Aman Ullah Malik

FOLIAR APPLICATION OF ZINC INFLUENCES THE LEAF MINERAL STATUS, VEGETATIVE AND REPRODUCTIVE GROWTH, YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN

Deficiency of zinc (Zn) is widespread in many citrus orchards of Pakistan, consequently hampering fruit yield. Effects of foliar applications of zinc sulfate on tree nutrition, growth, productivity and fruit quality were studied on ‘Kinnow’ mandarin. Leaf nitrogen (N), calcium (Ca), and manganese (Mn) were highest for trees sprayed with 0.2% zinc sulfate, while phosphorus (P) and iron (Fe) were highest with 0.6% zinc sulfate and potassium (K) and Zn were highest with 0.8% Zn sulfate applications. Trees sprayed with 0.6% zinc sulfate exhibited highest increase in height, crown width and stem girth, fruit diameter, fruit weight, ascorbic acid contents, and total phenolics compared to all other treatments. Pre-harvest fruit drop was lowest and total number and weight of fruit per tree was highest at harvest with 0.4% zinc sulfate application. In conclusion, foliar application of zinc sulfate up to 0.6% improved tree mineral nutrients, growth, and productivity with better fruit quality in ‘Kinnow’ mandarin.

FOLIAR APPLICATION OF BORON INFLUENCES THE LEAF MINERAL STATUS, VEGETATIVE AND REPRODUCTIVE GROWTH, YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN (CITRUS RETICULATA BLANCO.)

The effects of foliar application of boron (B) in the form of boric acid on vegetative and reproductive growth, yield and fruit quality of ‘Kinnow’ mandarin (Citrus reticulate Blanco.) were investigated. Kinnow mandarin was sprayed with different concentrations of boric acid viz. (0.1%, 0.2%, 0.3% and 0.4%) at fruit set stage. Leaf nitrogen (N), phosphorus (P), potassium (K), B, and zinc (Zn) along with flush length, tree height, tree spread and tree trunk diameter increased, while leaf length and leaf age showed non-significant results after foliar B application. Yield of the ‘Kinnow’ mandarin was significantly affected by foliar application of B and a significant increase in fruit weight at harvest was also observed. Soluble solid concentration (SSC): titratable acidity (TA) ratio, ascorbic acid, total sugars, total phenolic content (TPC) and total antioxidants significantly affected, while pH of juice, SSC, TA, reducing sugars and non-reducing sugars showed non- significant results.

Toxin production by Fusarium solani from declining citrus plants and its management

The core purpose of this current research was to meticulously survey four tehsils of Sargodha district and to probe the present status of citrus decline in infected citrus orchards. The utmost fungi (39.52%) were secluded from the roots followed by the soil (38.86%). The highest Fusarium sp. followed by Aspergillus, Phytophthora, Pythium, Penicillium and Alternaria species were remote from the collected samples of roots and soil from the four tehsils of Sargodha district of Pakistan. The maximum Fusarium sp. was isolated from the roots of declining citrus trees from tehsil Bhalwal (68.57%) followed by Kot Momin (65.87%), Sillanwali (55.87%) and Sargodha (50.32%). Toxin studies were also carried out using thin layer chromatography which revealed that F. solani produces toxins (anhydrofusarubin) which may cause decline in citrus. In vitro effect of fungicides on the mycelial growth rate of Fusarium solani exposed aliete to be more effective at 50 and 100 ppm, respectively. Ridomil Gold and Dithane M-45 showed same effect while Deconil showed least effect. Key Words: Citrus, citrus decline, Fusarium solani, toxin, Anhydrofusarubin, aliete.

Combined Application of Boron and Zinc Influence the Leaf Mineral Status, Growth, Productivity and Fruit Quality of ‘Kinnow’ Mandarin (Citrus nobilis Lour × Citrus deliciosa Tenora)

The deficiency of mineral nutrients, particularly of boron (B) and zinc (Zn) in many citrus orchards of Pakistan affect yield and quality. Effect of foliar application of B and Zn on leaf mineral nutrients, growth, productivity, and quality of ‘Kinnow’ were studied. Trees were sprayed with 37 mM boric acid and 49 mM zinc sulfate either alone or in combination at fruit setting stage or fruit setting and pre-mature stages. Leaf phosphorus (P), potassium (K), B, and Zn were significantly increased with treatments. Lowest fruit drop and maximum fruit weight and number, highest level of ascorbic acid, and reducing sugars were recorded in the trees sprayed with combine application of B and Zn at fruit set stage. In conclusion, combined application of B and Zn at fruit setting stage can be used effectively to increase nutrient uptake, reduce fruit drop, and increase yield with better quality of ‘Kinnow’ mandarin fruit.

