Guava Improvement in India and Future Needs

Guava (Psidium guajava L; Myrtaceae) is an important fruit crop of India. High heterozygosity and frequent cross pollination resulted in the present day variability in seedling populations from which promising genotypes have been selected. As of now, there are about 160 cultivars available in India, among which 'Allahabad Safeda' and 'Sardar' varieties are widely cultivated. Crop improvement work attempted in India resulted in release of several superior selections / hybrids. Also, interspecific hybrids resistant to guava wilt were developed at CISH, Lucknow which are graft compatible with commercial varieties of P. guajava. The use of new biotechnological tools like DNA fingerprinting to study the extent of genetic variation among cultivars, rapid multiplication through in vitro shoot-tip culture needs to be employed extensively. Attempts need to be made to spot genetic markers for wilt resistance to improve efficiency in developing wilt resistant clones and rootstocks. Survey to identify superior genotypes with Allahabad Safeda traits and high density planting characters like early bearing, compact plant type, favourable response to pruning, good branch angle to minimize branch breakage even under heavy bearing, and, with a high fruit : shoot ratio need to be paid due attention. Work on aneuploidy breeding, development of autotetraploids and in vitro genetic manipulation of somatic cells needs to be intensified

Resistance to Fruit Fly, Bactrocera dorsalis (Hendel) and Tea Mosquito Bug, Helopeltis antonii (Sign.) in Certain Wild Psidium Species

Five wild species of Psidium viz., Psidium cattleianum lucidum, P. chinensis, P. friedrichsthalianum, P. molle and P. quadrangularis were evaluated for resistance to fruit fly [Bactrocera dorsalis (Hendel)] and tea mosquito bug (TMB) [Helopeltis antonii (Sign.)], during 2002-04. Significant variations were recorded among species in their reaction to pests. Two species viz., P. chinensis and P. quadrangularis were resistant to fruit fly (<10% fruit damage) while P. quadrangularis was immune. Psidium. molle and P. cattleianum were resistant to tea mosquito bug. Pest incidence was correlated with fruit biochemical components viz., total soluble solids (TSS), total sugars, vitamin C and acidity. The TSS and total sugars were positively correlated with fruit fly infestation while acidity was negatively correlated. The TMB incidence did not exhibit significant correlation with any of these parameters

Genetic Variability in some Indian Mango Cultivars and Hybrids

Mango is a perennial and highly heterozygous plant. Therefore, it takes a long time to breed a variety in this crop. Information on genetic variability among cultivars and hybrids helps plan meaningful crop improvement programmes. Due to the high heterozygosity, complexity of its flowers and poor fruit-set, the progeny population that can be raised from a cross is very meagre. Hence, there is a need to choose parents that have good fruit-set and show genetic divergence. It would also be interesting to establish if the hybrids generated are truly open-pollinated progenies, or arise from controlled crossing. Basic information thus obtained would help chalk out a potentially successful breeding programme. A study in this direction was carried out by using morphological characters of twelve hybrids and their respective parents. Cluster analysis indicated a relationship between the parents and hybrids. Two major clusters were observed from the clustering pattern. In the first cluster, varieties Dashehari, Banganapalli, Manjeera, Sindhu, Janardhan Pasand, Ratna, Rumani, Amrapali, Neelgoa and Alphonso grouped together. The second cluster consisted of vars. Arka Aruna, Neelum, Arka Puneet, Neeleshan, Mulgoa, Mallika, Arka Anmol and Arka Neelkiran. The hybrid, Sindhu was observed to be genetically closer to Ratna than to Alphonso. The sub-clustering pattern also showed a close relationship between parents and their hybrids. The hybrid, Arka Anmol, was found to distantly placed from the centre (8.54), as also the hybrid, Arka Neelkiran (7.05). 'Sindhu' was also found to be closer to the centre (1.55)

Genetic Diversity in 'Appemidi' Pickle Mangoes

Mango is an important fruit crop grown extensively in India. An enormous diversity is seen in its flavour, taste and fruit form unique to particular regions of India. A large diversity for unique pickling types, called 'Appemidi' (tender mangoes), is seen in Uttara Kannada district of Karnataka. With rapid deforestation in several of these areas, surveys were conducted to collect and conserve these unique types. This resulted in collection of 33 unique accessions which have been conserved in the Institute's field gene bank. On evaluation of tender fruit, accessions 'Chansi Appe', 'Dodderi Jeerige', 'Mani Bhatta Appe', 'Gorana Appe', 'Isagoor Appe', 'Malange', 'Gurumurthy Appe' and 'Kashimidi' were found to possess good traits for tender, whole-fruit pickling

Morpho-biochemical characterization of Psidium species

Several Psidium species are available with many important traits, lack of intensive characterization limits their use in guava improvement. Therefore, the present study was carried out to characterize five wild Psidium species (P. molle, P. chinensis, P. guineense, P. cattleianum var. cattleianum and P. cattleianum var. lucidum) and two P. guajava genotypes (cv. ‘Arka Poorna’ and ‘H 12-5’), based on morphological and biochemical traits. Among morphological traits, fruit weight was ranged from 5.22 g (P. cattleianum var. cattleianum) to 225.14 g (‘H 12-5’), however, among biochemical traits, highest TSS (12.06 ºBrix) and total sugars (9.98%) were recorded in cv. ‘Arka Poorna’, while, lowest recorded in P. cattleianum var. lucidum. Highest ascorbic acid was recorded in P. chinensis (205.33 mg/100 g), whereas, lowest recorded in P. guineense (60.83 mg/100 g). A positive correlation was observed among wild Psidium species but none had correlation with P. guajava genotypes for quantitative traits

