Light response of sunflower and canola as affected by plant density, plant genotype and N fertilization

The combined effect of planting density and sediment fertilization on survival, growth and physiology of eelgrass Zostera marina

We subjected shoots of eelgrass Zostera marina to different combinations of planting density [300 (control), 450, 600, 750, 900 shoots m^-2] and sediment fertilization [0 (control), 35, 70, 105, 140 g m^-2] for 6 weeks under controlled conditions. We measured eelgrass responses in terms of survivorship, growth, productivity, leaf pigmentation and carbohydrate concentrations. The ramet frequency of Z. marina reached 47.8 % when exposed to the combination of 600 shoots m^-2 and 70 g m^-2, which was 3.2 times higher than that of shoots under the control. Survival analysis combined with growth assessment suggested that the optimal ranges of planting density and sediment fertilization for the propagation of Z. marina shoots were 501 to 530 shoots m^-2 and 51 to 60 g m^-2, respectively. The promotion of survival and propagation of Z. marina that stemmed from planting density and sediment fertilization mainly depended on the increase of chlorophyll content and accumulation of non-structural carbohydrate. The total chlorophyll content of Z. marina leaves exposed to the combination of 600 shoots m^-2 and 70 g m^-2 was 2.1 times higher than that of shoots under the control. The results will provide data that could prove helpful in the development of efficient artificial propagation technology for Z. marina shoots.

Effect of Planting Density on the Growth and Yield of Sunflower under Mulched Drip Irrigation

A field experiment was conducted to test the suitability of growing sunflower undermulched drip irrigation with saline water in the HID (Hetao Irrigation District), North China. Theexperiment included five planting densities in which the plant spacing was 30, 35, 40, 45, and 50 cmwith the same spacing (50 cm) between rows. The results indicated that mulched drip irrigationwith saline water was more water‐saving than traditional ground irrigation using fresh water, whilethe irrigation quota increased with the increase of planting density. Little difference of soilsalinization was found for the treatments in the 50–100 cm soil layer, which indicated that additionalmeasures should be taken for salt balance with saline water irrigation. The height and leaf area index(LAI) of sunflower increased in response to the increase of plant density, and the head dry mattertransferred to the stem at plant densities higher than 47,619 plants/hm2. Though the grain weightand 1000‐seed weight decreased with increasing plant density, the achene yield and biomassproduction increased. This research suggests that a plant spacing of 35 cm with 50 cm of row spacingis more suitable for sunflower mulched drip irrigation with saline water at concentrations of 3.0g∙L−1.