Effects of low nutrition on photosynthetic capacity and accumulation of total N and P in three climber plant species

To study the effects of low nutrition on pho tosynthetic capacity and accumulation of total nitrogen(N) and phosphorus(P) in three climber plant species Pharbitis nil(Linn.) Choisy, Lonicera japonica Thunb. and Parthenocissus tricuspidata(Sieb.et Zucc.) Planch, al climber plants were exposed to low nutrition at 6 levels(Hoagland solution as control, 1/2, 1/4, 1/8, 1/16 and 1/32 strength Hoagland solution) for 30 days. Photosynthetic capacity was determined by measuring leaf chlorophyl fluorescence, chlorophyll content, carbonic anhydrases activity and growth. Accumulation of total N and P was studied by measuring N and P content in plant tissues. Low nutrition decreased the photosynthetic capacity of P. nil while L. japonica maintained high photosynthetic capacity under low nutrition. Photosynthetic apparatus of P. tricu spidata suffered no damage when exposed to low nutrition L. japonica and P. tricuspidata had better adaptability to low nutrition than P. nil. With a faster growth rate, P. ni consumed more nutrition(N and P), and its growth was mainly affected by P deficiency under low nutrition Although L. japonica suffered damage from N and P deficiency simultaneously, but the nutrient deficiency was not serious except for 1/32-strength Hoagland solution P. tricuspidata grew slowly, so its requirement of N and Pwere the least, even if it was mainly affected by the P deficiency, it could still grow well under low nutrition.With the consideration of fertilizing N and P fertilizers in karst areas which were with lower N and P contents, plant species, N/P ratio threshold and low nutrition level should be taken into account synchronously. This study could provide a general consideration for the planning and developing low nutrition resistant plants and fertilizing the three climber plant species in the low nutrition environment.

To study the effects of low nutrition on pho- tosynthetic capacity and accumulation of total nitrogen （N） and phosphorus （P） in three climber plant species, Pharbitis nil （ Linn.） Choisy, Lonicera japonica Thunb. and Parthenocissus tricuspidata （Sieb.et Zucc.） Planch, all climber plants were exposed to low nutrition at 6 levels （Hoagland solution as control, 1/2, 1/4, 1/8, 1/16 and 1/32- strength Hoagland solution） for 30 days. Photosynthetic capacity was determined by measuring leaf chlorophyll fluorescence, chlorophyll content, carbonic anhydrases activity and growth. Accumulation of total N and P was studied by measuring N and P content in plant tissues. Low nutrition decreased the photosynthetic capacity of P. nil, while L. japonica maintained high photosynthetic capacity under low nutrition. Photosynthetic apparatus of P. tricu- spidata suffered no damage when exposed to low nutrition. L. japonica and P. tricuspidata had better adaptability to low nutrition than P. nil. With a faster growth rate, P. nil consumed more nutrition （N and P）, and its growth was mainly affected by P deficiency under low nutrition. Although L. japonica suffered damage from N and P deficiency simultaneously, but the nutrient deficiency was not serious except for 1/32-strength Hoagland solution. P. tricuspidata grew slowly, so its requirement of N and P were the least, even if it was mainly affected by the P deficiency, it could still grow well under low nutrition. With the consideration of fertilizing N and P fertilizers in karst areas which were with lower N and P contents, plant species, N/P ratio threshold and low nutrition level should be taken into account synchronously. This study could provide a general consideration for the planning and developing low nutrition resistant plants and fertilizing the three climber plant species in the low nutrition environment.