The Nutrient-Accumulating Dynamics during the Kernel Development in the Walnut (Juglans regia L.) Evidenced by Histochemistry

Walnut (Juglans regia) as a "Super Food" is packed with protein, fat, sugar and other nutrients that positively affect the body on a multitude of levels. The development and maturation of walnut kernel were a dynamic and complex process involving physiological, biochemical changes. Accumulation dynamics of fats, proteins, and sugars and identification where these nutrients were accumulated during the seed development of the walnut were determined. The nuts of precocious walnut cultivar 'Xiangling' were employed in this study. Semi-thin slices and histochemical localization technology were carried out and double-staining methods of PAS-Coomassie blue and PAS-Sudan Black were used. The results showed that during nutrient accumulation sugars were distributed at the cell periphery or in the intercellular space. Fats initially accumulated in the cell periphery, and gradually accumulated in the cytoplasm and formed large clumps which later occupied the whole. Proteins scattered in the cytoplasm in the form of protein particles, and changes in their numbers were consistent with the results of chemical determination. The study revealed the accumulating dynamics and the position in cell of nutrients during the walnut seed development.