Effect of Nitrogen, Phosphorus and Variety on Physiological Indices and Nutrient Composition of Livingstone Potato (Plectranthus esculentus N.E.Br.) in Gombe, Northern Guinea Savannah, Nigeria

Plectranthus esculentus N.E.Br. locally known as “rizga” is an important indigenous tuber crop in Nigeria which is currently endangered. One major factor that causes disappearance of this species, is the lower agronomic recommendations developed for growers and lack of information about nutrient contents leading to loss of interest in its cultivation. A field experiment was therefore conducted during the 2016 and 2017 rainy seasons to determine the effect of nitrogen, phosphorus and variety on physiological indices as an attempt to conserve and evaluate the potential of the crop in food security, source of income and its adaptation in the Northern Guinea Savannah of Nigeria. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Treatments consisted four levels of nitrogen and phosphorus (­0, 60, 90 and 120 kg/ha), respectively and two varieties (vat Riyom and vat Loang’at). Results from analysis of variance showed that nitrogen and phosphorus applied at 90 kg/ha significantly produced higher physiological indices in both years. Beyond this rate, there was a decline in physiological indices resulting in decrease in starch content and dry matter accumulation. Harvest index indicated a positive relationship between the proportion of the biological yield and nutrient levels. Although, varietal difference was not significant on harvest index. This is an indication that HI is purely a genetic trait as affected by environmental factors. It was therefore concluded that, for high yield of livingstone potato, soils should be treated with a moderate application rate of 90 kg/ha nitrogen and phosphorus for enhanced physiological indices which are measures of growth and productivity per unit area of land in the Northern Guinea Savanna of Nigeria.

Detection of Above-Ground Physiological Indices of an Apple Rootstock Superior Line 12-2 with Improved Apple Replant Disease (ARD) Resistance

(1) Background: The cultivation of resistant rootstocks is an effective way to prevent ARD. (2) Methods: 12-2 (self-named), T337, and M26 were planted in replanted and sterilized soil. The aboveground physiological indices were determined. (3) Results: The plant heights and the stem thicknesses of T337 and M26 were significantly affected by ARD. Relative chlorophyll content (June–October), Pn (August–September), and Gs (August) of T337 and relative chlorophyll content (June–July, September), Pn (September–October), and Ci (September) of M26 were significantly affected by ARD. ARD had a significant effect on Fv/Fm (June), qP (June–July), and NPQ of T337 (June–October, except August) and Fv/Fm (June) and NPQ (June-October, except July) of M26. Additionally, ARD affected Rfd of M26 and T337 during August. SOD (August and October), POD (August–September), and CAT (July-August, October) activities and MDA (September–October) content of T338 as well as SOD (July–October), POD (June–October), and CAT (July-October) activities and MDA (July, September–October) content of M26 were significantly affected by ARD. ARD significantly reduced nitrogen (October), phosphorus (September–October), and zinc (July) contents of M26 and potassium (June) content of T337. The above physiological indices were not affected by ARD in 12-2. (4) Conclusions: 12-2 could be useful as an important rootstock to relieve ARD due to strong resistance.

Screening of Wheat (Triticum aestivum L.) Genotypes for Salt Tolerance on the Basis of Physiochemical Characteristics and Bio-Physiological Parameters and Indices

Salt stress is a major threat for growth and development of wheat crop. Screening technique for salinity tolerance is an effective tool to identify tolerant cultivar and high yielding wheat genotypes. Present study was carried out to screen twenty wheat genotypes under laboratory terms utilizing various growth and physiological indices like plant fresh weight stress indices (PFSI), plant height stress tolerance index (PHSI), shoot length stress tolerance index (SLSI), germination stress tolerance index (GSI), plant dry weight stress indices (PDSI), root length stress tolerance index (RLSI), relative water content (RWC). Multivariate techniques like cluster analysis and correlation were used to analyze the variance between wheat genotypes. The correlations analysis indicated significant among different physiological indices like GSI, SLSI, RLSI, PFSI, PDSI and RWC. On the basis of cluster analysis 20 wheat genotypes were classified into three clusters: first cluster included (The genotype WL-711 was the premier scorer followed by Nifa Bathoor, ARRI-II and Millat-11) presents sufficient salt tolerating degree, on the other hand, cluster-2 is comprised of wheat genotypes (Inqilab-91, NIAB-09, Punjab-96, Sehar-2006, Tatara, AS-2002, SA-75, Lasani-09, FSD-08 and Galaxy-13) with medium level of salt tolerance and cluster-3 included genotypes (LU-26-S, Fakhar e Sarhad, Bakhtawar, Punjab-11, Barsat and Kohistan-97) did not perform upto the mark and have lower level of salt tolerance. Correlation analysis among different screening techniques indicated that physiological indices exhibited highly significant and positive correlations among GSI, PHSI, SLSI, PDSI, PFSI, and RWC while non-significant correlation existed among PDSI and RLSI. The correlation between PFSI and RWC was significant. Significant correlations between cluster analysis and different indices also proved that salt tolerant wheat genotypes screened.