No abstract

Local communities in southern Africa derive many benefi ts from marula [Sclerocarya birrea (A. Rich.) Hochst. subsp. caffra (Sond.) Kokwaro]. These include the contribution of this species towards health, nutrition, food security and conservation by sharing local skills and knowledge related to it. Marula fruits can be eaten fresh, squeezed to make juice, brewed in traditional beer or used to make jam and jelly. The kernels are also edible and can be pressed to extract oil for cooking and cosmetics, i.e., for skin and hair application. The bark, roots, seeds and leaves are exploited for traditional medicinal purposes. Marula has acquired signifi cant commercial value since its fruits and other products have entered local, regional and international trade in southern Africa. To diversify fruit production and satisfy the increasing demands for this resource, several domestication initiatives have been carried out at regional and international levels. The accumulated knowledge and skills relevant to the establishment and commercialization of marula therefore provide an effective guide in areas where marula remains undomesticated or underutilized. We discuss the great importance of marula in southern Africa to reveal its great potential to regions where it remains unexploited.

Photosynthetic activity is one of the most important indicators for evaluating the introduction and acclimatization of trees to new geographies. The aim of this study was to investigate the photosynthetic characteristics of marula [Sclerocarya birrea (A. Rich.) Hochst. subsp. caffra (Sond.) Kokwaro (Anacardiaceae)] and the environmental conditions relevant to its growth in China. We analyzed the diurnal dynamics of photosynthesis in two S. birrea varieties, one from South Africa and one from Israel, after introduction into China using a portable photosynthesis measuring system. Our results showed that the diurnal net photosynthetic rate (P n ) exhibited an atypical double-peak pattern that was influenced mainly by stomatal factors. Moreover, the diurnal change in stomatal conductance (G s ) was consistent with that for P n and showed an obvious double-peak curve, whereas the diurnal change in the transpiration rate (T r ) was opposite to that in intercellular CO 2 concentration (C i ), which presented a single-peak curve. The extreme values of the environmental factors we monitored occurred at approximately the same time of day and influenced photosynthesis by affecting C i , T r , and leaf temperature (T L ), with light intensity exerting an especially strong effect. The P n of the S. birrea variety from Israel was higher than that of the S. birrea variety from South Africa, while South Africa S. birrea exhibited superior growth trait in southern China. We suggest that the photosynthetic performance of S. birrea can be acclimated to a new environment.

In order to identify the relationship between diurnal changes in the net photosynthetic rate (P n ) of Pueraria lobata and environmental factors, diurnal changes in the P n of leaves of two P. lobata cultivars were measured using a CIRAS-1 portable photosynthesis measurement system (PP-Systems, UK). The results show that diurnal changes in P n of both cultivars could be interpreted as double-peak curves, indicating the occurrence of an obvious midday depression. Further analyses indicate that the correlation between P n and stomatal conductance was positive and extremely signifi cant (p < 0.01). The correlations of P n with intercellular CO 2 concentration and transpiration rate were positive and signifi cant (p < 0.05), while the correlations of P n with air and leaf temperatures were negative and signifi cant (p < 0.05). The results indicate that among the factors affecting photosynthetic properties, some can be grouped as stomatal limitations while others are non-stomatal limitations.