Effects of Pruning and Nitrogen Fertilization for The Rejuvenation and Physicochemical Characteristics Of Fruits of Declining Apricot Trees (Prunus Armeniaca L. CV. New Castle)

Effects of pruning and nitrogen fertilization for the rejuvenation and physicochemical quality of fruits, bearing on declining apricot trees (Prunus armeniaca L. cv. New Castle) were assessed. Studies were conducted from 2011 to 2015 on the 25 years old senile and declining apricot trees. Ten treatments comprised of a factorial combination of three pruning levels/severity (heading back of main scaffolds at 20, 40 and 60%) with three levels of nitrogen doses (500, 625 and 750g N/tree). For the first time in the year 2011, the experimental trees received the treatments during its dormant period (winter). In the successive years, all the treatments were followed by corrective pruning facilitate rapid restoration of growth and production of the orchard. The factorial treatment combination of heavy pruning (60%) with the lowest doses of nitrogen level (500g/tree) increased the qualities of fruits in terms of weight, volume, firmness, total soluble solids, sugars and acidity content. Whereas, the ascorbic acid content was facilitated by heavy pruning (60%) with the highest doses of nitrogen level (750g/tree) in all the following years. Bangladesh J. Bot. 50(4): 1119-1126, 2021 (December)

Elucidating Genetic Diversity in Apricot (Prunus armeniaca L.) Cultivated in the North-Western Himalayan Provinces of India Using SSR Markers

Apricot (Prunus armeniaca L.) is an important temperate fruit crop worldwide. The availability of wild apricot germplasm and its characterization through genomic studies can guide us towards its conservation, increasing productivity and nutritional composition. Therefore, in this study, we carried out the genomic characterization of 50 phenotypically variable accessions by using SSR markers in the erstwhile States of Jammu and Kashmir to reveal genetic variability among accessions and their genetic associations. The genetic parameter results revealed that the number of alleles per locus (Na) ranged from 1 to 6 with a mean Na value of 3.89 and the mean effective number of alleles (Ne) per locus 1.882 with a range of 1.22 to 2. Similarly, the polymorphic information content (PIC) values ranged from 0.464 to 0.104. The observed heterozygosity (Ho) (0.547) was found to have higher than expected heterozygosity (He) (0.453) with average heterozygosity of 0.4483. The dendrogram clustered genotypes into three main clades based on their pedigree. The population structure revealed IV sub-populations with all admixtures except the III sub-population, which was mainly formed of exotic cultivars. The average expected heterozygosity (He) and population differentiation within four sub-populations was 1.78 and 0.04, respectively, and explained 95.0% of the total genetic variance in the population. The results revealed that the SSR marker studies could easily decrypt the genetic variability present within the germplasm, which may form the base for the establishment of good gene banks by reducing redundancy of germplasm, selection of parents for any breeding program.

Alcohol Acyltransferase Is Involved in the Biosynthesis of C6 Esters in Apricot (Prunus armeniaca L.) Fruit

Short-chain esters derived from fatty acid contribute to the characteristic flavor of apricot fruit, and the biosynthesis of these compounds in fruit is catalyzed by alcohol acyltransferase (AAT). In this work, we investigated the AAT gene family via genome-wide scanning, and three AAT loci were identified in different linkage groups (LGs), with PaAAT1 (PARG22907m01) in LG7, PaAAT2 (PARG15279m01) in LG4, and PaAAT3 (PARG22697m01) in LG6. Phylogenetic analysis showed that PaAAT1 belongs to clade 3, while PaAAT2 and PaAAT3 belong to clade 1 and clade 2, respectively. In contrast, the three AAT genes present different expression patterns. Only PaAAT1 exhibited distinct patterns of fruit-specific expression, and the expression of PaAAT1 sharply increased during fruit ripening, which is consistent with the abundance of C4–C6 esters such as (E)-2-hexenyl acetate and (Z)-3-hexenyl acetate. The transient overexpression of PaAAT1 in Katy (KT) apricot fruit resulted in a remarkable decrease in hexenol, (E)-2-hexenol, and (Z)-3-hexenol levels while significantly increasing the corresponding acetate production (p < 0.01). A substrate assay revealed that the PaAAT1 protein enzyme can produce hexenyl acetate, (E)-2-hexenyl acetate, and (Z)-3-hexenyl acetate when C6 alcohols are used as substrates for the reaction. Taken together, these results indicate that PaAAT1 plays a crucial role in the production of C6 esters in apricot fruit during ripening.

Effect of Spraying With Cal-Boron and Potassium Humate and Maturity Stage on Fruit Quantity, Quality Characteristics of Apricot Prunus Armeniaca L. cv. "Royal"

This study was conducted on apricot trees Royal cultivar 9 years old in a private field located northern Kirkuk city - Iraq during The period 2020-2021, to study the spraying whit Cal-boron and potassium humate on fruit quantity, quality characteristics of apricot with three levels of Cal-boron (0, 1and 2) ml.L-1 and three levels of potassium Humate (0, 3 and 6) g.L-1. In addition to the control treatment (untreated plants). Combination of 2 ml.L-1 Cal-boron and 3 g.L-1 of Potassium humate excelled on leaf area Leaves content of chlorophyll, Vitamin C, and T.S.S. parameter compared with treatment with distilled water (control). A Randomized Complete Block Design (R.C.B.D) was used to implement the experiment, with three replications.