Search

Fruit quality is most important for commercially cultivated watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] cultivars and introgression of resistance gene from wild or related species is a major challenge and imperative to study the inheritance of internal and external fruit quality traits for utilizing in resistance breeding programme. Present study was carried out at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi during summer 2020 to 2022 involving 4 seasons for identifying source of resistance, developing F1 and other subsequent generations (F2, BC1P1 and BC1P2) and evaluation of parental lines along with breeding population in watermelon. The resistant line DWM-45 was used as a female parent and crossed with commercially popular sweet watermelon variety Arka Manik to produce F1 and other generation to study the inheritance of internal and external fruit quality traits. Based on the segregation pattern of progeny it is concluded that fruit shape, rind pattern, seed coat colour and colour of flesh at margin near rind and at carpellar region followed monogenic inheritance. Furthermore, our findings revealed a complex genetic control with epistatic interactions for other fruit quality traits such as fruit length, fruit width, fruit weight and total soluble solids. This study provides valuable insights into the genetic basis of various fruit quality traits in watermelon which can have practical applications in breeding programmes, facilitating the development of improved watermelon varieties with desirable fruit characteristics.

Purple blotch caused by Alternaria porri (Ellis) Cif., 1930 causes huge losses to bulb crop and seed crop of onion (Allium cepa L.). This is a major disease affecting successful onion production in majority of the onion growing areas. To identify resistant source against purple blotch, 34 onion genotypes with good marketable yield based on field evaluation trial in 2017 and allied species Pusa Soumya were screened under protected conditions during kharif, 2018 at insect proof net house facility of ICAR-Indian Agricultural Research Institute, New Delhi. The pure culture of Alternaria porri, isolated from infected leaf samples of onion crop raised under natural epiphytotic conditions during kharif, 2017. Highest change of disease severity index was observed between 1–2 weeks post inoculation (WPI) while highest disease severity index was recorded at 5 WPI suggesting that preventive measures must be employed as soon as disease symptoms appear in the field. The disease severity index ranged from 0.10–33.33 at 1 WPI, which increased to 9.33–89.33 at 5 WPI. The cultivated allied species Pusa Soumya was identified as novel resistance source with DSI value less than 10.0% at 5 WPI. Four genotypes exhibited moderately susceptible reaction, while 20 genotypes were susceptible and 10 genotypes were highly susceptible. The area under disease progress curve (AUDPC) value ranged from 22.33–240.17. Pusa Soumya had the lowest value and among onion lines Arka Kirtiman was found promising. Three onion genotypes had low relative AUDPC value and can effectively be utilized in resistance breeding programme. The average daily temperature between 20–25°C and relative humidity above 75% was found ideal for disease development.

Information on genetic diversity with respect to various agro-morphological traits and eating and cooking quality traits plays a key role in the improvement of rice (Oryza sativa L.). With this aim, we have characterized a set of 98 indigenous aromatic rice germplasm accessions for four agro-morphological, two physical and two physico-chemical traits. Significant variation was observed among the cultivars for all the traits. Correlation analysis showed negative correlation of DFF with KLBC (r= -0.29; p=0.022) and kernel L/W ratio (r= -0.25; p=0.003), while PL was significantly and positively correlated with KLBC (r=0.38; p=0.000) and kernel L/W ratio (r=0.43; p=0.0649). KLBC showed highly significant positive correlation with GC (r=0.22; p=0.614) while between AAC and GC a significant negative correlation was observed (r= -0.38; p=0.000).

The association of parental divergence based on simple sequence repeats (SSR) markers and heterosis in 96 rice (Oryza sativa L) hybrids was investigated for yield and component traits under four environments. Hybrids were derived from four cytoplasmic male sterile (CMS) lines and 24 iso-cytoplasmic restorers (ICR). The genetic distance (GD) and heterosis were significantly correlated for the number of productive tillers per plant (0.537) and panicle length (0.386) in Delhi under early sowing. Under late sowing, negative correlations were also observed (-0.435, -0.401) with pollen fertility percentage. The GD and heterotic performance of hybrids were significantly correlated for panicle length (r=0.35) and number of effective tillers per plant (r=0.51). At Karnal, significant association between GD and hybrid grain yield (0.615) was observed. Besides, insignificant correlations were observed for some other traits at different locations. The non-significant correlations indicated the need of employing trait related functional/ gene based markers as well as using more abundant markers for accurately predicting the hybrid performance.