Department of Vegetable Crops, University of California, 95616, Davis, CA, USA.
Planta. 1983 Dec;159(6):487-96. doi: 10.1007/BF00409137.
The plastochron model was used to evaluate the differences in the growth response of two Lycopersicon spp. grown under two temperature regimes (25/18 and 12/5°C). Two altitudinal accessions of L. hirsutum Homb. et Bnpl., from low and high altitude, a breeding line of L. esculentum (L.) Mill. and the hybrid between the latter and the high-altitude L. hirsutum were studied. The plastochron (P) values were estimated directly according to the formula of R.O. Erickson and F. Michelini (1957, Am. J. Bot. 44, 297-305), and indirectly through a linear model estimating the exponential rates of leaf elongation (r) and the ln of the plastochron ratios (q). The P values were obtained as P=q/r, and with one exception values obtained with both methods were comparable. Low temperature significantly decreased r in all genotypes, but the extent of this reduction depended on the genotype. The hybrid exhibited the least reduction, followed by the high-elevation L. hirsutum, L. esculentum and the lowelevation L. hirsutum. While the q values of the L. hirsutum accessions were significantly reduced by low temperature, those of L. esculentum and the hybrid were not. With the exception of the low-altitude L. hirsutum, low temperature significantly increased P, however the extent of the increase was significantly greater in L. esculentum. Analysis of temperature dependent changes of r, q and P indicate that L. esculentum extended its P by approximately the same factor its r was reduced. On the other hand, the L. hirsutum accessions increased P to a lesser extent, therefore having the ability to produce, comparatively, more leaves at lower temperatures than the cultivated tomato. The linear model of the plastochron is proposed as a tool for comparative studies of environmental growth responses of different genotypes. Plant size was reduced by low temperature. Considering plant size attained at high temperature as 100%, at low temperature sizes were reduced to 73% for the hybrid, 61% for the high-altitude L. hirsutum, 39% for L. esculentum and 30% for the low-altitude L. hirsutum. The low-temperature regime delayed flowering by two, three and nine plastochrons in the hybrid, the high-altitude L. hirsutum and L. esculentum, respectively, while the low-altitude L. hirsutum did not flower for the duration of the experiment. When artificially pollinated, L. esculentum yielded parthenocarpic fruits, while the high-altitude L. hirsutum and the hybrid produced fruits with viable seeds.
该 plastochron 模型被用来评估在两个温度条件下生长的两种 Lycopersicon spp 的生长反应差异（25/18 和 12/5°C）。对来自低海拔和高海拔的两个 Lycopersicon hirsutum Homb. et Bnpl. 的种系，一个 Lycopersicon esculentum (L.) Mill. 的选育系和高海拔 L. hirsutum 与后者的杂种进行了研究。Plastochron (P) 值是根据 R.O. Erickson 和 F. Michelini（1957，Am. J. Bot. 44, 297-305）的公式直接估计的，并且通过估计叶片伸长的指数速率（r）和 ln 的线性模型间接估计的 plastochron 比值（q）。P 值的获得方法是 P=q/r，除了一个例外，两种方法获得的值都是可以比较的。低温显著降低了所有基因型的 r，但这种降低的程度取决于基因型。杂种的降低幅度最小，其次是高海拔的 L. hirsutum，L. esculentum 和低海拔的 L. hirsutum。虽然低温显著降低了 L. hirsutum 种系的 q 值，但 L. esculentum 和杂种的 q 值并没有降低。除了低海拔的 L. hirsutum 之外，低温显著增加了 P，但 L. esculentum 的增加幅度要大得多。对 r、q 和 P 的温度依赖性变化的分析表明，L. esculentum 通过其 r 减少的大致相同的因子延长了 P。另一方面，L. hirsutum 种系增加 P 的幅度较小，因此在较低温度下能够产生相对较多的叶片。提出了 plastochron 的线性模型作为比较不同基因型环境生长反应的工具。低温降低了植物的大小。将高温下达到的植物大小设定为 100%，则低温下杂种的大小降低到 73%，高海拔 L. hirsutum 降低到 61%，L. esculentum 降低到 39%，低海拔 L. hirsutum 降低到 30%。低温处理使杂种、高海拔 L. hirsutum 和 L. esculentum的开花分别延迟了两个、三个和九个 plastochrons，而低海拔 L. hirsutum 在整个实验过程中没有开花。当人工授粉时，L. esculentum 产生了单性结实果实，而高海拔 L. hirsutum 和杂种产生了有活力种子的果实。
