Blossom-end Rot (BER) and Cracking in Watermelon Citrullus Lanatus (Thunb.) Matsum & Nakai)

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Cucurbit Genetics Cooperative Report 15:69-70 (article 26) 1992

Mohamed M.D., El Mekki and Ali E. El Jack
Regional Ministry of Agric. Wad Medani, Sudan, Dept. of Hort., University of Gezira, Wad Medani, Sudan

Introduction

Watermelon requires light soils for successful production. In heavy clays it faces many problems such as small size, fruit cracking and blossom-end rot (BER). To exploit the possibility for its production in the vast clays of central Sudan, varieties that are resistant to BER and cracking are required.

Materials and Methods

A variety trial was conducted at the University of Gezira, Wad Medani, Sudan in July to October 1987. Soil type of the site was heavy clays representing those of the Gezira area. The experiment layout was a randomized complete block design with four replicates. The trial included four elongated varieties and four round. The elongated varieties were ‘Charleston gray’, Charleston 76′, ‘Congo’, and ‘Fair fax’. the round varieties were ‘Crimson sweet’, ‘Sugar baby’ and the local collections ‘HSD0177′ and HSD0319’. The in-row and between row spacings were 60 cm and 3 meters respectively. Plot size was 6 x 7 m. Observations on percentage of fruits with BER and cracked fruits per plot were recorded.

Results and Discussion

Table 1. Percentage of fruits with blossom-end rot (BER) and percentage of cracking fruits in different varieties.

Variety

Fruit Shape

Percentage of BERz

Percentage crackingz
HDS0177 Round 01.8 d 04.8 d
Sugar baby Round 07.4 d 22.7 bc
bc Round 08.5 d 08.3 cd
Crimson sweet Round 31.6 c 45.3 a
Congo Long 38.4 bc 24.1 b
Charleston 76 Long 40.4 bc 22.9 a
Fair fax Long 44.9 ab 11.0 bcd
Charleston gray Long 53.1 a 18.7 bcd

z Means with the same lettter(s) are not significantly different at (P=0.001). S.E. for BER=+3.9 and S.E. for cracking = + 4.6 Data was subjected to angular transformation.

Varieties tested showed marked differences in BER and cracking, although the percentages of BER were generally higher. Those results support previous findings (1, 3) that spherical cultivars usually posses a complete or high resistance to BER and cracking. The round local collections were much better than the introduced round varieties in yield and resistance to cracking and BER. However, the local collections had a relatively lower sucrose percentage and a larger number of seeds per fruit. The round variety Crimson sweet marked susceptibility to cracking and BER was not in agreement with the mentioned established fact about round varieties being resistant.

It has been suggested that the resistance to BER in watermelon is inherited as a monogenic trait (2). Thus a breeding program aiming towards combining the desirable characters of the introduced varieties with the resistance to BER and cracking present in the local collections will be very useful for improvement of watermelon production in the heavy clays of central Sudan.

Literature Cited

  1. Abd elal, Z.E. 1975. The effect or irrigation frequency and cultivars on premature cracking and blossom-end rot of watermelon fruits grown in Sudan. Acta Horticulture No. 49-185-192.
  2. Brour, J.S., and K.S. Nandpuri. 1974. Studies on blossom-end rot in watermelon Citrullus Lanatus. Indian Journal of Horticulture (31(4):349-355).
  3. Cirulli, M..974. Preliminary results of varietal resistance and influence of irrigation frequency on the incidence of blossom-end rot of watermelon. Phytopathologia Mediterranea 13 (1/2):82-86.