Modeling the Potential Geographic Distribution of Black Pepper(Piper nigrum)in Asia Using GIS Tools

Known as the ＂king of spices＂,black pepper（Piper nigrum）,a perennial crop of the tropics,is economically the most important and the most widely used spice crop in the world.To understand its suitable bioclimatic distribution,maximum entropy based on ecological niche modeling was used to model the bioclimatic niches of the species in its Asian range.Based on known occurrences,bioclimatic areas with higher probabilities are mainly located in the eastern and western coasts of the Indian Peninsula,the east of Sumatra Island,some areas in the Malay Archipelago,and the southeast coastal areas of China.Some undocumented places were also predicted as suitable areas.According to the jackknife procedure,the minimum temperature of the coldest month,the mean monthly temperature range,and the precipitation of the wettest month were identified as highly effective factors in the distribution of black pepper and could possibly account for the crop＇s distribution pattern.Such climatic requirements inhibited this species from dispersing and gaining a larger geographical range.

断根胁迫下调控胡椒根系生长促进植株修复的生理机理

【目的】探明胡椒在不同程度断根处理和修复时间下根系自修复过程的生理机理,为胡椒及同类作物筛选适宜的机械耕作方法提供理论依据。【方法】以热引1号胡椒幼苗为研究对象,设不断根(对照,CK)、轻度断根、中度断根和重度断根4个处理,分别在断根后15、30和60 d测定分析幼苗根系内源激素含量、抗氧化酶活性、形态和活力指标、叶片光合速率和植株生长量,并对各指标间的关系进行结构方程模型分析。【结果】与CK相比,断根后30和60 d时,轻度断根和中度断根的植株鲜重增长量显著增加(P<0.05,下同),且断根后60 d的叶片光合速率显著提高,轻度断根60 d的株高增长量显著增加。断根促进根系形态指标生长量显著增加,其中,中度断根30 d的根系平均直径增长量及60 d的根系总长度增长量、表面积增长量和平均直径增长量均显著高于CK。断根后60 d,轻度断根和中度断根的根系活力显著高于CK,分别较CK升高92.0%和66.6%,相对于重度断根有显著修复优势。断根处理对根系内源激素含量有明显调控作用,断根后15、30和60 d,重度断根均促进赤霉素(GA)含量显著升高,断根后15和30 d重度断根也促进细胞分裂素(CTK)含量显著升高。断根后15 d,中度断根和重度断根的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性均显著高于CK;断根后30和60 d,3个断根处理的POD活性均显著高于CK。结构方程模型分析结果表明,断根通过影响根系内源激素含量、抗氧化酶活性和根系性状间接影响生物量性状,但不同修复时间下的影响指标和路径存在差异。【结论】胡椒断根后的生长修复是生长和生理指标相互作用的结果。前期根系内源激素促进根系生长,或通过正向调控抗氧化酶活性而间接促进根系生长启动修复;后期断根处理和内源激素负向调控抗氧化酶活性,促进根系生长完成修复。轻度断根和中度断根对胡椒生长修复有补偿或超补偿效应,重度断根时效性较低,60 d时才完成修复。