Alam Badre, Singh Rashmi, Chaturvedi Mayank, Newaj Ram, Chaturvedi O P
ICAR-Central Agroforestry Research Institute, Gwalior Road, Jhansi, Uttar Pradesh 284003 India.
Physiol Mol Biol Plants. 2018 Sep;24(5):985-992. doi: 10.1007/s12298-018-0537-0. Epub 2018 May 19.
Growth and physio-biochemical traits under different incident solar light intensities (100, 67, 50 and 25%) were studied in mustard in a semi-arid agroclimate region of Central India. Our comprehensive studies revealed that incident solar light intensities below about 67% were highly detrimental in mustard for its growth and grain yield. Major factors that contributed to the differential responses under varying light intensities were identified which holds importance for better understanding of low light adaptability in an important oilseed crop like mustard. Biomass index (ratio of dry biomass to height) has been established and evaluated for the differential growth performance of the crop under different light intensities. Biomass index progressively declined from 0.48 (open sunlight) to 0.11 (25% sunlight). Physio-biochemical factors were identified that were playing major role in manifestation of the differential growth and grain yield. Mustard exhibited its low light adaptive trends through differential down-regulation in the rates of net CO assimilation (P), stomatal conductance, transpiration, thylakoid electron transport rate (ETR) and leaf wax level. For example, P decreased from 35.88 (open light) to 11.64 µmol m s (25% sunlight). Photochemical events showed critical impact as evidenced by decreased PSII quantum yield, photochemical quenching (qP) and higher non-photochemical quenching (qN) that were clearly associated with physiological efficiency of the plants under varying light intensities. Leaf wax level decreased from 1.69 mg g fresh weight (open light) to 0.96 mg g fresh weight (25% sunlight). Our results indicated that limited ETR supply across photosystem II (PSII) decreased the photochemical efficiency and carbon gain under low light which resulted in reduction of biomass index and grain yield. Besides, it was found that overexpression of protein band around ~ 26 kDa in low light could be another adaptive feature for mustard related to light harvesting complex. Our findings would augment selection of traits for optimizing growth and grain yield of mustard for low light or light limiting agro-ecosystem.
在印度中部半干旱农业气候区，对芥菜在不同入射太阳光强度（100%、67%、50%和25%）下的生长及生理生化特性进行了研究。我们的综合研究表明，入射太阳光强度低于约67%时，对芥菜的生长和籽粒产量极为不利。确定了导致不同光照强度下产生差异响应的主要因素，这对于更好地理解像芥菜这样重要的油料作物的弱光适应性具有重要意义。已建立并评估了生物量指数（干生物量与株高之比），以衡量作物在不同光照强度下的差异生长表现。生物量指数从0.48（全日照）逐渐降至0.11（25%日照）。确定了在差异生长和籽粒产量表现中起主要作用的生理生化因素。芥菜通过净CO₂同化率（P）、气孔导度、蒸腾作用、类囊体电子传递速率（ETR）和叶蜡水平的差异下调表现出其弱光适应趋势。例如，P从35.88（全日照）降至11.64 μmol m⁻² s⁻¹（25%日照）。光化学事件显示出关键影响，PSII量子产率、光化学猝灭（qP）降低以及非光化学猝灭（qN）升高证明了这一点，这些显然与不同光照强度下植物的生理效率相关。叶蜡水平从1.69 mg g⁻¹鲜重（全日照）降至0.96 mg g⁻¹鲜重（25%日照）。我们的结果表明，光系统II（PSII）上有限的ETR供应降低了弱光下的光化学效率和碳同化，导致生物量指数和籽粒产量降低。此外，发现弱光下约26 kDa左右蛋白条带的过表达可能是芥菜与光捕获复合体相关的另一个适应特征。我们的研究结果将有助于为优化弱光或光照受限农业生态系统中芥菜的生长和籽粒产量选择相关性状。
