After reading this article you will learn about:- 1. Origin of Bottlegourd 2. Botany of Bottlegourd 3. Breeding Goals 4. Qualitative Genes 5. Breeding Methods 6. Seed Production 7. Varieties.
Origin of Bottlegourd:
According to De Candolle (1882), bottlegourd has been found in wild form in South Africa and India. However, Cutler and Whitaker (1961) are of the view that probably it is indigenous to tropical Africa on the basis of variability in seeds and fruits. This species appears to have been domesticated independently in Asia, Africa, and The New World.
The evolution of the bottlegourd is not well understood. Two principal variants are recognized as subspecies, i.e. subsp. siceraria of Africa and the Americas and subsp. asiatica. It is not known if the progenitor of the bottlegourd was a wild form of the species or one of the other extant species.
It is not known whether domestication occurred in Africa followed by dispersal to the Americas and Asia or the wild forms dispersed followed by independent domestication in the Americas, Africa and Asia. Was dispersal carried out by humans or by ocean currents? Bottlegourds can float on the oceans for many months without losing seed viability, hence the latter alternative is possible.
Bottlegourd (Lagenaria siceraria 2n = 2x = 22) is one of the important cucurbits in India, both as a rainy season and summer season vegetable. It is also known as white-flowered gourd. It is one of the most important vegetables of ancient China. Because of hard rind of mature fruits, it is, known as gourd.
Botany of Bottlegourd:
Bottlegourd is monoecious, annual vine with soft pubescence. The leaves are cordate-ovate to reniform – ovate, 15-30 cm across, not lobed. The flowers are white, solitary, showy and open at night. The flower has five petals.
The staminate flowers are on long pedicels exceeding the foliage. The pistillate flowers are single with short peduncle and hairy ovary. Ovary has three placentae with numerous ovules. A mature leaf is shown in Fig. 30.1.
The fruits are variable in size and shape. In shape, they are cylindrical, oval, egg shaped, club shaped, round etc. The fruits at maturity are hard-shelled, smooth surfaced, green to whitish-green or tan in colour, and variously striped or mottled.
There are three stamens, two as compound and one as single. Since flowers open at night, selfing/crossing must be done earliest in the morning. If possible, during evening/night also, it could be done.
Breeding Goals of Bottlegourd:
a. High yield
b. Greater fruit number
c. Fruit weight as per market demand
d. Earliness (appearance of pistillate flowers at early node number)
e. High female: male flower ratio
f. Round, long, club shaped, pear shaped fruit
g. Sparse hairs persisting on skin
h. Non-fibrous flesh at edible stage
i. Non-bitter fruit
j. Attractive green fruit with long colour retention
k. Resistance to powdery mildew, downy mildew and cummber mosaic virus and red pumpkin beetle
Qualitative Genes of Bottlegourd:
Very little is known about genes following simple inheritance in this crop. Kalloo (1993) has mentioned fruit colour to be monogenically determined. Pathak and Singh (1950) have demonstrated a single dominant gene for bitterness in Lagenaria leucantha (Duchs.).
They also reported that two genes have major effects on fruit shape, and a single gene pair determines patchy vs white fruit colour in L. leucantha. Singh (1996) obtained an andromonoecious sex form (staminate and hermaphrodite flowers on same plant) in a segregating progeny during the course of selfing in a monoecious local collection of bottlegourd. F2 and BC1 generations derived from the crosses between a stable monoecious line and the andromonoecious form indicated monogenic recessive inheritance for andromonoecious sex form.
Regarding exo-morphological features, observations over the years revealed that andromonoecious sex form was accompanied by certain special features. Whereas the staminate flowers of andromonoecious sex form (the line was named as Andromon-6) were similar to normal staminate flower of monoecious line, the hermaphrodite flowers showed a few variant features compared to normal female flowers.
The hermaphrodite sex form was characterized by long corolla (3.5-4.5 cm compared to 2.5-3.5 cm in normal), well developed anthers encircling full grown stigma and oval ovary that develops into a drum-shaped fruit sporting 12 light grooves.
