Principal Investigator: Donald Siyeni, Chitedze Research Station, Department of Agricultural Research Services
Project Objective: The goal of this project is to assess the adaptability of 4 introduced hybrid sunflower varieties to agroecologies in Malawi. Successfully identifying adapted hybrid sunflower varieties can lead to greater sunflower production in Malawi by improving the availability of better adapted varieties to smallholder farmers.
Methods: Four varieties of sunflower--Tutti, SY 4045, PAN 7049, and PAN 7351--were planted at Chitedze Agricultural Research Station. Crops were planted at the beginning of the rainy season in mid-January 2015. During the course of the growing season, the stand count at harvest and the days to bloom and maturity were determined. At 12 weeks after planting (April 11, 2015), the MultispeQ was used to measure chlorophyll content (SPAD), and the efficiency of photosystem 2 (Phi 2), linear electron flux (LEF), photosynthetically active radiation (PAR), and non-photochemical quenching (NPQt). The PhotosynQ protocols used to measure these parameters were ‘Chlorophyll content (SPAD) I’ and ‘The One Protocol (Phi2, PSI, NPQ) II,’ respectively. In each plot, leaves from three different positions on the plant--upper, middle, and lower--were measured from six plants. At physiological maturity, sunflower was harvested and plant height, head diameter, head weight, seeds per head, seed weight, and seed yield were calculated for each plot.
The study was a complete randomized block design with 4 replicates. Analysis of variance was used to analyze the effects of variety on plant growth outcomes, crop yield, and plant health parameters. Mean separation was based on Fisher’s protected least significant difference and differences were considered significant at p ≤ 0.05. Linear regression analysis was used to determine the effects of PAR, Phi 2, LEF, NPQt, and SPAD on plant growth characteristics and yield and effects were considered significant at p ≤ 0.05.
Results: Two varieties, Tutti and SY 4045 had significantly shorter days to bloom and maturity and Tutti had greater seed size than the other three varieties (Table 1). Additionally, Tutti had significantly greater crop yields then PAN 7351 and greater SPAD than SY 4045, PAN 7049, and PAN 7351 (Fig. 1). SY 4045 had significantly greater NPQt than PAN 7049 but there were no significant differences in Phi2. Plant photosynthetic characteristics, as measured by the MultispeQ, were significantly correlated with plant growth (Table 2). Head diameter, seeds size, and sunflower yield were positively correlated with SPAD. Furthermore, head diameter was negatively correlated with NPQt.
Based on the results of this study, Tutti would appear to be the best adapted to the agroecological conditions at Chitedze Research Station. This is based both on better plant growth outcomes and plant photosynthetic characteristics. Another variety, SY 4045, while seeming to perform equally to Tutti in terms of plant growth outcomes, doesn’t appear to be as adapted to the agroecological conditions at Chitedze. This is due to significantly smaller seed size, and lower SPAD and higher NPQt value’s compared to Tutti. Under more stressed conditions, we expect that the differences in plant photosynthetic characteristics would result in a greater reductions in plant growth and yields in SY 4045 compared to Tutti.
The results presented here are from the first year of the study. In future years we hope to expand the use of the PhotosynQ platform to assess the adaptability of these sunflower varieties in other agroecologies in Malawi. Additionally, we hope to collect MultispeQ data sooner and more often during the growing season to improve the ability of the PhotosynQ platform to help us achieve our project goals.
