Seedball technology counterbalances the effect of small seed-size and low soil nutrients on early pearl millet seedling performance

In the African Sahel region, pearl millet (Pennisetum glaucum (L). R. Brown) is often produced in low-nutrient soils. Seed weight could vary between 4 and 44 mg per seed. Evidence shows chemically infertile soil and small seed size significantly reduce seedling establishment and, in turn, cause low grain yield. Seedball technology can potentially counterbalance this effect. Therefore, the objective of this study was to investigate the influence of seedball on pearl millet seedling establishment. Conventionally sown and seedball-derived pearl millet seedlings of a local and an improved varieties were grown for 29 days from small and large seed sizes, in low- and medium-nutrient soils at a greenhouse of University of Hohenheim, Germany. Results showed that under low-nutrient conditions and with small seed sizes produced biomass was generally inferior to the other factor combinations. Seedball technology significantly enhanced seedling vigour, leaf number, plant height, dry matter, root length as well as fine root development, and nutrient uptake irrespective of soil nutrient level and seed size. These enhancement effects were more obvious in the local variety. A previous study revealed “early nutrient release in the seedling root zone” as seedball pearl millet seedling enhancement mechanism. The released nutrients presumably compensated for nutrient deficiency in low-nutrient soil and small seed seedlings. In the Sahelian pearl millet production system where (i) low soil nutrients, (ii) small seed sizes and (iii) local seed varieties are rampant, the application of the seedball technology under these conditions is proven effective for increased seedling vigour and is therefore recommended.

在非洲萨赫勒地区，珍珠粟（Pennisetum glaucum (L.) R. Brown）常种植于养分贫瘠的土壤中，其单粒种子重量介于4至44毫克之间。研究表明，土壤养分匮乏与种子粒型偏小会显著抑制幼苗建植，进而导致籽粒产量低下。种球包衣技术（seedball technology）有望抵消这一负面影响。因此，本研究旨在探究种球包衣技术对珍珠粟幼苗建植的影响。本研究选取本地品种与改良品种的珍珠粟，分别采用常规播种与种球包衣两种处理方式，使用大小两种粒型的种子，在德国霍恩海姆大学（University of Hohenheim）温室的低养分与中养分土壤中培养29天。实验结果显示，在低养分条件且使用小粒种子的情况下，植株生物量普遍劣于其他因素组合处理。种球包衣技术可显著提升幼苗活力、叶片数、株高、干物质积累量、根长以及细根发育水平与养分吸收效率，且该效果不受土壤养分水平与种子粒型的影响。该增效作用在本地品种中表现更为显著。此前有研究表明，“幼苗根区早期养分释放”是种球包衣技术促进珍珠粟幼苗生长的核心机制。释放的养分可有效弥补低养分土壤与小粒种子幼苗的养分匮乏问题。在萨赫勒地区普遍存在土壤养分匮乏、种子粒型偏小且种植本地品种的珍珠粟种植体系中，种球包衣技术在上述条件下的应用已被证实可有效提升幼苗活力，因此值得推广应用。