The fruit bears prominent blossom scar and majority of mature fruits contain a large number (400-700) of white/brown small empty non-viable seeds with underdeveloped seed coat. A few fruits bear 1-25 normal viable seeds. The full grown fruits are only about 25 cm in length and 45 cm in circumference (Fig. 30.2).
A new variant having segmented leaf has been detected by the author at Pantnagar. The entry has been designated as PBOG-54. The plant is vigorous, late in flowering, has completely segmented leaf in contrast to entire margin in normal types.
The fruits are somewhat crook necked, have green fruit skin with mottled appearance. The flesh is tender for longer time. It has been registered at NBPGR, New Delhi under registration number INGR 99022 as a novel type having segmented leaves (Fig. 30.3).
Tiwari and Ram (2006) reported its inheritance as given below:
The experimental materials comprised of five advanced parental lines of bottle gourd viz., Pusa Naveen, PBOG 13, PBOG 22, PBOG 54 and PBOG 61 grown in summer, 2003 where PBOG 54, a segmented leaf parent, was used as common male parent and crossed with rest of the normal leaf parents with entire leaf margin to generate four F1.
Further, F2 and F3 generatins were developed through selfing of F1 and F2, respectively. In addition, four backcross generations were also developed by crossing F1S to PBOG 54. The parental lines and various generations (F1; F2, F3 and backross) were grown during rainy season 2003 and 2004. Chi-square (x2) analysis was done to determine the goodness of fit into certain genetic ratios.
On self-pollination, the normal leaf parents viz., Pusa Naveen, PBOG 13, PBOG 22 and PBOG 61 produced only normal leaf progenies, whereas segmented leaf parent PBOG 54 produced segregated progenies in a ratio of 3 segmented : 1 normal leaf type plants. All the four F1S derived from crossing between normal leaf type parents and the segmented leaf type parent, PBOG 54 segregated in a ratio of 1 segmented: 1 normal leaf type.
These two unexpected segregations to a ratio of 3 segmented: -1 normal leaf in the selfed progeny of segmented leaf parent PBOG 54 instead true breeding and segregating of F1s into 1 segmented: 1 normal leaf shape ratio indicated that parental cultivar PBOG 54 was heterozygous for leaf shape gene where segmented type was dominant over normal type (Table 30.1, Fig. 30.4).
The F2 plants obtained from selfing of segmented leaf plants in the F1generation segregated in a ratio of 3 segmented : 1 normal leaf shape as x2 values were found to be non-significant whereas, the F2 plants obtained from selfing of normal leaf plants in the F2 were found to be true breeding for normal leaf.
The backcross generations derived from crossing normal leaf plants of four F1s (used as female) with segmented leaf plants of PBOG 54 segregated in a ratio of 1 : 1 for segmented leaf vs normal leaf plants. The F3 progenies derived from F2 plants were of three types.
In first case, the F3 progenies derived from selfing of true breeding normal leaf plants of F2s were again true breeding for normal leaf plants. In the second case, F3 progenies derived from segmented leaf plants of segregating F2s revealed confirmatory results.
The 1/3rd of the segmented F2 plants were true breeding for segmented leaf and the remaining 2/3rd segregated in a ratio of 3 segmented: 1 normal leaf type. In third case, F3 progenies derived from selfing of normal leaf plants of segregating F2s were true breeding for normal leaf (Table 30.1).
The schematic diagram of the advancement of generations is presented in 30.4. These segregation ratios gave a good fit to the hypothesis that segmented leaf was governed by a single dominant gene and the genotypes of the normal leaf parental lines could be ‘ss’ for Pusa Naveen, PBOG 13, PBOG 22, PBOG 61, whereas the genotype of segmented leaf parental line PBOG 54 could be as ‘Ss’ which should be ‘SS’ under pure-line conditions.
