Nutritional quality of different potassium efficiency types of vegetable soybean as affected by potassium nutrition

Pot experiments were conducted in 2017, 2019, and 2020 to examine the effects of potassium nutrition on the nutritional components of vegetable soybeans with different K efficiency at immature and mature stages. Two vegetable soybean varieties with higher K efficiency and two varieties with lower K efficiency were studied in the low available K soil under the condition of no K and normal K fertilization. The results indicated that almost all nutritional components in vegetable soybean were affected by K, genotypes, inter-annual differences, and their interactions. In general, no K fertilization increased protein and amino acid concentrations but decreased oil, soluble sugar, sucrose, K, Mg, and Fe concentrations in immature and mature vegetable soybean. The sensitivity of nutritional components to K nutrition differed among varieties. For instance, K high-efficiency varieties generally exhibited higher protein and amino acid concentrations without K application. K high-efficiency vegetable soybeans are low-K tolerance varieties to isoflavones. The results of this study provide insights for high yield and quality vegetable soybean breeding against soil K deficiency.

Potassium nutrition in rice: A review

Potassium (K) is the most neglected nutrient in Indian agriculture and accounts only 10% of the total fertilizer use. The increased cropping intensity and use of high yielding cultivars since the green revolution led to heavy withdrawal of K from soil. Persistent K mining over the past six decades has mined soil K level in many cultivated areas and continuously transforming sufficiency into deficiency. A recent soil test a little over 1 lakh samples from 33 states of India have categorized 41.1%, 29.3%, and 29.5% of soil samples as low, medium and high in available K respectively. Further, the trend of soil available K status showed a persistent decline in percentage of area under high and medium soil K. Consequently, the evidence of rice crop responding to K nutrition is increased. This review attempts the nexus of K nutrition in rice for devising strategies for potassium management in rice-based cropping systems in the country.

Potassium nutrition as a strategy to mitigate salt stress in melon grown under protected cultivation

The use of saline water is one of the major challenges of agriculture, as it can cause nutritional imbalances and thus reduce crop yield. This study proposes to examine the efficiency of potassium nutrition as a salt stress-mitigating agent in melon grown in a protected environment. The experiment was laid out in a randomized-block design with ten treatments in a 2 × 4 factorial arrangement represented by two melon cultivars (McLaren and SV1044MF) and four nutrient solutions (S1 - standard nutrient solution, 2.5 dS m-1; S2 - nutrient solution salinized with NaCl, 5.0 dS m-1; S3 - nutrient solution salinized with NaCl + 50% K, 6.5 dS m-1; and S4 - nutrient solution salinized with NaCl + 100% K, 7.5 dS m-1). Yield (average fruit weight, production, fruit diameter, internal cavity, and pulp thickness), quality (pulp firmness, total sugars, soluble solids [SS], vitamin C, pH, titratable acidity [TA] and SS/TA ratio) and nutritional (K, Na and K/Na ratio) variables were evaluated. Plants fertigated with standard nutrient solution showed the highest values for fruit weight (1,190.6 g), production (2,381.3 g per plant), fruit diameter (13.6 cm) and pulp thickness (2.6 cm). Cultivar McLaren produced heavier fruits (931.4 g) with larger diameter (12.4 cm) and pulp thickness (2.4 cm). The addition of NaCl to nutrient solution induced a reduction in the yield variables but did not influence fruit quality. The addition of extra K to salinized nutrient solution did not mitigate the deleterious effect of salinity on the yield of melon.

Nitrogen, phosphorus and potassium nutrition on ornamental Ipomoea purpurea growth

O estudo objetivou avaliar o efeito de nitrogênio, fósforo e potássio no crescimento de I. purpurea. As plantas foram fertilizadas semanalmente com 50 mL de solução nutritiva modificada de Hoagland & Amon (1950): Nitrogênio com 0; 0,0888; 0,201; 0,6003 ou 1,801 g L-1 de nitrato de amônio; Fósforo com 0; 2,1; 5,5; 10,3 ou 13,5 mL L-1 de ácido fosfórico e Potássio com 0; 0,3728; 1,1183; 1,8638 ou 2,2065 g L-1 de cloreto de potássio. I. purpurea apresentaram alta demanda por N, que resultou em aumento da área foliar. A maior concentração de N promoveu investimento preferencial nas áreas fotossintéticas, confirmado pela relação folha/raiz. I. purpurea é responsiva a fertilização com fósforo, principalmente para promover o crescimento de caule e raízes. I. purpurea não respondeu à fertilização com K. Os resultados do estudo recomendam a fertilização com 0,2001 g L-1 de nitrato de amônio e 5,5 ml L-1 de ácido fosfórico no cultivo de I. purpurea.