First Report of Alternaria alternata Causing Postharvest Fruit Rot of Jujube in Pakistan

Jujube (Ziziphus mauritiana Lamk), commonly known as “ber,” is a minor fruit in Pakistan that is cultivated on an area of 5.129 ha. In January 2017, severe fruit rot disease was observed in several markets located in the Faisalabad (31°25′15.7620″N, 73°5′21.4584″E) district of Punjab-Pakistan, with disease incidence ranging from 15 to 26%. Initially, small, oval, light to dark brown lesions (1 to 3 mm) were observed on the fruit surface, which gradually enlarged in size and led to total fruit rot. To isolate the pathogen, small tissue segments were cut from rotted fruit, surface disinfected with 1% NaClO for 2 min, rinsed three times in sterilized distilled water, air dried, and then placed aseptically onto potato dextrose agar (PDA) medium. Tissue samples were cultured at 25°C under a 12-h light/dark photoperiod for 3 days. Isolates were transferred to fresh PDA medium and cultured for 7 days. The cultured isolates consistently yielded dark brown to black colonies (85% isolation rate from 40 fruit tissues). Conidiophores were short, septate, 20 to 52 μm long, and 1 to 3 μm wide. Conidia were in chains (average conidial dimension 20 to 28 × 8 to 10 μm), brown and ovoid, with a short conical beak with both transversal (two to five) and longitudinal (one to three) septa. Based on morphology, the pathogen was identified as Alternaria alternata (Simmons 2007). To confirm the identification, genomic DNA was extracted and amplified using ITS1/ITS4 primers (White et al. 1990) and endopolygalacturonase gene using primers PG3/PG2b (Andrew et al. 2009). The resulting sequences were deposited in GenBank (accession nos. KY859867 and MF371420). BLAST analysis showed 99 to 100% homology to A. alternata sequences KJ957793 and AY295025 isolated from Korea and the United States, respectively. Pathogenicity tests were conducted on 20 surface-sterilized jujube fruit (cultivar Dilbhar) by spraying them with a conidial suspension (10⁶ conidia/ml) using a handheld sprayer. Ten fruit inoculated with sterile water served as a non-treated control. Fruit samples were kept in a moist chamber at 25°C and 70 to 80% relative humidity with a 12-h photoperiod. After 2 to 3 days of inoculation, all fruit displayed small, light to dark brown lesions followed by rotting. Reisolations from symptomatic fruit consistently yielded a fungus identical to A. alternata. Control fruit remained disease-free. Fruit rot of jujube caused by A. alternata has been reported in India and China (Wadia and Manoharachary 1980; Wang et al. 2009). To our knowledge, this is the first report of A. alternata causing postharvest fruit rot of jujube in Pakistan. The disease could represent a threat to jujube cultivation.

Adaptive significance of within-site variation in morphological and reproductive traits of naturalized wild radish (Raphanus raphanistrum) populations in South-Western Australia

Genotypic variation between and within populations of the outbreeding wild radish (Raphanus raphanistrum L.), was studied using seeds collected from 55 sites across the West Australian wheat belt along 2 transects in December 1999 and February 2000. The seeds were grown at the University of Western Australia field station at Shenton Park, Perth, WA over the 2000 growing season, and 14 morphological and phenological characters were scored. A high degree of variation was present in all traits, and within site variation was greater than between sites. The greatest variation was recorded in the reproductive traits such as time to flowering, seed weight, and pod weight. Variation between sites was associated with geo-clusters based primarily on rainfall and temperature. Populations from sites with a high annual rainfall and low average temperature had longer and wider pods, larger seeds and pods with more segments, compared to populations from sites with a low annual rainfall and a high average temperature. These plants also tended to flower later than those from hotter, drier sites. The results show that wild radish in the wheat-belt of Western Australia has formed genotypically distinct populations in the 150 years since it was introduced, that are adapted to the climate at the site of collection.

Locality and Orchard Management Influence Fruit Quality of Low Temperature Stored Mangoes

To investigate the impact of locality and orchard management on fruit quality, ‘Samar Bahisht Chaunsa’ fruit harvested from two commercial orchards were stored at 11°C and 80%–85% RH for 4 weeks. Physical fruit quality, fruit rot, and disorders were not influenced by locality. However, at the ripe stage, fruit harvested from orchard-1 exhibited reduced respiration rate (5.84 mmole kg−1 h−1), higher peel color (3.35), pulp color (7.33), aroma (6.66), taste (7.33), flavor (7.33), SSC:TA ratio (139.1), reducing (4.06%), non-reducing (10.38%), and total sugar (14.99%) contents. In conclusion, quality of mango fruit following cold storage is significantly influenced by locality and orchard management.

Tree age influences nutritional, pectin, and anatomical changes in developing ‘Kinnow’ mandarin (Citrus nobilis Lour × Citrus deliciosa Tenora) fruit

ABSTRACT An understanding of variation in fruit quality in relation to tree age can help understand the issue of poor fruit quality in young orchards; however, limited information is available on the citrus fruit. In this study, the endogenous nutritional status in rind, rag, and leaves; pectin status in rind and rag; and anatomical fruit growth parameter in rind tissues were studied in ‘Kinnow’ mandarins fruit during their development on trees from three age (6-, 18-, and 35-year-old) groups. In older (35-year-old) trees, rind, rag, and leaf nitrogen (N), phosphorus (P), and potassium (K) concentrations were superior. In fruit from all tree age groups, total pectin and protopectin reduced; however water-soluble pectin (WSP) improved. In rind tissues harvested from young (6-year-old) trees, cell density was more while cell size was less. In all tree age groups, cell density in rind tissues correlated negatively with rind WSP.