Optimization Of Rational Close Transplanting For Rice Based On Golden Section And Its Verification

The objective of this study was to explore the characteristics of growth development, dry matter accumulation, yield formation and yield components of double cropping rice grown under different transplanting densities which was quantified through the golden section method. Culm height of Xiangzaoxian24, Lingliangyou286, Xiangwanxian12, Fengyuanyou299were were51.5,60.0,64.2,71.1cm, respectively. Yuxiangyouzhan was74.1,84.2cm. Yliangyou1was69.7cm,84.0cm. Golden section method was presented for determining the transplanting densities:D1(67.9hills hm-2), D2(40.1hills hm-2), D3(26.5hills hm-2), D4(18.8hills hm-2), D5(14.0hills hm-2), D6(10.8hills hm-2), which depended on the culm height:50cm,65cm,80cm,95cm,110cm,125cm. Field experiments were conducted in two major rice-growing provinces in China in2011and2012. The experimental sites were located in Huaiji and Changsha of Guangdong and Hunan provinces, respectively. Xiangzaoxian24, Lingliangyou286and Xiangwanxian12, Fengyuanyou299were grown under early season and late season in Changsha, respectively. Yuxiangyouzhan and Yliangyou1were grown under double cropping season of Huaiji. The treatments were arranged in randomized block design with three replications. Grain yield, yield components, dry matter accumulation and N, P, K uptake amount of plants were determined at maturity. Growth analysis were conducted at key growth stages to determine tiller dynamic, Panicle-beaning tiller rate, heading dynamic, uniformity of rice panicle layer, leaf length, leaf width, highly effective leaf area index, amount of photosynthetically active radiation (PAR) interception. The results were showed as following:(1) The rational transplanting densities of Xiangzaoxian24, Lingliangyou268and Xiangwanxian12are401～679millions hills per hectare. Fengyuanyou299, late rice Yuxiangyouzhan and Yliangyou1are265～401millions hills per hectare. Early rice Yuxiangyouzhan and Yliangyou1are188～265millions hills per hectare.(2) Productive tillers dates and full heading stages were ahead under rational transplanting densities which were not only to the benefit of improving uniformity of tillers and heading, but also increasing significantly productive tillers per m2.Meanwhile, it was not significantly different of panicle-bearing tiller rate between rational close transplanting and sparse transplanting. Productive tillers dates of the others treatments have been delayed2～17days comparing with D1, full heading dates1-4days comparing with D1and D2. (3) Rational close transplanting could ensure basic seedlings sufficiently, and attained higher highly efficient leaf area index (2.40-4.96) in Changsha site, in the same time, improved the amount of photosynthetically active radiation (PAR) interception (82.49～96.73%).(4) The biomass of full heading stage and maturity and N, P, K uptake amount of maturity increased with increasing transplanting density, the former differences were significant. However, the percentage of biomass from full heading stage to maturity decreaseed insignificantly under different transplanting densities.(5) Grain yield of all cultivars have been improved significantly, except for Yuxiangyouzhan, Yliangyou1in late season in2011and Yuxiangyouzhan in early season in2012with increasing transplanting density. The panicles per m2were the primary components of grain yield in this study, and have also been improved significantly, in which the treatment D1have gained the highest grain yield and the lowest was D6. On the contrary, number of spikelets per panicle has been decreased significantly with adding transplanting density. There were no consistent variation in spikelet filling and1000-grain weight for the reasons cultivars and seasons among different transplanting densities.Therefore, rational transplanting densities determined by the golden section method can gain higher grain yield for suitable seedlings, stable panicle-bearing tiller rate, and much more biomass in full heading stage, higher highly efficient leaf area index, and more amount of photosynthetically active radiation (PAR) interception after anthesis, sufficient panicles per m2, and greatly coordinating grain yield with components.