The Role of Nitrate in the Osmotic and Nutritional Control of Plant Development

Abstract

I postulate that certain of the effects of nitrate on plant development are mediated by the combination of an osmotic effect on water uptake and a nutritional effect on protein synthesis. This hypothesis is discussed with reference to effects on seed germination, apical dominance, lateral root initiation, flowering and leaf senescence. The postulated osmotic effect of nitrate is consistent with the well-established role of both nitrate and reduced forms of N as major osmotica in plant cells, and also with the similarity and interaction between developmental effects of nitrate and water. Evidence of the nutritional component of developmental effects of nitrate is provided by a comparison of responses induced by nitrate and by other osmotica of less nutritional significance. Carbohydrate has also been reported to influence development by a combination of osmotic and nutritional effects. The proposed hypothesis is a unifying concept which provides a similar physiological explanation for a wide range of diverse developmental responses that are usually attributed to the effect or interaction of different hormonal factors.

Influence of sulfur and nitrogen supply on growth, nutrient status and concentration of benzyl‐isothiocyanate in cress (Lepidium sativum L.)

“…The N supply has frequently been shown to increase the water content, which is related to the contribution of accumulated nitrate and accompanying cations (mostly K + ) to the osmotic potential. 12 However, this effect on the water homeostasis was not observed in the current experiment (results not shown).…”

TheArabidopsisATNRT2.7 Nitrate Transporter Controls Nitrate Content in Seeds

“…This prompts us to propose that, rather than a nutritional function in seed maturation, this nitrate plays either a signaling or osmotic role during the first steps of imbibition. The role of nitrate in the osmotic control of plant development has already been suggested (McIntyre, 1997). In barley seeds, exogenous nitrate increased water uptake by the seedling (Lieffering et al, 1996).…”

Effect of fertilizer application on photosynthesis and oil yield of Jatropha curcas L.

“…Ma et al (1997) suggested that the delay in flowering time could be due to the slower leaf emergence, as the nonfertilized plants had lower growth rate. However, the mechanisms underlying the flower induction effect had not been determined, although some studies proposed that N and carbohydrate may contribute to floral induction by an osmotic effect on water uptake (McIntyre 1997).…”