摘要
在新疆气候生态条件下 ,研究了种植密度对棉花 (Gossypiumhirsutum)群体光合作用、冠层结构和产量形成的影响 ,探讨了新疆棉花高产的生理机理及进一步提高产量的途径。结果表明 :群体光合速率在盛铃期以前随密度增加明显增强 ,盛铃期以后 ,低密度 6万株·hm-2 的群体光合速率仍为最低 ,高密度 30万株·hm-2 群体光合速率迅速下降 ,中密度 1 8万株·hm-2 则保持较高水平。叶面积指数的变化与群体光合速率的变化相似 ,其峰值出现在盛铃期。冠层结构各指标的变化表现为 ,随密度增加平均叶簇倾角变大 ,株型变紧凑 ,但密度过大 ,群体散射辐射与直射辐射透过系数小 ,冠层结构不良 ,造成生育后期群体光合速率较快下降。增加密度能增加单位面积总铃数 ,但密度过高削弱了棉株个体发育 ,生育后期群体光合速率下降早 ,造成单铃重降低。群体总光合物质累积与群体光合速率在各生育时期呈显著正相关 ,籽棉产量与群体光合速率仅在盛铃期和吐絮期呈显著正相关 ;生产上要实现棉花高产及超高产 ,应使棉花生育前期群体光合速率稳定上升 ,至盛铃期达到高峰值 ,吐絮期群体光合速率保持较高水平。
Cotton ( Gossypium hirsutum ) is an important crop in the Xinjiang Province in Northwest China, and high yields of high quality cotton can be produced under irrigation in the arid, continental climate of this region. In order to increase cotton yields in Xinjiang, we studied the effects of planting density (three treatments: 60 000 plants·hm -2 , 180 000 plants·hm -2 and 300 000 plants·hm -2 ) on canopy photosynthetic rate, canopy structure and yield formation in two cotton varieties, `Xinluzao 6' and `Xinluzao 7'. Our results showed that canopy photosynthetic rates increased with planting density before full boll stage. Canopy photosynthetic rates of `Xinluzao 6' and `Xinluzao 7' at a planting density of 300 000 plants·hm -2 were 29.58 μmol CO 2·m -2 ·s -1 and 26.16 μmol CO 2·m -2 ·s -1 respectively, which was 10.4% and 6.5% higher than that of the medium density treatment of 180 000 plant·hm -2 . In later growth periods after full boll stage, the canopy photosynthetic rate was maintained at a relatively high level in the medium density treatment, remained low in the low density treatment, but decreased rapidly in the high density treatment due to the decline of the leaf area index ( LAI ). LAI increased with planting density before full boll stage and attained maximum LAI at full boll stage. Generally, the canopy photosynthetic rate at each growth stage was significantly correlated with LAI ( R =0.935 *-0.998 *, n =5) except for the `Xinluzao 6' in later full boll stage. The mean foliage angle of inclination, an important index for describing canopy structure, increased with planting density, whereas two other indices of canopy structure, the canopy transmission coefficient for radiation penetration and canopy transmission coefficient for diffuse penetration, decreased with planting density.Very high planting densities negatively impacted the canopy structure, resulting in a rapid decline of canopy photosynthetic rate. The accumulation of colonial photosynthetic product increased with an increase in planting density during the growth period. In the high density treatment, colonial photosynthetic product accumulation of `Xinluzao 6' and `Xinluzao 7' was 13 700 kg·hm -2 and 13 153 kg·hm -2 , respectively, which was 1.5% and 2.0% higher than that of the medium density treatment, and 34.3% and 54.6% higher than that of the low density treatment. The allocation of photosynthetic product to flower buds and bolls was enhanced from full flower stage to later full boll stage in the medium and high density treatments. Total boll number per unit area increased with planting density. Weight per boll in the medium density planting was 5.61 g and 5.48 g in the two varieties, which was 2.6% and 11.5% heavier than in the high density treatment for the two varieties and 8.7% and 13.5% heavier than in the low density treatments. The canopy photosynthetic rate at full flower stage and boll opening stage were significantly correlated with lint yield. Therefore, the enhancement of the canopy photosynthetic rates during the full boll and opening boll stage could lead to increased of yields of lint.
出处
《植物生态学报》
CAS
CSCD
北大核心
2004年第2期164-171,共8页
Chinese Journal of Plant Ecology
基金
国家"十五"重大科技攻关项目 ( 2 0 0 1BA5 0 7A_0 4_0 1)
国家自然科学基金项目 ( 3 9960 0 3 7)
