Growth analysis using curve fitting method in early and late sown sunflower.

Effect of sowing time on productivity of sunflower was studied. Sunflower seeds were first sown in August (early) and the second sowing was done in September (late). Growth analysis was done at an interval of 5-6 days from germination to maturation. Growth was measured in terms of dry weight and leaf area. Various growth indices like RGR, RLGR, NAR, LAR, LWR, SLA, etc. were calculated. Cubic polynomial was the best fit for all the growth parameters. The dry matter accumulation, leaf area, leaf dry weight and leaf number were significantly more in late grown crop than early grown one. The rate of total dry weight, leaf area and leaf dry weight were higher in late grown crop as compared to early grown one. RGR, RLGR and NAR were higher in the late grown crop from the beginning, which gradually decreased later on, in both the crops. LAR was distinctly more in late grown crop between d 30-40. Changes in SLA were similar to LAR while LWR was more in the beginning and decreased afterwards. RGR showed more correlation with NAR and very low correlation with LAR in both the crops. Thus it is concluded that the late sown crop had better growth, but still, to obtain maximum productivity in sunflower, improvement in RGR and NAR is required.