第一片叶

幼芽萌动的形式，尤其种子结构和第一片叶的形态：胚芽叶萌发时胚芽鞘膨大的形态；

The form of bud germination , especially seed structure and the morphology of the first leaf ;

结果还显示，春梢第一片叶比秋梢第一片叶表达信号强；

Results also showed that the expressional signal of the first fresh leaf in spring is stronger than that in autumn .

子叶：种子植物胚胎的第一片叶，在结构上通常比后来形成的叶简单。

Cotyledon ( seed leaf ) the first leaf of the embryo of seed plants , which is usually simpler in structure than later-formed leaves .

越冬卵孵化盛期为落花后至第一片叶展开之际，这是防治的有利时机。

The main period of egg hatching , which is the favourable opportunity for its control , lasts ho the flower fall-en to the first leaf Spreda out .

局部诱导（第一片真叶）的POD活性第6天达到最大，系统诱导（第二片真叶）的POD活性高峰出现在第10天；

POD activity reached maximum after 6 and 10 days of inoculation in the first and second leaves , respectively .

依据增强UVB辐射、NaCl胁迫及其复合处理不同天数，分别测定各处理小麦幼苗第一片真叶的净光合速率、气孔导度、叶肉细胞间隙二氧化碳浓度、叶绿素含量、黄酮含量和苯丙氨酸裂解酶活性。

During increased UV-B radiation , NaCl strees and their combined treatment , measuring the net photosynthetic rate , stomatal conductance , intercellular CO_2 concentration , PAL activity , the contents of chlorophyll and flavone of first leave of wheat seedlings respectively .

诱抗剂处理第一片真叶后可减轻上部叶片发病，上部叶片呈现较明显的抗病性反应特征。

Treating the first true leaf with oligosaccharide could reduce the disease severity on upper leaves , which showed remarkable resistance .

在播种后（萌前处理）或第一片真叶展开后（萌后处理）立即喷洒化合物。

Compounds were sprayed immediately after seed planting ( preemergence treatment ) or after the expansion of the first true leaf ( postemergence treatment ) .

在5个生长阶段（从第一片真叶到收获）中，共模拟了6种脱叶水平（0%一100%）。

Six simulated defoliation levels ( 0 % - 100 % ) were used over 5 timings of defoliation ( first true leaf to harvest ) .

观察到番茄第一到第三片叶的叶面积很小，以后随着叶位的上升有增加的趋势。

The results showed that the tomato leaf area from the first to the third was quite small , but other leaf area had a rise trend along with the promotion of leaf location .