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栽培西瓜（Citrullus lanatus var. lanatus）后代与饲用西瓜（C. lanatus var. citroides，对南方根结线虫（Meloidogyne enterolobii）具有抗性历史）的后代杂交后的表现。研究对亲本及其子一代（F₁）开展了该线虫的抗性评价。试验共设置11个处理，待西瓜幼苗长出第一片真叶时，将其移栽至6 kg容量的塑料育苗袋中。每个处理包含10株接种组（每株在茎基部土壤中接种5200枚线虫卵）与4株未接种对照组，采用完全区组设计。播种后62天，测定如下性状：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%显著性水平的斯科特-诺特（Scott-Knott）检验对接种组与未接种组的平均值进行比较，同时使用GENES软件开展双列杂交分析。结果显示，形态学性状无法有效区分亲本及子一代的线虫抗性，但卵粒数与繁殖系数可实现该区分。一般配合力与特殊配合力分析表明，该抗性相关效应极显著，证实存在加性基因效应、显性基因效应与上位性基因效应，可筛选出适用于西瓜育种项目的亲本及子一代材料，以提升其对南方根结线虫（M. enterolobii）的抗性。