钵苗机插密度对不同穗型杂交籼稻生长和产量形成的影响

Effects of Density of Mechanically Transplanted Pot Seedlings on Growth and Yield of Hybrid Indica Rice with Different Panicle Types

【目的】探明钵苗机插密度对不同穗型杂交籼稻光合物质生产特性和产量形成的影响,为推广水稻钵苗机插高产栽培技术提供科学依据。【方法】以大穗型品种超优1000和穗粒兼顾型品种徽两优630为材料,设置4个钵苗机插密度处理(D_(1):33 cm×12 cm,D_(2):33 cm×14 cm,D_(3):33 cm×16 cm,D_(4):33 cm×18 cm),分析不同机插密度对水稻群体茎蘖消长动态、光合物质生产和产量形成的影响。【结果】(1)杂交籼稻主要生育期群体茎蘖数随栽插密度的降低而减少;与低密度处理相比,大穗型品种高密度处理的成穗率更高,穗粒兼顾型品种成穗率受机插密度影响较小。(2)各生育期叶面积指数随栽插密度的降低而下降,但叶面积衰减率降低、粒叶比增加。(3)随着机插密度的降低,水稻产量呈先增加后降低的趋势。(4)大穗型和穗粒兼顾型品种分别以D_(3)处理和D_(2)处理抽穗期群体质量较优,粒叶比大,叶面积衰减率低,抽穗后干物质积累量高,从而获得高产。(5)机插密度主要通过调控单位面积上的有效穗数和穗粒数影响产量。(6)水稻有效穗数随栽插密度的降低显著减少,而每穗粒数和着粒密度增加,结实率有所降低,千粒重受影响较小。【结论】钵苗机插配套栽培大穗型杂交籼稻品种宜适当降低栽插密度,在足穗基础上增加每穗粒数更有利于高产;穗粒兼顾型品种需协调单位面积穗数和穗粒数,以充分发挥其增产潜力。

【Objective】Effects of planting density applied by the mechanical transplantation of pot seedlings on grain formation and yield of hybrid indica rice with different panicle types were studied.【Method】A field experiment was carried out with 4 planting densities(i.e.,D_(1) at 33 cm×12 cm,D_(2) at 33 cm×14 cm,D_(3) at 33 cm×16 cm,and D_(4) at 33 cm×18 cm)by mechanical seedling transplantation.Seedlings of two indica rice cultivars with different panicle types,i.e.,the large panicle type Chaoyou 1000 and the medium panicle type Huiliangyou 630,were planted.Tiller growth and photosynthetic matter generation as well as the grain yield and yield traits of the rice plants were monitored for analysis.【Result】(1)The number of stems and tillers at critical growth periods of the rice plants declined as the seedling density decreased.The productive tillers decreased significantly for the large panicle type cultivars but relative stable for the medium panicle type.(2)The leaf area index at key growth stages and the rate of change declined with decreasing planting density resulting in an increased spikelet per unit leaf area.(3)Reduced seedling density raised the grain yield initially followed by a decline.(4)Under D_(2) or D_(3),both cultivars showed better overall quality and grain yield with larger spikelets per unit leaf area,lower decreasing rate of leaf area,and the highest dry matter accumulation at late growth stage than the other treatments.(5)Varied planting density affected grain yield basically due to the altered number of effective panicles and spikelets per panicle of the rice plants.And(6)Lower seedling density significantly reduced the number of panicles but increased the spikelets per panicle.However,no significant differences on the 1000-grain weight were observed among the treatments.【Conclusion】In applying mechanical means for pot seedlings transplantation,it would be advisable to properly reduce the density of the hybrid large panicles indica rice seedlings to increase the spikelets per panicle by allowing formation of ample panicles to maximize the grain yield.For the medium panicle type rice,on the other hand,combination of increasing panicles and spikelets per panicle by altering the planting density seemed necessary to achieve the full yield potential.