Interactive effects of gibberellic acid (GA3) and salt stress on growth, biochemical parameters and ion accumulation of two rice (Oryza sativa L.) varieties differing in salt tolerance

Exogenous application of different plant growth regulators has raised some concern for improving quality and quantity of yield in different crops especially under unfavourable conditions. Rice (Oryza sativa L.) is an important crop in the world and salinity is one the main abiotic stress factor affecting its productivity. To determine genotypic and ontogenetic variations of different physiological activities including water and nutrient uptake during salinity and effectiveness of exogenous GA3 application on those parameters, two different rice varieties (Pokkali and MR219) were cultivated under controlled environment using five different salinity levels (0, 50, 100, 150 and 200 mM NaCl) and with or without application of GA3 (150 ppm foliar spray). A remarkable reduction in grain yield (even no grain formation at higher salt concentration) in both rice varieties was observed during our observation. Rice variety MR219 was less competitive than Pokkali under salinity while exogenous application of GA3 is useful to mitigate salinity stress in rice as it increased different yield components and yield (8.7% in MR219 and 16.7% in Pokkali). Considering the trends of growth reduction due to salinity and progressive impact of exogenous GA3 application on different morphological, physiological and biochemical activities, it can be stated that application of GA3 is useful to mitigate salinity stress and its effectiveness is more active to salt tolerant varieties

Genetic diversity of Libyan date palms cultivars using amplified fragment length polymorphism and biochemical analysis

Phoenix dactylifera L. is a flowering plant species commonly known as the date palm and is widely cultivated in most Middle East countries, including Libya. The present study analysed the biochemical and genetic diversity of fully mature eight Libyan date palm cultivars grown in different regions using the amplified fragments length polymorphism (AFLP) technique. Six pairs of AFLP molecular marker combinations were utilised to discriminate the eight date palm genotypes. Fruit dimensions (length x diameter) varied based on the type; Majhool Alheelo fruit had the highest value (15.29 cm2), while the lowest value was for Alkhadraya fruits (7.9 cm2). Reducing sugar content ranged from 10.4 per cent of flesh dry weight in Umfetity cultivars to 61.2 per cent in Sufeer-genab, which also showed the highest polymorphism percentage (P%=4.9), while Alkhadarya was the lowest (P%=0.519). The phylogenetic tree indicated that the most distantly related cultivars were Sufeer-genab, Alhamraya and Majhool Alhelo. The two most closely related cultivars were the Alsaeedy Show and Alkhadarya, grown in different regions. Our results indicate that the nutritional and genetic diversity of Libyan cultivars is not closely matched with the growing region