This study aimed to assess the morphological and physio-biochemical responses of a commercial watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) cv. ‘Crimson Sweet’ grafted onto a drought-tolerant rootstock of wild watermelon (bitter apple, Citrullus colocynthis (L.) Schrad, ‘Esfahan’) in comparison with an ungrafted ‘Crimson Sweet’ watermelon or one grafted onto a commercial interspecific Cucurbita hybrid (Cucurbita maxima Duch. × Cucurbita moschata Duch.) rootstock (‘Shintoza’) under water stress. The experiment was conducted in pots under a controlled environment in a greenhouse, and water stress was imposed by maintaining moisture level in pots at 100% (well water (WW)) or 50% (water deficit (WD)) of container capacity (CC). WD significantly decreased most of the morphological traits in ungrafted and grafted plants, while the decrease in growth traits was lower in grafted plants than ungrafted plants. The response of grafted plants onto wild watermelon rootstock (‘Esfahan’) for most of the affected parameters (shoot fresh and dry weight, vine length and internodal length) was, however, comparable to those grafted onto commercial Cucurbita hybrid rootstock (‘Shintoza’). Plants grafted onto bitter apple (wild watermelon) exhibited a relatively lower decrease in growth and biomass, besides showing higher antioxidant activity (e.g., guaiacol peroxidase) concomitant with the lower accumulation of malondialdehyde and electrolyte leakage in the leaf tissues in comparison with ungrafted plants. The overall growth performance, as well as those under water stress conditions in commercial rootstock-grafted watermelon, was related to its better plant water status (e.g., high relative water content) which was likely ascertained by its greater root efficiency. This suggests that watermelons grafted onto bitter apple rootstock and Cucurbita hybrid rootstock were constitutively more resistant to drought, with higher efficiency in mitigating oxidative stress than ungrafted treatment. The above findings demonstrated that bitter apple, a well-adapted desert species, can be used as an alternative rootstock to commercial rootstocks (e.g., ‘Shintoza’) for watermelon grafting under water stress conditions. In addition, bitter apple rootstock can be involved in rootstock breeding programs to improve drought tolerance in watermelon.

Nowadays the importance of selenium for human health is widely known, but most of the plants are poor in terms of selenium storage and accumulation because of the low selenium mineralization potential of the soil. For this purpose, foliar application of different sodium selenate concentrations (0, 5, 10, 15, 20 mg/L) was used to treat the cauliflower cultivars “Clapton” and “Graffiti”. Higher yields and other related vegetative attributes were improved at 10 and 15 mg/L sodium selenate application. At a concentration of 10 mg/L sodium selenate, photosynthetic pigments, total phenolic compounds and antioxidant capacity were enhanced in both cultivars, but the “Graffiti” cultivar responded stronger than the “Clapton” cultivar. The glucosinolates were accumulated in response to selenium fortification and the highest amounts were found in the “Graffiti” cultivar at 10 mg/L. Selenium accumulated concentration-dependently and rose with higher fertilization levels. In general, foliar application of selenium at 10 mg/L led to an accumulation of secondary metabolites and also positively affected the growth and yield of florets.

Water deficiency is an environmental factor affecting crop yield especially in arid and semiarid regions. It is necessary to improve water use efficiency in watermelon (Citrullus lanatus Thunb), a high-water requiring crop. The edible accessions, “TN-94-766,” “TN-94-769,” “TN-94–545,” “TN-94-485,” and “Crimson Sweet,” and the wild-type Colocynth were treated with the irrigation regimes of 100%, 80%, 60%, or 40% of soil available water. In all accessions, leaf area and shoot length decreased and root length increased as water availability decreased up to 40% AW. Colocynth had long shoots and roots, and high ascorbate peroxidase activity, and exhibited high resistance to water deficit. Yield of Colocynth exposed to severe water-deficit level was not changed. The edible accession “TN-94-766” was the most tolerant to water deficit having longer roots, more total fruit yield, and higher catalase and guaiacol peroxidase activities at 60% AW.

Climate and planting system can affect crop responses and morphological and physiological characters. Evaluation of genetic variation in crops provides useful information about trait affinity and helps to conserve and protect germplasm. Genetic and phytochemical diversity of pumpkin accessions were evaluated to identify characters in the selection of parents for future breeding. Comparison was made to three accessions of naked seed and 11 accessions of true seed involved C. pepo, C. moschata and C. maxima Duch were planted in May 2012. At ripening stage fruit were harvested and analyzed for fruit and seed morphological characters. Cluster analysis divided accessions into six main groups mainly on fruit and seed characters. The seed oil contains the unsaturated fatty acids oleic acid and linoleic acid. The maxima accessions were placed in a separate group. For those with naked seed, the Khomein accession had higher seed weight than other naked seed types. The Chaloos C. moschata accession was best based on fruit and seed characters and amounts of saturated and unsaturated fatty acids, and an accession from Isfahan had the highest content of oleic acid, a valuable nutritional component of seed. Seed width, fruit width, seed cavity diameter, and fruit weight and length were appropriate for improvement through breeding to enhance seed quality.

Rind color in melon is one of the major fruit attributes at harvest and postharvest during the storage period. Since commercially available chromameter results are expressed as the average values of few chosen points, these results may be inaccurate when representing the whole surface color of a large fruit such as melon. This research aimed to develop a portable and low-cost chromameter system to measure the color parameters of melon rind in CIELAB color space at harvest and calculate color changes after cold storage period using image analysis method. For this purpose, an imaging box with appropriate hardware was designed. A mobile phone was used to acquire the images. The utilized camera was standardized with a standard color chart. The obtained images were processed using ImageJ processing software. To evaluate the proposed system, the rind color parameters of 36 different melon genotypes were recorded using both the developed system and a standard chromameter device. A multivariate linear regression (MLR) correlation for each color component was extracted. The coefficients of determination (R2) for the regression models were 93.1%, 99.5%, and 99.9% for L, a, and b, respectively. After adjusting the image results according to the obtained models, Mann–Whitney test showed no significant differences in any of the color parameters (L, a, or b) between the developed system and the values recorded by the chromameter. The developed chromameter system has also shown a convenient ability to measure rind color changes even without data adjustment. Therefore, this system can be considered a valid alternative color measurement device, especially in postharvest research.