Morpho-biochemical characterization of Psidium species

Several Psidium species are available with many important traits, lack of intensive characterization limits their use in guava improvement. Therefore, the present study was carried out to characterize five wild Psidium species (P. molle, P. chinensis, P. guineense, P. cattleianum var. cattleianum and P. cattleianum var. lucidum) and two P. guajava genotypes (cv. ‘Arka Poorna’ and ‘H 12-5’), based on morphological and biochemical traits. Among morphological traits, fruit weight was ranged from 5.22 g (P. cattleianum var. cattleianum) to 225.14 g (‘H 12-5’), however, among biochemical traits, highest TSS (12.06 ºBrix) and total sugars (9.98%) were recorded in cv. ‘Arka Poorna’, while, lowest recorded in P. cattleianum var. lucidum. Highest ascorbic acid was recorded in P. chinensis (205.33 mg/100 g), whereas, lowest recorded in P. guineense (60.83 mg/100 g). A positive correlation was observed among wild Psidium species but none had correlation with P. guajava genotypes for quantitative traits

Evaluation of Unique Mango Accessions for whole-Fruit Pickle

Studies conducted to evaluate the suitability of nineteen unique mango accessions for preparation of tender whole mango pickles revealed that these varieties were characterized by their acidic taste and rich raw mango flavour, which are most prefered for pickle production. The physical and quality parameters viz. fruit shape, weight, raw mango flavour, firmness, titrable acidity, latex flow, pH, dry matter and vitamin C which are important in pickle quality, showed wide variations among different varieties. Based on the sensory evaluation of whole immature green mango pickle prepared by standard fermentation and curing method, the accessions viz., Kashimidi, Isagoor Appe, Malange, Appemidi, Dantimamidi and Jeerige were considered to be most suitable for preparation of tender mango pickles

TOXICITY AND SMOKE REPELLENCY EFFECT OF MIMOSA PUDICA L. AGAINST THE MALARIAL VECTOR ANOPHELES STEPHENSI (DIPTERA: CULICIDAE)

Mimosa Pudica Linn is a commonly used herbal drug against many diseases. The antivectorial activity of ethanolic leaf extract of Mimosa Pudica Linn was investigated in the laboratory. Different concentrations (0.2, 0.4, 0.6, 0.8 and 1.0 ppm) against different immature stages of Anopheles stephensi were tested and showed considerable toxicity effect against the immatures of Anopheles stephensi. Lethal concentration (LC50 and LC90) has been worked out on different larval stages of Anopheles stephensi. The LC50 values of M. pudica for I instar larvae was 0.723%, II instar was 1.150%, III instar was 1.540%, IV instar was 2.073%, and pupa was 2.835%, respectively.The LC90 values such as I instar was 3.578%, II instar was 4.079%, III instar was 4.833%, IV instar was 5.333 % and pupa was 6.717%, respectively. The smoke toxicity effect of M. pudica leaves exhibited a good knock down effect when compared with the commercial synthetic mosquito coil. The smoke affected gravid females and they lay only a fewer number of eggs and egg hatchability was also reduced. The percentage of population reduction was 79.5% in the plant exposed mosquitoes and in the positive control (Mortein coil), the percentage of reduction was 71.8%. &nbsp

Enrichment of Genetic Linkage Maps and Mapping QTLs Specific to Seed Strength-Hardness/Softness-In Guava (Psidium guajava L.)

The present research focuses mainly on molecular mining and morphological evaluation of guava genome within a full-sib population and, thereby, mapping of quantitative trait loci related to fruit quality traits, viz., seed strength (hardness/softness) and average fruit weight. Linkage maps were enriched for both parental lines, 'Kamsari' and 'Purple Local' using a set of 60 RAPD markers following the pseudo-testcross strategy on a panel of 94 progeny. A total of 480 scorable markers were identified, of which 131 were specific to 'kamsari' and 28 to 'Purple Local', segregating as test cross markers, and, 321 showing intercross pattern common to both. 'Kamsari' spanned a total length of 1959.1cM with average marker interval distance of 3.93cM, while 'Purple Local' spanned a length of 1537.9cM with average marker interval distance of 3.29cM, by forming 11 linkage groups. Estimated genome length observed was 93.02% and 92.77% in 'Kamsari' and 'Purple Local', respectively. Composite Interval Mapping (CIM) was computed at significance of 0.05 and LOD threshold greater than 3.0, which led to detection of one major QTL for the trait of average fruit weight, and, four QTLs for the trait of seed strength (hardness/softness). Of these, two were major and two minor QTLs. Our study provides molecular mapping information on marker-assisted selection for improvement of guava in a breeding program

Assessment of Genetic Diversity in Guava (Psidium guajava) Germplasm Using Microsatellites

Although the varietal diversity is fairly rich in guava, most varieties lack one or more desirable characters. Hence, attempts were made for improving specific traits, viz., attractive pink pulp colour, soft seeds, medium fruit size, high TSS and high ascorbic acid. Genetic diversity analysis is a prerequisite for identifying potential parents in breeding programs and germplasm conservation. Molecular characterization helps discriminate closely-related genotypes, as, this technique is unaffected by environment, rendering it more reliable. In this study, 48 polymorphic SSRs screened from a total of 115 SSR markers were used for analyzing marker segregation in 72 guava accessions. Statistical analysis was done using IDENTITY1.0 and CERVUS 3.0 software. Cluster analysis was done with DARwin 5.0 software, using Wards Minimum Variance method, and weighted group neighbour joining method, to check reliability of grouping among clusters. The trend in grouping was found to be similar in both methods. Dendrograms generated showed that the hybrids clustered with their parents; exotic collections fell into two different sub-groups based on productivity; the wild species formed one group; and Navalar cultivars from Dharwad clustered together, reflecting similar origin