Supporting evidences for the genetics of segmented (lobed) leaf character have also been given by several researchers in different cucurbits. Ganesan and Sambandam (1985) found single dominant gene ‘L’ responsible for lobing leaf characteristic over non-lobed leaf character in muskmelon.
Herrington and Brown (1988) also found that lobed leaf mutant was governed by dominant gene ‘Lo-2’ in Cucurbita equadorensis.
Mohr (1953) reported wild lobe leaf shape character was governed by incompletely dominant gene over non-lobing mutant characteristic in watermelon. However, in contrast to present study there are some reports where recessive gene is responsible for lobed leaf shape mutant in different cucurbits.
From this study, it can be concluded that segmented leaf phenotype in bottle gourd line PBOG 54 is governed by a single dominant gene and can be utilized as dominant seedling marker trait in large scale hybrid seed production where accidental selfs could be easily distinguished from true F1 seedlings provided the segmented leaf parent is used as male parent.
Vr, Wr graphical analysis carried out at Pantnagar revealed interesting finding on the genetics of fruit diameter and fruit length. Round fruited cultivars (BOG-68 and BOG-13) were far away from the origin and close to the point of intersection of regression line and parabola indicating the presence of mostly recessive genes for longer fruit diameter and lesser fruit length.
Conversely, all the four long fruited cultivars (BOG-22, BOG-7, BOG-40 and NDBG-1) were close to origin for both of these characters demonstrating the accumulation of mostly the dominant genes in these four lines (Fig. 30.5).
As a matter of fact these two characters i.e. fruit diameter and fruit length are manifestation of same biological process where if diameter is increasing, the length is decreasing and vice-versa.
Therefore complete parallelism with respect to distribution of parental points along the regression line for fruit diameter and fruit length is not surprising. Based on these results, it is suggested that long-fruited cultivars had AA genotype for long fruit shape and the round-fruited cultivars had aa genotype for round fruit shape with degree of dominance tending to be slightly partial.
Breeding Methods of Bottlegourd:
Inbreeding in land races followed by individual plant selection has been found effective method of breeding to develop pure-line cultivars of cucurbits including bottlegourd. Similarly two parental cultivars can be crossed and the typical pedigree/bulk/back cross method of breeding can be used.
However, in view of reported heterosis by some authors and the fact that cylindrical fruit shape could be easily obtained by crossing long fruited varieties of varying shapes, heterosis breeding has also been followed.
Some hybrid bottlegourd varieties were released as long back as 1971 by Indian Agricultural Research Institute, New Delhi. Pusa Meghdoot (long) gave an increase in total yield of 75 % while in Pusa Manjari (round) increase in total yield was 106%.
Once a good, heterotic parental combination has been identified, the hybrid seed can be easily produced by planting 3-4 rows of female parent alternated with 1 row of male parent.
The male buds of female rows are removed daily before anthesis and the fruit set on the female line is as a consequence of cross-pollination from male parent. This natural cross-pollination is carried out by the insects and can be further facilitated by keeping a few honey-bee hives in the seed production block which has to be at an isolation distance of about 1000 m from other bottlegourd fields.
Insect Resistance Breeding:
Nath (1971) has reviewed insect resistance breeding in cucurbits. The three major insects of cucurbits including bottlegourd are red pumpkin beetle (Aulacophora spp.), fruit fly (Dacus spp.) and aphid (Aphis spp). Red pumpkin beetle causes damage on seedlings and continues further.
For effective screening the adult beetles at the rate of one beetle per seedling at the cotyledonous stage are released inside the cage. In gourds, a final observation with regard to the damage by adult beetle on cotyledonous leaves is made 10 days after seed germination. Degree of damage on leaves is categorized as given in Fig. 30.6.
The degree of fruit damage by fruit fly is recorded in terms of damaged fruits showing punctures on each vine twice a week and after record such fruits are harvested. The fruits with no damage are left on vine till maturity to confirm their resistance against the fly at every stage of fruit development. The percentage of total fruit damaged throughout the season is calculated for each line.
