Phenology and production of Hassaoui grapevines as affected by climate anomalies in Al Ahsa region.

Climate change is a dramatic crisis that has left severe impacts on viticulture. Phenological events over 41 years and annual climatic anomalies' data over these years in Al Ahsa region were procured. Annual temperature and wind speed anomalies had the strongest influence on all phenological events of the varieties White and Red Hassaoui, starting from the beginning of budburst until harvest. Moreover, the average yield of both varieties decreased significantly by 319.4 and 317 kg ha-1 respectively between 1997 and 2019 in comparison with the interval of years 1979-1996. Earlier phenological events were positively correlated with annual temperature anomaly and negatively correlated with annual wind speed anomaly. The latter shortened the dates of occurrence of beginning and full veraison. Yield decreased with higher annual temperature, wind speed and total cloud cover anomalies, and lower annual total precipitation anomaly. Higher annual temperature and wind speed anomalies were correlated with a shorter period between beginning of budburst to beginning of veraison (P3). Shorter periods between beginning and full veraison (P6) and beginning of veraison and harvest (P7) of Red Hassaoui were positively correlated with annual precipitable water anomaly. Results suggest a high level of adaptation of both tested varieties to changing climate conditions in Al Ahsa, though irrigating vines after harvest on a weekly basis would help overcoming the minimal reduction in yield which was caused by the shortage in precipitation.

Effect of potassium nitrate on antioxidants production of date palm (Phoenix dactylifera L.) in vitro.

Antioxidants present in dates are necessary for all physiological processes of humans and animals. In Saudi Arabia date palm is a national fruit tree, produces millions of tons of dates for consumption and is considered a major source of antioxidants. The main aim of this study was to determine the role of potassium nitrate (KNO3) in the formation of antioxidants from explants collected from date palm cultivars in Al-Ahsa Oasis, Kingdom of Saudi Arabia (KSA) and to monitor the extent of its effect on growth and development of cells during callus formation stage via somatic embryogenesis. The results showed that full concentration of KNO3 was the best for callus formation in general. While, the half concentration of KNO3 played an important role for stimulating the explants to form phenolic compounds and the browning emergence for all the cultivars under investigation. On the other hand, the chemical analysis for measuring the phenolic compounds in the explants showed that all the explants formed antioxidants but with varying degrees. The highest mean of phenolic contents was found in those explants cultured with the half concentration of KNO3 for Shishi cv 2.053 ± 0.010a mg g(-1) and antioxidant activity by ABTS Inhibition and UM Trolox was 80.694 ± 0.439 and 801.575 ± 2.391, respectively.