EVALUATION OF THE REACTION OF WATERMELON PARENT AND F 1 PLANTS TO Meloidogyne enterolobii

ABSTRACT: The aim of this study was to evaluate the performance of progenies from Citrullus lanatus var. lanatus (cultivated watermelons) when crossed with progenies from C. lanatus var. citroides (fodder watermelon with a historic of resistance to the nematode Meloidogyne enterolobii). The parents and their F1s were evaluated for resistance to this nematode. In the initial stages of eleven treatments, watermelon seedlings plantlets were transplanted to plastic bags of six kilograms once the first leaves developed. Ten inoculated plants with 5,200 eggs in the soil near the stem of the plant and four non-inoculated ones were used in each treatment, in a complete block design. Sixty-two days after sowing, the following characteristics were evaluated: the length of the aerial part of the plant (LAP, in m), fresh mass of the aerial part (FMAP, in g), root fresh mass (RFM, in g), egg number (EN) and reproduction factor (RF). A comparison between the averages of inoculated and non-inoculated plants was performed using Scott-Knott test at 5% and the diallelic analysis was performed using the GENES program. The morphological characteristics did not allow for the identification of the parent plants or the F1s with respect to nematode resistance, but the variables EN and RF were useful for such identification. The analyses of the general and specific combining abilities indicate highly significant effects with respect to this resistance, showing additive gene effects as well as dominance and epistatic gene effects, allowing for identification of parents and F1s that can be used in watermelon breeding programs to improve resistance to the M. enterolobii.摘要：本研究旨在评估普通西瓜（Citrullus lanatus var. lanatus，栽培西瓜）的后代与饲用西瓜（C. lanatus var. citroides，该品种对於象耳豆根结线虫（Meloidogyne enterolobii）具有抗性历史）的后代杂交后的表现。本研究对亲本及其杂种一代（F₁）进行了该线虫的抗性鉴定。在11组处理的初始阶段，当西瓜幼苗长出第一片真叶时，将其移栽至6kg装的塑料育苗袋中。每组处理采用完全区组设计，设置10株接种组（每株在茎基部土壤中接入5200个线虫卵）与4株未接种对照组。播种后62天，测定以下性状：植株地上部长度（LAP，单位：m）、地上部鲜质量（FMAP，单位：g）、根系鲜质量（RFM，单位：g）、卵粒数（EN）以及繁殖系数（RF）。采用5%显著水平的Scott-Knott检验对接种组与对照组的平均值进行差异显著性分析，并通过GENES软件开展双列杂交分析。形态性状无法用于区分亲本及杂种一代的线虫抗性差异，但卵粒数（EN）与繁殖系数（RF）可有效实现该鉴定。一般配合力与特殊配合力分析结果显示，该抗性性状存在极显著效应，表明存在加性基因效应、显性效应以及上位性效应，据此可筛选出适用于西瓜抗象耳豆根结线虫育种的亲本及杂种一代材料。