ISHS Acta Horticulturae 700: International Symposium Towards Ecologically Sound Fertilisation Strategies for Field Vegetable Production
NUTRIENT EFFICIENCY OF VEGETABLE CROPS |
| Author: | M.K. Schenk |
| Keywords: | Brassica species, carrot, citrate exudation, curd quality, cytokinin, nitrogen, nutrient efficiency, phosphorus, potato, root:shoot-ratio, root hair length |
| Abstract:
The application of fertilizers involves the risk of nutrient losses to natural compartments of the environment, causing eutrophication (N, P) or pollution of the drinking water wells (N) there. One approach to reduce losses is the appropriate management of fertilizer application. Another avenue would be to consider nutrient efficiency of crops. Nutrient efficiency is generally defined as the ability of a plant to give high yield under conditions of limiting nutrient supply. This overview will discuss genotypic variation of N and P efficiency of vegetable crops. Comparison of three cauliflower F1 hybrids grown in the field revealed that N efficiency of cultivar ‘Marine’ was clearly superior. It achieved a higher percentage of class 1 curds under limiting N supply, since the downgrading of the curd quality due to N deficiency was less pronounced. Evidence is presented that this was related to cytokinin action in the plant. In pot experiments it was proven that P efficiency of cabbage was clearly higher compared to carrot and potato, a fact which was related to higher uptake efficiency. This ability of cabbage roots was caused by both long root hairs as well as root exudation of citrate. Potato had long root hairs only and carrot lacked both. However, exudation of citrate is not a general mechanism of the genus Brassica: cabbage originating from Ethiopia did not exude citrate but adapted to low P supply by increasing root hair length. With potato also, considerable genotypic differences in P efficiency were observed. In this case P efficiency was obviously related to both the amount of roots supplying a unit of shoot and root hair length. The results indicate the potential to enhance nutrient efficiency by taking the plant itself into consideration. The development of nutrient efficient cultivars would enable farmers to produce at a lower fertility level of the soil. This may be one strategy towards achieving ecologically sound production of field vegetables. | |
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