Search

During shoot apex development, the plants undergo a very complex transition phase of flowering for successful reproduction, seed/cone setting and fruit development. The conversion of vegetative shoot meristems to floral meristems depends upon numerous endogenous, exogenous factors and flowering genes for the development of floral parts. The perennial crops suffer from the limitation of the innate ability to keep some meristems in the vegetative state for the polycarpic growth habit leading to the long juvenile phase. Conventional breeding approaches viz. selection of early flowering parental lines, flower thinning and grafting are time-consuming requiring more time for the release of a new cultivar which is undesirable for rapid crop improvement. The best way to accelerate the perennial plant breeding improvement programs and to reduce the long juvenile phase is the induction of early flowering through the utilization of biotechnological approaches. The ability to allow the transmission of an early flowering gene to the progeny in a Mendelian fashion is the major advantage of biotechnological interventions. The introgression of early flowering traits from non-commercial germplasm or sexually compatible species to perennial species through the biotechnological aspects will act as a boon for crop improvement in future studies. The present review gives an overview of various flowering genes in perennial crops accompanying the implementation of biotechnological approaches including overexpression studies, RNA interference, Virus-induced flowering and CRISPR-Cas approaches that will help in reducing the period for induction of flowering in perennial crops. [ABSTRACT FROM AUTHOR]

An experiment on drip irrigation scheduling based on pan evaporation replenishment was conducted in Kinnow orchard at Punjab Agricultural University, Ludhiana during 2010-2018. Year was divided into six stages (stage 1 to stage VI) including two months in each stage. First treatment included irrigation scheduling with 30 and 40% ER, treatment two with 40 and 60% ER, treatment three with 60 and 80% ER, alternatively during stages I to VI. However, fourth and fifth treatments had irrigation with 80% ER and 30% ER, respectively, in all the stages. Maximum daily open pan evaporation (9.15 mm) was recorded in May and minimum (1.19 mm) was recorded in January. The water requirement varied from 2.8 liters day-1 tree-1 in stage-I to 58.3 liters day-1 tree-1 in stage-III. Linear increase in vegetative and reproductive growth was observed with increase in irrigation water. Polynomial relationship studies indicated the increase in water quantity applied to Kinnow with increase in temperature subject to the prevailing relative humidity. Similarly, volumes of water applied increased with increased mean evaporation. The study concluded that drip irrigation scheduling with 60 to 80% ER alternatively, starting from January to December save significant amount of water, without affecting yield and quality of Kinnow under subtropical conditions. [ABSTRACT FROM AUTHOR]

Kinnow mandarin (Citrus reticulata Blanco) is a popular citrus crop of northwestern India and it occupies maximum fruit area in Punjab. However, citrus juice processing industry is still suffering from delayed bitterness problem caused mainly by limonoid aglycones such as limonin. In order to study citrus limonoid metabolism, limonoid glucosyltransferase (LGT) gene, which encodes a natural debittering enzyme, was isolated from the fruit tissues of Kinnow mandarin. After confirmation and characterization, its full-length gene sequence (1533 bp) was submitted to National Centre for Biotechnology Information. Citrus reticulata limonoid glucosyltransferase (CrLGT) occupies a position on an independent branch in the largest subgroup and is phylogenetically different from those in other mandarin species like C. unshiu, showing its uniqueness in several features. The transcript expression of CrLGT, evaluated in different tissues such as young leaf, flavedo, albedo, sac covering and seed of Kinnow mandarin during early (90 days after flowering (DAF)), mid (150-210 DAF) and late (240 DAF) fruit developmental stages using semi-quantitative method, showed the highest expression in flavedo. Thus, it was concluded that the isolated LGT gene has an effect on limonoid metabolic engineering in citrus. Overexpression of this gene can reduce the delayed bitterness problem in citrus juice and enhance the accumulation of specific glucosides that have anticancer effects. [ABSTRACT FROM AUTHOR]