Assessment of Genetic Diversity for Yield and its Attributing Traits in Tomato (Solanum lycopersicum L.) Genotypes for Protected Conditions

Background: Tomato plant has high yield potential, although the yield is very low because of non-availability of superior cultivars for protected cultivation. Presence of diversity is an important for variety development. Hybridization among divergent parents is probably produce ample variability and helps to isolate superior recombinants. So, the study was carried out to assess of genetic diversity in tomato for choosing promising and genetically diverse parents for improvement in yield for protected cultivation. Methods: Fourteen genotypes of tomato were planted inside naturally ventilated polyhouse during September 2018 to May 2019. The data were recorded for twenty-one characters from randomly five tagged plants from each genotype and genetic diversity was computed by utilizing Mahalanobis D2 analysis. Result: All genotypes were arranged into five highly divergent clusters in which cluster I contain maximum genotypes followed by cluster II. The intra cluster distance was highest in cluster I and inter-cluster distance was highest among cluster-II and V. Cluster means indicated that cluster II had high mean values for maximum traits. The highest contribution towards genetic diversity was shown by fruit yield/plant followed by number of fruits per plant. Based on breeding objectives, potential lines are selected as parents for utilization in hybridization programme.

Evaluating the Potential of Protected Cultivation for Off-Season Leafy Vegetable Production: Prospects for Crop Productivity and Nutritional Improvement

The effects of different protective structures on horticultural and nutritional yield of amaranth and water spinach were studied in three seasons of 2020–2021 in Taiwan. The number of people that can receive recommended dietary intake of iron and β-Carotene from vegetables grown under different production conditions was also estimated. The yield of white and red amaranths was consistently better (7.68–19.70 t/ha) under pink poly-net house in all the seasons, but the yield of water spinach was consistently better under white poly-net house (16.25–20.88 t/ha). Spider mite (fall & spring) and aphid (winter) infestation was mostly observed on all crops under poly-net houses. Neoxanthin, lutein and β-carotene were almost two-fold higher in red amaranth harvested from poly-net houses than open field. Based on the RDI values, β-Carotene supply to both men and women (14+) was consistently higher in all crops produced under pink ploy-net houses in all seasons, except for white amaranth produced under white poly-net house during winter. Its supply to 64,788 more men and 83,298 more women was estimated for red amaranth harvested from pink poly-net house than other production conditions. α-carotene was 2–3 fold higher in amaranths and water spinach harvested from poly-net houses than open field. The iron content of the amaranths was lower in poly-net houses (234.50–574.04 g/ha) than open field (645.42–881.67 g/ha) in the fall, but its supply from pink poly-net house was comparable with open field in the winter. However, pink poly-net house was the highest iron supplier from water spinach (323.90 g/ha) in the winter, which was estimated to provide iron to 19,450–22,939 more men and women than other production conditions. Both poly-net houses were the sole supplier of iron through amaranths in the spring, with pink poly-net house supplying iron to 2,000–5,000 more men and women. Thus, protected cultivation not only leads to more marketable yields but also results in higher quantities of health promoting nutrients. Hence, pink poly-net house may be considered to produce more nutritious vegetables, especially during the off-season to bridge the gaps in the seasonal variations in vegetable consumption, besides providing better income opportunities to the smallholder farmers.

The Transcriptome and Metabolome Reveal Stress Responses in Sulfur-Fumigated Cucumber (Cucumis sativus L.)

Sulfur (S) fumigation is a commonly used sterilization method in horticultural facilities against fungal diseases. S fumigation damaged cucumber leaves, although the response mechanism is unclear. This study analyzes the growth, transcriptome, and metabolomic profiles of young and mature leaves, ovaries, and commercial cucumber fruits to decipher the mechanism of cucumber stress response under S fumigation. S fumigation significantly changed the photosynthetic efficiency and reactive oxygen species (ROS) in leaves, but not fruit development, fruit mass, and peel color. Transcriptome analysis indicated that S fumigation strongly regulated stress defense genes. The weighted gene co-expression network analysis revealed that S fumigation regulated ASPG1, AMC1 defense genes, LECRK3, and PERK1 protein kinase. The abscisic acid (ABA)-mediated model of regulation under S fumigation was constructed. Metabolome analysis showed that S fumigation significantly upregulated or downregulated the contents of amino acids, organic acids, sugars, glycosides, and lipids (VIP > 1 and P-value < 0.05). The opposite Pearson’s correlations of these differential metabolites implied that cucumber had different metabolic patterns in short-term and long-term S fumigation. Besides, the elevated levels of proline and triglyceride indicated that stress-responsive mechanisms existed in S-fumigated cucumber. Moreover, the comprehensive analysis indicated that S fumigation elevated secondary S-containing metabolites but decreased sulfate absorption and transportation in cucumber. Overall, our results provided a comprehensive assessment of S fumigation on cucumber, which laid the theoretical foundation for S fumigation in protected cultivation.

Root-Knot Nematodes a Major Peril to Protected Cultivation System in India: Current Status and its Management

Growing of vegetable crops under protected conditions are relatively, an innovative technology and most popular among farmers throughout the country. In last few decades protected cultivation has shown potential enhancement in horticultural production. The southern root-knot nematode, Meloidogyne incognita, is an emerging nematode under protected conditions. This nematode can cause chlorosis, stunting and reduce yields associated with the induction of many root galls on host plants. Root-knot nematode severely affect the plant root system by inducing specialized feeding cells i.e., giant cells in the vascular tissues. Recently, this nematode has been considered as a worldwide menace for combat root-knot nematodes, integrated nematode management strategies such as soil solarization, biological control, organic amendment, crop rotation, field sanitation, and fumigants have been developed and successfully used in the past. Here, in this book chapter discussed on biology and life cycle, control measures and proposed future strategies to improve Megalaima incognita management under protected conditions.

Influence of different protected cultivation structures on performance of cucumber (Cucumis sativus L.) in Indian hot arid region

The performance of gynoecious cucumber (cv. Terminator) was evaluated under three protected structures viz., naturally ventilated polyhouse (NVP), insect proof net house (INH) and shade net house (SNH) at Jodhpur, Rajasthan in hot arid region of India. The photosynthetically active radiation (PAR) inside these structures during cropping period ranged from 154-842 μmol m-2 s-1 which was much lower than the outside. Among structures, air temperature was 1.2°C and 0.7°C lower while relative humidity (RH) was 17 and 4 per cent higher in NVP and SNH respectively as compared to INH. Relatively low air as well as soil temperature, coupled with high RH and optimal radiation in NVP led to better plant growth and physiological activity which resulted in 42 and 142per cent higher yield than INH and SNH, respectively. Hence, it can be recommended that NVP is the best low-tech protected structure which modifies the microclimate favouring successful cultivation of greenhouse cucumber in Indian hot arid regions.