Papaya is a tropical crop increasingly cultivated in the greenhouses of subtropical regions such as South East Spain, where the determination of the best planting season is important to ensure a stable fruit production and quality during the year. In this work, we studied plant growth, yield, and fruit quality, comparing spring and autumn planting seasons in ‘Intenzza’ cultivar. The results showed that planting in spring favors plant growth, leading to an earlier entry into production. Total yield and fruit quality were similar in both planting seasons, although the spring cycle provided higher profits due to greater commercial yield and lower discards. Our results confirm that adverse environmental conditions affect the crop in a similar way regardless of the planting season, so different growing cycles are not very useful for filling the production gaps and fighting against seasonality in our region, unless unfavorable climate conditions are avoided inside the greenhouse.

Relationships between plant water status and gas exchange parameters at increasing levels of water stress were determined in Algerie loquats which grown in 50 I pots. Changes in soil water content and stem water potential and their effects on stomatal conductance (G s) and net photosynthesis (P n) rate were followed in control plants and in plants without irrigation until the latter reached near permanent wilting point and some leaf abscission took place. Then, the irrigation was restarted and the comparison repeated. Soil water content and stem water potential gradually diminished in response to drought reaching the minimum values of 0.9 mm and-5.0 MPa, respectively, 9 days after watering suspension. Compromised plant water status had drastic effects on G s values that dropped by 97% in the last day of the drought period. P n was diminished by 80% at the end of the drought period. The increasing levels of water stress did not cause a steady increase in leaf temperature in non-irrigated plants. Non-irrigated plants wilted and lost some leaves due to the severity of the water stress. However, all non-irrigated plants survived and reached similar P n than control plants just a week after the irrigation was restarted, confirming drought tolerance of loquat and suggesting that photosynthesis machinery remained intact.

The main objective of this work was to determine the optimum level of pruning in pitaya. In addition, we want to establish the relationship between pruning levels and the intensity of flowering, and between flowering levels and heavy flower bud drop that affects this species. With these aims, two experiments were performed on Hylocereus undatus [(Haw.) Britton and Rose] cultivated in greenhouses and trained in a trellis system. Our results conclude that cane pruning leaving 15 cladodes per meter in a trellis system is the most productive, as it yielded more fruit of similar weight. Positive relationships between flowering and setting, regardless of pruning levels, justify less severe pruning. Fruit set and size did not depend on pruning levels, although we found a fruit weight reduction when a single cladode developed more than one fruit. Flower buds drop was proportionally higher in cladodes forming more flowers, suggesting that bud competition plays a role in their drop. However, flower bud thinning seems unnecessary, although if a flower is to be chosen, it is better to select those formed at the apex of the cladode since they produce larger fruits.

Papaya (Carica papaya L.) is one of the few fruit crops still propagated by seeds. However, its trioecious condition and the heterozygosity of the seedlings make urgent the development of reliable vegetative propagation procedures. In this experiment, we compared, in a greenhouse sited in Almería (Southeast Spain), the performance of plantlets of ‘Alicia’ papaya originated by seed, grafting, and micropropagation. Our results show that grafted papayas were more productive than seedlings papayas (7% and 4% for total and commercial yield), while in vitro micropropagated papayas were the least productive (28 and 5% less in total and commercial yield than grafted papayas, respectively). Root density and dry weight were both higher in grafted papayas, while the seasonal production of good quality, well-formed, flowers was also enhanced in grafted papayas. On the contrary, micropropagated ‘Alicia’ plants yielded less and lighter fruit despite these in vitro plants blooming earlier and setting fruit at desirable lower trunk height. Less tall and less thick plants and reduced production of good quality flowers might explain these negative results. In addition, the root system of micropropagated papaya was more superficial, while in grafted papayas, the root system was larger and had more fine roots. Our results suggest that the cost-benefit ratio does not favor the choice of micropropagated plants unless elite genotypes are used. On the contrary, our results encourage more research on grafting, including the search for suitable rootstocks for papaya.