Effects of Molybdenum on the Intermediates of Chlorophyll Biosynthesis in Winter Wheat Cultivars Under Low Temperature

The objective was to probe the site where the biosynthesis of chlorophyll was blocked under Mo deficiency at low temperature, which led to the decrease of chlorophyll in winter wheat cultivars. The intermediates of chlorophyll biosynthesis were analyzed in winter wheat cultivars in soil culture, miniblock culture, and solution culture to study the effects of Mo on chlorophyll biosynthesis without Mo addition （CK, soil available Mo 0.112 mg kg^-1） and Mo addition （＋ Mo, 0.13 mg kg^-1 Mo was added）. Laevulinic acid （LA）, the competitive analog of δ-aminolaevulinic acid （ALA） was also introduced in the experiment. The ratio of Chl a/Chl b was constant between CK and ＋ Mo treatment, whereas it increased at low temperature, which indicated that Mo deficiency did not inhibit the transformation of Chl a to Chl b at low temperature. Under Mo deficiency, the contents of protochlorophyll （Pchl）, Mg-protoporphyrin Ⅸ （Mg-Proto Ⅸ）, protoporphyrin Ⅸ （proto IX）, and uroporphyrinogen Ⅲ （Uro Ⅲ） decreased [Uro Ⅲ decreased significantly （P 〈0.01）], whereas ALA and glutamate increased significantly （P 〈 0.01） compared with that of Mo addition, which suggested that the transformation from ALA to Uro Ⅲ might be inhibited. The content of ALA reversed after addition of LA, it was significantly higher （P 〈 0.01） in Mo addition than in CK. The results indicated that the transformation from ALA to Uro Ⅲ was blocked under Mo deficiency, which resulted in the inhibition of the biosynthesis of chlorophyll and led to the decrease of chlorophyll in winter wheat cultivars.

Different growing strategies of two winter wheat cultivars under rainfed conditions during dry years in North China Plain

The North China Plain(NCP)is a severe water shortage region,especially during the wheat growing season.Understanding the response of grain yield and water availability in winter wheat cultivars(Triticum aestivum L.)is important to adjust planting structure under groundwater reducible exploitation in rainfed dry years of NCP.Field experiments were conducted at the Luancheng Agroecosystem Experiment Station of the Chinese Academy of Sciences,Hebei,China.Two different drought resistant winter wheat cultivars(Jinmai47 and Shiluan02-1)were grown under rainfed conditions during four years of 2010-2011,2011-2012,2012-2013 and 2013-2014.Grain yield and its components,aboveground biomass(AB),dry matter accumulation translocation efficiency,water consumption,water use efficiency at field scale,and photosynthetic characteristics were measured.The results showed that Jinmai47 rapidly accumulated AB by higher tiller and photosynthetic potential comparing with those of Shiluan02-1.Its grain yield was 16.49%higher than that of the drought-sensitive winter wheat variety Shiluan02-1 during the four rainfed years.However,the dry matter remobilization efficiency(DMRE)and contribution of dry matter remobilization from heading stage to maturity stage to grain(CDMRE)of Shiluan02-1 was higher than those of Jinmai47.The average water use efficiency at grain yield level(WUEy),WUE at aboveground biomass level(WUEab),and WUE at grain yield under rainy conditions(WUEr)of Jinmai47 were 11.08%,16.41%,and 17.21%higher than those of Shiluan02-1.There was a significant difference in the WUEab and WUEr between the two wheat cultivars.The two wheat varieties under drought condition have different growing strategies.Jinmai47 has more tiller number,earlier vigor,and higher AB than Shiluan02-1,helping it to adapt to the fluctuations in the environment.