Sabyasachi Mitra

Start codon targeted (SCoT) polymorphism reveals genetic diversity in wild and domesticated populations of ramie (Boehmeria nivea L. Gaudich.), a premium textile fiber producing species

Twenty-four start codon targeted (SCoT) markers were used to assess genetic diversity and population structure of indigenous, introduced and domesticated ramie (Boehmeria nivea L. Gaudich.). A total of 155 genotypes from five populations were investigated for SCoT polymorphism, which produced 136 amplicons with 87.5% polymorphism. Polymorphism information content and resolving power of the SCoT markers were 0.69 and 3.22, respectively. The Indian ramie populations exhibited high SCoT polymorphism (> 50%), high genetic differentiation (GST = 0.27) and moderate gene flow (Nm = 1.34). Analysis of molecular variance identified significant differences for genetic polymorphism among the populations explaining 13.1% of the total variation. The domesticated population exhibited higher genetic polymorphism and heterozygosity compared to natural populations. Cluster analysis supported population genetic analysis and suggested close association between introduced and domesticated genotypes. The present study shows effectiveness of employing SCoT markers in a cross pollinated heterozygous species like Boehmeria, and would be useful for further studies in population genetics, conservation genetics and cultivar improvement.

INTERACTION EFFECT OF POTASSIUM AND SULFUR FERTILIZATION ON PRODUCTIVITY AND MINERAL NUTRITION OF SUNNHEMP

The interactive effect of potassium (K) and sulfur (S) fertilization on productivity and mineral nutrition of sunnhemp (Crotalaria juncea L.) was evaluated in a field experiment during 2008 and 2009 cropping seasons at Uttar Pradesh, India. Potassium and sulfur fertilizers increased fiber yield and nutrient uptake of sunnhemp. It was observed that an application of K and S at 40 kg ha−1 each significantly increased the total dry matter, fiber yield, and nutrient uptake of sunnhemp. The crop yield response to the added S was greater than for K and the nutrient use efficiency was also higher at lower levels of fertilizer addition. The increased levels of K and S improved the number of nodules and crude protein content of sunnhemp leaves.

Effect of weed management practices on productivity and profitability of jute fibre

A field experiment was conducted at Kendrapara, Odisha to find out suitable and cost effective weed management practices for jute. Different doses of pre-emergence butachlor (both liquid and granule formulation) and post-emergence (quizalofop-ethyl) herbicides followed by (fb) one hand weeding (HW) were tested in jute crop and the treatment effects were compared with unweeded and two hand weeding treatments. Application of quizalofop-ethyl 60 g/ha at 20 days after crop emergence (DAE) followed by one HW at 15-20 days after herbicide application recorded higher weed control efficiency (78.3%), plant height (351 cm), basal diameter (1.40 cm) and fiber yield (2.9 t/ha) of jute as well as higher B:C ratio (2.13) compared to other weed control treatments. Values of the said parameters recorded with the quizalofopethyl treatment were statistically at par with those recorded with two hand weeding. Butachlor 1.5 kg/ha fb one HW at 20 DAE was the next best treatment with respect to weed control efficiency (68.7%), plant height (341.0 cm), basal diameter (1.39 cm), fibre yield (2.64 t/ha), and B:C ratio (1.99). Thus application of pre-emergence herbicide butachlor 1.5 kg/ha or post-emergence herbicide quizalofop-ethyl 60 g/ha in combination with one manual weeding may be recommended to the jute growers as more effective and economic weed control practices compared to the existing manual weeding practice.