorus-potassium (PK), 75% recommended phosphorus with 100% nitrogen-potassium (NK), and 75% recommended potassium with 100% nitrogen-phosphorus (NP), were selected based on soil analysis and were arranged as the second factor; and three levels of organic manures, namely zero and eight tons of vermicompost per hectare, and 10 tons of rotted manure per hectare was the third factor. Results revealed that the highest paddy yield occurs with vermicompost and manure consumption for both cultivars. Moreover, the highest paddy yield (3962 kg ha^?1) occurs with 100% recommended NPK and vermicompost consumption. For both cultivars, the most chlorophyll a and chlorophyll ab content was produced with application of 100% recommended NPK. The most grain nitrogen content, grain nitrogen uptake, protein content, and protein yield were observed with 100% recommended NPK applied with 10 tons of rotted manure and eight tons of vermicompost usage per hectare. Therefore, in view of the ever-increasing use of chemical fertilizers and irreversible damage thereby, the additional use of these compounds can benefit the environment and human health. The global attention to sustainable agricultural concepts and organic manure can, in addition to producing reasonable yields, be considered as an appropriate alternative to chemical fertilizers.     

Effects of part and whole straw returning on soil carbon sequestration in C3–C4 rotation cropland

Long‐term no‐tillage management and crop residue amendments to soil were identified as an effective measure to increase soil organic carbon (SOC). The SOC content, SOC stock (SOCs), soil carbon sequestration rate (CSR), and carbon pool management index (CPMI) were measured. A stable isotopic approach was used to evaluate the contributions of wheat and maize residues to SOC at a long‐term experimental site. We hypothesized that under no‐tillage conditions, straw retention quantity would affect soil carbon sequestration differently in surface and deep soil, and the contribution of C3 and C4 crops to soil carbon sequestration would be different. This study involved four maize straw returning treatments, which included no maize straw returning (NT‐0), 0.5 m (from the soil surface) maize straw returning (NT‐0.5), 1 m maize straw returning (NT‐1), and whole maize straw returning (NT‐W). The results showed that in the 0–20 cm soil layer, the SOC content, SOCs, CSR and CPMI of the NT‐W were highest after 14 years of no‐tillage management, and there were obvious differences among the four treatments. However, the SOC, SOCs, and CSR of the NT‐0.5 and NT‐W were the highest and lowest in 20–100 cm, respectively. The value of δ¹³C showed an obviously vertical variability that ranged from –22.01‰ (NT‐1) in the 0–20 cm layer to –18.27‰ (NT‐0.5) in the 60–80 cm layer, with enriched δ¹³C in the 60–80 cm (NT‐0.5 and NT‐1) and 80–100 cm (NT‐0 and NT‐W) layers. The contributions of the wheat and maize‐derived SOC of the NT‐0.5, NT‐1 and NT‐W increased by 11.4, 29.5 and 56.3% and by 10.7, 15.1 and 40.1%, relative to those in the NT‐0 treatment in the 0–20 cm soil layer, respectively. In conclusion, there was no apparent difference in total SOC sequestration between the NT‐0.5, NT‐1, and NT‐W treatments in the 0–100 cm soil layer. The contribution of wheat‐derived SOC was higher than that of maize‐derived SOC.