Environmental variables influence the developmental stages of the citrus leafminer, infestation level and mined leaves physiological response of Kinnow mandarin

Morpho-physiological and biochemical characterization of Kinnow (Citrus reticulata) in response to canker pathogens (Xanthomonas axonopodis pv. citri)

Fruits play an important role in human life on our planet, since they supply a variety of essential services. One of the paramount crops in Pakistan is Citrus reticulata (Kinnow), which plays a vital role in the country's economy. The citrus crops are confronted with various challenges such as fungi, bacteria, nematodes, and viruses, all of which have adverse effects on the quality and yield of the fruits. Citrus canker, in particular, stands as the most fatal disease, affecting numerous citrus species worldwide, inflicting devastating consequences. The objective of this study was to evaluate the impact of citrus canker on the morphology, physiology of leaves, and the quality of citrus fruits. The research was conducted in four major citrus-producing tehsils of the Sargodha district. The study found significant differences in morphological and physiological traits between healthy fruits and those infected with citrus canker. Healthy fruits exhibited higher values in fruit weight (FW) of 149.02 g, peel thickness (PT) of 3.76 g, rag weight (RW) of 35.95 g, leaf area (LA) of 22.49 cm2, and juice weight compared to the citrus canker-infected fruits. The significant variations in fruit weight, juice weight, chlorophyll content, vitamin C content were present between healthy and diseased fruits and leaves. A biochemical study revealed that healthy fruits had greater levels of total soluble solids (TSS), TSS-acid ratio, vitamin C, and reducing power (RP), but citrus canker-infected fruits had a higher acidity percentage. The significant decreases in important morphological and physicochemical characteristics, emphasizing the necessity for immediate disease control techniques to safeguard the citrus sector and maintain food security.

Comparative mineral and biochemical characterization of Citrus reticulata fruits and leaves to citrus canker pathogens, Xanthomonas axonopodis

Pakistan's economy greatly benefits from citrus production since these fruits are sold and consumed all over the world. Although citrus fruits are easy to cultivate, they are susceptible to diseases caused by bacteria, viruses, and fungi. These challenges, as well as difficulties in obtaining the proper nutrients, might negatively impact fruit yields and quality. Citrus canker is another complicated problem caused by the germ Xanthomonas axonopodis. This germ affects many types of citrus fruits all over the world. This study looked closely at how citrus canker affects the leaves and the quality of the fruit in places like Sargodha, Bhalwal, Kotmomin, and Silanwali, which are big areas for growing citrus in the Sargodha district. What we found was that plants without the disease had more chlorophyll in their leaves compared to the sick plants. Also, the healthy plants had better amounts of important minerals like calcium, magnesium, potassium, and phosphorus in their fruits. But the fruits with the disease had too much sodium, and the iron levels were a bit different. The fruits with the disease also didn't have as much of something that protects them called antioxidants, which made them more likely to get sick. This study helps us understand how citrus canker affects plants and fruit, so we can think of ways to deal with it.

Bifunctional peptides as alternatives to copper-based formulations to control citrus canker

Citrus canker is an infectious bacterial disease and one of the major threats to the orange juice industry, a multibillion-dollar market that generates hundreds of thousands of jobs worldwide. This disease is caused by the Gram-negative bacterium Xanthomonas citri subsp. citri. In Brazil, the largest producer and exporter of concentrate orange juice, the control of citrus canker is exerted by integrated management practices, in which cupric solutions are intensively used in the orchards to refrain bacterial spreading. Copper ions accumulate and are as heavy metals toxic to the environment. Therefore, the aim of the present work was to evaluate bifunctional fusion proteins (BiFuProts) as novel and bio-/peptide-based alternatives to copper formulations to control citrus canker. BiFuProts are composed of an anchor peptide able to bind to citrus leaves, and an antimicrobial "killer" peptide to protect against bacterial infections of plants. The selected BiFuProt (Mel-CgDEF) was bactericidal against X. citri at 125 μg mL-1, targeting the bacterial cytoplasmic membrane within the first minutes of contact. The results in the greenhouse assays proved that Mel-CgDEF at 250 μg mL-1 provided protection against X. citri infection on the leaves, significantly reducing the number of lesions by area when compared with the controls. Overall, the present work showed that the BiFuProt Mel-CgDEF is a biobased and biodegradable possible alternative for substitute cupric formulations. KEY POINTS: • The bifunctional fusion protein Mel-CgDEF was effective against Xanthomonas citri. • Mel-CgDEF action mechanism was the disruption of the cytoplasmic membrane. • Mel-CgDEF protected citrus leaves against citrus canker disease.

Climate variables effect on fruiting pattern of Kinnow mandarin (Citrus nobilis Lour × C. deliciosa Tenora) grown at different agro-climatic regions

Kinnow orchards grown in different agro-ecological regions of Punjab, Pakistan, namely Sargodha, Toba Tek Singh (TTS) and Vehari districts, were selected to assess the effect of climate variables on fruit-bearing patterns. Experiment was laid out in RCBD while selecting identical features Kinnow plants and labeled twigs at analogous canopy positions in all three sites. Temperature was reported higher in TTS and Vehari areas, while relative humidity in Sargodha accounted for different levels of agrometeorological indices by computing more variations in warm districts. Climate variables influenced fruit-bearing habits and vegetative growth trend in all three flushes while recording heavy fruit-bearing plants during on-year and light fruit-bearing in off-year at Vehari. Similarly, three vegetative flushes were recorded unevenly in all three sites due to different fruit-bearing patterns induced by climate variables. Harvesting pattern of orchards began earlier in Sargodha, where maximum orchards were harvested before new flowering to add evenness to fruiting habits during on & off-years. In warm conditions, fruit ripening arrived in the peak of winter and mostly domestic market-driven harvesting resulted in late start of fruit picking with more erratic fruit-bearing habits. Both physiological and pathological fruit drops have been significantly affected by climate variables with a higher degree of physiological drop in warm regions and pathological effects in the humid conditions of Sargodha on heavy fruit-bearing plants. Fruit yield and grading quality were also affected in both seasons by showing more asymmetrical trend in yield and fruit grading in warm areas of TTS and Vehari due to an irregular fruiting pattern compared to Sargodha. From now on, the climate variables of the three sites directly influenced the fruiting patterns, vegetative flushes, fruit drops, yields and grades of Kinnow mandarin.