The rating system is as follows:
Immune – no damage
Highly resistant – 1-10% damage
Resistant – 11-25% damage
Medium resistant – 26-50% damage
Susceptible – 51-75% damage
Highly susceptible – 76-100% damage
For screening against aphids, artificial infestation in the seedling stage is required.
PI 271353 – resistant to cucumber mosaic virus, squash mosaic virus, tobacco ring spot virus, tomato ring spot virus, watermelon mosaic virus.
Doodhi Long Green and
Three Feet Long Green – moderately resistant to five isolates of Sphaerotheca
Taiwan variety Renshi – highly resistant to Fusarium wilt.
Varietal Identification through Seed Protein Electrophoresis:
The increasing number of varieties and the degree of morphological similarity between them have created the need for better systems of identification and characterization of crop varieties. Use of protein profile/isozyme phenotypes assumes significance in this context.
In bottlegourd this technique needs serious consideration as most of the varieties show a greater degree of similarity and perhaps this technique has not been applied so far in bottlegourd.
Upadhyay (1995) applied this technique in bottlegourd based on the procedure of Orf (1980 ). Polyacrylamide disc gel electrophoresis of water soluble seed proteins conducted on 15 cultivars of bottlegourd demonstrated the presence of eight electrophoretic bands occupying two zones.
The 15 cultivars could be divided into seven groups each having a different protein profile. Three morphologically indistinguishable varieties, namely, 130G-61, BOG-15 and BOG-40 characterized by long vines, long fruits and non-segmented leaf margins, could be distinguished though this technique.
However, it was also observed that two morphologically distinct cultivars. viz. BOG- 15 (non-segmented leaf) and BOG-54 (segmented leaf) had similar protein band but for some minor difference in intensity of few bands (Fig. 30.7). Dubey and Ram (2008) elaborated this technique further as given below.
The experimental materials for this investigation consisted of eight advanced breeding lines viz., PBOG 13, PBOG 22, PBOG 54, PBOG 61, PBOG 76, PBOG 117, PBOG 119 and Pusa Naveen and two F, hybrids i.e. PBOG 13 × PBOG 61 and PBOG 13 x PBOG 76, which were derived from parental lines PBOG 13, PBOG 61 and PBOG 76. Out of these, PBOG 13 is round- fruited. The remainder had long fruit. PBOG 54 has segmented leaves in contrast to normal leaves in other types.
The variability of seed storage proteins was analyzed by using SDS-PAGE. Seeds of eight advanced breeding lines and two F1 hybrids evaluated in the field were collected and 0.1 g seed was taken in pestle and mortar and adding 1000 µ1 extraction buffer (1M Tris- HCL-pFI 8.0, 2% SDS, 10% glycerol, 1 mM PMSF-phenyl methyl sulphonyl fluoride and 2% β-mercaptoethanol). The sample was homogenized and heated in a boiling water bath for 5 min at 100°C.
The contents were centrifuged for 30 min at 10,000 rpm in a refrigerated centrifuge at 4°C and the supernatant (protein fraction) was stored at 20°C. Sample buffer (Tris-pH 7.4. 2% SDS, 2% mercaptoethanol and bromophenol blue) was heated in boiling water bath for 5 min at 65°C just before loading in the gel.
A standard SDS gel was made. Protein samples (7/µ1/ well) were loaded and run at a constant 100 V with electrode buffer (Tris-glycine and SDS, pH 8.6) using a protein molecular weight marker.
The gel was stained overnight in staining solution (0.25 g Coomassie brilliant blue R-250, 60 g TCA, 180 ml methanol, 60 ml glacial acetic acid), then replaced with distaining solution (3% NaCl) and lightly shaken to remove the blue background.
The gel was visualized on a Syngene Documentation System (Fig. 30.8). Cluster analysis and the generation of a hierarchical dendrogram was achieved through UPGMA using the software package NTSYSpc.
