Nfluence Of Leaf And Silique Photosynthesis On Seeds Yield And Seed Soil Quality Of Oilseed Rape

Leaves and siliques of oilseed rape are respectively main photosynthetic organs at different growth stage. The objectives of this study were to systematically analyses and compare the differences between photosynthetic characteristic of leaves and siliques and dry matter accumulation regulation, and research the effects of leaves and siliques photosynthesis on grain yield and quality, and explore the relationship between yield and quality by measuring photosynthetic indexes of rape leaves and siliques and above-ground dry matter accumulation at reproductive growth period firstly, and then determining seed yield and quality under removing leaves at initial flowering stage and removing leaves or shading siliques at flowering ending stage. Field experiments were conducted in 2014-2015 at Hybrid Rapeseed Research Center of Shaanxi Province(Yang ling) with ‘Qinyou NO.7 ’(Brassica napus) as material. The main results are as follows:1. The photosynthetic pigment content, net photosynthetic rate and stomatal conductance of leaves was significant higher than siliques. The diurnal variations of net photosynthesis rate of oilseed rape leaves and siliques presented same trend bimodal curve and an obvious “midday break” phenomenon occurred. Leaves area was the maximum at full-bloom stage, and siliques shell area reached maximum level after flowering ending stage. In addition to, The main photosynthetic organ was leaves at initial flowering stage, then leaves and siliques were all main photosynthetic organs during the period from flowering ending to before filing, but after filing, the main photosynthetic organ was only siliques.2. Rape photosynthetic product mainly supplied for stem growth, inflorescence differentiation and young silique formation during progress from initial flowering stage to flowering ending stage. Then photosynthetic product mainly distributed to siliques and supplied for siliques growth quickly and grain formation during period from flowering ending to silique layer formation. After filing, photosynthetic product mainly transferred to grain and ensured grain yield and quality.3. Compare to CK, grain yield of per plant significantly decreased 15.08%, 34.13% and 86.03% under removing sessile leaves, removing short petiole leaves and removing all leaves at initial flowering stage respectively, moreover, grain oil content also decreased 1.18%, 2.75% and 10.71%. Besides, removing short petiole leaves at initial flowering stage significantly decreased siliques number and seed number per silique, but increased seed protein content. However, removing sessile leaves significantly reduced seed number per silique and erucic acid content, but increased cetylic acid content significantly.4. Compared to CK, removing leaves at flowering ending stage reduced grain yield by 15.86%, and significantly reduced seed number per silique, but there were all no significant effects on content of seed oil, seed protein and fatty acids composition. In addition, shading siliques at flowering ending stage reduced grain yield and seed oil content by 44.2% and 25.01% respectively, at same time, silique number, seed number per silique, 1000-seed weight, seed oil content and proportion of linolenic acid all decreased significantly. However, shading siliques significantly increased seed protein content and proportion of cetylic acid, stearic acid, oleic acid, arachidic acid and behenic acid.5. There was significant linear positive correlation between oilseed rape grain yield per plant with silique number or seed number per silique. With increase of silique number or seed number per silique, grain yield all rose up gradually. However, the relationship between oilseed rape grain yield per plant and 1000-seed weight presented very significant non-linear correlation trend. With 1000-seed weight rose up, grain yield increased firstly and then decreased.6. There was a very significant logarithm positive correlation between oilseed rape grain yield and seed oil content. With grain yield rose up, seed oil content increased quickly at first and then kept in a stable range. But the relationship between grain yield and seed glucosinolate content was very significant logarithm negative correlation. With seed yield increased, seed glucosinolate content decreased quickly at first and then also kept in a stable range. In addition, there were no significant relationship between proportion of fatty acids compositions and seed yield.Rape leaves area was the maximum at flowering stage, and the effects of short petiole leaves photosynthesis on seed yield and quality was higher than sessile leaves. After flowering ending stage, siliques shell area was the maximum, and the effects of siliques photosynthesis on seed yield and quality was higher than leaves. In addition to, leaves photosynthesis had greater influence on seed yield than siliques, but siliques photosynthesis had greater influence on seed quality than leaves. From these results, we can conclude that selecting variety which has big short petiole leaves area and siliques area is good choice when breeding high photosynthetic efficiency rapeseed varieties.