Modelling the growth and yield of choy sum (Brassica chinensis var. parachinensis) to include the effects of nitrogen and water stress
2014
Teh, C. B. S. | Kamarudin N. K. | Hawa Z. E. J.
The response of choy sum (Brassica chinensis var. parachinensis) to water and nitrogen (N) stress is still uncertain and no growth and yield model exists specifically for this crop. Consequently, this study conducted a field experiment to determine the growth and yield of choy sum grown under several watering frequencies and N application rates. Measured crop parameters were then used to aid in the crop model development and in model validation. Choy sum growing under the once-a-day and once-a-week watering treatments did not experience water stress unlike the water-stressed choy sum grown under the once-every-twoweeks watering treatment. The optimal volumetric soil water content level and N application rate for maximum yield were determined to be 40% and between 30 to 40 kg N ha-¹, respectively. Model validation showed that the choy sum model had an overall mean estimation error of 7.3% for leaves dry weight, 28.9% for stem dry weight, 28.9% for roots dry weight, 41.7% for leaf area index, and -0.8% for plant height. The model errors could be due to the assumption of an open-field energy balance growing environment and the lack of accuracy on the leaf area index estimation.
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