Studies of foliar feeding of chemicals and PGRs on quantitative, qualitative and molecular attributes of litchi (Litchi chinensis Sonn.)
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Date
2023
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Department of Horticulture (Pomology), BAU, Sabour
Abstract
Litchi (Litchi chinensis Sonn.) is an important subtropical fruit crop with attractive colour, high economic and nutritional values. Bright red colour of the fruit skin and fruit quality is considered to be important quality attributes that contribute to consumer preference and market price. The fruit skin colour is desirable characters to fetch premium price by the litchi growers, but Deshi cultivar fruit colour is light red colour at maturity time. Keeping this in view, the present study entitled “Studies of foliar feeding of chemicals and PGRs on quantitative, qualitative and molecular attributes of litchi (Litchi chinensis Sonn.)” was conducted at litchi orchard of Horticultural Garden, Bihar Agricultural University, Sabour, Bhagalpur, Bihar (India) on Deshi variety of Litchi during the year 2020-22. Experiment was designed in randomized block design with three replications and twelve treatments including control. Pre-harvest application of potassium nitrate at 10 days after fruit setting resulted in maximum fruit length, fruit diameter, fruit weight, aril weight, pericarp weight, seed weight and fruit yield per tree as to the control (T1). Fruit quality parameters like TSS, TSS/Acid ratio, total sugar and anthocyanin content was improved by the pre-harvest application of abscisic acid @ 150 mg/L (T10) at colour break stage as to the control (T1). The highest titratable acidity and vitamin C was obtained in control (T1) while minimum in treatment of abscisic acid @ 150 mg/L (T10) at colour break stage. Fruit colour of the litchi pericarp was observed maximum in all treatments as compared to the control (T1). Pre-harvest foliar application of potassium nitrate at 10 days after fruit setting resulted in higher leaf chlorophyll at all stages as to the control (T1). The highest fruit chlorophyll was obtained in control (T1) at all stages however minimum was found in treatment of magnesium Chloride @ 2% (T9) at 10 Days after fruit setting and abscisic acid @ 150 mg/L (T10) at colour break stage.
Pre-harvest foliar application of potassium nitrate at 10 days after fruit setting resulted in higher nitrogen, phosphorus, potassium, calcium and magnesium in leaves and in fruits at all stages as compared to the control (T1). The conclusion was pre-harvest foliar application of potassium nitrate at 10 days after fruit setting considerably improved the fruit yield as compared to the control (T1) while pre-harvest foliar application of abscisic acid @ 150 mg/L (T10) at colour break stage enhance fruit quality as compared to the control (T1).
Sample of litchi fruit was collected at colour turning stage for NGS transcriptome analysis. Total RNA was isolated from pericarp tissues using the RNA kit (Promega) and further cDNA library was prepared. The total assembled base was 10.10 million by RNA sequencing Illumina platform. The average total transcript per sample was 83,362 and average protein encoding genes was 40825 with median contig length was 881 and average contig was 1212.24 per sample. The GO database was used to classify the function of the predicted litchi pericarp unigenes. Approximately 825,599 unigenes were classified into three main categories: biological process, cellular component and molecular function. Within the Biological process involved gene was 459865, in cellular component process involved gene was 146422 and in molecular function involved gene was 219312. In order to observe the role of genes involved in pericarp colouring, and analysed the genes involved in flavonoid biosynthesis pathway. Eighteen genes involved in flavonoid biosynthesis pathway of litchi pericarp identified. In eighteen genes common unregulated genes in flavonoid biosynthesis pathway validated through qRT-PCR technique, which are directly associated in flavonoid biosynthesis pathway in early or late stage that responsible for anthocyanin synthesis. The conclusion was pre-harvest foliar application of abscisic acid @ 150 mg/L (T10) at colour break stage and ethylene @ 500µL/L at (T11) at colour break stage found better in colouration of litchi pericarp as compared to combination of abscisic acid @150 mg/L and ethylene @ 500µl/L (T12) at colour break stage and control (T1).