Nitrogen reduction combined with organic materials is an important measure to achieve or even increase crop yield retention at the background of fertilizer reduction. We conducted a pot experiment to explore the effects of nitrogen reduction combined with organic materials on yield, photosynthetic characteristics, and product quality of agricultural products of maize-cabbage rotation system in yellow soil area of Guizhou. There were five treatments, including no fertilizer (CK), conventional fertilizer (CF), nitrogen reduction (20%, the same below) combined with biochar (RF+B), nitrogen reduction combined with rapeseed cake (RF+O), and nitrogen reduction combined with both biochar and rapeseed cake (RF+BO). Leaf photosynthetic characteristics were measured in maize (seedling stage, jointing stage, heading stage, and mature stage) and cabbage (seedling stage, growing stage and harvest stage). The biological characters, yield and quality indices were investigated in the harvest period. Compared with CF, RF+BO significantly enhanced the yield of corn and cabbage by 9.7% and 39.2%, respectively, while RF+O had no effect, and RF+B did not affet maize yield. RF+BO improved the biological properties of maize and cabbage, including the 100-kernel weight of maize, and plant height, maximum leaf length and total biomass of cabbage. Furthermore, the green holding period and high photosynthetic duration of maize and cabbage were prolonged, among which, maize leaf SPAD was increased respectively by 42.7%, 11.0%, 12.8%, and 30.3% at seedling, jointing, heading, and mature stages, the cabbage leaf SPAD was increased by 13.5%, 9.2%, and 30.3% in seedling, growing and harvest stages, respectively. The net photosynthetic rate (Pn) of maize was increased by 11.1%, 10.9%, and 119.8% in seedling, jointing, and mature stages, while that of cabbage was increased by 12.7% and 14.6% in growing and harvest stages, respectively. The stomatal conductance (gs) of maize was increased by 58.3% and 41.7% in jointing and harvest stages, while that of cabbage was increased by 10%, 64.7%, and 19.2% in seedling, growing, and harvest stages, respectively. The transpiration rate (Tr) of maize was increased by 55.0%, 10.6%, 14.0%, and 143.9% in seedling, jointing, heading, and mature stages, respectively, while that of cabbage was increased by 26.1% in growing stage. The nutritional quality of maize and cabbage was significantly improved. The contents of reducing sugar, starch, and crude protein in maize were increased by 16.2%, 3.5% and 20.3%. The contents of Vc, amino acid, and reducing sugar in cabbage were increased by 26.3%, 21.0% and 27.8%, separately. In conclusion, 20% nitrogen reduction combined with biochar and rapeseed cake had positive effects on crop growth, yield increase, green retention period, high photosynthetic duration, and agricultural product quality improvement in Guizhou yellow soil maize-cabbage rotation system, the overall effect of which was the best. Nitrogen reduction combined with single organic material overally did not affect crop yield, photosynthetic characteristics, and quality.
减氮配施有机物料是实现农作物减肥不减产甚至增产的重要措施之一。为了探究减氮配施有机物料对贵州黄壤区玉米-白菜轮作系统作物产量、光合特性和农产品品质的影响,本研究采用盆栽试验,以玉米和白菜作为供试作物,研究了不施肥(CK)、常规化肥(CF)、减氮(20%)配施生物炭(RF+B)、减氮配施菜籽饼(RF+O)、减氮配施生物炭和菜籽饼(RF+BO)处理,对玉米苗期、拔节期、抽穗期、成熟期和白菜苗期、生长期、收获期植株叶片光合特性、生物性状、产量和品质的影响。结果表明: 与CF处理相比,RF+BO处理显著增加了玉米和白菜产量,增幅分别为9.7%和39.2%,RF+O处理对玉米和白菜产量的影响不显著,RF+B处理玉米增产不明显。RF+BO处理改善了玉米和白菜的生物性状,显著提升了玉米百粒重和白菜的株高、最大叶长、总生物量;延长了玉米和白菜持绿期及高光合持续时间,其中,玉米苗期、拔节期、抽穗期和成熟期叶片SPAD值分别增加42.7%、11.0%、12.8%和30.2%,白菜苗期、生长期和收获期叶片SPAD值分别增加13.5%、9.2%和12.5%;玉米苗期、抽穗期和成熟期的净光合速率(Pn)分别增加11.1%、10.9%和119.8%,白菜生长期和收获期的Pn分别提高12.7%和14.6%;玉米抽穗期和收获期的气孔导度(gs)分别增加58.3%和41.7%,白菜苗期、生长期和收获期的gs分别增加10%、64.7%和19.2%;玉米苗期、拔节期、抽穗期和成熟期的蒸腾速率(Tr)分别增加55.0%、10.6%、14.0%和143.9%,白菜生长期的Tr增加26.1%。同时,玉米和白菜的营养品质明显改善,玉米籽粒还原糖、淀粉和粗蛋白含量分别提高16.2%、3.5%和20.3%,白菜Vc、氨基酸和还原糖含量分别提高26.3%、21.0%和27.8%。这说明本试验条件下,减氮20%配施生物炭和菜籽饼组合对贵州黄壤玉米-白菜轮作系统的作物生长、产量提升、持绿期和高光合持续时间的延长、农产品品质改良均有积极效应,总体上在所有处理中提升效果最佳。减氮下单一配施有机物料对作物产量、光合和品质的整体影响不明显。.