‘Patharnakh’ (Pyrus pyrifolia Burm.) (PN), a hard pear and ‘Punjab Beauty’ (Pyrus communis L. × Pyrus pyrifolia Burm.) (PB), a soft pear are dominant low-chill pear cultivars of subtropics of India. Present investigation reports the changes in sugar metabolism and related enzymatic activities in fruits of ‘PN’ and ‘PB’ cultivars harvested at different developmental stages from 45 to 150 days after fruit set. Total soluble sugars, fructose, and sucrose contents were higher in ‘PB’ as compared to ‘PN’ during fruit growth and maturation stages. Total phenols and flavanols increased initially and then showed a decreasing trend towards maturity. Sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities strongly correlated to sucrose content in ‘PN’ but SPS was weakly related in ‘PB’ fruits. Acid and neutral invertases showed a negative correlation with sucrose content in ‘PN’, and a reverse trend in ‘PB’ cultivar was observed. It is concluded that SS and SPS are crucial for sucrose accumulation in ‘PN’, but invertase enzymes are also important for sucrose accumulation in ‘PB’ fruits.

Present investigation reports the variability in phenolics and activities of some enzymes involved in their metabolism in pericarp tissue of 'Calcuttia' and 'Seedless' cultivars harvested at one week interval after fruit set. Total phenolics, fl avonols, and phenolic acid contents in litchi fruit pericarp increased after 49 days following fruit set (DAFS), while proanthocyanins showed a small increment initially and then decreased signifi cantly up to maturity. Polyphenol oxidase, phenylalanine ammonia lyase, and cinnamate-4-hydroxylase activities followed the similar trend as observed in phenolic content at respective developmental stages, while peroxidase activity in pericarp was low at initial stages and increased gradually with fruit development. Higher phenolic content with low polyphenol oxidase activity in pericarp during initial stages of fruit development in 'Seedless' as compared to 'Calcuttia' cultivar suggests the slow ripening. A negative correlation between anthocyanin content and anthocyanase activity was recorded. Total phenolic constituents, ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity showed positive correlation with higher values of these parameters in 'Seedless' as compared to 'Calcuttia' cultivar. Knowing the phenolic profi les, antioxidant activity, and activity of related enzymes during fruit development gives the insights into its potential application to reduce the post-harvest browning of litchi.

In the modern era, nutraceutical properties of horticultural crops are indispensable to determine their adaptability to different agro-ecological regions. The present study exploits the potential of mulches (P: plastic mulch; S: straw mulch; N: No mulch) in relation to drip irrigation (I1: 100%, I2: 80%, I3: 60% of crop evapotranspiration (Etc)), and fertigation (F1: 100%, F2: 80%, F3: 60% of recommended dose of fertilizer (RDF): 125 kg N, 62.5 Kg P2O5, 62.5 kg K2O per ha) on Pak choi at three maturity stages in the North West region of India. Plant fresh weight was the highest at 55 days after transplanting (DAT); however, maximum soil plant analysis development (SPAD) values were registered at 45 DAT. Antioxidant activity, FRAP, DPPH, phenols, flavanols, total sugars, ascorbic acid, free amino acids, and irrigation water use efficiency were observed significantly higher in plants grown on plastic mulch at different levels of irrigation and fertigation. It is envisioned that Pak choi plants had the highest nutritional value at 45 DAT from plots mulched with silver-black, irrigated at 80% Etc, and fertigated at 100% RDF. The nutrient enriched plants are used for green salad and as ingredients for the preparation of many recipes in the semi-arid and sub-tropic areas of India.