The cluster analysis separated the eight advance breeding lines and two F] hybrids into four major groups. Despite the fact that PBOG 54 has a distinct leaf trait i.e. a segmented leaf (novel genotype), cluster analysis did not separate it into a separate group, showing the weakness of SDS-PAGE in correlating protein profile data with morphological traits.
This result also demonstrated that an obviously distinct type of breeding lines based on a particular morphological variation, for example leaf shape conditioned by qualitative inheritance may not necessarily show wide diversity based on SDS-PAGE.
The weakness of the correlation of the method to SDS-PAGE banding patterns is further demonstrated by the fact that long fruit types, e.g. PBOG 117, PBOG 22, PBOG 54, PBOG 61, PBOG 76, PBOG 119 and Pusa Naveen were clustered into different groups and had different banding patterns.
Seed Production of Bottlegourd:
Isolation distance for breeder/foundation seed is 800 m and that for certified seed is 400 m. However, higher distance will be preferable. 1000 seed weight is about 150 g and seed yield is about 8 q/ha.
Varieties of Bottlegourd:
Pusa Summer Prolific Long:
This was developed at IARI through selection from local germplasm. It is particularly suitable for growing as summer crop, although it can be grown in rainy season also. Fruits are 40-50 cm in length and 20-25 cm in girth and it has been released by IARI, New Delhi.
Pusa Summer Prolific Round:
This was developed through selection in local germplasm at IARI and has been released by the same institution. It has vigorous growth, round fruits of 15-18 cm girth. It is prolific bearer and heavy yielder.
This is an F1 hybrid cultivar between Pusa Summer Prolific Long and Sel-2, developed and released by IARI, New Delhi in 1971. Fruits are long, light green and attractive. It is relatively early and suitable for cultivation in spring-summer season.
It has shown considerable yield heterosis over Pusa Summer Prolific Long. No more in cultivation. Pusa Manjari. This is a round fruited F1 hybrid cultivar developed and released at IARI in 1971 from a cross of Pusa Summer Prolific Round and Sel-11. It has given 48% higher early yield and 106% total yield over Pusa Summer Prolific Round. Not commercially cultivated now.
This is a new variety developed and released by IARI. More than 75 collections were purified and evaluated under the renewed programme which was taken-up in 1984-85. Sel-48 was released as Pusa Naveen by IARI variety release committee. It is high yielding (300 q/ha), and takes about 60 days for first harvesting. Fruits are perfectly cylindrical and straight without any crook neck or curve. Average fruit weight is 850 g.
It is an early maturing, medium sized, oblong fruited variety developed and released by PAU, Ludhiana. Marketable fruits are available in about 70 days after sowing. The fruits are light green with pubescence. There are 10-12 fruits per vine. The fruits are tender and borne on medium long, thin pedicels on 4th or 5th node onwards. It is tolerant to cucumber mosaic virus. The yield potential is 400 q/ha.
This was developed and released by IIHR, Bangalore. This is a selection in local cultivars of Karnataka. Fruits are straight, devoid of crook neck, medium in size, each weighing about 1 kg. The skin is light green. The flesh is shining, tender. The yield potential is about 400 q/ha in 120 days.
Kalyanpur Long Green:
This variety was developed at vegetable research station, Kalyanpur of CS Azad University of Agriculture and Technology, Kanpur. The vines are vigorous and long. Fruits are long with tapering and somewhat pointed blossom end. The yield potential is 300 q/ha in 120 days.
Pant Sankar Lauki 1:
A hybrid of PBOG 22 and PBOG 40 developed by GBPUAT, Pantnagar was released by CVRC in 1999. Fruits are 35 cm long. Yield is about 400 q/ha.
Pant Sankar Lauki 2:
A long fruited hybrid developed at Pantnagar.
A few bottle gord hybrids from private seed companies in India are Warad, Shashi, Satya, etc. These are about 30-40 cm long, weighing 800-900 g at marketable stage.