Thakur, AnirudhHarmanjeet Singh2017-12-202017-12-202017http://krishikosh.egranth.ac.in/handle/1/5810037945The present investigations entitled “Effect of photo-selective coverings on physiology and growth of citrus nursery plants under protected conditions” was carried out during 2016 -2017 in the Citrus Nursery, College Orchard, Department of Fruit Science, Punjab Agricultural University, Ludhiana. The effect of five photo-selective coverings viz. white, silver, green, red and stainless steel net house along with open (control) was studied on the growth of rough lemon and Carrizo citrange rootstock seedlings. Further, the effect of these shade nets house was also studied on Kinnow and Daisy mandarin plants budded on rough lemon and Carrizo citrange seedlings, respectively. The white shade net resulted in better seedling height of the rough lemon and Carrizo citrange seedlings as compared to the other growing conditions. In both rough lemon and Carrizo citrange rootstocks, the highest stem diameter was recorded under open conditions followed by red shade net house. In both the rootstocks, maximum improvement in growth attributes viz. leaf area, number of leaves per plant and root shoot ratio along with photosynthesis rate and stomatal conductance was recorded under red shade net house. In comparison to open conditions, lower maximum temperature, relative humidity and canopy temperature were recorded under the shade net houses during the hot summer months. However, maximum light intensity and PAR interception was recorded under open conditions. Leaves of rough lemon and Carrizo citrange show higher N, P and K content under red shade nets. In both the rootstocks, maximum proportion of buddable seedlings was recorded under open conditions. Highest budding success (86 and 68.67% in rough lemon and Carrizo citrange, respectively) was recorded under red shade net house followed by white shade net (83.67 and 62% in rough lemon and Carrizo citrange, respectively). The different growing conditions had no significant effect on the sprout length of Kinnow mandarin under different growing conditions. However, in Daisy mandarin the highest sprout length was observed under red shade net followed by green shade net and open conditions, respectively. It was concluded that white shade net proved to be better for increasing plant height of the citrus rootstocks followed by the red shade net. The improvement in photosynthesis rate, stomatal conductance and relative humidity; reductions in air and canopy temperatures demonstrates the potential of red shade net over the other shade nets and open conditions in citrus nursery production.ennullThesis