Effects Of Red,Blue And White Light Qualities And Supplemental Light Duration On Growth Of Tomato Seedlings

Using LED(light-emitting-diode)as light sources,the effects of red,blue and white light qualities with different ratios(3R1B-CK,3R1B1 W,9R3B8W,3R1B6 W,3R1B16W and W)under the same light intensity on the morphogenesis,photosynthesis and later yield from tomato seedlings were studied.After that,the best ratio of light quality was selected as the supplemental light test of tomato seedlings under solar greenhouse in winter(Before opening the heat preservation quilt in the morning(08:30)and after covering the quilt in the afternoon(16:30).The daily supplemental light duration was 1,2,3 and 4 h,respectively)to ensure the differences among different light supplement durations.The main results are as follows:1.Compared with 3R1B(CK),treatment of 3R1B1 W could significantly increase stem diameter,leaf area,dry and fresh weight and root architecture parameters of tomato seedlings.There was no significant difference in these parameters between 9R3B8 W and CK,but these were lower in treatments of 3R1B6 W,3R1B16W and W than those in CK.Root activity for each treatment was lower than CK,except for 3R1B1 W,which was significantly higher than CK.Combination of red and blue light added by lower amount of white light could significantly increase the thickness of leaf palisade and sponge tissues,improve the PSII performance of the optical system,and enhance the net photosynthetic a nd transmission rate of photosynthetic electron,and the best ratio was 3R1B1 W.The activities of sucrose synthetase and sucrose phosphate synthase were highest in 3R1B1 W treatment,and there was no significant difference between 9R3B8 W and CK.2.Compared with 3R1B(CK),the first flower blooming time was significantly advanced under treatment of 9R3B8 W,followed by 3R1B1 W,but there was no significant difference among other treatments and CK.Treatment of 3R1B1 W increased the fruit setting rate of first flower significantly,followed by 9R3B8 W,but other treatments had no significant difference with CK.3R1B1 W,9R3B8W and 3R1B6 W increased the yield per plant evidently,followed by 3R1B16 W,it was the lowest under W.3.Compared with the nature light with no supplement(CK),supplementing light of tomato seedlings under solar greenhouse in winter significantly increased plant stem diameter,leaf area and dry and fresh weight,enhanced ratio of root to crown,parameters of root system configuration and root activity,as well as the PSII performance.Furthermore,this treatment could promote the growth of seedlings and was beneficial to produce strong seedlings,among which,the supplemental light duration of 4h was the best.